Sun Nov 08, 2020 9:32 am

Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
 
Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
Sun Nov 08, 2020 9:32 am linkquote
haha thats what i was expecting... its a pancake of tire mount, tractor light mount and tractor light.

I kinda want one of those!
Sun Nov 08, 2020 9:33 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Sun Nov 08, 2020 9:33 am linkquote
reminds me of a bed pan
Sun Nov 08, 2020 10:14 am

Ossessionato
79 P200E, 62 Allstate, 2008 Stella
Joined: 11 Jan 2006
Posts: 2165
Location: Florence, OR
 
Ossessionato
79 P200E, 62 Allstate, 2008 Stella
Joined: 11 Jan 2006
Posts: 2165
Location: Florence, OR
Sun Nov 08, 2020 10:14 am linkquote
hibbert wrote:
reminds me of a bed pan
Heh heh... Thanks for the pics. It is pretty cool....
Mon Nov 09, 2020 3:43 am

Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1744
Location: Rochester, Minnesota
 
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1744
Location: Rochester, Minnesota
Mon Nov 09, 2020 3:43 am linkquote
hibbert wrote:
Ok but tractor light
I like tractor lights for some reason. This could be my next spare with light. The tire holder would cover up the holes from the light I took off.
Mon Nov 16, 2020 12:30 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Mon Nov 16, 2020 12:30 pm linkquote
If I could get out of my own way I may get the Bajaj dialed in and tuned.

Stepping down the main jet is difficult for me. Dropped the main from 125 to 122 after changing to a BE5 atomiser and had been riding it around for a week or so. It was better less chunky but not perfect. Still something missing when cruising, closing the throttle and opening. Took it for a hundred mile spin for SWARM5 and took the Arroyo Parkway home again at 55mph. It felt OK but maybe too much vibration sensing something wasn't good enough.

Dropped the main again to 120. Oh my gosh different scooter. Changed like atomiser maybe better. Face hurts from smiling. Still something missing on the bottom so I broached the 52-160 pilot I made to 165. Hoping this alteration would be easily felt either right or wrong. Seems to be right. The 120MJ took out a major amount of vibration at higher RPM and made the scooter extremely more responsive throughout. I'm still smiling. The increase in pilot seems to have smoothed out the lack of response when opening and closing throttle. It sounds better when closed as well. Tried to see if the engine is quieter, think it might be in low speed, it just purrs along effortlessly now. Other thing scooter drives easier barely any throttle needed.

Think the game changer is the increase in float bowl passage to 2.0mm. At least seems like that was where the roadblock was in my set up. The raised float bowl did not seem to improve and may have added some unwanted variables.


SWARM5


2nd gear WOT chop
52-165 pilot
2 1/2 turn air fuel mix
120AC BE5 120MJ
BR7HS spark plug


2nd gear WOT chop
52-165 pilot
2 1/2 turn air fuel mix
120AC BE5 120MJ
BR7HS spark plug

Mon Nov 16, 2020 1:19 pm

Hooked
2005 Stella 2T
Joined: 14 Jun 2020
Posts: 127
Location: MA
 
Hooked
2005 Stella 2T
Joined: 14 Jun 2020
Posts: 127
Location: MA
Mon Nov 16, 2020 1:19 pm linkquote
hibbert wrote:
Stepping down the main jet is difficult for me. Dropped the main from 125 to 122 after changing to a BE5 atomiser and had been riding it around for a week or so. It was better less chunky but not perfect. Still something missing when cruising, closing the throttle and opening. Took it for a hundred mile spin for SWARM5 and took the Arroyo Parkway home again at 55mph. It felt OK but maybe too much vibration sensing something wasn't good enough.

Dropped the main again to 120. Oh my gosh different scooter. Changed like atomiser maybe better. Face hurts from smiling. Still something missing on the bottom so I broached the 52-160 pilot I made to 165. Hoping this alteration would be easily felt either right or wrong. Seems to be right. The 120MJ took out a major amount of vibration at higher RPM and made the scooter extremely more responsive throughout. I'm still smiling. The increase in pilot seems to have smoothed out the lack of response when opening and closing throttle. It sounds better when closed as well. Tried to see if the engine is quieter, think it might be in low speed, it just purrs along effortlessly now. Other thing scooter drives easier barely any throttle needed.
Just had a similar experience myself. MJ120 was harsh at mid-rpms (no tach but guessing 4-6K) and then smoothed out again approaching WOT. Changed to MJ118 and now the motor is smooth as silk from 1/3 throttle on. Still chasing some low-rpm bogging though. Need some warmer weather before I can tackle that, but at least now I know the mainstack isn't drowning out the pilot jet circuit.
Mon Nov 16, 2020 1:54 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Mon Nov 16, 2020 1:54 pm linkquote
Keep at it Kowalski it is rewarding.

I am having one issue not sure about. When I do my plug chops in 2nd gear sometimes it will break up at the end. It's always in a higher RPM than I typically drive it. Not sure it is carburetion though almost feels like ignition. It's embarrassing when this happens on my street and have to "go again" and shut it down before breakup.

The chops aren't looking as clean as expected either so maybe there is still more leaning to be done.






2nd gear WOT chop
52-165 pilot
2 1/2 turn air fuel mix
120AC BE5 120MJ
BR7HS spark plug

Mon Nov 16, 2020 4:02 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Mon Nov 16, 2020 4:02 pm linkquote
If you have a BE4 you should try it now. Not that it might be better but to be sure it's worse. Although it might be better.

Guess if you ride it like this forever it would be fine but sounds like a few tweaks from perfection.

Igntion issues can cause a WOT rich feeling. Need to be really sure it's just jetting.
Tue Nov 17, 2020 9:52 am

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
Tue Nov 17, 2020 9:52 am linkquote
Hebert
Curious - how are you running your "chops" before you are showing the plug?
Plug can be deceiving if you are idling or driving slower before you pull it as you get an "averaging" of throttle positions.
Generally - it looks quite good to me.
The ceramic is not sooty like after your SWARM ride - and you can feel and hear it really singing now.

The issue with it breaking up at the top - any chance you are running the float bowl dry? That can also give the symptoms you are describing.
Do you have a fast flow fuel tap on this build?
Tue Nov 17, 2020 9:55 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Tue Nov 17, 2020 9:55 am linkquote
Got some test results. Popped in a BE4 and went for a ride. Seems rich all around a little 4 stroking off the line cleans up then sputter in high RPM. Didn't take long to analyze.

Dropped the BE5 back in and dropped the pilot to 50-160, wanting to see if the low rev issue would return but it seems to be good.

Gave the Chetak a good wring out and had break up again in high RPM. It's feeling almost like ignition, or misfire not exactly a backfire. Looked over my notes and remembered similar behavior when I was walking down the MJ on the BE3 so thought it could be a different symptom of richness maybe a different spectrum moving towards the need to be just a little leaner side? It's not sputter. Lately the scooter drives so good gotten used to driving more causal not pushing the envelope.

Nervously dropped the main jet to 118. Again less vibration good performance not as big of a jump from 122 to 120 but scooter wants to go faster and rides better. Can still create some breakup if riding above normal RPM range. I pulled it past 65 today and vibration felt like 40 and engine does not feel like it is getting tired. Now that the vibrations are going away higher speed is beginning to feel safer.




2nd gear WOT chop
50-160 pilot
2 1/2 turn air fuel mix
120AC BE5 118MJ
BR7HS spark plug


2nd gear WOT chop
50-160 pilot
2 1/2 turn air fuel mix
120AC BE5 118MJ
BR7HS spark plug


2nd gear WOT chop
50-160 pilot
2 1/2 turn air fuel mix
120AC BE5 118MJ
BR7HS spark plug

Tue Nov 17, 2020 10:12 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Tue Nov 17, 2020 10:12 am linkquote
Good points Charlie maybe my descriptions will uncover what is really going on. Or I may need to make a video. Could be jetting still not sure.

When I do a plug chop I will shift into 2nd then go WOT let the engine reach maximum RPM then hit the kill switch and pull the clutch leaving throttle open. Coast into driveway pull plug and photo.

Not sure about float bowl emptying maybe. Seems when I reduced the MJ to 118 break up occurs later or higher RPM and less of it. Also remember this behavior when I walked down the main jet on the BE3 after having reduced the pilot.

Another thing might be crank float? I can see the flywheel push out when revved and sink back in.
Tue Nov 17, 2020 10:18 am

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
Tue Nov 17, 2020 10:18 am linkquote
^What fuel tap?
Stock or fast flow?

Plug read method seems pretty good.
Maybe a little better read with more load if possible in my experience - i.e. 3rd up hill.

Your 118 is using a bit less fuel.
If you are running dry at WOT - it might lessen with smaller main like that.
Of course it could be something else...
Tue Nov 17, 2020 10:26 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Tue Nov 17, 2020 10:26 am linkquote
charlieman22 wrote:
^What fuel tap?
Stock or fast flow?

FAST FLOW

Plug read method seems pretty good.
Maybe a little better read with more load if possible in my experience - i.e. 3rd up hill.

AGREED

Your 118 is using a bit less fuel.
If you are running dry at WOT - it might lessen with smaller main like that.
Of course it could be something else...
Same conclusion or lack of

If I hold the throttle open on the stand it will break up at XRPM right before it sounds like lift off past the power band not sure its running out of gas.
Tue Nov 17, 2020 1:12 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Tue Nov 17, 2020 1:12 pm linkquote
Not sure you gave the BE4 a proper go. When richening the atomiser the main jet needs to be a few sizes smaller. As BE5 is not bad at 118 and the plug chop still looks not lean, the BE4 could probably go to 115 before WOT starts to run clean.

Fuel tap is ok as it is. When it's an issue there is no doubt.
Tue Nov 17, 2020 1:27 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Tue Nov 17, 2020 1:27 pm linkquote
You're right only gave BE4 2 miles. Thought it was more of an exercise than to try and make it work.

Seized on 115MJ BE4 and 52-120 pilot according to my notes 3 miles at 60mph on the freeway coming home from Charliemans.
Tue Nov 17, 2020 3:54 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Tue Nov 17, 2020 3:54 pm linkquote
May have had a fouled plug.

Dropped MJ to 116 and still would NOT rev out on stand. Seemed ignition cut out.

Got to thinking remember this occurring before after significant changes to the jetting. This might be the 3rd or 4th time same symptom.

Put in a fresh BR8HS that I had revs clean again on stand. 118MJ back in for test ride tomorrow.
Tue Nov 17, 2020 9:22 pm

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
Tue Nov 17, 2020 9:22 pm linkquote
Quote:
Seized on 115MJ BE4 and 52-120 pilot according to my notes 3 miles at 60mph on the freeway coming home from Charliemans.
Was that with the carb drilled to 2mm?
Wed Nov 18, 2020 3:07 am

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Posts: 2813
Location: London UK
Wed Nov 18, 2020 3:07 am linkquote
Is great keeping notes. Could turn out to be a good save. As CM1 said, drilling 2mm would make a difference here. Was the drilling after the seize?

If BE4 115MJ is a seize, then BE5 118MJ is about the same. With the new spark plug, up jet to splutter point again and work down. Always good to check. Can't be too careful here.
Wed Nov 18, 2020 6:50 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Wed Nov 18, 2020 6:50 am linkquote
seized before drilling carb should be richer now.
Thu Jan 07, 2021 4:34 pm

Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1744
Location: Rochester, Minnesota
 
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1744
Location: Rochester, Minnesota
Thu Jan 07, 2021 4:34 pm linkquote
How is finding parts for the Bajaj Chetak, looking at a 1981? There is one for sale locally, 4000 miles price has been marked down to $1000.00. Been for sale for a few months.
Fri Jan 08, 2021 7:52 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Fri Jan 08, 2021 7:52 am linkquote
The Bajaj chetak is basically a Vespa 150 2 port engine the cylinder mating surface has more meat than some Vespa's and easy to add 3rd port without additional modification.

Overall fit and finish is not equal to Piaggio. Seems heavier, mine weighs 420 pounds with me (180) and a full tank. A bit a of clumsier ride but improved with better tires and shocks.

Engine part wise would not be concerned everything available. Special parts would be chassis items like headset, glovebox that might be more difficult to source from India.
Mon Jan 11, 2021 8:23 pm

Ossessionato
79 P200E, 62 Allstate, 2008 Stella
Joined: 11 Jan 2006
Posts: 2165
Location: Florence, OR
 
Ossessionato
79 P200E, 62 Allstate, 2008 Stella
Joined: 11 Jan 2006
Posts: 2165
Location: Florence, OR
Mon Jan 11, 2021 8:23 pm linkquote
hibbert wrote:
Special parts would be chassis items like headset, glovebox that might be more difficult to source from India.
I love the Bajaj glovebox - it's HUGE!
Thu Jan 28, 2021 3:19 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Thu Jan 28, 2021 3:19 pm linkquote
Update for 2021. Decided the BE5 atomiser might not be right so started over again with the BE4. Regular driving on the streets I could get a good tune and plug read. When I'd put the scooter on the highway or longer WOT stretches things began to look different and not good. Things felt good and great but plug would show detonation residue so I forced myself again to go rich and walk it back down again. In that process I also walked the pilot down in order to clean up the bottom. Went through a few custom pilots that I drilled to allow for more aire which seems to be the call on my carb set up with T5 air filter that covers the pilot jet. Seems to like jets with 160 minimum on the aire.

Current set up with 24e 120 air corrector BE4 mixer 130 main jet 42-160 pilot jet air fuel set 2 3/4 turns.

Ordered spark plugs from the auto supply. Received NGK 6715 solid terminal type for marine and motorcycle. Plug is heavier I like them.




120AC-BE4-122MJ


120AC-BE4-128MJ














120AC-BE4-130MJ
42-160 pilot


120AC-BE4-130MJ
42-160 pilot



Last edited by hibbert on Thu Jan 28, 2021 3:38 pm; edited 1 time in total
Thu Jan 28, 2021 3:37 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Thu Jan 28, 2021 3:37 pm linkquote
For the science they are nice pepper pictures. Hopefully piston is still ok for a while.

When this happens the issue is probably more timing than jetting. Where did you leave yours set?
Thu Jan 28, 2021 3:50 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Thu Jan 28, 2021 3:50 pm linkquote
Dang it I was wondering what I was doing. BE4 feels good but am concerned now at the bottom end on the pilot.

The timing was at 17 or 18 I think is what was recommended. What should be checked now.

Thank you
Thu Jan 28, 2021 4:08 pm

Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
 
Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
Thu Jan 28, 2021 4:08 pm linkquote
Man I feel for you.. you've been plugging away at this for a long time! The last photos look good but Jack is the expert and his timing suggestions sound right. Looks like when my timing was too advanced and seized.

Your piston is earning its keep at this point!
Thu Jan 28, 2021 4:19 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Thu Jan 28, 2021 4:19 pm linkquote
17 or 18 is typical for a Pinasco. However yours is not the usual Pinasco anymore.

Timing should be set as needed and yours needs to be less. 2 degrees retarded from wherever it is. And start jetting again.


Edit: To expand on that flippant statement. Timing requirement is determined by cubic capacity, fuel grade, head profile, squish size/angle/turbulence/clearance, compression, port timing, cooling capability, exhaust.....pretty much every characteristic of the top end.
Manufacturers state what the timing should be if just bolted on, with everything as laid out in their instructions. If you grind lumps out of the ports, fit a different head and use tighter tolerances, then, the timing requirement will be different. Riding it and testing is the best way.
Exactly what you are doing now.
Sat Jan 30, 2021 7:28 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Sat Jan 30, 2021 7:28 pm linkquote
Feeling a little defeated but dang-it still willing. Took a few degree's away today only using the strobe light to confirm the move.

On test ride scooter seemed pretty good maybe better in the mid range, wasn't expecting that but when it reached 60 it broke up or began to sputter. Jack must be right needing jetting after ignition change. After a few tries could not get engine to run above 60 or RPM@60 and above it would break up and stop firing successfully.

Thinking it might be rich sputter dropped main jet from 130 to 125. Seems like maybe some of the misbehavior is gone but not 100%. Seems like plug is fouled can go WOT in lower RPM engine pulls fine no sputter but still can not run above 60 or it breaks up. Beginning to determine maybe break up is ignition/rpm related and not rich sputter based on throttle positions & RPM experiment. Getting up to 60 mph feels good enough maybe better not sure but something else wrong now.

New plug in break up seems like it might be gone. Scooter runs OK but seems like more vibration now in high RPM. Maybe 125 is too small now ignition is working again. The plug just retired looks good but no will longer run above 60mph.

Home after 8 thrash miles on fresh plug and it looks like a sphere or two of piston melt or carbon?


Timing set at 18 BTDC


Timing adjusted to 16 BTDC


Fouled Spark Plug
AC120-BE4-125MJ
42-160 pilot


AC120-BE4-125MJ
42-160 pilot
Timing 16BTDC


AC120-BE4-125MJ
42-160 pilot
Timing 16BTDC

Sun Jan 31, 2021 1:07 am

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Sun Jan 31, 2021 1:07 am linkquote
There are 5 degrees between the A and IT marks. Would guess you are now at 14 degrees.

When it won't rev or missfires at WOT it's usually way way too lean. White plug and seriously hot looking electrode might confirm that. When changing the timing, it's safest if jetting starts from zero, right back to the beginning. Go full flood out to be sure it's nothing else but way too rich and work down.
Sun Jan 31, 2021 6:02 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Sun Jan 31, 2021 6:02 am linkquote
Jack221 wrote:
There are 5 degrees between the A and IT marks. Would guess you are now at 14 degrees.

When it won't rev or missfires at WOT it's usually way way too lean. White plug and seriously hot looking electrode might confirm that. When changing the timing, it's safest if jetting starts from zero, right back to the beginning. Go full flood out to be sure it's nothing else but way too rich and work down.
Good to know is 14 degrees ok for now or does this need more.

Wondering if we're still having fuel delivery issues. Can get scooter tuned perfectly to 60 mph but something changes there.

Was feeling a sense of fuel starvation in addition to missfire when the scooter was cutting out at 60. When back off throttle would recover open again to WOT would wind up fine then breakup when reach X RPM come back on then off on and off unless close throttle to a recovery point.

Maybe need to increase the float passage more?
Sun Jan 31, 2021 7:48 am

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Sun Jan 31, 2021 7:48 am linkquote
Take out the main jet and have a ride with just the atomiser and air corrector. If there is a fuel delivery issue it's going to be very obvious as soon as you get the rpm up.

14 degrees might be not enough. Leave it there for now and see if this jets in as it is.
Thu Mar 25, 2021 5:44 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Thu Mar 25, 2021 5:44 pm linkquote
Time for an update and request wisdom from the universe. Tried to run the air corrector and mixer without the main jet but it does not screw in.

Added a little more time on the ignition put it half way between A and IT maybe it is at 16 now.

Could not get the low end to run clean with the BE4 mixer and going down to a 40-160~ pilot.

Went back to a BE5 mixer, a 130 main jet seems to run clean with a 45-160 pilot. Was getting sputter with 132 main and larger. Fouled plugs, have fouled more plugs on this project than any other perhaps rich jetting?

Still seemed like top end wasn't happy like maybe starvation on extended runs similar to when fuel pump went out on my P200. Ordered a hand drill mandrel and broached the carb float passage again. 2.0mm drill went deeper to the bottom and more junk came out on the drill. The reverse solid side of the drill slides easily into the bore now. Having the control of the hand mandrel made things easy compared to the 3/8" drill motor I used before. Also drilled the banjo to 3/16" and opened up some of the fuel entry seems better.

Running a BR7HS at the moment it's all I had on hand maybe too hot? Still feels a tad rich on the bottom.








BR7HS spark plug
120AC-BE5-130MJ
45-160 pilot
2 1/2 air fuel


BR7HS spark plug
120AC-BE5-130MJ
45-160 pilot
2 1/2 air fuel



Thu Mar 25, 2021 6:18 pm

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
Thu Mar 25, 2021 6:18 pm linkquote
Plug looks a little hot based on where the color break is.
Personally - I would move to an 8.
I can never read new plugs - they all look like grandma's nether regions.
Much easier to read change of color - if you let it get fully colored first.

Carb drill issue is significant.
Were you able to make splutter with oversized MJ before/ now?
With improved carb hole - you should probably now go back to ensure you are on right MJ.
I would put your tuning on a 118 - 122 range if carb is drilled sufficiently not to neck down flow - but that is just a guess.

CM
Thu Mar 25, 2021 7:16 pm

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Thu Mar 25, 2021 7:16 pm linkquote
Good points Charlieman. Began decreasing the pilot to clean up the low end and got down to a 40 before deciding the BE4 was too much. But in going down on the pilot I noticed the carbon build up on the rim was going away even with mileage plugs.

Fairly certain a 132 pre and post carb re-drill causes sputter. What I thought I was feeling was possible starvation on longer 4th gear runs in the 60mph range.

Going to drop back to a B8 plug and see. I fouled a plug giving WOT in a low RPM situation which makes me think main jet might be rich. Also low end could be cleaner. Tried a 42-160 and went back up to 45-160.
Thu Mar 25, 2021 7:23 pm

Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
 
Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
Thu Mar 25, 2021 7:23 pm linkquote
Are you sure you aren't mistaking idle leanness as richness?

Both of those idle jets you are talking about are very very lean.

Edit: Possibly you are going extra rich on main to compensate for really lean idle based on how it responds at the crossover point to your mj changes. The seesaw seems unbalanced.

Last edited by swiss1939 on Thu Mar 25, 2021 7:41 pm; edited 2 times in total
Thu Mar 25, 2021 7:35 pm

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
Thu Mar 25, 2021 7:35 pm linkquote
I'd go up to the 8 based on burn line.
Then get that main right.
Then pilot.
Swiss could be right on lean pilot.
Wondered about the non fully colored rim.
Sounds like you have same suspicions.
Agreed if that has remained after use - might be lean down low.

One thing for sure.
If you did not have the hole all the way drilled - then drilling it fully now will have an effect.
If you find that you are moving all the way down to the low 120's then its a sign your hole was not allowing the flow.
Thu Mar 25, 2021 7:55 pm

Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
 
Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 3177
Location: Staten Island, NY
Thu Mar 25, 2021 7:55 pm linkquote
I have a feeling cm22 is probably close with his mj thoughts. You are on a 130 mj with an air filter. I'm at 128mj with no air filters at all, and i might even be slightly rich at 128. Just seems all your jetting "weight" is on the mj and none on the idle if thinking of it as a scale where you are trying to find balance between them.

Just confirming.. you are on a 24/24 carb right? And the bajaj is a reed or rotary valve engine? If rotary, wouldn't that also equate to even more rich mj compared to reed valve engine no air filter at 128mj same AC.

Edit: this could possibly explain why you couldn't get a be4 to work, it's making the mj even more rich going from be5 to be4. But you were dealing with a richening of the middle range with that switch while the idle has been lean all along, and having similar symptoms but for opposite reasons right next to each other in both the low end and middle ranges. A stock rotary valve 150 uses a 55/160 idle, and you have long stroke crank and increased cc which i would assume needs a richer than 55/160 idle, but you are currently on a much leaner idle on top of the extra cc.
Thu Mar 25, 2021 11:41 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2813
Location: London UK
Thu Mar 25, 2021 11:41 pm linkquote
All points covered I think. Strobe the timing to check where it is. As usual the timing mark says 20 degrees plus or minus 5 degrees, like is normal. Exactly on 18 degrees is fine for now.

Pilot jet should be 45/140 at the smallest. It is conceivable that BE5 is correct. If you can now see the back of the drill bit down the stack hole, then it's all good. Hole should be over 2.0mm and less than 2.5mm. Any smaller and the main jet gets too big.

If you get splutter at WOT there is no starvation issue.
Sun Mar 28, 2021 10:39 am

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
 
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1298
Location: California
Sun Mar 28, 2021 10:39 am linkquote
Thanks universe still tinkering. Decided to test the latest recipe and go back up into elevation to see if the increase in mixer helped with the surging I was having on decel.

For starters now on a BE5 instead of BE3. Have ruled out the richer BE4.

Main jet is now a 130 from 125. Pilot is 45-160 instead of 48-165.

In steep incline lost power and torque in 4th and had to shift to 3rd much sooner than expected. On the previous trip up was able to use 4th gear most of the way. This time not so but was able to use it if could get 3rd above 40mph. Once I felt the optimum tried to keep it there but soon 4rd began to fade and sputter at about 3,000 ft and had to stick with 3rd. Finally 3rd began to sputter maybe above 4,500. Decided not to risk fouling and began decent. Previously was able to reach 6,000ft in fourth gear.

Think the BE5 is good it feels great no hiccups. Maybe 130 is too much but seems to be great for city work. With confidence of it being wealthy I took it up to 65-70 and no solder balls on the plug which is good. Dam it is fast. I like it but it won't work in the hills like this.

The photo of the stator in previous report was in error this one is where it's at. Put in a fresh BR8HS solid terminal.


maybe 16 degrees


BR8HS
120-BE5-130MJ
45-160 pilot 2 3/4 turn air fuel


BR8HS
120-BE5-130MJ
45-160 pilot 2 3/4 turn air fuel


Angeles National Forest

Sun Mar 28, 2021 11:30 am

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
 
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2315
Location: california
Sun Mar 28, 2021 11:30 am linkquote
Surge on deceleration is generally too lean on pilot end.
next time you are in a situation where you get that - just go richer on pilot to convince yourself.
You can turn surge on and off with pilot richness basically.

Plug looks like you are running rich on main to me.
Of course - I'm not sure when you pulled it - so its a mix - but if it was shortly after the climbing - then that dark would suggest main rich along with your experience of power loss.

I suspect you are 4-6 points high on your main - but just a suspicion.
Perhaps run that hill again with a bit smaller jet and have a look at plug when you get to the top.
It will certainly take on an average color from being under load like that for the entire climb.
Perhaps you can sneak into the browns and away from the charcoals.
Should be telling.
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