Need power for a TRX 90

[Redpower]

Alright guys I am hoping you can help me out here. My son is running in a stock class with a TRX 90 and everybody is pulling away from him. They say all stock right but these other kids can't be all stock so can ya'll help me get some more power out of this thing? We have cut the pink wire to the cdi and done a little jetting but is there anything else we can do and stay "within the stock" rules. Thnks for any help.

[Oouthere]

I don't know exactly what your rules state but this high compression piston and 5 degree key may fit the bill:

http://www.icracingcomponents.com/engine-kits.html

Something else to consider is final gearing. Heavier rider? Drop it down a tooth in the front.

We just traded-in a 80 Raptor and bought a new TRX90 and are going through the upgrade pangs but the difference is there is no limits except the bike has to start with 100cc or less stock. After that, it's up to you.

I would imagine you could clean-up the ports in the TRX head with a dremel tool and throw in a cam.

Let's us know what you come-up with,

Rich

[zman2]

We went up 1 tooth in the front and dropped from 50 to 48 in rear it seemed to really help with take off and track speed. We got a 6 degree timing advance key from Robbsracingengines.com However we have 2 rider's still pulling away one trx 90 claims he is stock but runs w/Predator that has over $12,000.00 invested. We too are looking for more horsepower. Any replies would be greatly appreciated!
Zman2
trx 90
fmf powercore 4
6 degree timing key
jetted carb
pink cdi wire cut

[Oouthere]

Zman2,

Does the timing key make a substantial difference? What type fuel are you having to use?

Thanks,

Rich

[AtvMxRider]

Originally posted by Oouthere
Zman2,

Does the timing key make a substantial difference?



Thanks,

Rich

And also where did you get the sprockets from?

[zman2]

Yes timing key made a difference, we got the sprockets from our local Honda dealer just make sure it is steel not aluminum and our fuel is 1/2 & 1/2--113 octane(turbo blue) & premium. Zman2

[Redpower]

Thanks for all the advice and we have been thinking about a timing key and my question now would be am I going to have to be concerned with the valves hitting once the key is added since we have milled the head? I guess ICRacing would be able to answer this one.

And as Zman states we also have changed gears and we run a 50/50 mix with premium fuel and high octane fuel which seems to work better than straight high octane.

[Oouthere]

Ok, I'm officially confused.

Is the degree key only for the flywheel? If so, doesn't this only effect the ignition timing?

Or is it also for the crankshaft gear which would effect camshaft timing?

Or is it for both?

Thanks,

Rich

[zman2]

It does it all-pull flywheel replace key, reinstall flywheel and good to go. Rbbs racing sent us instructions along with the key. we didn't have to do anything with timing. You will need a flywheel puller though. anyone have any more ideas for more power without spending a fortune? We are wanting to change the head pipe and next year do engine work. Zman2

[zman2]

Redpower,
Sorry I forgot to answer your question anyways I really don't think you have to worry about the valves hitting but check with ICracing to double check. My answer is no but I don't want to steer you wrong. All it does is give 1-1 1/2 horse all around especially bottom & mid range. Zman2