[HC head install] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

Pages:1

HC head install
(Click here to view the original thread with full colors/images)

Posted by: forgiven

I am going to put on my koso head on the 90. Is there anything I should know...unbolt, replace gasket, rebolt...right?

Posted by: drr wizard

torque your nuts in a cross pattern starting at 5 lbs each , then torque to 10 lbs each and then 12 lbs . retorque your head after 1 hour of run time and your ready to rock . premium fuel only!
drr wizard

Posted by: forgiven

I was actually wondering about the torque specs...thanks

Posted by: kenjolly

I just put a 220 psi head on our 07 water cooled 90, i havent changed the fuel yet and add a 125 main jet. am i close on the jet or do i need to go up some. havent run it yet do to the chain breaking when i was replacing the swing arm,piece of s??? chain.
it doesnt seem to be as noisy but smoother.

any thoughts

Posted by: markvette

did you test the compression and get 220 or was that what the person you bought it from claimed. 220 is asking for crank bearing failure. seen a brand new race motor waste the crank bearings on first test run with 220

Mark

Posted by: kenjolly

no i didnt test it, what would make sound different its not as raspy or as loud. i got the wrong uni filter so the stock one will have to do for now.

Posted by: bulldogfallon

HC Compression equals smaller main jet, but race fuel means larger main jet...

Run it and do some quick plug checks

I wouldn't open the main air screw up to the 2.48mm like the mod recomends.....start smaller and see if it helps..

I am not 100% sold on the OKO mods yet

Posted by: ecmini1

Ken,
Great talking to you the other day, Bulldog is correct on jetting nothing in text will give you your jetting plug reading is the way to determine correct jetting. You might find out the 125 might be close or on the rich side.

Posted by: kenjolly

I will check the plug as soon as i get a new chain, the master link fell apart in my hands, im going to try the 50/50 mix drr wizard mentioned.

we missed you yesterday at PAX ecmini1, had a good time much more relaxed than daecity. i should have ran the 90 not the 70. not a bad day finished 2 to mod trx 90.