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

impulsive · Member

rear coil spring rate?

ttboof · Super Guru

I had mine checked and was OK for my 96kg

Was a bit soft prior to the shock rebuild and a bit of an upgrade now it's good maybe a little stiff but I think that's the shock . Running it at half adjustment was all the way up only .

Works on mine biggrin

impulsive · Member

Thanks for the reply.

I did see you post that info in the rear shock mega thread.

Did some more searching and found Teknik TTR250 page that also lists stock rate at 6kg/mm:

https://www.teknikmotorsport.com/complist/yamaha/tt-r250/2001/

I definitely need something softer for my weight.

ttboof · Super Guru

impulsive wrote:
Thanks for the reply.
I did see you post that info in the rear shock mega thread.

Did some more searching and found Teknik TTR250 page that also lists stock rate at 6kg/mm:
https://www.teknikmotorsport.com/complist/yamaha/tt-r250/2001/

I definitely need something softer for my weight.

at 30kgs lighter than me you may be on the right track , short term maybe back off the compression damping (wheel under the tank) wind it out to the last one or two clicks the , re- bound back off a couple of clicks , not too much or it will be a bit of a pogo stick (bottom of shock )
be careful not to wind the rebound off to far as it is possible to wind it right out .

something the guy who did my shock showed me was , when mine was low on gas the rebound barely clicked once re-gassed it had definite clicks again ( an easy way to determine if the gas is a bit low

impulsive · Member

when mine was low on gas the rebound barely clicked once re-gassed it had definite clicks again ( an easy way to determine if the gas is a bit low

I can barely feel 3-4 clicks and that's it. Compressing the shock all the way it takes a loong time to extend.

Can I get away with just adding more gas for now or does it need rebuilding?

And I noticed Teknik lists the 98 & earlier spring rate as 5.7kg/mm

https://www.teknikmotorsport.com/complist/yamaha/tt-r250/1998/

ttboof · Super Guru

The clicks on the rebound the ring at the bottom of the shock should have several clicks if all's well

It's the bottom one that gives an idea of gas. If it seems to be working for the entire stroke a bit of gas may give back the moment over the small sharp stuff . If you have access and you can top up the gas easy it might be worth a try mines 140psi.then you should have the rebound clicks back again I think mines about 12 clicks out (I'd have to check)

Remember the oil does break down but still works OK as long as the seal isn't leaking .

If as you say the shock is slow to return the rebound may be set too high which tends to keep the shock working low in the stroke as a result a bit on the rough side .

Also regreasing all the rear linkage bearings helps too. Just watch you don't loose the rollers

When I got mine done by pro moto all up it was $175 . Tecnic asked for a few times that

-- Edited by ttboof on Saturday 4th of January 2020 05:29:28 AM

impulsive · Member

There wasn't any gas in my shock, pressure gauge didn't move when I stuck the needle in.

This may explain why the previous owner had cranked the spring preload down so tight it buggered up some threads on the shock body.

I put in 150psi of air using a mountain bike shock pump and it takes a fair bit of muscle to push the shock in and it rapidly extends back out. Rebound adjuster feels good, very distinct clicks and more than the 3 or 4 I barely felt earlier. No oil leaks and can hear it moving in the shock so should be good enough for now. Eventually plan to open it up for a refresh and maybe gold valve but that will have to wait.

Pulled the linkage & it is pretty stiff and the seals mostly crumbled away. New seals & fresh grease are on the to-do list. And of course the upper shock bearing collars are both broken.

Scored a 5.5kg/mm(54 N/mm) Ohlins spring for pretty cheap. The application is for newer KTM & Husqvarna models. Stock spring is 60x61x247, the Ohlins is 61x61x250 so very close dimensions. I got a 58 to 61 collar/adapter to take out the slop at the bottom seat. Out of curiosity I first installed it on the shock w/the stock part, it wiggled a bit but was solid as soon as there was any spring pressure. Probably could have gotten away without the adapter piece but it was only $7.

Hopefully it's not too soft, we'll see what kind of sag numbers I get. At least I have confirmation the 06310 series of spring fits and there are other rates to chose from.

And it occurred to me, the "OE" in the faq perhaps references the "Open Enduro" model whereas I was thinking "Original Equipment", as in stock spring on the blue models.

https://www.ohlins.eu/en/products/packages/ttx-flow-series-06310--35/

http://www.ohlins.uk.com/ohlins-mx-spring-kits.html

http://shock-treatment.mybigcommerce.com/locating-collar-spsc-b6158/

ttboof · Super Guru

Thanks for the update

-- Edited by ttboof on Saturday 18th of January 2020 01:14:28 AM

TTRfan · Super Guru

Great information - many thanks!

It sounds very much that you know (more than most of us anyways!) what you are doing technically which is great but, just in case you missed it, check the bottom spring retainer isn't catching on the swing arm as shown in photo.

Brian

impulsive · Member

Thanks for pointing that out, I'll be sure to keep an eye on it.

I'm not sure I really know what I'm doing, this is my first motorcycle that I picked up only a few months ago & I confess to never touching a carburetor before this.

I do come from riding a full suspension mountain bike( coil f & r ) and know having suspension right makes all the difference in the world. Also have a background playing w/EFI turbo cars and 4wheel drive trucks that have no aftermarket support - I've gotten proficient at adapting parts meant for something else.

Spent months searching & learning from this board to inform myself before buying my TTR, as such I feel obligated to share anything I may discover to add to the collective knowledge pool.