Standard Rim Sizes GK76a

[KiwiBiker]

My GK76a track bike has rims of width 3.5" front and 4.5" rear in three spoke design. Is this standard sizes? The reason I ask is because I can't get my rear tyre warmer on because of a lack of clearance on the brake caliper strut, chain and even the swingarm clearance is tight. My rear tyre is a Dunlop Sportmax 160/60/17.
Any suggestions welcome. I've thought about changing to a 150 width tyre but the one I have on is near new...

[moforockband]

Yes it is correct. I used to race on a 150 Dunlop on those rims, but that was ss400 which didn't allow warmers. A 150 is the correct fitment for the bike, but a 160 supercorsa will also be ideal. (you can get s/corsa in 150 to give more clearance, but they are quite hard to find).
Try a thinner tyre warmer? Like a Diamond warmer?
Don't go down the route of putting a 4" bandit rear wheel on the back, as you will be de-speccing the bike.

[KiwiBiker]

Yes it is correct. I used to race on a 150 Dunlop on those rims, but that was ss400 which didn't allow warmers. A 150 is the correct fitment for the bike, but a 160 supercorsa will also be ideal. (you can get s/corsa in 150 to give more clearance, but they are quite hard to find).
Try a thinner tyre warmer? Like a Diamond warmer?
Don't go down the route of putting a 4" bandit rear wheel on the back, as you will be de-speccing the bike.

Thanks for that. Ive invested $500 in the track warmers I have, so will stick with them. Ive worked out that if I get a longer chain I can slide the wheel back further and gain more clearance as the swing arm is tapered towards the front. The chain has enough sideways movement that I can sneak the tyre warmers past it but it's not ideal and I will invest in a 150 once the 160 is stuffed. Looking at the Bridgestone S20 Evo's. Have had good reviews.

[Variablevalves suck]

D'ont know how it will feel with a 150 in, should slow the turn in maybe due to a lesser arch on the tyre but the 76a was supplied from the factory with a 160 only the 4.5" wheeled 73a had 150's.

[KiwiBiker]

D'ont know how it will feel with a 150 in, should slow the turn in maybe due to a lesser arch on the tyre but the 76a was supplied from the factory with a 160 only the 4.5" wheeled 73a had 150's.

thanks, yes I understand what your saying about the profile. Will keep you posted on how it pans out.

[Variablevalves suck]

You can claw a small amount back, and when i say small i mean small, maybe a couple of mm if you convert to 520 chain.
If you use a 520 dr400 front sprocket this is slightly wider than than stock with a step on one side, you would machine this till you have a correct fit then put the step engine side,
you would then space the 520 rear (SV650 520 conversion) sprocket the couple of mm out, i use a Talon ally one.
Like i said not a lot but everything helps.

Be careful what chain you use as my 520 Renthal was thicker than my 525 EK so worth a look at as many chains as you can.

[moforockband]

Be aware that even though it may say 150 on the side, doesn't always mean it is thinner than someone else's 160. You need to visually check.
I weighed a 150/160 supercorsa and they weighed the same??
I raced on Dunlop 207gp's on a 150, and the turn in was super fast with a kr364 on the front. The narrow dunlop was mint until it wore out and threw me off. The wheels the same on 73 sp and 76 as far as I know?
I personally think gsxr400's turn a little slow, compared to modern stuff when you put rounder tyres on. They are porky little pigs weightwise!

[KiwiBiker]

I ended up fitting a non Oring chain in the end to give me a little more room and extra length to pull it back in the axle slots. Cheap option.