I am posting this for a friend who needs a bit of help, and since I'm a Red Rider, I didn't know the answer. He has a 1991 LT250R, with an '86 cylinder, head, AND intake manifold installed. He is wanting to go back to a late model cylinder and piston, but as you yellow riders know the later model intake and '86 IS NOT interchangeable. He found out that to get a new intake manifold for the late model he HAD to order the airbox assembly too(in one big $$$ package from Suzuki). My recommendation was to purchase a Boyesen Rad Valve for the late model and bolt it all up. I knew that my Rad Valve on my TRX250R had the carb to manifold boot built into the reed cage. Is this the SAME style offered for the late model LT250Rs!?! If it is, his problem is solved. Late model cylinder and piston, PD Cool Head w/180 psi static compression, and the Boyesen Rad Valve to make all of this possible. Will the Rad Valve solve the compatability problem???? [img]i/expressions/face-icon-small-confused.gif[/img] Thanks in advance from my pal.

 

To clarify your question, your friend probably has a 91 LT with an 87 cylinder ( 85-86 totally different), He wants a later (88-92) cylinder, he can use the rad valve and it does come with the boot. the 87 LT cylinder is unique in that it looks basically the same as the 88-92 but it has a much larger intake with only 5 reed valve mounting bolts instead of 6 on the 88-92. Some people say that the 87 cylinder is the way to go (if you port it) as the larger intake, and reed assembly that flows much better than the 88-92. The 88-92 has a little bigger intake ports on the cyl and a higher exhaust port which flows better in the top end, but this advantage in 88-92 can be negated by porting the 87 cylinder.

 

I called my pal on the phone and was corrected that the cylinder IS an '87. Thanks for the clarification! I also found out on MacDizzy's site that the '87 uses an 8 petal compared to the 6 petal of the '88 and up models. In order to gain more lowend, we normally need to run fewer reed petals(ie 4 petals) so this would support the later cylinder for more lowend. Unfortunately raising the roof of the exhaust port on the later models actually will hurt lowend a bit(decreases powerstroke). Do you have any additional comments for my friend? THANKS![img]i/expressions/face-icon-small-smile.gif[/img]

 

my brother has a '90 LT250R, with rad valve, it does come with the manifold and boot that goes to the carb. we had to replace the cylinder recently too...so we know all about this stuff. lowest priced sources for these parts i've found new... 88-92 cylinder-YSA powesports(look 'em up in dirtwheels)
88-92 rad valve- rocky mountain ATV
if he's running a 38-39 mm carb, LRD makes a custom ported rad valve, as well as a different rad valve boot to fit the larger carb.
we also found it was almost less expensive to buy a new cylinder(if you havent had it ported) than to have it re-sleeved locally. my brother's cylinder needed thread inserts and studs pulled too, so a new cylinder got ordered.

 

Hey, did the LT250R ever come with case-reed induction like the RM?

 

no, the quadracer never had case reed induction

 

Just a note for anyone with head studs pulled on a 250, usuaully the back two will pull. these studs can be replaced with stud from a 500, they have the same size stud for the head but the base were it goes into the cyclinder is large. you can have the old stud hole drilled and retaped for the large 500 stud base. Almost gurantied that you will not pull a 500 stud out.

 

man, i miss hearing the word 'quadracer'. with more factory support and more determination from other OEMs, maybe suzuki now will say, "screw you," to their lawyers and ressurrect this name for their new 450. i know it was off topic, but the quadracer term just brought back some memories.

 

That is what I just ordered. I think it is about the best option if you have a big carb. I ordered a stock intake last week and had to return it...no way it was going to stretch enough to fit the 38mm carb.

 

your crazy that boot will and does fit i have a 86 frame with 90 motor.38 pwk and stock boot. i also have a 1987 with a 38mm airstryker stock boot. just so ya know it does fit ask 800 screws he has his ona 38 i believe.