What is the big difference in a 85-86 LTR and a 87-92 LTR that they dont sell or make Rad Valves or Ram Valves, etc... for the 85-86 LTR's?? Or is there somewhere that sells them?

 

Totally different cylinders. 87+ have powervalve.

 

I just took off my cylinder yesterday to rebuild the motor and I couldn't figure out where the reeds were at since I've never had it apart since I got it. It turns out they are in on the underside of the cylinder and I think that the 87+ QRacers are right in the intake tract.

 

both of you are right. there is some other differences to. the 85 quad comes with a 32mm carb. they changed it to a 34mm in 86 and kept it ever since. in 87 they added a power valve. in 88 they changed the head for higher compresion, and a different pistion skirt design that alows for a longer intack duration. and ever since 88 the only diference is the adjustment specs for the powervalve return spring.

 

The 85 and 86 Lt250 are piston port cylinders which means the piston itself closes the intake.The best way to get extra power is to lower the intake port or shorten the intake side of the piston skirt.Some porters do both.Drop the inlet port 6mm and take 4mm off the piston skirt and hang on to your hat.There are differences between the 87 and 88 onward cylinders.The 87 had a larger inlet reed cage area and ran 8 petal reed cages and the 88 onward ran smaller 6 petal cages.The 87 onward cylinders did not run a variable exhaust port height power valve as such.The mechanism they ran changed the tuned length of the exhaust pipe.