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

Well - it's done and ready for testing.

Here is a shot of my 13 tooth gearbox sprocket showing signs of being hooked:-

I thought it was going to be a struggle getting the sprocket nut off but I found it comparatively easy.

I left the old chain in situ and applied the rear brake. Using a 30mm socket and extension bar the nut turned with little effort.

Here is a comparison shot of old sprocket and new. Guess which is which.

This is the new sprocket and chain as fitted. I didn't need the new tab washer because the old one had two tabs and only one had been used.

I changed the rear sprocket to keep the overall gear ratio similar. Here are old and new.

Whilst the wheel was out I took the opportunity to replace the brake pads too, here is the old set

and here is the new

I also adjusted the chain guide clearance and renewed the rubbing block ....

These are the old pads and block that I renewed.

I also replaced the front brake pads too - all I have to do now is get out more and use it.

Martyn

I'm lead to believe (by the handbook) that the standard sprockets for my 2000 TTR250R are 13 gearbox and 52 rear wheel. 13:52 = 4.00

As purchased mine was 13:48 = 3.69

I have now changed to 14:52 = 3.71

So mine is now geared mid way bewtween what it should be and what it was.

I don't know what it performed like on original gearing but I've a good knowledge of what it has been like since I got it.

I will undoubtedly post my findings - but I'm hoping the difference will not be too discernable.

Martyn

Agree with Brian (Oracle).

Second hand, my Official UK Import came with 13/44 and spare origonal 14 tooth rubber damped front sprocket in spares box.

For a trip to Portugal last year (in overlanding trim) I reverted to 14/44 trim and spoilt a good holiday, bike was sluggish.

Upon return, I purchased a 14/48 together with 'O' ring chain from Brian, now I am a happy bunny, bike revs out like Brian says.

Doing the maths, 13/44 is not much different than 14/48.

Alec

Thanks Martyn, for taking the time to post.  Its always nice to see really productive posts like this.  I'll be heading in to the Man Cave to see what I have on mine.  I haven't checked since I bought it last year..

I am still trying to get to grips with the whole TTR thing, import/official/grey/euro/usa...etc.  I don't know what mine is?  Its Blue! lol. But I do need to find out.

Thanks, Paul

California obviously insisted on some extra mods to their TTRs and you will sometimes see a model number with a C added which denotes its the Californian model - as per your handbook cover TTR250R(C).

Brian

Success - I've just returned from a testing and apart from the need now to lower the chain guide block more (chain catches it still) it performs just as before.

I tried a few of the steep lanes near where I live and the bike is just as tractable as before. Out of Otterton and uphill is still all second gear, as is Cop Hill Lane and its nadgery top bends, all in second (chug-chug).

The bike now needs de-sludging because the lanes are a little damp still.

The wheel is as far back as it can go because I wanted to preserve the rubber flap a bit more.

If needs be I can remove another complete link, but the tyre would then catch the flap. For the record the chain is currently 114 links.

Martyn

dfaz wrote:

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There is so much conflicting information on gearing jetting modifications its dificult to know what to do at times.Brian how do you find the 13 tooth is it in your opinion stressfull on chains and bearing in mind the bike will be used mostly offroad,or is it better in your opinion to keep the front 14 and change the rear .although Martyn has sucessfully fitted the 14/52 im unsure how many problems he needs to overcome with catching and wear on the chain guard I suppose we will have to watch this space Martyn.

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Fettling dirt bikes is a bit like gardening.

Ask gardeners the best way to grow a certain plant and each will give you their own personal method and a lot of the information will be conflicting BUT they all grow the plants perfectly well 

If you are unsure about what modifications to make to your TTR then my advice is to stick as close to standard as you can and, if you do make changes, do them one at a time so you can evaluate the change before making another.

Regarding gearing, I can only talk from my own experience of trail riding in Devon and Cornwall plus the occasional foray into Wales and Southern Ireland.

Although my preference is for 14/52 gearing, I am running 13/48 on my TTR at the moment and it is perfectly fine.

I don't know what sort of riding you have in your area but, if it isn't too technical then 14/48 might be perfectly adequate.

The reason I run reduced gearing is so that, in the lanes, I don't have to use 1st gear except for the very gnarliest sections. The rider has less control of the bike in 1st gear as it is so responsive to throttle movements, either voluntary or involuntary 

It is much easier to ride in the higher gears, especially in the ruts - just fan the clutch when needed.

Logic says that the bigger the front sprocket the kinder it will be to the chain but, that said, I know many American TTR250 owners put 12 tooth front sprockets on as they have dedicated dirt trails and their TTRs don't necessarily ever see tarmac.

I found that putting the long chain guard back on my TTR at least doubled chain life so this has much more effect on chain life than 13 v 14 tooth front sprocket.

Happy to answer any questions as best I can but remember I am not really giving you answers, just my opinion 

PS If you really want to start a debate amongst dirt bikers, go onto a 4-stroke dirtbike forum and ask for a recommendation as to what engine oil to use 

I adjusted my chain guide block carrier with a small round file to slot the two fixing holes.
Only a small amount is required.
I also renewed the orange bakelite wear block in the guide. The chain still catches the block occasionally, mainly under acceleration when the lower run is slackest. As time progresses it will wear a groove and lessen the contact. 

I have, in all honesty, not noticed any difference in the ride performance since changing ratios. She still pulls as well as before uphill in high gears and there is just as much oomph and slogability. Top speed is just the same too.

Chain and sprocket wear will be watched and I imagine I will get less wear on the gearbox sprocket with the tooth addition. The old 13 tooth sprocket lasted at least 3,000 miles before it got slightly hooked and I changed it.

Time (and use) will tell.

Martyn

Your choices are between 13 and 14 teeth for the engine sprocket
and
between 44 to 52 for the rear sprocket.

Divide the gearbox teeth by the rear teeth and you get the ratio between the two. The higher the ratio the lower top speed - but greater the sloggability.

I think most riders would prefer to use 14 for the engine in order to extend the life of the sprocket AND the chain, but these riders would tend to use their TTR on the road AND lanes.

Since you prefer to use yours purely OFF tarmac you would be OK in choosing 13 teeth on the engine.

For ultimate sloggability your choice for rear sprocket would be 52 teeth giving a final ratio of 1:4
a rear sprocket with 50 teeth gives 1:3.8
a rear sprocket with 48 teeth gives 1:3.7
a rear sprocket with 46 teeth gives 1:3.5
a rear sprocket with 44 teeth gives 1:3.4

Doesn't seem much difference, but for what you require my suggestion would be 13 gearbox and 52 rear sprocket.

You can source the bits you need from this CLICKY THINGY but there are others.

Whatever you choose you must keep us all informed.

Martyn

TDVT wrote:

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My bike has the 13/52, possibly stock US config, & I'm changing up to the 14/52 when I get a new chain. Already have the 14T sitting here in the office which I got from Brian, as that size isn't readily available here.

As for the the 13/52 gearing, I DO run out of steam on the top end & don't know how many times I've gone for another gear on the road, only to find I'm already in 6th . Had to add a speedo for registration & while I haven't tried to find top speed, I have managed 65mph, but it's winding out at that point. Generally, I'm only on tarmac linking up off-road sections & would like a little headroom.

Even with the 13/52, I wish the front end was a little lighter than it is, though that could be due to the rider (likely).

---

 Good point

That is the reason why i'm tossing up between 13/50 or 13/52

Want to go 14/52 but a little bit of modifying of the chain block and front gaurd may be needed first so i don't end up with r***ted chain gaurds/chain block

After what TDVT just wrote i think i might go 13/50 so as to not lose too much top end speed but still have the bottom end power i need for trail riding

Also thinking about getting lighter wheels as the standard OEM rims seem to be too heavy to maintain a good wheelie

If anyone knows where to get titanium rims or strong lighter rims eg. Talon,Excel ect..please let me know

I'm running the 14/52 ratio, if I was going to have a purly Dirt machine I would run the 13/52 without doubt, it would give you the ability to lift the front end easly, as it is now I use the rebound or a convenient rock etc to help wheelie

IMO the main thing keeping the front end on the ground is the weight over the forks, A light weight headlight and speedo would help heaps, you can feel the weight of these things when you swing the bars from side to side.

The problem with this ratio is it's suddenly like losing 6th gear, only makes highway travel comfortable to 80-90kph I think

I removed the chain guide completly, so far it hasn't been a problem, I may build a custom guide/guard soon out of aluminium sheet, shouldn't be to hard I guess,  Ha Ha, famous last words

Cheers

Thanks for that info Steve,

                                       I will now be going from 13/48 to 13/52,should be a bit of a difference i'm hoping

thanks a million for the info.
Is my "recipe" for the gearing right? cause I havent seen anybody using it.
My main concern is if the "snails" will be able to give the tension needed for when I change to my "offroad set-up"

From the 15-48 to 13-48.