well i have a 87 QR with prodesign coolhead and i was wondering if the stock head is better for top speed ,reliability,and overall better outcome because i keep blowing gaskets and then burning up pistons and i am so sick of this that i am thinking about getting a stock head instead of putting it back on and burning up another piston. i have run the head and cylinder on some sandpaper so its flat and i wasn't using OEM gasket so if i did that would help , plus i also read that taking the head stay bolt out it would help. plus i also read that higher compression loses reliability. all i want is the head NOT to blow a gasket in a few weeks, not overheat, plus i heard that you lose top speed with highcomp. head .please give me your honest advice to my problems[img]i/expressions/face-icon-small-sad.gif[/img]

 

Have you tried a cool head with an O ring? I have had no problems with mine, LRD milled mine from a gasket to O ring. My other LT500 has a stock head on it and it will stay that way. I read on here about a stock head being better by design but can not remember who was saying this. It was a chat about "squish" cutting down gasket to bump compression.
Good Luck

 

actually the head has inner o-ring seals in the head itself. i was using aftermarket gaskets between the head and cylinder but i heard they suck so i was thinking about getting genuine suzuki gaskets.

 

Genuine suzuki gasket will only work up to .040 over. No bigger. Sounds to me like you need to mix 50:50 pump premium and race gas. Maybe all race if you have lots of compression. Your probly detonating.

 

why only .040 over and not bigger?[img]i/expressions/face-icon-small-confused.gif[/img]

 

whats detonation like ? how does it sound / act before it blows or breaks.

 

Are you talking about a 250 or a 500. The stuff I relpied to was about 500`s. I dont have any experience with the 250. Im sure there probly the same at .040 for the head gasket. The stock gasket is only that big. if you bore the jug to lets say .080 then the outer edges of the piston hit the metal ring of the gasket. Usually you cant hear detonation on a quad. You should take a compression test and call one of them shops like trinity and see if they recomend race gas. I know on a 500 that anything over 170 and you should run race. But if you have porting you might need to run race even if compression isnt that high. The pressure builds more at rpm`s when ported.

 

actually its a 250 bored .080 over with the standard dome size that comes with the prodesign cool head when you buy it. i think its a 22cc dome size because you have to buy any smaller dome sizes. how could i tell if i detonated anything? what signs of wear and tear do i expect with detonation?plus how could i tell if the gasket is too small?[img]i/expressions/face-icon-small-sad.gif[/img]

 

We went thru this same scenario with an 87 500.

Couple of questions first.
How long have you had this bike? Did you buy the coolhead? What for absolutely sure is the dome size? Have you run a compression check? What carb? Jetting?


If you are running a head gasket (not o-ringed to the block) the stock Suzuki gasket is best, period. I know the coolhead has o-rings that seal the dome to the head, this is not what we are talking about. Use the genuine Suzuki gasket, spray both sides with copper coat, install the head @ 21ft pounds torque on the nuts. Run a compression test, besure and use a tester that has the same length of threads(or reach) that your sparkplug has (VERY IMPORTANT FOR ACCURACY). Hold the throttle wide open while kicking it and kick until the gauge does not climb higher. If you have more than 165#'s then you need race octane fuel.
You must make sure the carb jetting is correct or a little an the rich side for safety. The Zilla we were working on had the exact same symptoms you describe (short run times, blow the gasket, ruin a piston). We found the previous owner had not rejetted the new carb when it was installed! We ASSUMED the jetting was ok. The main jet in that bike went from a 162 to 190 (Keihn) ! No more problems....

 

YES listen to truck racer he knows what hes talking about. Checking the compression often is useful for diagnosing your problem but remember with a new piston and rings yuor compression will be low at first, until the motor is broken in. MY lt 250 had like 160 lbs. then after about 3 hours on motor jumped to about 190, and stayed there. A fter every break in cycle of riding and allowing it to cool re-check your compression. For example if you get a significantly smaller compression reading than the last something may be wrong and you can fix it before you blow another motor.