carbs and fuel pumps
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Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
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Wed Mar 18, 2020 8:05 pm quote
Took a long time to start but started and sounds strong.

Jetting is still a way out so wouldn't ride it just yet.

Needle should be X3. That X4 is too weak, as you can see by how you can get near full throttle on the stand before any break up. If it is X3 and you just made a typo then you'll need some more needles.

With a more correct needle the pilot jet will be too big. Your carb has a mixture screw so can be in quite a way before needing to drop the jet. I would aim for over 2 turns out when finally done but for now it doesn't matter so much.

Do the same with the X3 and see how much better is feels.

Last edited by Jack221 on Wed Mar 18, 2020 9:16 pm; edited 1 time in total
Molto Verboso
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Wed Mar 18, 2020 8:42 pm quote
Good I didn't change the needle to X3 it was still X4.

Do you think the AS266 is good?
Jet Eye Master
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Wed Mar 18, 2020 9:15 pm quote
Try the X3 first. AS266 is probably too small but the X3 is thinner diameter.

Don't spend too much time on the pilot jet, when its rich enough at the top that will change.

You need to mark the throttle grip, so you know where it is. I use Tippex as it can be easily removed when done.

With the X3 hold at 1/4 throttle on the stand and see how it feels.
Molto Verboso
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Sat Mar 21, 2020 6:46 pm quote
WOW scooter is waking up X3 needle in and AS268 atomizer, it needed it, pilot is down to 46 air fuel is at 2 1/4. Needle is at clip 4 bottom position.

Did not know you can drive scooter with no main jet WOW. With X3 needle and 268 atomizer things are feeling much better. With clip in position 3 scooter can run pretty good to 3/4 throttle and begin to sputter. On the stand it breaks up maybe past 3/4 . If at 1/4 throttle engine revs to heaven and have to close throttle. If not moved past 1/4 fast enough engine revs to heaven and won't sputter. If rotated fast enough can get sputter at WOT. Tested in position 2 as well also with 266 atomiser.

Clip in bottom position 4 and 1/4 throttle scooter still revs to heaven but breaks up earlier the 1/4 throttle part might feel better than position 3. On test drive scooter breaks up much sooner than on stand maybe just past 1/2 throttle and earlier compared to clip 3.

Do I need a 270 atomizer?

On the head temp what should I expect seems like things are good around 300 but get sketchy around 350.
Jet Eye Master
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Sat Mar 21, 2020 7:47 pm quote
Seems like after 26 years she is waking up. Hope you're finally having fun together.

X3 and 268 would seem like they are not too far out. That was sort of the upper limit of what I was thinking. With a 246 needle that's quite strong. Scooter will be a handful. This is good.

You sure the float height is good and you sorted the float opening issue? Float should hang right down and when lifted must stop no more than 24mm from the carb body.

If float height is fine the clip should be set when riding between 1/4 and half throttle. Like 3/8. Whatever clip runs best here is the one. If this is clip 3 you don't need the 270, if its clip 4 then you do.

On the stand holding at any position will rev to the moon but is a fair test and listening to the right noises and a good bit of experience, can get the jetting quite close.

When riding the no main jet break up point should be before 3/4. Lets see how that goes.

Temperature should be controlled to stay around 300 for now. If going beyond this before you know the jetting is good puts you in serious detonation risk (naming no names, we've all been there). Where did you set the static timing?

Already good progress. When the pilot jet starts getting smaller its close.
Molto Verboso
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Sun Mar 22, 2020 1:53 am quote
Thanks Jack the float drop was adjusted to 25mm fuel raises and reduces this dimension. The float was at 30mm when I started.

The scooter feels better on the stand on clip 4 but better on the road at clip 3. Feels as if clip 4 had a main jet it might be better and better than clip 3?

Will get a AS270.

What size main are you thinking the largest I have is 147 will we need more?
Jet Eye Master
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Sun Mar 22, 2020 2:32 am quote
If clip 3 is better at 3/8 throttle on the road the AS270 will make it worse and will end up on clip 1 and pilot jet down another 5. You don't need the AS270.
If the AS270 were right then the needle would be wrong. Its good as it is on clip 3.

Main jet should be something like 155 but might be 165.
A full set would be best but if not just 150, 155, 160 and 165 should cover it.

First I think your float might need checking again. Holding the carb as it is on the scooter, the float should drop to about 30mm. When lifted to the top to close the fuel, it should be 24mm (23 is better). Do this first. Quick Sunday ride to check clip 3 at 3/8 throttle. Video to show the lads. Then shopping for jets.

Where is the ignition timing set?
Molto Verboso
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Sun Mar 22, 2020 10:27 am quote
Will follow up on float position in next post this one for 2 vids of X3 needle in 268 atomizer. First vid is clip 4 bottom position. This breaks up just past 1/2 throttle and does not take to 4th well. About halfway in both vids I pause to get a listen to idle speed and how well it holds at 1/4 throttle. Almost impossible to keep 1/4 throttle from going to the moon in 3rd clip. 2nd video run it out of gas again for the audience this time left fuel OFF.

Molto Verboso
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Sun Mar 22, 2020 6:34 pm quote
Adjusted the timing to 19 degrees. Seems to have changed idle need to adjust. Might rev out smoother didn't test drive.

A few photo's of the float again. I adjusted the stop tab so the float drops to 26mm. The float rises and needle seats at about 22mm. The needle seating is making the 22mm. Do I need to bend the needle tang so this occurs at 24mm?

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float drop 26mm

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float rise 22mm

Jet Eye Master
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Sun Mar 22, 2020 7:34 pm quote
Starting and riding not bad. Sounds like clip 3 is the one. On the thinner tip needles the clip can be quite sensitive. The important position here is 3/8 and this is where 4th gear starts pulling. Best clip that pulls is the one.

Timing at 19 is better for yours but need to watch the temperature on the high speed runs.

So with clip 3 the riding WOT break up is between 1/2 and 3/4 throttle?

Float level better but should be dropping 30mm and raising to 24mm (22/23 better if it doesn't leak). Need to bend the stop tab out a bit.
Molto Verboso
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Mon Mar 23, 2020 8:07 am quote
OK easy enough to adjust float drop a little more now knowing how.

The universe works in strange ways. The stator plate died (after having it rewired in anticipation in 2018) but it has served me well since 1989. Trying to trouble shoot the ignition borrowed the original P200 flywheel back from the Bajaj. In doing this found two stroke oil under the Bajaj stator. Some of the crank case bolts had signs of oil and needed to be snugged up. Actually all the case bolts needed tightening. Used a 1/4" drive socket and just snugged to feel. Fly seal is good. Hope that helps.

Replaced P200 stator with a BGM unit. Installed all the way clockwise as where original plate was set. After strobing turned stator counter clockwise maybe 4 degrees to get it to 19 was probably at 15 during video. Timing seems to have reduced engine speed at idle and need to adjust.

Scooter does not take to 4th gear well with clip in 4. Am amazed at how well scooter will run in position 3 but it will break up in 3rd gear at the end and in 4th much earlier closer to 1/2 seems 3rd gear can take it much higher RPM than 4th.

Need to get main jets.

Having a little issue with the exhaust blowing off. Used a SIP exhaust gasket and snugged to 168 inch pounds. Was waiting on 60mm exhaust spring found something to work in the meantime but it's something we've struggled with since 94.

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This is where the exhaust seems to want to stay with a spring

Hooked
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Mon Mar 23, 2020 3:09 pm quote
Rubber mallet and a few whacks and it still doesn't move?
Jet Eye Master
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Mon Mar 23, 2020 7:12 pm quote
A few events at once. Sounds like Bajaj testing is over until you can get some parts. Stator can probably be fixed but easier and often cheaper to just get a new one.

Exhausts slipping off the old 210 is a common issue. Big whack and a shorter spring will do it. Maybe a second spring to the head too? Overtighten and the stub will deform.

If the timing was at 15 degrees and now at 19 it might need a slightly bigger pilot jet. Clip 3 does sound like where it needs to be and this should be unaffected. You can see that running without a main jet for a while allows some focus on getting the basics done. If you are still happy with starting hot/cold and smooth running up to half throttle is ok, the next step is try a main jet. This is where you see it really go. Probably hasn't even hit the power properly yet.
Molto Verboso
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Wed Mar 25, 2020 5:11 pm quote
Snugged exhaust by feel when warm. It's not moving and not leaking.

Ran a 165, 160, 155 and 150 main jet. 150 feels the best and maybe still rich not sure. Had a little mid to upper range sputter with the 155.

Trouble with idle. Tried pretty much every size up to 70. Think 60 is close but having the same symptom with all. After a run idle comes down fine for about 30 seconds all is good then it loads and I have to give it throttle to keep it alive. A little dirty on take off.

Can't seem to get a good idle beat on the stand. Not sure if it's a reed valve thing, light flywheel, non of those, still jetting? Whatever I do it seems too fast or too fast and too rich.

Finally switched flywheels. Put the lightened 2.6kg stock P200 flywheel borrowed back from Bajaj. Like it. Slower to reach RPM but shifts better more torque and pulls 4th much better. Think my driving style works better with the heavy flywheel.

Idle still an issue but better with heavy flywheel.

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150mj

Jet Eye Master
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Wed Mar 25, 2020 7:05 pm quote
If 150 is not spluttering I would leave it there. CHT on a long high speed run will determine if it is correct. Should hold under 350F even after 10 miles at WOT. The richest that doesn't splutter is the fastest on a 2 stroke.

60 idle jet will be too rich. If you ride hovering at 1/8 throttle and there is any kind of splutter at all the pilot jet is too big.

When the jetting is correct and tickover won't slow down there is usually an air leak somewhere. Doesn't need to be a big leak. Pressure testing is the only real way to tell but that means taking the exhaust off again.

Is 4th gear pulling ok? I remember your gearing is something higher than stock. Plug is looking ok but a little cold and rich, probably the pilot jet is too big.
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Thu Mar 26, 2020 8:29 pm quote
Haven't ruled out an air leak but some promising changes. Spent more time working on float level. This time I've seated the needle in the valve and adjusted the float to 24mm. In the photo I placed a M8 nut to weight the float needle is seated at maximum rise of 24mm measured. Also adjusted the drop to 27mm. When the scooter is left to idle on stand for more than 5 minutes you can hear the filling cycling as idle speed slightly modulates.
Adjusted float seems to have improved on the road idling issue with loading thanks Jack and Jimscoot.

Brought the pilot down to 50 for the moment think it might be rich. Tried the 46 again, thought felt a slight bog on opening throttle after long idle. Want to try 48. Engine seems to respond better now with a smaller pilot and floats adjusted and re-torqued head. Throttle opening felt better with 50 than 46.

Tried running a little faster now on the 150 main jet but 3rd began loosing power at the end and 4th was not making good power. If at 40 mph in 4th and WOT engine power would fade and almost die like running out of fuel and could not recover. Would not restart with two kicks but would with choke.

Tried again with 155 main jet same maybe worse. Thinking something bad was going on removed head which looked OK but some carbon. One cyl head nut was loose and stud pulled threads, wasn't turned in far enough, locktited and should be OK.

Retorqued head and on 145 main jet now. Better. Down to 140 main jet better again. Didn't give it much testing but seems better.

Temps seem to have dropped with dropping the main. Cruising at 45 is below 300 now. Was creeping up to 350 with larger main jets and much more vibration.

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float weighted 24mm

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float weighted 23mm

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float drop 27mm

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looking good and can see new piston port lines

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not leaking but loose stud

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50 pilot 2 1/4 turns 140MJ 266AS X3 needle Clip 3

Jet Eye Master
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Thu Mar 26, 2020 9:11 pm quote
Still making progress. Piston looks good with no damage. So far so good. And no air leak.

The main jet should only be adjusted for what happens at WOT, once less than WOT its all on the needle taper. Look where the throttle is positioned when you have a lack of power. Might need to drop to clip 2.

Adjust the main jet at the top of 3rd. 140 is still in the zone but I would have hoped for higher. If you find a long straight slightly uphill, the correct main jet will make the fastest speed in 3rd. If its not uphill it will end up too weak.

When over rich (which is how your plug looks) temperature and vibration go up due to excessive compression. Not worried about this. Crusing around your on the atomiser/diameter/slide and yours should be plenty rich enough. 275F is pretty typical.

If the pilot jet feels rich as the throttle is opened but ok by 1/8 its just the mixture screw too far out.
Molto Verboso
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Thu Mar 26, 2020 9:41 pm quote
Can't run in 4th gear more than 45mph for very long with main jets above 145 or strange things happen. Think I'm fouling or loading up in 4th on the larger mains. It's not sputtering it felt like seizing, power fades engine dies sounds like run out of gas, no response to throttle as dying periodic fire as it dies. Restarts with choke? Felt sputtering with larger pilots in the higher revs but no sputtering with 50 pilot just vibration or less of it and more power with smaller mains,

Adjusted the pilot from 46 to 50 because felt a bog off throttle on the stand. Engine RPM drop was slower than 50. 50 does not sputter totally clean but do not like idle. Picks up better off throttle than 46 but might like idle with 46 better. Want to try 48. Plug ring looks very rich.
Jet Eye Master
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Thu Mar 26, 2020 10:00 pm quote
Where is the throttle when this is dies in 4th? Wide open? 45mph is way out of the power but too rich will make it die. Try dropping the needle to clip 2 or 1. If this doesn't work it needs a weaker needle.

Edit: having a think about this and with 246 diameter and a 266 atomiser, this must be too rich. You have a 264 atomiser?
Molto Verboso
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Sat Mar 28, 2020 10:05 am quote
Will lowering the needle to clip 2 require revaluation of the main jet?

Made a 40 mile round trip still with clip in 3. Ran really good but doing same loading at just cruising speed in 4th. On a long level straight maybe 2 miles in started having problems maybe at 45mph and 1/4 throttle. When it would occur giving throttle did not help closing throttle could allow engine to recover.

Went over a slight hill could not hold 4th and had trouble holding 3rd. Loosing power if RPM is not right and temps also increasing so backing off on power to keep temps reasonable. Kept temp from going above 325.

Just cruised at speed of traffic to see how it behaves never went above 50. Much more drivable, better torque and can cruise in 4th down to 30 mph comfortably with no four stroking.

Clip in 2 now it is amazing like room temp butter on hot toast so good.
Jet Eye Master
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Sat Mar 28, 2020 7:59 pm quote
If clip 2 is so much better than clip 3, then as I said before the atomiser might actually be too big. With the 246 diameter in an AS266 it is the same as a 250 needle in an AS270. I think this is too big. If you have one, change the atomiser to AS264 and back on clip 3. If you don't have one, run as it is but might need to go down to clip 1. For a good set up I always like to end up on clip 3 but that's more OCD than gospel.

Get the pilot jet and mixture set to run clean with no bog. Should be able to sit ticking over. Quickly open to full throttle and shut again immediately. Scooter should instantly rev up high, then drop to tickover and not stall. If you can do this the pilot jet is not so bad.

Once pilot is done. To test how the clip is, ride at 1/4 throttle cruise and see what the CHT temperature is. Looking for about 275F. If the clip/slide/atomiser are ok this is what it will be.

Worry about the main jet later. The size of the main jet is only gets important over 3/4 throttle
Molto Verboso
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Sun Mar 29, 2020 2:53 pm quote
Spent some time working on the pilot again with X3 needle in clip 2. Was on a 50 tried 46 again ended up on a 52.

Started out for a longer ride but early on still having 4th run out and die. Baffled.

Tried X44 needle in clip 3. Pilot is too rich now or clip and 4th runs out and dies if over 45 and 2 miles in. If catch it soon enough and close throttle engine might recover if left alone but usually just feels like it's run out of gas and dies. Will only start again with choke.

Wondering if my fuel pump has enough back pressure. Sorta feels like the float bowl may be running out of fuel. I added a spark plug top to the return line but maybe there is not enough pressure and the fuel is returning and not filling? Major flow and bubbles in the return line plug top moving back and forth in the line.

What is the smallest orifice I can put into the return line?

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Jet Eye Master
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Sun Mar 29, 2020 8:01 pm quote
This is now getting weird. There is an issue somewhere.

The starting with choke after it dies is odd. Only ever seen this when the main oil seal has fell out. Never been a better time to pressure test it.
Molto Verboso
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Mon Mar 30, 2020 3:51 pm quote
Still have not ruled out an air leak but don't have a leak tester.

Back to X3 needle in Clip 2:

Tried adding restriction to the return line. Seems to have helped. Had a spark plug top with a 3.75mm hole in the return line. When the engine is revved the top spins and begins migrating towards the fuel pump. There is a lot of fuel blowing past the top and on high rev a lot of air bubbles. Seems lacking back pressure.

Made a few restrictors out of 1/4" stock. They fit easy inside fuel line not tight but not loose, tighter than the spark plug top and solid on the sides. Began with a 2.6mm restrictor then 1.6mm and ended on 1.2mm which was the smallest drill bit that would tighten in the drill motor. The 2.6 and the 1.6 slightly migrated but mainly stayed pressured to the end.

Seems to have stabilized things to a point. 4th now running good to about 50 no sense of fading and everything feels more robust like when I drilled the carb on the bajaj. Not doing what it was doing before and dying. Cruising at 40 mph seeing 285 degrees move up to 45 mph temp creeps to 300 and if holding for some time maybe up to 310. Up to 50 mph temp creeps up to 325.

Tried to see what it would do holding 3rd a little past 50 seeing a temp spike to about 350 which drops as fast as you can shift but slowly temperature is creeping up to 350 if working out 4th. Still uncertain of what is going on feeling some power fade again or something around 55 mph and temps aren't staying down. Everything feels a little richer until I reach the 55 mph point. Think I may drop the pilot back to 50 and see if that help down low but not sure what to do on the 4th gear issue. Seems maybe a little power fade at the end of 3rd as well if stretching it into the 50 mph range.

Two videos of the fuel pump return line, first one with spark plug top 3.75mm hole second video 1.2mm restrictor. Even with 1.2 lot of air bubbles at high rev but overall more fuel in line. Don't normally rev like this on the stand but wanted to get video of high rev pumping.



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3.75 plug top, 2.6 & 1.6 restrictor

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X3 needle clip 2 AS266 atomiser 140MJ w/ 1.2mm pump restriction

Jet Eye Master
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Mon Mar 30, 2020 7:50 pm quote
Fuel seems to be moving slowly and where is all that air in the return pipe coming from? Might there be a leak somewhere? Maybe inside the pump?

Sounds rich at high rpm when you rev it on the stand. Maybe try a smaller main jet?

Edit: If the pump has a leak there will be gas in the vacuum line. This would then make it over rich. Just a thought.
Molto Verboso
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Sat Apr 04, 2020 5:37 pm quote
Replaced the gasket set in the fuel pump and have the return line full of fuel again with spark plug top. Also replaced petcock with a BGM fast flow.

Big difference smoothed everything out runs very good 1st - 3rd. Still having same problem with 4th gear after a mile into 4th it seems to run out of gas and die.

Temperature seems to have come down with pump rebuild and speed has moved up, getting up to 55 now before having problem in 4th. When having problem in 4th not seeing temp spike and not feeling power loss like seizing there is no pinging everything is perfect and then it starts to fade as if it's running out of gas. Checked return line when this happens it's full so think good on fuel delivery. Seems this is happening at 1/2 throttle opening more just sounds more empty engine does not respond.

Went from 140MJ to 160MJ. Not feeling any sputter. May need to remove MJ again to remind what sputter feels like. What is going on?

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Jet Eye Master
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Sat Apr 04, 2020 6:53 pm quote
Pump was an issue then. That's one thing out the way. We're getting better at this but this 4th gear problem is a concern. If the return line is still full then its not the fuel delivery.

Float bowl overflow/breather not blocked?

When it starts to fade in 4th if you drop the throttle, does it pick up again or still die?

Have a check of the gear oil? Just make sure its still there and not full of fuel.

If a 160MJ is not flooding then it could be something wrong with the float bowl. Taking the main jet out is a good idea. If that won't flood then its certain.
Molto Verboso
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Sat Apr 04, 2020 7:11 pm quote
Yes when 4th begins to fade if less throttle power comes back but loosing speed at same time.

Will check gear oil and breather tubes tomorrow.
Molto Verboso
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Mon Apr 13, 2020 1:37 pm quote
Scooter was behaving as if float bowl was emptying out in 4th gear. New petcock and rebuilt fuel pump helped but did not solve the 4th gear issue.

Got to thinking about the bypass again. Guessing the 250 float valve jet is a 2.5mm hole so I put a 2mm restrictor in the bypass line. Seems to have helped scooter is now making power in 4th gear and not running out.

Hopefully the sun will be out tomorrow and a good test ride to report on. Still on 160MJ.

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Ossessionato
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Mon Apr 13, 2020 5:31 pm quote
I was having similar issues. I just installed a self-regulating Delorto 55lph pump with no regulator or bypass and it's working like a charm. You should definitely check it out.
Molto Verboso
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Mon Apr 13, 2020 5:42 pm quote
chandlerman wrote:
I was having similar issues. I just installed a self-regulating Delorto 55lph pump with no regulator or bypass and it's working like a charm. You should definitely check it out.
Thanks Chandlerman did notice that on your rebuild thread and was curious. What makes it self regulating?
Ossessionato
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Mon Apr 13, 2020 5:56 pm quote
hibbert wrote:
chandlerman wrote:
I was having similar issues. I just installed a self-regulating Delorto 55lph pump with no regulator or bypass and it's working like a charm. You should definitely check it out.
Thanks Chandlerman did notice that on your rebuild thread and was curious. What makes it self regulating?
I was suspicious myself, but decided to give it a shot. It's been performing wonderfully. I'm going to try and get it out on the highway in the next few days and really put it to the test, but it blew past the point of prior fuel starvation with no issues at all over the weekend.
Jet Eye Master
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Thu Apr 16, 2020 5:04 am quote
How you get on with the 160 main jet? If it floods out at WOT there is no starvation issue anymore. Seems like it was the pump all along.
Molto Verboso
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Thu Apr 16, 2020 5:33 am quote
Streets are becoming a challenge for testing, running out of room for speeds above 55 and not ready for freeway testing. Wasn't feeling any sputter with the 160MJ so tested 165MJ.

Can the main jet be determined in 3rd gear? Seems if I shift early into 3rd and do WOT it slowly climbs hits a sputter in the middle clears and revs out.

Think 165 might be rich but need more room. It was good to feel sputter again.
Jet Eye Master
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Thu Apr 16, 2020 6:08 am quote
You can use 2nd or 3rd for splutter. It's actually very difficult to do in 4th. 165 is big for yours, especially on the X3 needle. Have a go in 2nd with no main jet. You have to be sure you can get splutter at high rpm or it will never jet in.

Edit: rich in the middle (or 3/4) and weakening at the top is typical of fuel starvation. Sounds like yours still has an issue. Take out the main jet and see how it goes.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Thu Apr 16, 2020 2:51 pm quote
Took the main jet out and went for a ride. Wow amazing. Scooter seems to be doing what it should runs fantastic in 2nd and 3rd it will sputter at 3/4 throttle close a little runs perfect again. In 4th begins to sputter sooner maybe 1/2 throttle close a little perfect again. If shift into 4th at 40 mph and hold throttle at 1/4 scooter running perfect engine will increase to 55 mph and then need more throttle to move faster to the point it will reach the sputter point. Best 55 mph I've ever felt on this scooter in a very long time. Temp seemed to hovering 300.

Think I felt sputter in 3rd gear on the 165MJ and 160MJ felt a little bloated gonna try a 155MJ and see.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Fri Apr 17, 2020 9:32 pm quote
Sounds like it's better now. If the main jet works at 155. That's exactly where it should be. See how the CHT settles down in 4th and can decide where to go next.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sat Apr 18, 2020 6:19 am quote
Don't think I ever had the correct back pressure on the fuel pump once the bypass was jetted smaller than the float valve it worked.

Cannot believe how well the scooter will run with no main jet. I can almost keep the scoter with no main jet and ride it like this it runs so well.

Does this indicate the jetting is good prior to the main jet sputter point in other words should I ever be concerned about seizing or too lean at the below main jet point, it feels prefect?

After tuning the PHBH it's become clearer that in most cases not even on the main jet until 4th gear with this carb. But why does 4th gear go rich at 1/2 throttle but 3rd goes to 3/4?

Now that it's become more clear where the main jet is needed to eliminate the sputter do I try to create sputter and come down from there? Might need larger than 165 to make it sputter like with no main jet.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2376
Location: London UK
Sat Apr 18, 2020 7:39 am quote
Are you still using the X3 needle? Bigger than a 170 means there is still something wrong with the float level.
Splutters earlier in 4th because there is more load on the engine. Throttle open wider for the same rpm.
Main jet is not needed until 3/4 throttle when set up well. Get splutter in 3rd and walk the jet down until o splutter and good power.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1166
Location: California
Sat Apr 18, 2020 8:07 am quote
Yes still on X3 2nd clip.

Pretty sure was having sputter in 3rd with 165MJ but engine can deal with it. Going to get a 170MJ and see.

Based on how it ran with no main jet it seemed to sputter exactly when it should and felt outstanding backing it off to before it sputters.
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