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Need power for a TRX 90
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Posted by: 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.

Posted by: 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

Posted by: 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

Posted by: Oouthere

Zman2,

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

Thanks,

Rich

Posted by: AtvMxRider

quote:
Originally posted by Oouthere
Zman2,

Does the timing key make a substantial difference?

Thanks,

Rich

And also where did you get the sprockets from?

Posted by: 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

Posted by: 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.

Posted by: 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

Posted by: 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

Posted by: 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

Posted by: Oouthere

I managed to install the 106cc kit and after dropping the piston clip into the engine I am now intimately knowledgeable

of the motor. If the key is only for the flywheel it will not effect valve timing so I wouldn't be concerned. The flywheel key and the crankshaft/camshaft gear are not related.

Rich

Posted by: zman2

did the 106 kit help a lot what else are you running with it

thanks zman2

Posted by: Oouthere

I only rode the quad once before installing the kit so I really can't say about the power difference. I can tell you it pulls back a great deal more when starting and the power delivery comes on strong at 50%+ rpm. I believe the midrange power is due to the camshaft (full monster version) and she revs great!

I hate to keep dumping money into this thing but I'll probably have to in order to bring out the full capabilities in the machine. I installed 1 1/2" rear wheel spacers this evening (though the ad said 2") and am now considering a-arms instead of spacers on the front. Listed below are the intended and possible upgrades:

Intended: cdi box
Big Gun exhaust
Nerf bars

Possible: a-arms
custom shocks
tires and rims