Fork Oil Help

[MikeyG]

Mornin' all.

I'm changing the fork seals and oil on my bike and was wondering the effects of using different weight fork oils. The bike is a suzuki GN250, I'm 115kg/250lb and the roads I ride on are bumpy from earthquakes.

To me the forks feel underdamped but I don't know what weight oil is in them, or even if there is any oil left. Given my weight and the road conditions I'm thinking a heavier weight oil than stock would be suitable but would like to know what the suspension gurus on the forum think.

Maybe I should just use stock oil and lay off the beer but I don't really see that happening.

Cheers Mike

 

[hillsy]

You might be confusing under-damped with under-sprung. The GN was sprung quite soft straight off the showroom floor, so a few years later things won't have improved much.

Not sure what the OEM oil weight is (10-15?) but you could try using 5 weight higher as a starting point. It won't help the spring pre-load, but will help slow the pogo effect if that's what's happening now.

You could also try a spacer under the fork cap to tighten the springs a bit (about 1/2 - 3/4 inch).

 

[Tim]

I'm betting you have the original springs in there too. Some new springs, maybe splurge on cartridge emulators and fresh fork oil would likely work wonders.

Where are you located? One of our good friends Doug is at DEK Performance - he'd probably have some good advice for you.

http://www.facebook.com/DEKPerformance

 

[MikeyG]

I'm in New Zealand.

Emulators and springs would cost more than the bike, i just want to improve handling a little without breaking the bank.

Spacers to increase preload and slightly heavier oil sound like a good plan so far. Would bronze bushes work for spacers or are they too soft?

 

[hillsy]

They'll be OK. In fact, some of the replacement spring kits come with PVC pipe as the spacer - just cut it to the desired length. I kid you not.

 

[pterodactyl]

I put Motul 15 wt. medium/heavy in my gl forks. It did help some. It's worth a try I think. Make sure to measure and put the specified amount in each fork. I've heard the spacers work well but I havnt tried it yet

 

[hurley209]

im pretty sure you need 20w

 

[Ringo]

I'm betting you have the original springs in there too. Some new springs, maybe splurge on cartridge emulators and fresh fork oil would likely work wonders.

Where are you located? One of our good friends Doug is at DEK Performance - he'd probably have some good advice for you.

http://www.facebook.com/DEKPerformance

Definitely contact Doug! He'll set you straight in no time. Very knowledgeable guy.

 

[MikeyG]

Just checked the manual and it says 10wt fork oil. Will going to 20wt be too big of a jump?

 

[MikeyG]

Thanks for the info everyone. Maybe this is a stoopid question but is it worth changing the slide bushings as well as the fork seals? It will mean dismantling the forks and the manual says i need a special tool to remove the damper rod.

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