Modern Vespa

Maybe a small leak from the cylinder base. It's hard to tell. These machines are filthy pigs in the best of conditions. As probably mentioned, a pressure test when the case is buttoned up is the best thing you can do. Most after assembly leaks turn out to not be the clutch side seal. Usually easy things to sort out.

I should of mentioned that when I first got my P I drained the gear box oil and that gear oil smelled like nasty old gas.

Hec

That's typical.

If it happens right away on your fresh build you have problems, but otherwise I wouldn't worry.

Lotta leaking going on across the board there. Probably fly side seal, almost definitelyl cylinder base, and 110% the exhaust stub.

SaFis,

You called it! I finally started assembly of the engine and realized the 36 Tooth 4th gear I bought will not work. You were right!
All,
I installed the Cush gear and axle and noticed 4th gear doesn't mesh well with the Christmas tree. In fact it was hard to spin the gears by hand and would lock up in about 2 revolutions. So I removed the 36 Tooth 4th gear and installed the stock 44 Tooth 4th gear. Much better! That gear spun effortlessly and meshed well with tree. So for now I'm running the stock 44 Tooth 4th gear.
I made some progress and installed all 3 BGM Viton Seals, crankshaft, axle, and Cush drive. I also rebuilt the clutch(new clutch plates, drive plates, springs, Malossi gear and SIP grooved bushing), clutch cover and right engine case.
I did try to trial fit the clutch on the crankshaft but it won't slide onto the new Mazz crank. I can get it to go on about 2mm but that's it. It will slide right on the stock crank though. I didn't want to tap on the clutch for fear of messing up the crank. Any suggestions for getting the clutch on?


Hec

Update:

I got my clutch on! I watched FMP's clutch install video and voila! It slid on! I needed to wiggle the Cush gear back and forth so it would mesh with the gear on the clutch. Those two gears are now straight cut so it's critical they mesh on the install! I feel dumb that I didn't put 2 and 2 together and figure it out. At least I didn't take a Mallet to the clutch! Sometimes you just need to step back and take a break from the project ! I went ahead and installed the clutch nut and its locking washer before I closed up the engine as this gave me better access to the Cush gear for wiggling. I torqued the clutch nut to 30 Ft-lbs or 41 Newton-meters. All I need to do is fold a tab on the clutch nut locking washer and install the release plate. Speaking of release plates. I received a new release plate with my clutch rebuild kit. It isn't as nicely finished as the stock one. I don't know if that matters. Should I install the stock release plate or the one that came in the kit?

Next is sealing case gasket to right side case.

Hec

Use the new pressure plate on the right. That one on the left has some wear on it. It's a disposable part until you get to ball bearing pressure plates, and then they last forever.

I don't think I've ever put the clutch on before putting the cases together. not saying it's wrong or anything, but just seems unnatural to me?

one point though, have you or did you tighten up/torque your primary (x-mas tree) before installing/torquing the clutch up?

I don't have any hard reasoning behind it, but I believe that's something that should be done before the clutch. but again, not right or wrong just different than how I've done things.

Greasy,

The securing nut for the secondary shaft was hand tightened when I torqued down the clutch nut. I followed Andre's video regarding this. He does install the clutch after the cases are closed up. So I'll torque the secondary shaft once I have the cases closed up since the secondary shaft is supported by the right side case. That's the plan anyways. So far everything spins easily with no binding.

Go to 5:40 on the video.
Hec

I'm with Greasy...I don't know that there's anything necessarily "wrong" with doing the clutch first, but I agree, it just seems off to me, too.

When tightening the clutch without the fly side it would put a toe curling twisty force on the main bearing. Not for me

All,
So I went ahead and loosened up the clutch nut to just finger tight for now. I don't think I put any lateral stress on the crank bearing when I torqued it initially. I positioned the crank so that it was parallel to the ground which allowed me to put pressure on the clutch nut with the clutch nut tool so it would bite. I had to stand on the fly-side to accomplish this. That's one thing about using the clutch nut tool, you can't apply any lateral forces to it or it will slip off the clutch nut. You pretty much have to apply pressure axially to get it to bite and stay engaged.

I appreciate everyone's comments! Who knows maybe I'll have the engine ready for install before I get the frame back from paint! I'll be checking on the painter this Thurs.

Hec

In theory, having the clutch installed before closing the cases is possible.

only advantage I see is with the woodruff key falling. But a paper towel stuffed into the hole stops all accidents.

Making sure the 3 shafts don't bind and checking the bearings is much easier without the clutch attached.

If things don't align, I can imagine the clutch bearing and seal won't be in a happy place with the crankcase. and you'll have to take the clutch off again anyways.

Best to test the kickstart without a clutch installed too. You'll see if things spin free.

A little surprised you're not looking at a clutch nut upgrade.

Maybe I'm missing something?

To tell you the truth, I didn't even know one existed! Thanks for the heads up! That is way better than Jacking around with the OEM clutch nut! What a PIA! I am definitely going to order one if I can find it! This is what Scooter Speed sells. The lock washer is different.

https://scooter-speed.com/vespa-clutch-nut-hex-bgm-pro-m12-v2i-7671201/

You guys are keeping me heading down the right path!

Hec

Agreed. Sure, castle nuts work, but they're unnecessary pain with modern fastener options.

Update:

I ordered the BGM Clutch that 108 posted. It's coming from the UK. Should have it in a couple of weeks.
So I have moved on to the oil injection. I disassembled it to find hardened grease on the pin and 2 hard O-Rings on the Gear bushing. My SIP Gasket Set had the oil injection gasket and both O-Rings for the Gear bushing! That's great! I did not take the nylon bushing, spring and check ball out. I did run all parts through the ultrasonic cleaner though. I reassembled everything, put a dab of grease on the pin and gear plate, and primed the oil pump with 2- stroke oil. I spun the pump drive shaft counterclockwise and saw oil apear in the flow channel! So it's working fine!

Hec

Good job!

I cleaned out mine and put the air hose to it and promptly lost the spring and ball bearing. Such a bone headed maneuver.

Fortunately Whodatchrome had a set and sent them to me pronto. I haven't made that mistske again!

did you check all the surfaces for flatness? always a quick and easy check while it's apart...

solid work. no stone unturned!

Thanks Greasy! I didn't check for flatness . The surfaces looked good! That SIP gasket is extra thick! Fingers crossed that I get a good seal.

Here's a question for everyone. Is this hole an oil return passage for oil that is drawn upward by the spiral cut grooves on the oil injection drive shaft allowing oil to drain back to the clutch side of the case? This passage was completely clogged up with black grime. Its clean now!

Hec

Could the hole in your first picture be for the cylinder stud? I think one of them is drilled straight through. If the stud is screwed in too far it can interfere with the pump shaft.

I will take better pictures of the passage tonight and post them.

I do know that the upper left clutch cover bolt will interfere with the pump shaft if its screwed in too far. I learned this while using the clutch holding tool. I had the tool attached to the upper left clutch bolt and I had it threaded in all the way for fear of stripping threads. Then I went to install the pump shaft, while the clutch holding tool was still in place, and the pump shaft wouldn't drop down in it's bore. I scratched my head for a while until I figured that one out!

Hec

Here's what I am working on now. I am building an engine pressure test kit to pressure test my engine when it's done. This design is right out of the MacGyver School of Engineering Class of 1996!


I have built an intake block off plate out of 1/8" plate steel using the air box gasket as my pattern. The plate is slightly oversized for now.
To air up the engine I was thinking of using a piece of wheel barrow inner-tube to act as the sealing gasket and utilize the Schrader valve to supply the air. I am planning on cutting a piece of inner-tube big enough to span the block off plate and center the Schrader Valve on the intake opening. I figured what the heck, I need a gasket and way to put air in so why not use a piece of inner-tube. I still need to drill the hole for the Schrader valve to pass through the block off plate.
I have a cordless tire inflator that I can set to deliver 5 PSI. It has a digital pressure read out so I can monitor pressure. It will stop pressurizing once it achieves the desired set pressure. I currently use this inflator to connect to a Schrader Valve I installed on my 25 gallon portable fuel caddy's gas cap. I pressurize the fuel caddy with 5 PSI of air which allows me to transfer fuel quickly and fuel things higher than the fuel caddy. Works Great! Just like being at the gas station pump!
I would block the exhaust spigot with a rubber plug.

What do you guys think?

Hec

Looks good - a nice thick piece of inner tube is what I use too. Good job!

this is what I did as well. plate with a valve and inner tube gasket. I used rubber cement to glue the gasket to the plate so it's less fiddly fitting and I wouldn't lose it.

I've always used a mityvac to pressurize but going to switch to a BP cuff and dial instead that way I can keep everything together as its own testing kit.

All,

Here are some better pictures I promised earlier. As you can see, I have inserted my oiling tube in the hole ,next to the pump shaft bore, on top of the engine. You can also see where the passage enters the clutch side of the case.
Tonight I ended up drilling and tapping a hole 1/4"NPT for a Schrader valve in my pressure testing block off plate vs using one from an inner-tube. I did cut up an old inner-tube but didn't like the bulge in the rubber caused by the Schrader valve. I have a roll of black EPDM rubber that's the same thickness as an inner-tube. It's smooth on both sides unlike an inner-tube. I glued the rubber to the block off plate using some very strong contact cement. I'll let it dry overnight then trim it up. The block off plate fits nicely too!

Little by little!

Looks similar to my block off plate but a million times better.

I put a piece of silicone baking mat under an old carb body to block off my SI intakes. It was leftover from my homemade vacuum chamber when I was experimenting with resin pouring and works perfectly.

Update:

Today I took inventory of the parts I have ordered and realized I am short 4 M-7 lock washers. So I won't be able to torque the case bolts down till I get some. Speaking of case bolts. I ordered a case bolt set from Scooter West. I think the original black case studs are made out of harder steel than the new ones. Should I reuse the originals with new hardware or the new case bolts? Probably overthinking things again.
I prepped the right side case for installing the case gasket. I took the case bolts and wrapped blue painters tape till they fit snug and wouldn't fall out. This did two things. It centered the studs in the holes and also centered the case gasket on the case bolt holes. I applied Elring Dirko HT sealant or Sealing Mass for you party peoples over seas! I applied a thin coat on the right side case sealing surface and then installed the SIP case gasket over the case studs. I applied even pressure to the case gasket using a plastic scraper and small flat screwdriver and wiped away any excess that oozed out. I'll let it set up overnight for good measure then assemble the cases.

I think I am ready to assemble cases.
* New Bearings and respective retainers and cir-clips are in
* New Viton Seals are in
* New Mazz Stroked and Cut Crankshaft with it's bearing race is in
* Secondary shaft rebuilt with Malossi up gear kit is in
* Axle assembly has been checked and reassembled with all original 4 gears. BTW the axle has .15mm of float too! is in.
* Oil pump drive gears, shims and circlip are in
* Plastic oil diverter is in.

I think all I need to install is the new kick starter spring and new kick start gear. The right side case has all been gone through with new kick start bumpers, bearings and seals, and kick start shaft 0-ring and case gasket sealed to it.

I hope I'm not forgetting anything?

Hec

Here's the finished block off plate for pressure testing. I think I'll leave it installed to keep crap from falling in on top of the rotary valve until it's time to mount the carb!

Hec

1) leaving it in place is a pretty good idea
2) I think you have the nicest pressure test blanking plate I've ever seen.

Yeah, that's pretty slick.

Thanks for the nice compliment! I fabricated it using my angle grinder, a drill and 1/4" NPT tap. No special tools needed. I had everything I needed to fabricate it just laying laying around.

Just as a demonstration, I had my cordless inflator set to 5 PSI. With the rotary valve closed the pressure got up to 3.5 PSI. See pic .

Let's hope the Scoot also turns out good!

Hec

Here are some pics of the engine in its current state of assembly. I think I'm ready to close it up now. Please take a look and let me know if anything needs attention. In preparation for closing I have cleaned the gasket surface with alcohol. The right side case is ready to go! Still waiting for the delivery of my BG Pro clutch nut. Everything spins freely by gabbing the kick start gear and spinning it. All gears engage and disengage too.

You guys have an Eagle Eye for details!

Much appreciated!

Hec

stop obsessing and put it together.

Good looking moist maker.

This.

Greasy,

I put the O in OCD!

I will proceed with closing up the engine.

Stay tuned.

Thanks guys!

Hear-ye, Hear-ye!

The engine is closed up! I greased all the shafts, lubed the gears and con-rod bearings, right side case bearings with 2-stroke oil. Then I applied a thin layer of the Elring Dirko HT sealant to the other side of the case gasket already sealed to the right side case. I lined up the right case and pulled down on the kick start lever. The right side case slid right on. I only needed a few light taps with the rubber mallet and she was on like Donkey Kong!
I installed all new M-7 hardware and reused the original case studs. Blue loc-tite was applied to all threads. I initially torqued everything to 15 Newton-Meters starting with the 4 center studs then moving on to the case studs. I repeated this with 18 Newton-Meters of final torque.
Kick start lever ratchets and rotates the crankshaft nicely. I then checked the Rotary Pad clearance at the front and rear of the intake opening while rotating the crankshaft forwards and backwards. A 0.08mm feeler gage will lock up the crank shaft. A .07mm will slide tightly but not lock up the crank. So I'm good! I'll trim the excess gasket material from the cylinder base area tomorrow.
The VMC Stelvio 177 top end is next for install. I am waiting on my Cosa Performance Gudgeon pin installation tool to come in first.

Stay tuned!

Hec

Definitely closed at that torque. Still no guarantee it won't oil suck. Cylinder on then pressure test.
What was the port timing decision? Bolt it up and hope for the best?
Looks very clean.
If the piston is hot, the pin will slide in.