carbs and fuel pumps
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Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Tue Jul 14, 2020 1:26 pm quote
It is close but that temperature thing is a problem that will catch you out one day.

Here's something to try. The very bottom is too rich causing mid to be weak. Reduce the pilot jet until you need to go richer one clip on the needle. Adjust main to suit.

Timing is 18 so unlikely to be an issue at 55mph. Jetting is the issue.

Power jet carbs are really for engines that rev very high as to avoid using multiple taper needles. This carb will jet in. For most it was probably done a long time ago. For me they have to be like factory smooth or they're no good.
Getting there.
Addicted
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1003
Location: Rochester, Minnesota
Tue Jul 14, 2020 3:52 pm quote
hibbert wrote:
Wow Christopher that might be a rabbit hole I don't want to go down. Not totally against the idea but darn just got the carb dialed in. I'm running an old PHBH 30 BD with the adjustment screws on the wrong side. Not sure where temps are going to fall but the carb seems tuned better than ever in the last 23 years.
I like the phbh, I have one in a 70cc scooter.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Wed Jul 15, 2020 2:29 pm quote
Been a fan of the PHB's since...

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Addicted
2007 Stella 150
Joined: 02 Nov 2019
Posts: 1003
Location: Rochester, Minnesota
Wed Jul 15, 2020 3:13 pm quote
What year was that picture?
Enthusiast
px244gs, cosa221LX, sprint177, gilera runner 180, triumph tiger 955
Joined: 09 Sep 2013
Posts: 61
Location: vienna/austria (the other one, w/o kangaroos)
Wed Jul 15, 2020 11:21 pm quote
hibbert wrote:
New float seems to solve emptying float bowl issue.
it cant solve it sustainable.

Why not using a fuel pump?
Only with a pump a vespa engine with a big carb will be on the safe side: for sure TOO MUCH fuel instead of always close to or already in starvation.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Thu Jul 16, 2020 5:39 am quote
those photo's probably 1988 got the PHBL24 in 86.

Hi freakmoped the new float helped with the levels in the float bowl I had an older float that required setting the height which I didn't set up properly. The new float was fixed I just had to install as is. This along with a new diaphragm in the fuel pump, an increase in the float valve and a spark plug tip in the return line the fuel pump seems to be working good.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Fri Jul 17, 2020 10:32 am quote
Raised needle to clip 3 oh my gosh. Wow think it was a good move. Seems like more power all around temperature is not spiking and I'm just beginning to feel 4th gear making power beyond 55mph now that temperature is under control. Wow never felt it hitting the power band with so much to go in 4th like this before.

Haven't made any other adjustments and didn't need to it's not four stroking and seems to have filled a flat spot in the mid range. Going to give it some miles and see.

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Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Fri Jul 17, 2020 1:09 pm quote
Now that's more like it. If you can hold half throttle and stay under 300F that's the clip done.

Pilot jet at 62 is probably too big. Main jet probably too small. Riding around a while will get both set. On this carb best to fine tune the pilot first.

It really should be quite quick. With the tuning done, I fully expect it to do easy 75mph on the freeway. Possibly more than you will want to do on it.

With that port timing and a real expansion exhaust (pipedesign) the power band would be even more interesting but sure it's the best it ever went since you had the long hair.

Once you trust it at high speed it will be a lot of fun.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sat Jul 18, 2020 2:39 pm quote
Would have not thought of raising the needle Jack.

It keeps getting better. Dropped pilot to 60 and increased main jet to 150 back in the BGM main jet pack I question where the OG 148MJ fails in sequence to the BGM pack. One observation as the tune improves so does slow speed drive-ability not always about the top speed, could be a sign of age. Fourth gear has never had this much torque.

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Scooter Speed

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Servetta Jet 200 1979

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Performer Jet 200

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2 miles on odometer

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Sun Jul 19, 2020 1:57 am quote
I like low speed drivability too. So many tuners have a bad habit of making the bottom end rich and ruining the drivability for no reason.

How many turns on the mix screw with 60 pilot? Need to have more than 2 turns. 2.5 is ideal.

How is the temperature on sustained 55mph cruise? Would expect just less than 300F holding steady.

If you get a chance do a riding video and I can hear if there are any issues. Very near to done by what you're saying.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Thu Jul 23, 2020 2:12 pm quote
Changed the pilot from 60 to 58 taped phone to leggy and went for ride.

Idle is too fast in video. Later adjusted air fuel from 2 to 2-1/2 and turned out throttle stop 1-1/2 turns which dropped the idle beat to acceptable. Seems to have better pick up feels 'lighter' and 'deeper' at the same time.

Temps seem great up to 55mph just passing 1/2 throttle and under 300F. When I go more see an increase up to 325F and 60mph. It's not climbing like it was before. When I hammer it see it spike into the 350's as power is applied.

At 11:50 I do a low speed 3rd gear WOT pull to about 55mph. Listening it sounds like it might have a little more in it on the saddle it's run about out.

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Fri Jul 24, 2020 8:55 am quote
This is a cold start after making the pilot change and adjustment to the air fuel and throttle stop. Pilot 58 2-1/2 turns on air fuel AS264 atomiser X3 needle clip #3 150 main jet.

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Fri Jul 24, 2020 10:20 am quote
Very useful. I think your needle is still too low. Go to clip 4. And up the main jet to 155.

All sounds lean as you ride. Should only be 280F at half throttle. And creeping up to 325F should only happen on the freeway when pinned at WOT for many miles.

Pilot is good at 58 by the sounds of it. 2.5 turns gives better progression. Tickover should be as slow as possible while holding the clutch in.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Fri Jul 24, 2020 2:35 pm quote
Ran more tests first raised needle to clip #4 it ran OK. Increased main jet to 155 ran OK might have detected a mid range sputter in 1st gear. Overall it felt slower at making power needed more throttle maybe less vibration maybe temps slightly down.

Went to 160MJ sputtering now in 3rd and 4th past 1/2 throttle no longer making clean power.

Back to 155MJ + lowered needle back to #3 feels better. Picked up a grommet at the auto parts to fill the gap in the spark cap.

Temperature might still be an issue not sure. Don't think it's an issue in 1st-3rd gears no fear in those. Seems like the temperature in 4th begins to drop once in the power band. Problem is street too short and balls too small.

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Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Fri Jul 24, 2020 10:44 pm quote
Sounds like clip 4 is too much. Get a half washer for the needle. You can go to clip 3.5 then.

https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/vhsa-vhsb-vhsc-parts/needle-washer/

Go on the freeway to test 4th. Doesn't feel as fast there.

Running lean is faster but engine wear is much higher. If you can hold stable temperature at under 325F over a long distance , then it will last.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sat Jul 25, 2020 7:20 am quote
Thanks will get the 1/2 washer and maybe a few other things.

Put some denim trousers on, riding jacket, gloves, helmet sunglasses and onto the 605. At 55 it is perfect just a little past my 1/2 throttle mark and at 300F steady.

Anything past this temperature changes with speed. At 57 and above the needle can go up to 350 and bounce. The needle is never stable above 300.

When going at incline temp goes up as power demands. On a downward not much but where gravity is pulling engine faster temps drop to 300 when above 55 but as you get past 60 start to climb again.

Did two 2 mile runs exit to exit then a longer 5 mile stretch and a final 3 mile. When the temps reached 350 and I got nervous closing throttle to 55 again dropped temps immediately. Idle was excellent coming off freeway. Came home pulled plug. Looks totally different now rim gone pale.

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this is 55mph and 300 or beyond 55 bouncing up to 350

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hot plug after 15 miles on fwy

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hot plug after 15 miles on fwy

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Sat Jul 25, 2020 8:26 am quote
Well done. This plug looks more like how I hear it run. Too lean.

Whatever plug that is, go one number less. Not running hot enough. The plug not the engine.

I think the half clip will do it at 3.5. Does need a bigger main jet but just 152. Where is the timing?

If you put on clip 3 and ram a second circlip under the clip 3 circlip, it will work until you get the washer.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sat Jul 25, 2020 8:34 am quote
This is a BR8ES will pick up a BR7ES.

Timing is at 18.

In the meantime while waiting on the 1/2 washer will try the hotter plug and a few more main jets.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sun Jul 26, 2020 11:52 am quote
Put in a B7 and 160MJ. Seems better more top end less vibration temp same.

Then 165MJ and 170. Felt it begin to break up not a complete sputter but struggling in 3rd & 4th at WOT on the 170. No longer making clean power at WOT. Perhaps a burst of power when closing throttle in 4th at WOT on the 165MJ.

Not noticing much change in temp with main jet. Pretty much like clockwork anything above 55 temp goes from a stable 300 to a fluctuating 325-350 on my analog VDO gauge. On the other hand it doesn't go past 350 like it had done before. Shift to 4th at 45 WOT temp dives below 300 making beautiful power at 55 needle begins to move as power builds.

Pilot seems good now no matter how hard or casual I drive the idle returns perfectly. Struggled with this before it's so nice to have the scooter idle on it's own. Starts great hot or cold. When at idle it's a sleeper.

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25 miles on B7 and final 170MJ

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25 miles on B7 and final 170MJ

Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sun Jul 26, 2020 1:53 pm quote
one side of the plug is darker
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Sun Jul 26, 2020 11:13 pm quote
Really is close now. The B7 plug looks so much better. The plug is at an angle, one sided is a good sign it's closer.
Pilot sounding like done. Main at 160 makes me happier. This is more like it. Just need to get the mid temperature down and 3.5 clip should do that.

The 4th gear getting to 350F and no more is still acceptable. Is not ideal but it is ok. Clip 3.5 will reduce this a bit as well as the mid.
Your gauge might not be so accurate, maybe check it with a cheap battery one.
If temperature is real, could drop the timing but as said a while back, I think you need a newer style cylinder head.
I would say it's perfectly usable as it is and plenty of fun.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sun Jul 26, 2020 11:41 pm quote
Thanks for the feedback just wondering about the B7 plug was surprised to get that much color in just 25 miles but can you point out how it looks better.

Going to the 264 atomizer must have brought us back up to a larger main. Wanted to say the 160MJ felt best but it was also first ride and better than before.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Mon Jul 27, 2020 1:37 am quote
It doesn't have lumps all over it because they burnt off and black/darker on the flat. To check the main jet it's read at the bottom of the cone after a long WOT run in any gear. Can just hold it wide in 3rd for a mile. Same result. Can't over rev a two stroke. This is your next step to confirm if the 160 is the one.

When changing anything in a carb other parts are affected. Changing to the 264 made all positions above 1/8 throttle leaner.

Will no one lend you a newer Malossi head to test?
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Wed Aug 05, 2020 12:20 pm quote
Took a long 70 mile ride to pick up a tag on the 160MJ and X3 needle clip 3. Hot and bothered again took some freeway home. I do not like riding on the freeway. Coming off freeway idle was slow and heavy. Kept temp at 300 which kept speed just below 55. Above 55 temp bounces between 325-350. It was 90F this day.

Received my Eurocarb order and popped in the 1/2 washer and clip at 3 1/2 now. Dropped pilot to 55 and still on 160MJ. Seems better has better mid range power and it's moving up to 60 easier and feels better. The feels better part is the engine performance improved to the point it feels safe going faster. Had a slight WOT sputter in 2nd. 1/4-3/4 throttle in 4th feels excellent. Temperature hasn't changed much but it feels better. Need to do some miles and see.

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BR7ES plug 160MJ X3 needle clip 3 58 pilot

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BR7ES plug 160MJ X3 needle clip 3 58 pilot

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Thu Aug 06, 2020 1:18 am quote
At 3.5 clip if the low and mid feel better and cruise holds 300F, it's good enough. With the higher clip WOT may need to go down one size. If 160 was correct before 158 or 155 may now be correct. There should be no splutter at WOT. Reduce until there is no splutter in the gears.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Thu Aug 06, 2020 6:24 am quote
Thanks Jack need to ride some more to understand the sputter it felt like when the engine is cold and not a complete burn.

When engine is HOT idle can become very slow. Think dropping pilot to 55 might have improved some at the bottom and pick-up. Maybe 55 still be too big?
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Thu Aug 06, 2020 6:41 am quote
How many turns out is the mixture screw, when starting from a long way out and turning it in until it runs fastest?

Should always be set up for a hot engine. I always adjust mixture screws during a long run to ensure its fully hot.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Thu Aug 06, 2020 7:07 am quote
mixture is at 2 1/2 and nearly impossible to adjust while scooter is running because screw is on wrong side.

Plug looked a little bumpy on the rim with 60 pilot.
Ossessionato
1963 VBB2T
Joined: 07 Nov 2012
Posts: 2249

Sat Sep 12, 2020 9:25 am quote
Wow this was interesting to read, nice work guys.
Is this carb the same setup as a CV carb, CV carbs were always the best performance maker when I was messing around dialing in the big bike.
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