sachs g3 pipe problems please help!

so im working on a friends sachs g3 with the 75cc kit gianelli pipe. my friend daniel used the wrong bolts and stripped the holes so i had it retapped and helicoiled. the bolt/washer configuration didnt work out too well as the bolt kept vibrating loose so i put green loctite and ground down an allen bolt ( what it originally had ) to work.. another reason i think the pipe kept coming off was that the rear mounting bracket my friend had wasnt sturdy enough. as a matter of fact it didnt really suspend it at all. so that exhaust is kickin around chewin up the manifold against the cylinder. i cut off the little mounting bracket in the rear and rewelded it to the proper place and used a flat piece of metal as an extension to bolt it to one of the sidecover bolts. now this thing held real sturdy and didnt budge one bit. today i test rode it for 15 minutes and i know the engine is vibrating real hard and the pipe (where the header clamps onto the flange) just snaps. so now i have a flange bolted to the head and no neck.

can someone tell me whats wrong and why it did that? are sachs engines supposed to flex? did i make that mount too rigid? ive only really worked on puchs and never had a problem like this. please help me!

Re: sachs g3 pipe problems please help!

That's pretty strange, I know on the sachs 505's they do have rubber mounting bushing type things, but at most they could only flex +/-1cm MAYBE in the most extreme case. I suppose if your mounting arm was ungodly rigid, it could be the engine flexing, but really unlikely.

I guess make sure that the mounting arm wasn't forcing the pipe into an unnatural position to begin with. But to be honest, maybe running it previously unsecured weakened the metal/welds on the pipe.

Re: sachs g3 pipe problems please help!

a mount that attaches to the bottom of the engine case would be ideal. I don't know how thght those pipes are, but I've found that a lot of stuff can be made from 1x1 aluminum angle stock. Bicycle reflector brackets have worked wonders for me too.

Re: sachs g3 pipe problems please help!

i think there may be a little flex in the design

Re: sachs g3 pipe problems please help!

well originally the bracket didnt hold it up at all. the one i made was in fact ungodly rigid. i do know a puch would respond well to this but then the engines dont have any play at all. ive never worked on a sachs. remember its a right side mounted pipe so i dont know what the left side mount looks like whether its rigid or not. thanks for the input ill look into it tomorrow

Re: sachs g3 pipe problems please help!

Stock Sachs pipes are mounted very rigid. i've been having nothing but issues with my exhaust as well... i've worked with stock 25/30mph pipes, stock 35mph pipe, and a modified Bullet. The larger stock pipe didn't like the mount for the original, but it did work with a bit of modification. It was too restrictive for the 70cc though, and I did have the pipe blow off the flange a couple times (using the stock clamp and even tried a BMX seat clamp too). Alternatively I've also lost the bolts twice now, which causes some problems.

I've noticed my motor moves A LOT. It always has. Seems to sway back and forth when sitting still as much as a CM each way...

At this point i'm temped to have a flange cut and welded onto the pipe (like most every other bike out there) and install some studs...

Re: sachs g3 pipe problems please help!

Same problem I have with the engine swaying left to right, it gets really scary past 40mph but so far no injuries...

Re: sachs g3 pipe problems please help!

the thing is that the flange neck snapped right off. :( i dunno what to do. what material is the flange made out of? i dunno if it could be welded

Re: sachs g3 pipe problems please help!

Joe

remove the flange and use that as a template to make a new flange out of steal and have it welded to the end of the pipe.

fuck working with the neck

get some studs (i'm pretty sure VW Rabbit exhaust studs are the same size) and you should be good to go

i'm REALLY thinking this is the only way to do it right on Sachs kits.

the reason i suggest studs is that they provide a different force than bolts. Find a car out there that still uses bolts for exhaust manifolds... You'll also be MUCH more unlikely to strip the cylinder with studs than you are with bolts every time you need to remove the exhaust to de-carbon.

Re: sachs g3 pipe problems please help!

youre right. it seems that the stock pipe is mounted to the botto m of the engine given some pics. i may be wrong but it would make more sense so that the pipe moves with the engine without snapping it

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