chain problems...

[DCC!]

ok so i just got my bike running and tested it out and the chain keeps poping off

its tight enough but not to tight i think...

it only really happends when i turn at higher speeds or go above like 25 mph

what yall think it could be?

 

[Affair_driven]

Alignment is critical.
Chain should not be tight.

 

[brendonv]

yes the chain has to be dead straight. Roll the bike and look at the back sprocket and see if its going side to side. U may need to tighten some of the sprocket nuts and loosen others. Also the sprocket may not be centred or in other words. Tight in some places loose in other which can throw the chain off. Also having a chain to loose can throw it off. To tight and it will lock up and other bad things. The chain should have about 1/2" of movement side to side. Hope that helps. Chains can be a ***** sometimes haha.

 

[anderkart]

I agree ^

Besides making sure your rear sprocket is lined up perfectly, you also need to make sure your engines mounted square to the axle. (sometimes you can simply loosen the engines mounting bolts, square the engine up and then re-tighten)

Try to find a good carpenters level or some other sort of perfectly straight edge. Then with the chain off you can lay it across both sprockets to check how everything is lining up. I've also noticed that closely looking from about 15 feet back will sometimes help you more easily notice chain alignment problems.

One guy here recently posted that he'd used some sort of Plum Bob to check for proper sprocket alignment, I thought that was a pretty good idea. I'm assuming he stood the kart upright to use this method.

These work good too: http://www.google.com/products?sour...a=X&oi=product_result_group&ct=title&resnum=4

 

[DCC!]

haha wow chains can be a *****

how tight should it be?

thanks for all the help yall!

 

[anderkart]

I've heard prety knowledgeable guys swear by 3/4" - 1/2" - 1/4' and sometimes even less mesured slack as long as its not too tight and binding up. (always spin the wheel by hand first to make sure it rolls smoothly)

I usualy try to stay somewhere between a 1/4" and a 1/2" of slack but if every thing's lined up corectly my chains always seem to stay on at most any of the above adjustments. If you've thrown the chain serveral times, I've got a feeling your dealing with some sort of sprocket mis-alignment issue here.

 

[DCC!]

its probby not a out of alinment a lot bc it look straight and roll strait even from the 15 ft away thing

would the only at high speed or turning thing make a difference?

 

[Affair_driven]

Visual alignment does not work, unless you're extremely lucky and just happen to get the sweet spot.

 

[DCC!]

ok then i need a very long straight edge...

 

[brendonv]

Undo ur clutch grub screws and push ur kart forward and the clutch will self align, then tighten it back up. This will work providing ur clutch isnt fused to ur shaft. XD If it is then loosen it up first then do this. It worked for me anyway. I have to agree with affair driven on this one, u cant really align a chain with one eye closed. Because chains need to be dead straight so ur eye just doesnt work. If u look at it from a slight angle it may look as if its straight or not straight. Hope that makes sense. They apparently dont use grub screws in the max torque clutches anymore, they just have "floating clutches" so the clutches always self align. I dont think this is good since when my grub screws loosened once the clutch flew out and locked up the chain. I use locktite on the grub screws now and it doesnt happen. Anyway getting off track. Hope u get it aligned. If it is only coming off when turning, ur wheel could be not tight enough so its moving side to side just enough to throw it off. Also u could have a slightly bent rim if its one that mounts to the rim. Probably not but maybe if u bought cheap ones.

 

[DCC!]

Undo ur clutch grub screws and push ur kart forward and the clutch will self align, then tighten it back up. This will work providing ur clutch isnt fused to ur shaft. XD If it is then loosen it up first then do this. It worked for me anyway. I have to agree with affair driven on this one, u cant really align a chain with one eye closed. Because chains need to be dead straight so ur eye just doesnt work. If u look at it from a slight angle it may look as if its straight or not straight. Hope that makes sense. They apparently dont use grub screws in the max torque clutches anymore, they just have "floating clutches" so the clutches always self align. I dont think this is good since when my grub screws loosened once the clutch flew out and locked up the chain. I use locktite on the grub screws now and it doesnt happen. Anyway getting off track. Hope u get it aligned. If it is only coming off when turning, ur wheel could be not tight enough so its moving side to side just enough to throw it off. Also u could have a slightly bent rim if its one that mounts to the rim. Probably not but maybe if u bought cheap ones.

hey thanks! ima try this when ever i get a new master link...

 

[fowler]

the chain should be tight so you cannot lift it off the gear but u cand move it side to side on the gear

 

[modelengineer]

In the middle of the chain you should be able to move it 1/4"

 

[hd4ou]

worn sprocket will also cause this in addition to what these other fellas have told you. may even have the wrong chain size or sprocket if this is a new to you mini bike but if it a new problem and has worked fine in the past then that isn't your issue.

 

[Stratogeezer]

I am having the same problem with my chain coming off. I'll try the method above and loosen the clutch screws and try to get it to self-align first.

But - I'm also thinking of building a makeshift chain guide - designed to not let the chain move off the sprocket(s). Has anyone tried using a chain guide to keep it from coming off? It's no substitute for alignment I know - but may help keep it on if it's reasonably close to being aligned.

 

[robin]

it woul be better to fing the cause of the problem imo

 

[mike75925]

i'm guessing this is about minis. but when i first got my vtr250 running it threw the chain 3 different times. the master was on right, the sprockets were a match to the chain, slack was correct etc. it always broke at the master. i bought one more master and it never happened again. sometimes it is just bad parts.

 

[BriggsTwins]

could the frame be twisting at speed? does this only occur on turns? check for a possible broken weld, or slack in the locking collars for the axle shaft, if it only happens while turning at speed, then there must be a serious amount of twist happening somewhere.

or it could just be bad parts.....

have a picture?

 

[Stratogeezer]

Pictures of the chain issue

Here are a couple of pictures of the kart rear end showing the engine and sprocket and axel assembly. As you can see it's a longer than normal reach for the chain to reach the sprocket.

I moved the engine forward to tighten the chain some, and tried to ensure everything was as aligned as possible.

You'll also see on the more close-up photo that I started fabricating a chain guide, that is not yet finished. I'm still thinking of the best way to build the rest of that custom chain guide.

 

[KartRacer695]

there could be a few reasons;

chain alignment (obivously)
worn out sprockets or chain.
there should be about a 1/2" of slack.