My chain is saggy

Acraze

Acraze

Member
Hi I'm new here, just got the kit installed on my 29 bike. Now a friend did install this for me. My chain was loose it even came off, but I got it back on. I took a video, will the experts here tell me if this looks mounted correctly? Seems like the chain idler needs to be moved closer to engine.
YouTube - Bicycle engine kit chain tension

Thanks for any advice.
 
Way too loose.
You'll want 1/2 to 3/4" slack in the upper chain run measured by engaging the clutch and rolling the bike forward just enough to tighten the upper chain run.
You should be able to get that much adjustment by raising the tensioner wheel just a little.
Chain tension and alignment are very important for a reliable drive system.
Tighten that chain and check for straight line alignment between the engine drive sprocket and the rear wheel driven sprocket. The tensioner wheel also must align with the chain path. Sometimes that means bending, or twisting the tensioner bracket so the wheel is aligned with the chain.
Tom
 
Thanks Tom. I looked every way I could and it looks straight. I did move the roller up some the bottom is tight but the top has about 2 1/2 inch of play. Should I move te whole bracket forward some? It has been grinding the rear sprocket some but thy are cheap :)
 
"Grinding the rear sprocket"
Not quite sure what you mean here. If the chain and sprockets are aligned there should be no grinding.
As for getting the proper tension; you might have to remove a link. In the case of roller chain that is in reality two links. The tensioner bracket can be moved forward or toward the rear to get the tension right but if there isn't enough adjustment to get that 1/2 to 3/4" slack I mentioned then you'll need to shorten the chain.
If you don't have the tools or experience with shortening chains either a bicycle or a motorcycle shop should be able to help you. Tools are available, called 'chain breakers'.
Tom
 
I have a dremil! But yes I do not have all the tools to mess around with it. I did have a 14 socket and that is what fit the chain tension nuts. I'm looking at other pictures of peoples mounts and theirs are mire forward then the way a friend mounted mine.

4129d5f9.jpg
 
Moving the tensioner bracket forward will decrease your chain tension. Moving it back will increase it. The tensioner wheel can be moved up in the slot. That will tighten the chain but possibly not enough. You still might be faced with shortening the chain.
In addition to master links there are also half links which might be a way for you to get the right tension.
Don't forget: 1/2 to 3/4" slack on the top run with the bike moved forward against a compression stroke of the engine, clutch engaged. More or less tension and you're asking for trouble.
Tom
 
zptJust get yourself a chaintool and take out alink or so. This MB thing is getting your hands greasy man! Learn by doing, thats the only way one learns.
 
Well done basic explanation on the tensioner Tom. It does look like even raising the tensioner roller might not get enough slack out of the chain. Raise the roller up and if that doesn't do it you might have to remove a link or two like Tom says. Take your time and get it right. Dan
 
Thanks everyone. I didn't have to remove a link, just a simple tension adjustment. I need to buy the upgraded spring one. OKAY I'm still having issues. First was gas leaking from cheap hose, I bought better hose and clamp to fix. NOW I have a problem where he spark plug keeps loosen! Can't keep the bike going more than 2-3 blocks :(
How to keep spark plug snug?
 
I really don't think a springed tensioner is a "need to have it" thing, it's kind of a luxury thing.

With as much slack as you've got, I would seriously pull links out. Optimally, you don't want to have the tensioner right up on the sprocket, which I assume is the only way you would be able to adjust it, even by maxing the pulley to the very top.


On the spark plug:

There's a crush washer that should keep it snug, I would really put money on it just not being put in tight enough, or the crush washer going out. You can replace the crush washer, though, I would also have to assume it's a chinese plug that came with the kit, and they're honestly junk.

Worst case scenario is that the threads in the head are going out - which of course we are hoping is not the case. So you know, locktite won't do it, as it's removed with heat, and once it's fired up the heat will be enough to where it wouldn't cut it.
 
Do you have a torque wrench? If yes, torque the plug to 120 inch pounds. That should squash the crush washer (gasket) and seal the plug in the cylinder head. Are you using the kit supplied spark plug? Some aftermarket plugs such as Autolite, and some Champions don't use a gasket but rely on a tapered seat to seal. No matter, the plug needs to be tight. It's not a semi-truck lug nut so don't over tighten it but it has to be more than snug.
DO NOT use any thread sealer or thread locking compound. If anything a good anti-seize product is all that should ever go on spark plug threads.
Tom
 
Thanks for the input. I think the chain is good now, I didn't have to move the bracket just te roller up some. See pic
7d236020.jpg



Now for the spark plug, it is coming loose easily. I tried auto zone for better spark plug but they didn't have it.
The only thing I know to do is keep a wrench on me
 
That chain is looking pretty good. The video made it seem 4 links too long! :D

Since you're looking for a different sparkplug, there is SUCH a huge array of topics covering different brands and heat ranges, I'd say just search for "spark plug" and see what's out there. You should be able to find something that's in stock at your local auto shop.
 
for me when i had a similar issue with my plug, i just took a pair of pliers, hand tightened the plug, then cranked it down with the pliers to tighten it all the way. worked for me.
 
Ok here what's happened now. Found old spark plug either from a trashed B&S motor or a xr200 engine, either way it threaded in and hasn't unthreaded compared to the other stock one... It makes it purrrrr. There is a catch though, as I read on a other thread here a guy had a good spark plug but the top was to big for the boot connector. That's my issue, it only Came off one. I'll just buy recommended plug later. Man I have a bigger issue now! There always seems to be oil build up around the plug, cylinder head. I think it could be the head gasket? I'm not sure but i would
Hate for oil to get above the piston
 
matthurd said:
for me when i had a similar issue with my plug, i just took a pair of pliers, hand tightened the plug, then cranked it down with the pliers to tighten it all the way. worked for me.
Click to expand...
If you relied on pliers you didn't get it tight enough. Pick up a spark plug socket from any tool supplier. You'll be glad you did. Most of the plugs that will work in the Chinese 2 stroke engines require a 5/8" socket. Probably less that $5.00 most places.
Pliers will not allow you to torque the plug correctly without rounding off the wrench flats provided on spark plugs or properly seat the plug against leakage.
Tom
 
2door said:
If you relied on pliers you didn't get it tight enough. Pick up a spark plug socket from any tool supplier. You'll be glad you did. Most of the plugs that will work in the Chinese 2 stroke engines require a 5/8" socket. Probably less that $5.00 most places.
Pliers will not allow you to torque the plug correctly without rounding off the wrench flats provided on spark plugs or properly seat the plug against leakage.
Tom
Click to expand...

i don't have the frame clearance for a socket thats deep enough to catch a spark plug. got plenty of sockets that would fit, but i'm not going to take off my motor every time i want to look at the plug.

plugs been fine for over 150 miles now.

i agree a socket piece is by far the best choice in many cases, just not for mine it seems.
 
matthurd said:
i don't have the frame clearance for a socket thats deep enough to catch a spark plug. got plenty of sockets that would fit, but i'm not going to take off my motor every time i want to look at the plug.

plugs been fine for over 150 miles now.

i agree a socket piece is by far the best choice in many cases, just not for mine it seems.
Click to expand...
Matt,
Have you tried the 'shorty' version plug? I had to use it on a 24" bike I built for my nephew because of clearance issues with the cantilever bars.
It is an Autolite #2976. It has performed well for me in a couple of low clearance bikes.
Admittedly I use a box end wrench instead of a socket but it's still better than pliers. :)
Tom
 
Last edited:
haven't tried one, but i think i know a place near by me which mite have the champion version of the plug you listed, worth looking into i suppose. i carry 2 ratchets with me in my bag (as well as an adjustable wrench, 8/10mm wrenches, a screw driver, and pliers) when i ride anyways an extra socket piece certainly wont bother me.
 
WOW effin spark plug the most smallest fix, I wouldn't even say fix. The top of th plug where the boot goes.... Unscrews to fit EFFFF! Wonder how many ppl really went on a rampage cause if not knowing this :)
 
You must log in or register to reply here.
Back
Top