Unable to mount engine correctly

L

Lachiepower0402

Member
Hi everyone,

I have a Ebay chinese 48cc motorised bike which I am having troubles with mounting it seems to be in a good spot but I just can't get it to stay still, no matter what I have done the motor still moves from side to side if i move it with my hand which doesnt require much force.

I have bought a threaded rod and cut it up and replaced the studs, then I locktitted the thread inside and out. Waited 24 hours and all i had to do was run it and it was loose again. What makes it even worse is I cant do the nuts up very tight because the last time I did that the stud opposite it popped out of the thread when it was screwed in.

I am sorry if I rambled on but I frustrated with my awesome engine.

Thank you in advance
 
Pictures are going to help a lot. Is the treaded rod you installed the same thread size as original studs? How long are thee rods you installed?
 
Some members have rigged up a 3rd, top motor mount between the head and top tube, The 3rd motor mount normally isn't necessary.
 
The photos are attached in the 3 posts following this message because I can only upload one photo at a time on iphone. Also I would be interested in the top motor mount, Would this be possible with my build?
 
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I have seen pics of top motor mounts but I had no luck searching for them. The top motor mounts are home made. There are really more of a support strap. They restrict the movement of the top of the motor, which helps the front and back motor mounts stay tight.
One end is bolted to a head bolt in the top of the engine. The other end is bolted to a clamp on the top tube. The best material for the strap is usually a piece of thin wall steel tubing, available at hardware and home improvement stores. Hammer the ends flat, like 2 inches on each end. Leave the rest round.
Drill holes in the ends and bend them as needed for fit.
The clamp on the top tube can be a conduit clamp. If the clamp has no padding to protect your paint, use bicycle handle tape or some old inner tube.
 
a bit hard to tell from the pics, but you may have the rear mount too high

the rear is where all the force goes and should be mounted such that the studs are nicely perpendicular to the bike frame - I also like to saw off a bit of PVC pipe and put it between the mounting block & the frame to make a solid seat (I sometimes use more PVC at the front to fill space if it fits a bit short of the frame tube)

note also that the studs will always stretch for the first several miles and need re-tightening before every ride for a week or so
 
I don't know if can tighten any of the mounts because they are all locktited. But I have tightened my chain and now the motor does not move as much because the chain is tighter. I will probably have to make a top motor mount to fix my problems. What kind of deflection should I be getting on the chain.

I also tried putting a bit of hose inbetween the seat tube and the mounting bracket about a month ago and it didn't make any difference.
 
Do not put any rubber between the engine and the frame. That will only cause you more problems.
Proper chain tension is 1/2" to 3/4" of slack. To measure the slack you'll need to leave the clutch engaged then gently roll the bike forward until the piston comes up into a compression stroke. At that time the top, upper chain run will go slack. That is where you want to measure.

Good luck.

Tom
 
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