A forum for owners of Yamaha TTR250 trail and enduro bikes!

TTRfan · Super Guru

Sprocket question

Michael TTR250 · Veteran Member

Hi Guys,

I am swapping out my standard 14 tooth front sprocket for a 13 tooth one and noticed (as shown in pics) the current one seems to have rubber on both sides that the new one doesn't. Is this something I need to mount on the new one???? Or just an option that is not really necessary??

Thanks, Michael

matador · Veteran Member

Morning Michael, Yep the original Yamaha part has the rubber inserts - these can be expensive to replace, so most go for aftermarket ones at say 1/4 the price at about 15 quid a go. It will fit ok just buy a new tab washer. If you have a problem fitting let me know - I have a few tips, but won't 'Grandad' and go through it if you don't me to.

You can see from my post in the sprocket section I have had problems with 'Talon' sprockets supplied from Brian (no fault of his) as you don't expect a sprocket to be 0.010" or 10 thou thicker. This caused chain chatter, so if when you replace your sprocket and have this problem, I ground it down by still causing chain chatter - giving the original on a go later..

I also had a problem with a new front sprocket on my XTR, caused by a different profile - never had problems with sprockets before.

Michael TTR250 · Veteran Member

Thanks for your response, happy for you to go into details about trouble shooting the fitting if you can save me some hassles. Thanks for letting me know I can use the new sprocket (as shown in the pic) as is without the rubber inserts.

Cheers, Michael

Michael TTR250 · Veteran Member

Hi Brian,

As I have already purchased the sprocket without the cush from my local place here in Aus do you also feel that it will be ok to use it as is?

Cheers, Michael

TTRfan · Super Guru

Michael TTR250 wrote:
Hi Brian,
As I have already purchased the sprocket without the cush from my local place here in Aus do you also feel that it will be ok to use it as is?
Cheers, Michael

Absolutely - should be 100% OK wink

Michael TTR250 · Veteran Member

Thanks Brian & matador.

matador · Veteran Member

TTRfan wrote:
Retail price for an original sprocket with the cush is £36.22
I am a bit baffled about the problems Matador is experiencing with the Talon sprockets and am glad for clarification that the width of the Talon sprockets isn't the issue!
We live fairly near the Talon HQ and I am happy to take up with them any detailed problems, or put an owner directly in touch with them, if that helps?
We have sold literally hundreds of Talon 13/14/15 tooth sprockets with only positive feedback. I have used them on all my TTRs for more years than I care to remember with no issues.
They are an important part of our "Totally TTRs" chain and sprocket sets so I would have hated for potential customers being unnecessarily put off.
I think that chain noise is a fixture on all 250 dirt bikes and will still exist when everything in the drive train is 100% - it is the nature of the beast.
Cheers
Brian

I fitted a Talon 13T with my old chain = no probs, the same 13T is now on my son's TTR different chain again no probs, but when I fitted a new chain sprocket set & 14T, I didn't test it before going out on a Horse trial, so was committed to riding the bike all day. The noise was really bad, chain whipped and put marks on the inner chain guard, I tried different tensions. Later thinning the sprocket helped but still not quite right, now I have noticed slight wear marks on the teeth, could be from the vibration. I just tried out the old original sprocket (bit worn) and it's better again - down to normal chain whip. I'm going to buy a different front sprocket to try it out, will let you know next week. One idea is the chain was a bit stiff, but I oiled it well. It's a real problem, I have knocked out x2 chain rollers. It's odd nobody else has had a problem.

I say with the XTR, simular 520 chain, one sprocket with a slightly different profile and at +50mph it vibrated through the seat - fitted a new set/chain and totally sorted.

matador · Veteran Member

I've just got in from my shed trying to solve my chain whip problem. I took the bike out with the original 14T sprocket (52T on the back) and it ran ok - no chain whip. I then fitted a new 15T Talon (10 thou thicker) and again it ran ok, with some chain whip but not a problem. I then took another 5 thou off my Talon 14T sprocket, so it's now the same as the 12 assorted front and back 520 sprockets from different bikes. Took it out for a run and it ran prefect no chain whip at all = sorted. The thinned down sprocket ran the best.

Out on trail runs, I noted other bikes with 520 chains mainly KTM, some have to me slack chains, others too tight, most no oil, and none had a chain whip problem on the road

The original problem must have been a combination of a new stiff chain and the thicker 14T sprocket, the bike sounded like a 'brick in a cement mixer'.

I only put up these posts for info and as a QA issue. I had a problem with a JT sprocket on my XTR, changed sprocket make to Sun star = perfect.

Another similar chain problem was an large industrial site, none of the engineers could solve it, so they gave the problem to two very experienced bike engineers. Even then it too ages to solve, again the chain ran ok over the sprockets at slow speed but not at working speed they accurately measures the chain rollers and all components, it turned to be a slightly different batch of chain from the US. Hope this helps.