1st build and a couple of questions

Shadeslay · #1 03-09-2009, 10:06 PM

I've had it together about 2 weeks now and tinker with it every other day.

At first I was little disappointed with the power but it seems to be gaining power. And runs a lot better after changing the plug and a few other tweaks. But I've run into a couple of minor issues I just can't figure out.

Low end power, it really bogs down on take offs. I've read it could be the mixture "running 20:1" for the break in. And I've read I could go to 24:1, but when I look at the plug it's actually slightly tan colored which suggests it might be too lean of a mixture "I think" for break in?

Second is the chain, when I put the clutch in and roll the bike, the chain goes tight "almost to tight, then loose "almost too loose. My first thought was the sprocket was mis-aligned. But I really don't see how, it was a perfect fit over my dust cap and I actually had to tap the last little bit in so it was snug. And looking at it when I roll the bike there is hardly any side to side wobble. My second thought is the rim, which doesn't look bent. But I'm really not sure where to go from here other then replacing both the rim and sprocket and hoping that fixes the problem.

Third thought just came to me as I was writing this, could it be the chain? I've read they can stretch, but it can't that much can it?

Any suggestions or tips would be greatly appreciated.

mvandor · #2 03-10-2009, 02:52 AM

Now, as far as these smaller engines are concerned...do you have a 2 or 4 stroke engine?
2 strokes have much less low end torque than a 4 stroke, when they get to revving though thats when they come alive. I just built my first MB a 50cc 2 stroker and i notice how the directions say to pedal the bike when starting from a start or accelerating from a slower speed- not that you can't start w/o pedaling but w/ a 2 stroke you are gonna get nowhere fast and might damage the motor (that I really don't know, just seems likely if its done too much)

Shadeslay · #3 03-10-2009, 11:46 AM

It's a 2 stroke, I do pedal on take offs or up hills "really have too most times. It's really not even that it bogs down, it's more how long it takes to get up and going when it starts bogging down. It just seems off from what I've seen on the you tube videos and the bikes around town.

I guess I'll just keep tinkering with it, hopefully I'll stumble on the solution.

The chain problem, I found it's about a 32nd of an inch out of alignment looking at the sprocket from the rear, so I'll try to get that perfect. Kind of doubt that will cure the issue seeing it goes from tight to about an inch of slack, but hopefully it helps. Thought about modding the dust cap so there's adjustment room for the center hole, but figure that will just make the problem worse. I'll try to test it today too see sprocket hole is centered "one would think".

toytime · #4 03-10-2009, 02:22 PM

Normally they say it takes two tanks of gas to break them in. The chain and sprocket may mate with each other by that time as well. I've found that things settle down after a few weeks. Just be patient

ibcnya · #5 03-10-2009, 02:29 PM

To fix the off idle to WOT bog move the clip on the carb needle down one slot. If/when set rite you should be able to go WOT off idle without any hesitation.

**2door** · #6 03-10-2009, 02:39 PM

Shade,
Are you using the kit supplied chain? They are notorious for poor quality. My first kit chain actually had a twist in it. It was easy to see and although it seemed to run true it certainly looked scary as it moved through the sprockets. I replaced it within the first few days with a good quality #41 chain. I've also seen the kit chains with tight spots in them, rollers not rolling, which gave the appearance of loosening then tightening. Before you do to much modifying I'd suggest replacing the 415 kit chain with #41. It's available at Grainer, Tractor Supply and even Ace Hardware carries it and master links. Hope this helps you out.
Tom

Shadeslay · #7 03-10-2009, 03:00 PM

Thanks for the tip toytime and ibcnya's.

2door's yes it is the stock chain, I've been thinking of going with the #41 chain, maybe I should bite the bullet and get one. And yes there are a few spots in the chain that do not bend at all, actually one of the links I just took out was like that and the chain can't get any more greased then it is now.

Thanks looks like I'll head to Ace later today.