I'll upload pics later if I get time, but I finally finished the mini bike yesterday. It's scary fast, but the problem is that it's idling super high and it engages the clutch as soon as I start it up. And it keeps throwing the chain. From what I can see, it looks like it's aligned perfectly. But I'm glad that I just kept the motor stock. adding more would just be overkill. it's not as torquey as I thought it was going to be, which is fine because it's right where I want it to be performance wise. I'm going to have a lot of fun when I get this chain issue straightened out.
Manco Thunderbird build
- Thread starter kycustoms
- Start date
The chain popping off even when it looks straight can be caused by a couple different things or a combination of things.
Are you using the old chain? If so, that could be the issue. I've experienced this on a couple mini's and also on my T-Bird. I tried aligning things, tightening the chain etc to no avail. It simply was stretched and wouldn't line up with the tooth spacing on the sprockets and it would come off. A new chain solved all issues.
Buy a new chain and try that.
Another issue is a known problem with T-Bird's. The engine mounting plate will twist or flex when TQ is applied. You need to reinforce it good and solid to stop that from happening.
Idling fast? Are you still using the governor? How did you hook up your throttle cable? Have you tried turning the idle screw counter clockwise to lower it?
Slap on a new chain and stiffen the motor plate and you'll be doing wheelies very soon.
Danford1
Are you using the old chain? If so, that could be the issue. I've experienced this on a couple mini's and also on my T-Bird. I tried aligning things, tightening the chain etc to no avail. It simply was stretched and wouldn't line up with the tooth spacing on the sprockets and it would come off. A new chain solved all issues.
Buy a new chain and try that.
Another issue is a known problem with T-Bird's. The engine mounting plate will twist or flex when TQ is applied. You need to reinforce it good and solid to stop that from happening.
Idling fast? Are you still using the governor? How did you hook up your throttle cable? Have you tried turning the idle screw counter clockwise to lower it?
Slap on a new chain and stiffen the motor plate and you'll be doing wheelies very soon.
Danford1
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I wish it were that easy with the chain. the clutch chain and sprocket are brand new. Now I didn't think about torque flex, but I don't think that is the issue. My best guess, and I've been at work all day to ponder this; and either the motor is vibrating backwards and giving the chain too much slack causing it to throw the chain or it's out of alignment just barely enough to throw it. And I am still using the governor. All the reading I've done today tells me that I need to check that throttle bolt that was tightened down for shipping and make sure that the idle screw is out, and to make sure that the butterfly isn't stuck open. if none of those fix it, I will post a video or some pics of my issues.
Torque flex is going to be a contributor. Rather than weld up the plate like Danford did, I used the engine and made a girdle to lock the front of the plate to the engine. Since the rear of the engine sits right on the cross member, it'll lock it in place. Worked great with the GC160 I had on my 'Bird.
I made that with a sawzall, a wooden mitre box, 1/2" hand drill, and an angle grinder. I posted details in my Manco budget Build (which became the usual money pit). Took about an hour and a half. :thumbsup: Since I sold the 'Bird, I don't have the means to take measurements anymore. But thanks, guys!:thumbsup: