Modern Vespa

I have just dropped off the engine. He is going to test it over the weekend and go from there. I will feel better once I know there are no leaks.

So there is a leak around the base of the cylinder. I used a Pinasco standard gasket and some Hylomar Blue. Torqued it down correctly and the the correct value, 15nm as per instructions. Any tips on better ways to reseal the base of the cylinder? I plan to do this tomorrow.
Thanks.

Use Permatex Motoseal or one of "the bonds" (Yamabond, Hondabond, 3-bond). Let it cure overnight.

I have some Threebond 1215 to hand. Will that suffice? Thanks.

If you use Threebond you want the 1184.

Sorry, I have 1207F. I think this is Yamabond, Suzukibond etc. Shall I use a gasket as my squish was 1.5mm?

Thanks.

1207f is for coolant systems not gas or oil according to technical data.

What do you have for a gasket with a squish of 1.5mm? If that is without a base gasket, I'd try a good bonding sealer with no gasket.

Check the area where the leak was. If you find some old gasket, great. If there is some imperfection, then silicon with no gasket is the way, and will help with the squish.

The cylinder has a big leak near the flywheel area. Won't seal without a gasket. With the gasket it took quite a bit of sealant to seal it. Leak down test is OK but I don't know whether it will hold. Only time will tell I guess. Both the barrel and cases look in good condition so I don't know why I am having issues with that side of the cylinder. Its like the cylinder hangs over the casing a bit where the leak is. Weird.

Cylinder studs might be in the wrong way around. Should be short thread into the casing. If the long thread is in the casing it leaves threads uncovered that can catch on some cylinders.

DON'T JUST TURN THEM AROUND.
Check the threads are smooth and free with a new nut before putting into the casing. If the thread is even slightly stretched it will strip the casing. YHBW.

I fitted new studs and used a bit of blue loctite on them. Short thread into the casing. They were all nice and tight. Screwed in just until the threads are not visible. New nuts and washers used. It revs and idles much better now and is running a bit rich now the air leak has been repaired. I just hope it lasts.

The bike now runs better than it ever has done. Idles nice, if a little rich but I will adjust the screw later. Slight stutter when winding it on but I am running a 132 main. This will probably go down to a 130 or 128 as Jack said. So the combination of 120/BE4/132 and 55/160 idle seems to be a good choice. CHT is around 90-130 dpeneding on revs and load. What is the max temp I sould be looking for before being worried? Another post on here says 350 should be the comfortable max but is it different for this cylinder kit? Thanks once again.

One small issue. Bike won't idle. Seems very rich. Idle screw fully in. When revved, throttle responds slowly then picks up Nice. Idle jet too rich now? Mixture screw 2.5 out. Gone down to a 128 main. More responsive now. Feels even better.

Sounds good so far. Air leaks really mess up the jetting.
Get the main jet right first. 128 is possibly not bad. Two tests to verify.
Hold it at wot in 2nd, be sure that it gets to where you feel max rpm is and it still feels slightly heavy and wet when screaming.

Next, ride at 3000 rpm in 2nd, suddenly open to wot, should accelerate immediately. Hopefully not flipping you off the back. If it delays before accelerating, it's too lean. If it splutters or bogs, the main is too rich.

This is how to jet for road fast. Track jetting or economy jetting have many other methods to end up with different jets.

Did the tests. 130 main jet is the best. Instant pick up. No bogging or hesitation. Temps are around 150 C at 60mph cruising on flat road. Seems low. I will leave the idle jet as it is. All other keys seem good. Dyno booked for a couple of weeks time to fine tune it. What is economy jetting, a few sizes leaner?

What's the full jetting set up now? 150C is actually a bit hot

50-120 idle, 120/BE4/130 Main. According to some posts on here, anything up to 220-230 degrees celcious is acceptable. Of course, that maybe wrong. I am using a trail tech under plug temp gauge. Seems pretty accurate so far. Might step up to 132 main and see how that feels.

Just so I can tune the jetting a bit, when closing the throttle from anything over 5000 rpm, should it pop from the exhaust? The richer the jetting I use, the less popping from the exhaust. With a bigger jet in it does not pop at all until around 3000 rpm. I have sprayed carb cleaner around the base of the cylinder and it has no effect. I assume all air leaks are gone now as it passed the leakdown test.

128 is not enough . Popping run down and high temperature both mean its lean. Do these tests again. Increase the main jet to the point that it will not rev out and really splutters bad. Work down from there.

Pilot jet is possibly a little lean too. Something that starts with 52 next time.

Just about had enough with this bike. Doing my head in. So it will run with any main jet 138 or below. Slight splutter with 138 so probably a tad rich. With a 145 main jet it splutters like mad but eventually picks up and revs out but feels shite. No power at all. No matter what idle jet I put in, the mixture screw has very little effect and runs with the mixture screw fully in or out. Sometimes the bike stalls when I put it in to gear. Sometimes it doesnt. Sometimes the bike runs crap with the carb cover on like it is restricting the air but how? It can't be right that the bike runs with the mixture screw fully tightened with all three idle jets. Something is not right at the low end of running. Very frustrating. Just when I think I have cracked it, something else goes wrong.

Maybe it's time to try a 24/24 carb. I can't see any other solution at the moment.

Can you work with someone local to get it sorted? Local scoot club? TBH at this point it's hard to keep track of what the setup even is, what the symptoms are, and I think it's going to be really hard for people to help you dial it in over the web

Most of the people have Lambrettas and said they can't help me. Low end seems really rich as the mixture screw does nothing with any size idle jet in there. That cannot be right. I know its difficult trying to sort stuff out over the internet. Not ideal. So my current setup is 120/BE4/138 with 55-160 idle. Wont run with air filter on as it's too restrictive. Runs ok with carb cover on and no air tube. Not ideal but that's where I am. Runs better with no carb cover on but spits a lot of fuel back from the carb. I can see it being spat out when I rev it from idle. Maybe the case is worn and not selaing properly at the flywheel. I know it has two pads which can wear. I can get a 0.10mm feeler gauge between the crank and these pads. 0.15mm feeler gauge locks up.

Spitting fuel back out sounds like either rotary pad or reeds aren't sealing (whichever one you have). Also should probably check your float cover is on tight and not loose.. or your float needle is working properly.

Just sounds like you might have something else going on. But also being really over rich can run but have lots of issues and trick you into thinking you are lean. Really need to confirm what your plug looks like at each position in the throttle range to confirm which you are. Given you are on a 190 kit, I doubt you are too rich.. so that's why I think something else is going on with the carb, inlet or fuel supply.

Ok, 138. Thats big but it is a 20/20 carb on a serious kit (Pinasco RX 190 for those still awake). If you want to keep autolube get a 26/26. If not get a 30mm (max on rotary).

138 is a bit over and the bottom end is going to splutter with that. Are you sure the float bowl is drilled to 2.5mm?

It is fixable just stick with it.

The guy from reedpseed who fitted the Pinasco SI 24/26 Float Chamber Cover asured me it has been drilled out correctly. I can only go from what he said. It runs but not perfect. I will stick with it until I can get hold of a bigger carb and go from there. Thanks for all your help. This post is dragging on a bit now. Lol.

I am going to strip it all again and triple check everything. When I pulled the carb there was loads of gear box oil coming up from the oil pump shaft. That can't be good. The spark plug was very white with a bit of black. Again not good. I hope that the rotary pads are not causing these issues. How do you even repair them? I don't want to ruin this kit. Expensive. The gap front and rear is about 0.13mm. I read that they should both be 0.5mm. Maybe this is not helping. Are reed valves easy to fit if my pads are worn?

Oil coming up the autolube shaft is good. Up the shaft, round the gear and down the hole next to the shaft. Is called lubrication.

Rotary pads have to be really bad to cause issues.

If your engine just held a pressure test and is not making strange noises, then there's nothing wrong with it.

Carb is just too small for the kit.
https://www.ebay.co.uk/itm/195106585905?hash=item2d6d423d31:g:ekMAAOSwV5RimibH
temporary carb to get you to big7 at the weekend.

Edit: I would run a 2.5mm drill bit through your carb float bowl to check before doing anything

I understand the principle of lubrication. When I took off the carb box, there was too much oil in my opinion. Loads of it sat under the carb box. I ain't going anywhere for a while. Engine is out again. Going to strip it and replace all gaskets before pressure testing and going from there. Thanks for the link to the carb.

How about this carb? https://www.scooter-center.com/en/carburettor-bgm-pro-faster-flow-dellorto/spaco-si24/24e-vespa-px200-type-with-autolube-bgm8570

This would be better
https://www.ebay.co.uk/itm/154548345772?hash=item23fbcc9bac:g:VrsAAOSwHXRfqYdV

Use the float top from the 20/20 if a better type. Drill out to 2.5mm, some pre drilled carbs are only 1.8mm.

Best way to remove crank without proper tools?[/img]

On my P200, I tapped it out from clutch side protecting threads etc. Put a nut on and use a punch to tap out.

Also please don't hit either end of crankshaft so you push two halves together or twist it.

You need to pull crankshaft back in from same side.

So where am I placing the punch? When you say don't hit the crankshaft, what do you mean. I have to hit it with the punch.

So I fit the cylinder onto the two engine halves. Shone a torch from behind. I can see light all the way around the cylinder. They are clean too l. Just not sitting flat at all.

Think of the crankshaft as an accordion, you can tap out from side still in case as your not pushing against anything. If you try to hammer it back in hitting the other end, you will ruin the crank it will accordion and twist.

Screw a nut into the clutch side you are going to tap out from.. then use a rubber mallet to tap it out... Hitting the nut protects the clutch threads. Just don't smack it cause you can unbalance it. Tap tap tap.. it will come out.

It's worth it to get the crank installation tool. Then you don't have to worry about screwing the crank up by hitting it to get it back in. It just pulls into place easily. The tool is not expensive.

I watched the below videos and had never taken a Besos motor apart. I ended up buying tools and watching a lot of video but it was worth it. Motor starts on one kick and I have put on a few hundred incident free miles since rebuild.

Would be interesting to see pictures or a video of what you're seeing, would be helpful to rest of us trying to help you.


This is a good video series to watch, to make sure you get it back together correctly.


https://youtube.com/playlist?list=PLobZTXT9sfxOAGlpg9K4PDM63K-df439M

Another good series to watch,

Engine disassembly.

Engine reassembly

This thing is not moving at all. I will have to take it somewhere to get it pulled out.

Or if you plan on doing this again some time.

https://www.sip-scootershop.com/en/product/tool-crankshaft-sip-disassembly-clutch-side_38886000

80 UK pounds? Too expensive. I will take it to a garage to get pressed out.

For a lifetime of crank removal.