Chain tight then loose

[Anthony Siragusa]

We have a Birel AR28 with a KPV-1 on it. I noticed that the chain gets tight and loose about every rotation and a half, let me tell you what I have replaced so far.

Axle, Sprocket & Sprocket hub, rear bearings, chain, front drive bearing, and drive hub, we have tried a different engine, and different engine mounts.

the only thing I can think of now is Frame is bent, but it still doesn’t make sense why does it happen on ever rotation and a half.  we are running 79tooth in rear and 11 tooth up front, I am also eating up front sprockets like crazy . I am on SoCal  Orange County…HELP!!

 

 

 

[Patrick Roth]

I’ve had that issue with a worn out front or rear sprocket or a brand of chain I’m not used to.  I suggest using a high quality chain (I use a DID HTZ) and see what it looks like.  As chains wear and stretch the distance between the links grow and this little change can cause what u are seeing.

 

[Paul Makarucha]

Change all gears and chain at the same time, then see if problem persists

[Anthony Siragusa]

Thanks guys, I have changed everything all at the same time today, even tried another engine, and yes of course chain, I also have the benefit of having another birel Cadet that I can try everything out on, I have swapped all the stuff that worked on one Kart to the other and it still does it on the AR28

[tony zambos]

How much is the difference in chain tension is there from when the chain is at its loosest point to the point where it’s the tightest? At its loosest, measure the amount the chain travels up and down at a point halfway between the gears. At the same position, measure the chain when it’s at its tightest. Does it go from 40 mm to 5 or does it go from 25 mm to 10?

You indicated that the problem occurs every rotation and a half. Of what, the axle or drive gear? But either way it doesn’t make sense. If the problem was the drive gear, with every rotation of if the chain should tighten. And rotating the drive gear would get you a half turn on the axle. Sorry, but you can only have one bend in the axle. Rotating the axle should get you over seven turns of the drive gear.

Think you’re at a point for some careful measuring. Check the axle for run out and then the gear carrier on the axle. With new gears, check their alignment. I’m guessing you’ll find the drive gear is either toed in or out. The wear pattern on the front sprockets should give you an indication.

Good luck.

LAD Specialties customer / tony kart / rotax / kt100

[Anthony Siragusa]

Tony, I think you are right, I used some basic tools I have in my garage, small bullet level, and a straight edge, and it looks like the bearing carrier is toed out by 2degrees, I didn’t notice (until your post) that the short tube that is on the back, in front of rear bumper ( looks like it could connect to tube on other side of frame) is tilted up by 2 degrees, any suggestions how and where to straighten frame here in So Cal anyone?? or should I just stick a large socket in it with a large handle and start bending?

[tony zambos]

Anthony, think it’s time to find a shop that specializes in frame straightening.  I don’t believe that having one bearing hanger toed out will cause your problem.  The axle will center itself between the two hangers.  Suspect that the hangers are not in line, either not is the same horizontal or vertical plane.  In other words, either one hanger leads or trails the other or possible one is higher than the other.

Call the shop first so the shop can explain what condition he’ll want you to bring the kart in.

LAD Specialties customer / tony kart / rotax / kt100

[David Palomino]

Well since you changed everything to the other chassi and it still did it… i would think it has nothing to do with the chassis. I would take a look as someone suggested that one of the drive gears? has to be the culprit. The part that does not make sense is that it takes one and a 1/2 rotations to see the problem that goes agains it being the gear which would complete a revolution in one turn?? could it be a problem with the crank or axle?

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