keeping my chain on

[Link 177]

After some advice on keeping my chain from jumping on my PRD125,lightning chassis.
I have run a straight edge from front sprocket to rear and its inline,have used new chain, f&r sprockets, assorted lubes (shell atm) tight chain,loose chain and everywere inbetween...Is there a recomended amount of deflection/freeplay?
thought it may have been due to sprocket hitting the ground due to its size, 94/95 tooth, so have been running a 90 and slightly higher rear tire pressures 10+psi....and yet i still had 2 DNF's at lucindale on the weekend due to chain throwing...long way to drive from Radelaide to DNF.
I am looking at swapping out the rear end,new axle,wheel bearings and sprocket carrier even tho they all look ok?
Rather not spend all that $ if i dont have to tho...
I even set a dial indicator on carrier to check run out and its straight?
Would slight movement/freeplay in rear wheel bearings be a cause?? only thing i can think of...
Can a thicker/wider chain be used? or some sort of guide be set up to try and ensure it runs true and stays on...looking in rule book atm and cant see anything that says i cant? Or am i over thinking it and missing somthing simple?
Any tech tips or advise would be greatly appreciated...
Thanks in advance
Lincoln Kart 177

[toms]

A couple of things:

With the clutch karts, the front sprocket is forced all the way out to the thrust washer when the clutch engages. Make sure you align the chain with the front sprocket as far outboard as it will go.

I always used to run a chain guard underneath my rear sprocket, in my experience unless the track is very smooth your rear sprocket WILL be hitting the ground at times, then ti just depends on how much slip you have in the rear of your kart at the moment the sprocket touches the track.

You will need to run at least a 93 tooth rear sprocket at Lucindale to be competitive, 10-15psi rear tyre pressure will be OK (higher pressure as track gets grippier).

You can get chain guides, a lot of the USA dirt karters use various different brands. I have a ChainDragGone which i will be using when i return to karting, i didn't get the time to try it previously but the yanks swear by them.

If you don't like the idea of running something directly under your sprocket, there are guards that you can bolt directly under your rear bearing hangers that drop down to below the level of your rear sprocket that will prevent it from hitting the ground. PM me for a picture of the guard i used to run.

One final thing is that if you are running a very soft axle, or running very wide rear track on narrow hubs the axle can flex over bumps enough to throw a chain (similar to getting hit from behind). If this is the case you will need to play with your set-up to allow you to run a stiffer rear axle.

Run the motor as far back as you can, chain free-play around 10-15mm.

Good luck.

[Link 177]

Thanks for the tech tips Tom!
I have just changed to the PRD all metal clutch and after looking at the throw out you mentioned it was actually moving over by 4-5mm...
i cant see why that would be needed?
so have installed a shim/washer to remove that movement,now less than 1mm.
fitted new sprockets,chain and realignment of carrier and i will have to hope this works for Morgan this weekend.
Just ordered the ChainDraGone
have reduced chain overall length and moved motor back as far as i can but I'm limited due to seat support bar which I'm thinking of modifying a little.
about to head out to the shed to make new cover for clutch assem to keep the dirt out...
gotta love Tafe RDO's!
A pic of your set up would be appreciated!especially of that rear gaurd... [e-mail]
Thanks for your time
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