Modern Vespa

Hey all,

Installed the reed valve on old malossi crank cases with the PWK 35 airstriker and a fuel pump with the vacuum taken from the crank case

Seems to be running ok, besides some small details...

I did a leak down test, seems to be holding air well...

Malossi 210 worb5 ported
Stock px200 gearing
Vforce4
MRP manifold
60mm stroke crank
PWK 35 airstriker,
45 pilot 1.5 turns out
BGP needle
150 main
Scooter and service low compression head
Scooter and service newline exhaust
0.5mm head gasket
0.25mm base gasket
malossi Vespower MkI 1.2kg+400g

Exhaust 191 deg 32.4mm
Transfers 137 deg 45.7mm

However... After passing the leak test, (I'm assuming it's air tight and no leaks at the clutch seal) but it seems to have quite a bit of black oil (has the smell of the 2T oil, but it's quite thick...) at the exhaust tip of the exhaust after WOT... I was thinking it might be an overly rich main... but stepping down from 160, 155,152, then arriving at 150... it's still there...

I'm wondering if it's an oil sucker at higher crankcase pressures? Is the only way to find out is to measure the amount of oil in the crank case and see?

Or could it be the fuel pump pushing fuel out too much? How to make sure the pump is working properly at high vacuum?

Video attached

https://youtu.be/VLr7Usw9DhU

108- are you running WOT yet?
If yes - a pic of the plug after 5 seconds of that will give better read of rich/lean question.

Can do the same thing basically with 1/8 throttle then pull plug and shoot.

This will show too and bottom and give better sense if one is way rich (which I suspect bottom is).
Just a guess tho - but oil out tailpipe is rich somewhere in all likelihood.
Might not be your main.

Nice spec. MHR or Sport cylinder before tuning? You have some measurements of the port heights in mm?
What's the ignition timing set to?

As said, sounds like it's too rich at low rpm and goes lean when you rev it. Main jet should be much bigger, something over 170 would make me feel comfortable. All the black oil will be just the rich low throttle.

Anything wrong with the fuel pump will be more obvious.

A sound recording of riding around would help.

Hey CM22!

So just before this video, theres a 1/4 mile i can get to WOT... its not for long... I reckon a second or two...

So I ride around constantly in 1/8 throttle in a 200m loop (lol) and gauge the running... havent pulled a plug, because it seems really difficult to get anything scientific and consistent.

(with other setups, I had a lovely chocolate brown plug... but I only got that (im guessing...) because i was rich before and the pilot leaned out the colour...)

just seems too many variable before and after the riding (collection of fuel etc)

I've gone through 1/8 to 3/4 and the BGP needle seems to be more rideable at different speeds and gears... was hoping to tweak the top and bottom with the pilot and main...

But so good to get your ears on the video... second guessing myself all the time!!

Thanks Jack!

Totally forgot to mention the important parts of all this, been staring at the engine too long...

Its a Sport cylinder modified by the Worb5 guys... thought id be interesting to test it out... brought it a while back, had it installed then took it off for a good 2 years...

Measurement were:
Exhaust 32.4mm
Transfer 45.7mm

(I remember some of the timings wrong, updated the previous post!)

Im using the malossi Vespower MkI 1.2kg+400g weight (totally regret getting a variable setup its just a PITA, and I'm not even using it to its full potential, also brought it way back when i had no idea what i was doing) -8Deg @8000rpm

I've strobed it at 21Deg @1500rpm and @4000rpm, the mark slowly disappears in a clockwise motion, so im trusting its retarding properly (I dont have an advanced timing light)

With my riding, I'm not at 6500rpm for a sustained about of riding time, so thought 21deg would be a good place to be... even at WOT in 4th (which doesnt happen too often for me...) I cant see the revs go way past 7000rpm

I've added a curve chart to map out 21deg @1500rpm. The yellow box is where i imagine i'll be spending most of the time... seems to be a balance for the 18deg expected for the malossi 210 sport

Yeah i'd be hoping the bottom was overly rich, but I was thinking it shouldve cut out and stalled by now... 5 mins idling and its still running...

[UPDATED the previous post to be Google SEO friendly]

UPDATE:

So change the jetting and dialed in the carb to:

Pilot 42 1.5 turns out
MJ 170

Seems to be running a lot more responsive, but couldnt get WOT to check if the MJ was ok, bumped into morning traffic (engine seems to appreciate the extra fuel)... but did get to crank the throttle open in bursts and it seems to be growing rich (growing boggyness towards the top)... (oil/fuel/black mix coming out of the exhaust tip too)

Will take it for another spin later today

Ok first things first. Your cylinder is still good but not as hot as those numbers. With a 0.25mm base the piston will be poking out the cylinder, hence the need for the head gasket. This means minus in the deck height. -1.1 not +1.1.
This gives 183/130/26.5 which is not so hot but perfectly fine.

Timing. If set at 21 degrees and -8 @8000 then it's 13 degrees @8000. This is 15 degrees when average riding about. Nice and safe but not going to be blowing anyone's socks off.

Your cylinder head is a low compression type. This can take more advance than a normal head. A normal Malossi cylinder head at 1.2mm squish, can take 18 degrees @8000. Yours could probably take more. A starting point while setting up should be, 18 degrees @8000, which is 26 degrees static. So 5 degrees under. This is why there is all the black spooge.
Once you advance the timing to where it should be the jetting goes critical. Any slight sign of weakness for a sustained period and it will start doing real damage.

Keep the jetting with a smaller pilot that gives 1 turn max or it bogs and a spluttering main jet at WOT until all the mid throttle positions are good.

Ah damn... yeah its +1.1 not minus, input the wrong number! (such an idiot)

Yeah, im definitely not blow any sock off at 15deg... feels safe which was refreshing.

Will give it a try, was a little scared to go all out to 26Deg because i dont spend too much time at 8000rpm

But i'm a little out of ideas for the setup... looks like i'll be going back to richer jetting if i advance that much in the timing...

Attached the timing curves here again... I'm not riding hard like that other CM22 fella, so hopefully wont be blowing up and pistons...

(sorry CM22 for the low blow...)

26 degrees is not all out but it's getting there. Even SIP say 23 degrees on that chart as a starting point. 26 is where I would start at. Not just saying that, this is what I would do. 25 is about the minimum to go properly. With the low compression head you've reduced your options.

Jetting is not so hard if you don't try to do it all at once. Get the pilot and main out the way like I said. Focus on 3/4, 1/3 and 1/2 throttle. Realise you will need a pile of needles. Relax into it and don't ride hard or sustained throttle until set up and it will all be fine.

Yeah, i've been doing it the way you've suggested, ever since you mentioned in a previous post... its much easier to go through with that method...

Previously i was just guessing and slapping jetting combinations and hoping for the best... wasted so much time doing that... not that the method you mentioned is any less time consuming, but much easier to identify problem spots...

I have a pile of needles already and ive already narrowed it down to a few which are usable... the PWK ones are more expensive per needle too!

The flywheel will be coming off today!

Additional question, should i aim for higher exhaust and transfer timings?

Something like 190/136/27?

Get what you have running well first and then decide. I would expect, when correctly set up, your porting will do 70mph anywhere, uphill, into the wind, maybe even 80mph on the freeway. How fast you want to go?

When you up your ignition timing be sure to put your needle on the richest clip ( 5, bottom) and remove the main jet completely. If not rich enough it will blow up. When it splutters holding just under half throttle, reduce the clip until it just about runs clean at half throttle. If it doesn't splutter at half ride home carefully and change the needle for a steeper taper. Once the half throttle is barely spluttering and almost clean, you will notice when fully hot, at half throttle is pulls very hard and goes like stink.

Yeah baby steps... i'll look into the timings further down the line once I've jetted and have it running properly.

Strobed to 26 deg now... i had it at 25, and was tempted to stop, but thought what the hell, might as well give it a try seeing i had the flywheel off and tools out...

Stuck the 45pilot back on to play safe, but will be going leaner after this mornings quick test run ended up a little smoky...

Must ride quite different now running 26 degrees. I'm sure low rpm torque feels like probably just tripled.

When you get settled into the higher timing, don't think you will have this jetted by tomorrow and it all gets a lot easier.

With the 1 turn pilot jet and no main jet, get just under half throttle (marked with some tape and pen, so you know it's exact) to very slightly splutter when held at steady speed. If you have a CHT gauge it should settle at about 280f if adjusted correctly and you hold this throttle position long enough. Write down the needle and clip position. You'll need this later.

The PWK 35 is about the simplest to set up. A few more steps and several needle changes and it's there.

But would my air mix screw will eventually end up at 1.5 turns after that 1 turn testing right?

That's what I aimed for before..

The 1 turn pilot jet is just for setting up (as is the missing main jet). I depends on how the set up goes. Airscrew is the last thing to be adjusted in about 10 steps time. 1.5 turns will be the minimum.

If the pilot is correctly sized during set up it becomes a confusing mess and you don't know what to do next.

Got it.... yeah assumed so...

See you in 2 weeks regarding the progress.... lol

I'm imagining after the taper and clip is done, I need to go 1/2 -1/3 throttle and identify the needle diameter... then the pilot and 1/8 throttle (also identify needle diameter), then the air screw then main jet?

1/4 and 3/4 as well. By about step 4 it will be going a whole lot better.

Doing it in the right order gets it done quickest.

Pulls like a freight train now, even with terrible jetting, the extra torque is definitely there

Thanks for the advice on the carb jetting... just spent half the day testing out the needle at 1/2 throttle... and seems to have landing on a B taper... was using a bgp and bgn for comparison... the C taper was way too rich... so stuck with the B. Problem is now... I haven't even gotten past 1/2 now as I've run out of road before going any further... I was going to test 3/4 before going back to the looking at the bottom... but the spooge is back at just past 1/2 throttle... I did have a 180 jet but I can't imagine it kicked in at 1/2 throttle... stumped on that finding... what should be my next step? Bottom or top?

Holding just under throttle you can cruise along at 280f? B taper what is the full needle code and which clip? Don't worry about anything else until this is correct.

Did Jack have you remove the main for this? On my carburetor I got a surprise when I did it, the main was my restriction at 1/2 throttle or a little less. I have been working on making the needle do its its job, before I go back to running a proper size smaller main jet. It got cold here so I stopped for the winter.

BGP was the needle middle clip... not sure if it's 280f, don't have a ChT to check... definitely cruising though.... worryingly smooth and pretty fast.... lol Yeah having the main out was a little scary... but gave it a try

As Christopher just said, without a main jet 1/2 throttle should be very slightly rich for this test. If you go to clip 4 does it run spluttery rich at just under1/2? Need to be sure that clip 3 is set on the threshold of rich. If this is the case then step one is done.

With no main jet during these early stages, there is no confusion.

UPDATE:
So I realised my fuel pump might not be doing me any favours... so out of curiosity I took the pump off, blocked off the crankcase and added a gasket... took a spin around the block and the spooge was gone...

So second guessed the mornings tests... I decided to find a longer road and redo the runs. Back to square 1...

jack so yes this time without fuel being pumped into the carb... 3rd clip runs scarily fast..! Like pants on fire fast...! A little bogging around 1/2 throttle just before I bottled it with cars coming the other way... re-did a bunch of runs and seems to be the smoothest with a slight bog. 4th clip position it just splutters past 1/4 throttle all the way to 1/2 throttle and no where near the scary speed of 3rd clip

All done without the main... haven't bothered reinstalling it... just spluttered home

At least that's step one done, pump or no pump it's close enough. BGP clip 3 for 1/2 throttle.

Really should put the pump back on. A spark plug top is just the right size for the bypass. With the pump removed the working float level is lower. That's why the spooge is less. If you fit the pump under the tank, the longer vacuum line makes it a bit weaker. Real pump issues are very obvious. You will be in no doubt if you have pump issues.

Will fit the pump back on at a later date... by accident, the vacuum hose was a little long... measured wrong and wanted to play safe as I didn't know where to install it... I wanted to have it out, just in case there where any problems with the pump so it's easier to look at...

So with the clip done I imagine it's a case of going to 3/4 throttle now?

One issue with not having a pump is you might have to do this entire set up again, once it's fitted. The float level is the base for the jetting. With a pump the level is maintained high throughout. Without a pump it's a bit more analogue.

Pump or no pump the next is step is 3/4. Still with no main jet rev it on the stand and make sure it can get near to 3/4 throttle before spluttering. Keep your foot on the brake and hand over the clutch. If it jumps into gear at 10,000 rpm it will be a bad day. If it doesn't get there or can rev right out change the needle for a leaner/richer taper. Only focus on 3/4 and forget about 1/2. When you feel it's ok, take it for a ride, ignoring everything else on the way up, it should get to 3/4 and then flood out so bad it won't rev out anymore and tries to cut out. Write down the needle code and clip position. This is the hardest one to do and involves a bit of guess work.

Got it, is this the step where you're not friends with the neighbours anymore? 7000rpm and it sounds like its about to explode.

And sounds like i need to find a airport runway to get to 3/4 without dying...

Will give it a try today...

Forgot to ask, "hand over clutch" as in pull the clutch in? Or just get ready to pull in if something happens?

I don't like holding the clutch in while revving. Holding the clutch in for longer periods with heavy clutch springs doesn't do the clutch and bearing any good. Do what makes you happy. Many years ago, one wheelspun off the stand but I got the clutch in and it just fell over. Now always cautious.

[UPDATE]

Couldn't get past 8000rpm at 3/4 throttle, at standstill...

I'm assuming it's lean, because there's no smoke, and I can't imagine it's an "A" taper I would need... looks like I'll be ordering needles...

Anything I should note when buying needles?

If you can get to 3/4 on the stand, take it for a ride and see how far you get. It's going to splutter very bad all the time but should get to 3/4 before its so rich it won't run. Is really hard to judge.
Your carb is regular not powerjet?

Yeah 8000rpm is definitely easy to get to... rolling off the throttle it would die... but got the consistent 8000rpm each time at 3/4 throttle...

Riding around was generally ok around 1/2-3/4 throttle range but only got to around 7500rpm max, didn't get past 1/2 much to be honest... but splutters everywhere else. Will go for another ride and try push past 3/4 and get it spluttering

It's just a normal airstriker... not getting into powerjet territory... it's just extra trouble

Would the 8000rpm bottle neck be something related to the exhaust? The S&S newline doesn't seem to get far past the 8000rpm mark from the dyno chart they posted...

Really could go to an A taper by the sounds of it but don't worry about that. As long as it isn't lean it's fine. Call it A taper and clip 3 for step 2 and we'll carry on.

Not going to rev so high in gear. The S&S pipe is not so sporty and your porting is not so sporty either. It's going to go well but there's more potential in it. Yours will be a bit better than the one in this with the chart as it's been adjusted. What did you set your squish at?

Squish is at 1.5mm with the 0.5mm head gasket... again, playing it safe...

I did think about pulling the gasket off... i know the 210 should be around 0.8mm... I'll take it off when i reinstall the fuel pump

1.5mm squish is massive for this set up. It's not actually safer because the tighter the squish the better the piston is cooled. The safest is the correct clearance.

Diameter next. This is hard to get right first time as it's affected by everything else. First check the airscrew. Have to check it and maybe change pilot jet between changing needles too. Put in a pilot jet that can only have 1 turn on the airscrew. By that I mean if you set at 1.5 turns and it is sitting ticking over, quickly go full throttle, then close it. It should bog and hesitate before revving up. Turn the airscrew in to 1 turn, open full throttle and it revs up immediately. When this is right, go for a ride, warm it right up, then check 1/8 to 3/16 throttle. Put in an ever smaller diameter needle until it goes rich, then increase diameter until its running fully clean. Write down the needle code and clip position.

Yeah will get the fuel pump back on and take the gasket off, i should be able to get to a 1mm squish... I'll try redo some of the needle work and see if theres any difference...

Im guessing the pilot should be small but rich enough to be able to rev at full throttle smoothly...

I'll go test it tonight, the 1/8 to 3/16 throttle

Good you're doing this now. I doubt your 1/2 or 3/4 will change with the squish but without the pump it might. The important thing for diameter is that the pilot jet is a smaller size than the final size. If the pilot is the correct size or bigger, adjusting the diameter is near impossible. By 1/4 throttle every component in the carb (except the choke) is in play.

When changing needles on step 3, as well as rechecking the pilot each time, roughly adjust the clip, so under 1/2 is not awful.

Small pilot correctly adjusted, should rev out just like the correct size does.

Not wanting to interrupt where you're going with Jack, but something else to think about down the line is the slide. The 35mm Airstrikers come with a rich slide (4.5?) and many people with this kind of setup, myself included, end up changing to a no.6 slide. My 221 is a stock 57mm MHR cylinder, 60mm bell, ported piston, S&S reed block and 35mm AS. I'm at just shy of 127/184 port timings and I'm currently at 170 main jet, BGN clip 3, 45 pilot, and 0.85mm squish for reference.

Thread if you're interested: Cylinder vs crankcase (reed) induction