Modern Buddy

Okay guys any sites I can get a complete bottom end rebuild kit. Just had my scoot freeze up on me . I have a new top end on it just looking a whole bottom end rebuild . Thanks guys

Howdy, Neighbor.

Sometimes its hard to find a one-stop shop. I got nearly all the stuff I needed from David at http://scootermercato.com/
The rest from
https://www.sip-scootershop.com/

Instead of a kit, I just ripped everything apart until I knew what parts needed replaced.

For the bottom end you definitely have to disassemble it to see what youre dealing with.

What specific problems are you dealing with to make you focus on the lower end?

mjrally wrote:For the bottom end you definitely have to disassemble it to see what youre dealing with.

What specific problems are you dealing with to make you focus on the lower end?

Agree fully.

Also agree with using Mercado. Highest quality bearings I have found, no counterfeits.

There are parts that are sacrificial like the cruciform and other "as long as I'm in here" things but there is a lot going on in the bottom end.

So what is the problem? Seal leak, twisted crank, dropped woodruff key, chipped teeth, clutch asploded, blown out cush drive? etc. You won't know until the cases are split.

As said there is no "rebuild kit". There are parts that wear or break and need to be replaced. If you replace every part it will be cheaper to buy a new or rebuilt motor.

Bnutty wrote:Okay guys any sites I can get a complete bottom end rebuild kit. Just had my scoot freeze up on me . I have a new top end on it just looking a whole bottom end rebuild . Thanks guys

Please tell us more about new top end and "freeze" Sounds like a tight new top end seize or carb not properly jetted. ere the ports chamfered, ring gaps and piston clearance checked?

Have you pulled the top end or at least taken a peak through the exhaust port?

Well after taking the motor out and building a stand so I can work like a gentleman. I have found that the lower ports(cutouts) of the piston broke and currently having a party all inside the casing

So I will be doing a full tear down . Thinking about going the big bore route with forged crank and so on .

Pretty much this all started with having no compression bought an lml stock top end installed it idled great then for the test drive the piston was destroyed lol . I have no idea what I did wrong but at least ill learn how to fully rebuild these motors aha

What top end did you use and where was your timing set at?

Sorry for the late reply! I'm pretty sure I got a stock lml top end from piston and ported but I would have to double check to be sure . Had a friend check the timing ( im new with vespa and two strokes period). He said the timing was good so there was that .

But im well into a full build now, I just pulled apart the casing tonight and had to stop 0n the clutch castle nut because I decided just to buy the specialty tool before I ruined it .

I did find two cracks in the crankshaft housing on the flywheel side of the casing . Not sure if the other side is messed up untill I get that damn castle nut off . So if anyone can point me into the right direction to get a flywheel side crankshaft casing ill appreciate it . If both are cracked from what I seen I may be better off buying a new motor .

Thanks guys I appreciate the guidance this is a huge learning experience for me with these motors . So by the time this is done I should be pretty spot on with these motors hahaha

Ouch! Sorry to hear about the cracks in the casing. Are they really cracks or just casting marks? Sadly you cant just buy one half of an engine case. The two are mated together from the factory. Replacement cases are very pricey. Might be better to find an aluminum welder.

How was the top end? You said your friend inspected it. Did he notice any seize marks? Have him check your crankshaft big end bearing.

You originally said your wanted to find a bottom end kit. Now that things are opened up, have you found your problem? What was it?

Unfortunately the top end is junk I could possibly rehone it but would just rather go with a different top end . I didn't chamfer the ports on the newly installed top end and piston so I'm assuming it got caught up and broke the cheap lml piston.

My thing with welding the casing the cracks are on a thin lip right where the crank rotates . Im worried about warping and clearances. Guess it doesn't hurt to try since it is pretty much junk how it sits .

So did the piston shatter causing the lockup? Pics now that you have things disassembled.

On the lip you could also JB weld the hell out of it. That way you dont warp anything. Again pics!!

I'll take some pics either today or tomorrow. Its in my buddy's shop . And yes the piston shattered causing the lock up .

I don't think it's time to blame the LML piston yet, especially since you said you didn't know what top end it was. Saying that someone said the timing was good really doesn't provide any info we can use to help.

If the ports weren't chamfered it leads me to believe a lot of other things weren't done quite right either. That's kind of top end 101 day 1. Ring gap, piston clearance, squish, heat cycling and retorquing the head etc?

So what happened? I don't have a clue. Could have just snagged a too tight ring on an unchamfered port and then...yeah that could easily do it.

Do you have a flywheel puller, clutch holder, clutch tool, piston stop, degree wheel, etc? You will need them.

If I was in that position I would junk the top end and the side case, both have already had the snot jacked out of them. Don't forget to check the crank that it's not twisted. Start pulling parts out and keep them for spares.

It sounds like you may be better off sending this out to be repaired or just replacing the entire motor.