Dangerous chain jaming ..

If you put a longer bolt through the clutch cover and housing.
The one right by the seat tube and attach a small metal bracket to the bolt to brace the motor against the seat tube it will not tip too the left.
But the chain will still stretch and come loose.
BTW there isn't anything we can do about the 10T
 
One of the reasons i went with friction drive (despite the inefficiency) was because of "paranoia" about chain jamming, it happens often enough on regular bikes. I think if i was to upgrade i would go with a belt drive.
 
Hi Bobby. I think that a spring tensioner is a necessity on these things. In my opinion, to make things reliable and trustworthy, we need a decent roller on the bottom as a main tensioner, then an additional spring tensioner on the bottom to take out slack as the chain tightens/loosens as it rotates and a simple non-roller UHMW (ultra-high molecular weight) plastic guide on the top to stop the chain jumping around too much during starting/throttle off/downhill with clutch in.
... Steve

Hi Steve ,
I've built a good spring tensioner out of 2 ball bearing nylon glass door rollers , works OK .
Think I've fixed the jamming problem by taking off the clutch cover and bolting a half rubber brake shoe in the top left corner where it always kinks up & locks the back wheel .
Had to drill a hole through the inside casing for the thin bolt to hold it in place , now it can't lock up !
Also its now got a rubber stopper bolted to the seat tube to stop the chain flicking up .

Have Fun
Bobby.
 
If you put a longer bolt through the clutch cover and housing.
The one right by the seat tube and attach a small metal bracket to the bolt to brace the motor against the seat tube it will not tip too the left.
But the chain will still stretch and come loose.
BTW there isn't anything we can do about the 10T

Good idea thanks , as for the 10T , beats me sorry .:unsure:
 
Hi All,

Has anyone solved this HP motor engineering flaw when the chain gets bound up trying to clear the small drive sprocket causing the back wheel to lock up .

.

Is HP the same as a Happy Time? If so mine had the same problem. The chain that came with mine I think is a 415.

It looks to me that the chain is having a problem getting over the very tall teeth of a very small front sprocket and sometimes climbing it. I have read in the past that some have filed on the front sprocket but I couldn't remember where on the teeth to do it. I was going to do that but my kit didn't come with a puller.

Then I just figured fug it and rode the thing as a bicycle for a few miles with the clutch lever pulled in. That seemed to help things match up a bit.

After that I got the thing running and it seems that when the chain is being pulled tight by the motor there hasn't been this problem however it can still be seen when riden as a bicycle.

(granted Ive only got about a mile on the motor and there is still time for a chain related catapult)

I don't know if any of that can help you but I did notice that lubeing up the chain real good helped a bit. Also that the chain is rubbing against the clutch cover a bit and against the engine quite a bit. Hopefully it wont self-destruct.
 
I think that Bobbyoutback is on the right track. A guide inside the countershaft cover that only allows room for the chain to stay on the sprocket sounds good. I'd still use that white, high density plastic (UHMW) that's used on dirt bike chain tensioners etc., though, for longer life.
meatwad, I found that mine definitely was worse when backing off the throttle, rolling down a hill etc. That's when the top of the chain is loose, allowing it to pull off the sprocket. If your chain is also hitting the engine case or mounting bracket, then the chain is probably a bit too loose.
If you turn the back wheel until the chain is at it's tightest, then adjust the tensioner until you have about 1/2", (13-15mm), of slack, you'll reduce your problems.
I've tried centring my back sprocket so that the chain tension remains even, but I'll need to file out the sprocket's centre hole to do it properly. I still get a little bit of variation. That's why a spring tensioner would be good on the bottom to remove slack while under power, with a guide on the top to keep the chain in line when the throttle is backed off or during starting.
... Steve
 
You know, in my opinion this is the weakest link with these kits. Over the next week or two I'll get the new tensioner setup organised and see how it goes.
I have plenty of faith in the engine, it's running reliably and at a nice temperature etc, with over 200 km, (120 miles), on the clock, but I'm cautious about going too far from home with the standard chain setup. It's an accident waiting to happen. (I'd give my right arm for a shaft drive strong enough for these engines.)
...Steve
 
Is HP the same as a Happy Time? If so mine had the same problem. The chain that came with mine I think is a 415.

It looks to me that the chain is having a problem getting over the very tall teeth of a very small front sprocket and sometimes climbing it. I have read in the past that some have filed on the front sprocket but I couldn't remember where on the teeth to do it. I was going to do that but my kit didn't come with a puller.

After that I got the thing running and it seems that when the chain is being pulled tight by the motor there hasn't been this problem however it can still be seen when riden as a bicycle.


Also that the chain is rubbing against the clutch cover a bit and against the engine quite a bit. Hopefully it wont self-destruct.

Hi there Meatwad its a HT not a HP my typo whoops "
I have never had to file the sprocket teeth down on my bikes , nor any rubbing on the housings , sorry can't help there.
 
You know, in my opinion this is the weakest link with these kits. I'm cautious about going too far from home with the standard chain setup. It's an accident waiting to happen. ...Steve

Yep Steve thats the worry , notice that when the motor is not pulling the chain under power the top of the chain slops about ( even when tension is right ) causing the lock ups .
This can happen anytime unless they are modified ..
 
meatwad, I found that mine definitely was worse when backing off the throttle, rolling down a hill etc. That's when the top of the chain is loose, allowing it to pull off the sprocket. If your chain is also hitting the engine case or mounting bracket, then the chain is probably a bit too loose.
If you turn the back wheel until the chain is at it's tightest, then adjust the tensioner until you have about 1/2", (13-15mm), of slack, you'll reduce your problems.


Yeah I think I'll try to take more slack out of it and see if that helps. Also like the guide near the front sprocket idea. Thanks.
 
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