Engine mount disaster

M

madscihighpsi

New Member
This started by a week of running perfectly smooth. I checked the bolts put thread locker on them and made sure everything stayed tight.

The problem started when I was making my trek home from school. I felt a slight wobble while doing around 20mph and the next thing I know the engine felt like it locked up, a huge pain in my leg, and the rear tire screeching to a halt.

After pulling over I looked at the back of the tire. The tensioned had gone in between the spokes and the chain had snapped.

I strapped the chain around the handle bars tucked my tail between my legs and pedaled home... I have taken apart my motor and found out the motor mount broke. The one broke during the accident and the other when I tried to remove it.

To repair the rear mount I drilled and tapped the one to accept a larger bolt. Then I replaced all the others with grade 8 bolts.

I took the burs out of the tensioner and tried to see if I could at least get the thing to slide right but it won't slide right. So, I then decided to try the sprocket took it off and it seemed straight I took it off and checked it put it back on and it seems to twist on the top between the engine and the sprocket and throwing the tensioner into the wheel.

I bought a new tensioner, and upgraded 32 tooth sprocket. I am decided whether I should buy a new rim along with a new chain.

I have 50 miles on the bike if you can please let me know if anyone else has experienced this.
 
madscihighpsi said:
This started by a week of running perfectly smooth. I checked the bolts put thread locker on them and made sure everything stayed tight.

The problem started when I was making my trek home from school. I felt a slight wobble while doing around 20mph and the next thing I know the engine felt like it locked up, a huge pain in my leg, and the rear tire screeching to a halt.

After pulling over I looked at the back of the tire. The tensioned had gone in between the spokes and the chain had snapped.

I strapped the chain around the handle bars tucked my tail between my legs and pedaled home... I have taken apart my motor and found out the motor mount broke. The one broke during the accident and the other when I tried to remove it.

To repair the rear mount I drilled and tapped the one to accept a larger bolt. Then I replaced all the others with grade 8 bolts.

I took the burs out of the tensioner and tried to see if I could at least get the thing to slide right but it won't slide right. So, I then decided to try the sprocket took it off and it seemed straight I took it off and checked it put it back on and it seems to twist on the top between the engine and the sprocket and throwing the tensioner into the wheel.

I bought a new tensioner, and upgraded 32 tooth sprocket. I am decided whether I should buy a new rim along with a new chain.

I have 50 miles on the bike if you can please let me know if anyone else has experienced this.
Click to expand...

I had an almost simliar experience but instead of the tensioner getting into the spokes on the tire My tensioner wheel fell off on the side of the road. suffice it to say I spent the better part of two days walking along the side of the road looking for the thing.
 
mad...you can buy steel sit pins at lowes...they are about 1/8 dia...you drill a hole smaller than that thru your tensioner and frame...all the way thru...tap the pin in so it goes thru both sides...i also put Goop on the frame and the inside of the tensioner before you put it togeather...good luck that should solve the tension problem...Dennis
 
I will try that once the new tensioned comes because I feel like the old tensioned is so messed up that it won't be able to function properly.

Does anyone have any good techniques on how to balance the rear sprocket onto the rear wheel?
 
I think if you will look for the sticky on swapping a 44 tooth rear sprocket to a 36 tooth sprocket I show how to aline the sprocket to spot the wobble side to side and up and down.
for the tensioner look at the sticky tensioner.
both of these stickys are in Norm's two stroke repair center
 
One would think that one terrible experience with a tensioner would teach a lesson ~ get rid of the tensioner and make your chain the correct length, to begin with!

Those things are potential death traps and yet people keep using them!
 
DudeZXT said:
One would think that one terrible experience with a tensioner would teach a lesson ~ get rid of the tensioner and make your chain the correct length, to begin with!

Those things are potential death traps and yet people keep using them!
Click to expand...
DudeZXT,
You must keep in mind that all bikes will not allow for running without a tensioner. Frame clearance, non-adjustable drop outs etc. dictate that a tension of some design be used. When properly installed and secured against movement they serve the purpose they were intended for without trouble.
This subject has been hashed to death and thousands of words have been written dealing with the tensioner issue. Still people install them without securing them properly and fail to get or keep the chain tension/alignment correct which leads to the problem the OP had.
It is unfortunate that there isn't a way to get this message out to newbies before they destroy their rear wheels or injure themselves by not heeding the good advice that can be found here with just a little effort.
Tom
 
yeah I installed my engine on my bike before I saw this forum and the first thing I did was drill the freaking tensioner down and into the frame... so it will not move anywhere. Now I am stuck with the problem of a crankcase that had a broken thread tried to drill and easy-out it but it wouldn't work so I oversize drilled and tapped for a bigger bolt but still didn't work so I jb-welded a bolt in there. Any other suggestions for making the engine more secure? I feel like the mounts are so fragile (I did the grade 8 bolt upgrade.)
 
The mounting is/are fragile and the best strength is when they are mounted firmly seated on their place to be mounted, then clamped tight(6 -7 foot pounds is all,I think, not much at all) set at an angle won't allow them to work,kinda like setting a water glass balanced on an edge or set it down like it wsa ment to be,flat on the bottom
 
DudeZXT said:
One would think that one terrible experience with a tensioner would teach a lesson ~ get rid of the tensioner and make your chain the correct length, to begin with!

Those things are potential death traps and yet people keep using them!
Click to expand...

I feel the same way. MUCH HATE for the tensioner.
 
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