Yamaha tt 250 front fork oil level

[spike916]

The front forks are leaking on my 1980 yamaha TT 250. I'm attempting to replace the forks seals and replace the fluid. When I talked to the dealer they were unable to tell me exactly how much fluid needed to go into each fork nor the proper measurement to determine how much fluid was necessary. Any help would be greatly appreciated!!

[Robert Taylor]

The front forks are leaking on my 1980 yamaha TT 250. I'm attempting to replace the forks seals and replace the fluid. When I talked to the dealer they were unable to tell me exactly how much fluid needed to go into each fork nor the proper measurement to determine how much fluid was necessary. Any help would be greatly appreciated!!

Was it a franchised Yamaha dealer you spoke to? Did you purchase the seals and fluid off them? Every franchised Yamaha dealer can access the national distributor for such info if they dont have it to hand, but reasonably also you should be purchasing the seals and fluid off the very same dealer.

[T.W.R]

316cc or 10.75 fluid oz +/- .07 oz per fork

TT250s of that era ran air valves too (think 0-10psi was the range limit)

[Robert Taylor]

316cc or 10.75 fluid oz +/- .07 oz per fork

TT250s of that era ran air valves too (think 0-10psi was the range limit)

Dont run them at above atmosphere though, air pressure creates seal friction. Tht is why you dont see pressurising air valves on modern bikes. If its too soft fit firmer linear wind springs and Race Tech emulators to bring it into the modern world

[spike916]

Dont run them at above atmosphere though, air pressure creates seal friction. Tht is why you dont see pressurising air valves on modern bikes. If its too soft fit firmer linear wind springs and Race Tech emulators to bring it into the modern world

Thank you both for the info. In regards to the air vavles, are you saying to not run any pressure at all in them?

[T.W.R]

running at atmosphere means zero pressure internally or equal to external air pressure.

The original design was as a cheap form of adjustable damping, but as people thought that running the higher end of the pressure range was a good idea the pressure build-up blows the seals.
They weren't a bleed off valve as per more modern designs

[spike916]

316cc or 10.75 fluid oz +/- .07 oz per fork

TT250s of that era ran air valves too (think 0-10psi was the range limit)

So I drained the forks finally and only pulled out about 6 oz. out of each fork? I have an old YAMAHA SR500 service manual and it says to only put 7.34 oz. in each fork. Granted this is a different model and my forks were definately leaking......so my question is what happens if I put to little or too much fluid in for that matter? T.W.R are you getting that number from a service manual from a 1980 TT 250? Thanks for the help

[Robert Taylor]

So I drained the forks finally and only pulled out about 6 oz. out of each fork? I have an old YAMAHA SR500 service manual and it says to only put 7.34 oz. in each fork. Granted this is a different model and my forks were definately leaking......so my question is what happens if I put to little or too much fluid in for that matter? T.W.R are you getting that number from a service manual from a 1980 TT 250? Thanks for the help

Low oil level equals less secondary air spring compression ratio and therefore more chance of bottoming out and less brake dive resistance. Higher oil level equals more air spring secondary compression ratio so firmer in the latter 1/3rd of stroke, less likely to bottom out and more brake dive resistance. There are sensible limits either way, start with standard first.

[T.W.R]

So I drained the forks finally and only pulled out about 6 oz. out of each fork? I have an old YAMAHA SR500 service manual and it says to only put 7.34 oz. in each fork. Granted this is a different model and my forks were definately leaking......so my question is what happens if I put to little or too much fluid in for that matter? T.W.R are you getting that number from a service manual from a 1980 TT 250? Thanks for the help

Can't compare a SR500 to a TT250 :nono:

The oil capacity is Yamaha specs