Fork oil level - Triumph Forum: Triumph Rat Motorcycle Forums
Trophy Trophy 3 & 4 - for all 900 and 1200cc models 1991- 2004

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post #1 of 4 (permalink) Old 06-21-2013, 04:58 AM Thread Starter
Grand Prix 500
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Fork oil level

OK, FINALLY got my fork seals sorted and after reading posts on this forum, decided to insert a 3/4 inch spacer and fill the forks to 125mm below top of forks (compressed)
Struggled like crazy to insert the spacers and finally gave up and used just the standard triumph one. However, forgot to drain some oil out of the forks before putting them back together. The forks seem pretty damn stiff now, but is this just because they are rebuilt with new seals/oil or is it because the air gap is wrong?
'97 900cc trophy, Showa forks.

Ooops, forgot, I've also used 15w fork oil which is thicker so I guess that may be contributing....

Last edited by simonjrwinter; 06-21-2013 at 05:03 AM.
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post #2 of 4 (permalink) Old 06-22-2013, 01:22 AM
Main Motorcycle: 2001 Trophy 1200, T509
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15w fork oil would't be too heavy, book calls for 10w20 so 15 seems right there, and new seals definately would have nothing to do with increased stiffness. My factory manual is showing an air gap of 133mm for Showa equipped Trophys though. Too high a fluid level will stiffen up the fork action.
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post #3 of 4 (permalink) Old 06-22-2013, 06:17 AM
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The 15w oil is contributing if factory spec is 10w; however, RB is right in that a smaller air gap also stiffens things up. It's likely to be a combination of the two "modifications".

Bear in mind that as well as stiffening the forks, thicker oil slows down the bound and rebound, so the forks are slower to react to changes in the road surface.

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post #4 of 4 (permalink) Old 06-22-2013, 11:05 AM
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stiffening up the fork a bit doesn't sound like a bad idea to me, it's pretty soft in std. trim
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