Chains 66cc HT shifts over and loosens chain during riding

[aaronreihl]

Hey guys, lurked around here for quite a bit and got a HT kit just to play around on and didnt expect any German engineering or anything of that respect.
I am having a weird problem that I haven't read at all here yet. My HT engine is mounted on a 90s 26" men's Schwinn Mirada Sport. After a ride longer than 10 minutes or so, my motor shifts over on the tube of my bike, causing my pedal to grind into the plate covering the magneto ignition thing, and my chain to loosen. I've tried anything I can to remedy this except Loctite on the head studs before I tighten the nuts and buying a new chain. More inner tube, less inner tube, no inner tube, running without a chain tensioner, shortening the chain, and I've drilled a set screw into the mount facing my front wheel to hold it to the tube. It warped over and I noticed after 20 minutes of riding the screw nearly fell out from the vibrations . I pushed the engine over with my jacket protecting my hand and tightened the screw back and that got me home.
Is the solution sitting right in front of my face? I'm thinking I need to buy some loctite (blue?) and tighten the nuts on the studs and wait 2 days or so for it to cure, and then try it out.
Thanks for any suggestions.

 

[HeadSmess]

make sure the rear mount is sitting square on the frame. shim the front. try a strip 3mmx10x25... rather than wrap something around the tube...

make a head steady bracket that mounts onto existing cylinder studs and goes to top tube.

weld the mounts on. replace studs with bolts.

if its twisting it simply isnt tight enough and loctite isnt going to do a thing.

some people make a bracket up that goes from the long bolt for the clutchcover/chain guard to the seat tube... depends which way its twisting if that will work...

 

[motorpsycho]

"I've tried anything I can to remedy this except Loctite on the head studs"

What would this have to do with your engine moving to the left?

 

[aaronreihl]

It was just an idea, and I thought it was shifting because of the vibrations moving the nuts and allowing the motor to shift freely. The set screw is working okay, but it doesn't hold up well. I did find an old thread yesterday about the same issue, and it was because of the bike he used. That makes sense, as the bike it's on right now is a lightweight aluminum all-terrain bike. I will try the solution he posted, it looked like he took a piece of steel and bent it into an L and drilled holes in it, securing the clutch housing to the seatpost tube.

 

[Al.Fisherman]

Sure fire way of keeping the engine upright without over tightening the nuts on the studs.


Also make sure that the engine is mounted correctly. Here are some tips.
http://s982.photobucket.com/albums/ae309/Ron-Becker/Engine Mounting/

 

[aaronreihl]

Ah yes, that's the picture I saw. Thanks.

 

[HeadSmess]

get a steel frame.

alloy may just try and kill you one day.

 

[Big Red]

Frame

I think HeadSmess is right. I've NEVER had good luck with aluminum frames. The vibration digs into the soft metal and loosen's the engine and will sooner or later break the frame. I'll still do an aluminum frame for a customer if they insist, but will warn them of the perils of this choice. Rubber mounting helps some, but a steel frame is still the way to go. Bicycle makers use aluminum for the weight factor. They assume you will only be peddling the bike. They don't even THINK for a moment that some crazy people like us are gonna strap an engine to it. I'm sure you will get some that think an aluminum is just fine, and of course this is just MY opinion, GET A STEEL FRAME.
Big Red.

 

[HeadSmess]

yup.
aluminum has no fatigue limit. bend it a little, bend it a lot, it all adds up to reduce its lifespan. a million tiny taps, three good whacks...all the same.

steel on the other hand, can be bent a certain amount an infinite number of times without failing. once this amount is exceeded, then the lifespan is reduced. a million tiny taps wont do a thing but make noise. 3 good whacks would seriously weaken it but still not fail... four would.

something like that

an engine at 6000rpm is 100 up then down shakes a second.... addds up real quick...

(dont ask what the piston is made of cus metallurgy is complicated!)

and a pushy isnt meant to have an engine on it as red said

 

[Big Red]

Frames

yup.
aluminum has no fatigue limit. bend it a little, bend it a lot, it all adds up to reduce its lifespan. a million tiny taps, three good whacks...all the same.

steel on the other hand, can be bent a certain amount an infinite number of times without failing. once this amount is exceeded, then the lifespan is reduced. a million tiny taps wont do a thing but make noise. 3 good whacks would seriously weaken it but still not fail... four would.

something like that

an engine at 6000rpm is 100 up then down shakes a second.... addds up real quick...

(dont ask what the piston is made of cus metallurgy is complicated!)

and a pushy isnt meant to have an engine on it as red said

Exactly right HeadSmess. NONE of them were meant to have an engine on them, but if your gonna, Steel is about your only option.
Big Red.