anyone run this setup. i have a 92 lt250r with foam filter no lid, 38 pwk airstryer carb, rad valve, bored once over cylinder. i just got the carb and have not installed it yet. i was wondering if i could get a starting point with the jetting so i don't have to spend alot of money on jets. thanks

 

Sorry man, I can't help you out, but try calling the local dealer or an engine builder in your area and they can look it up in a book for you taking into account your elevation and the outside temperature you'll be running in.

 

JJ, What engine are you running?

 

1989 RM250 motor. mildly built. (piston, rod, head, reeds, pipe/stinger, etc...)

I'm RMLT250R Quadracer from Macdizzy if you were wondering. Can't wait to get back on that site soon. I check on it almost every day to see what's being posted! Stupid paypal.

 

I thought that might be you. How does it run compared to a built LT engine? Also, is the vibration theory true? I keep hearing about it, but people do it anyway.

 

I estimate something between 40 and 50 hp. Power is pretty good all around, but I want to try a flywheel weight in the future to make the motor a little bit more suited for a quad frame.

the vibration theory is definitely true, but I still believe it can be overcome! that's my goal with this project to completely get rid of all vibration. I have an anti-vibe steering stem and some other stuff but the shakes are still there a little bit in the higher RPMs. I had rubber washers in the motor mounts before and it really helped get rid of vibration but then I tied everything in solidly again because I was worried that the engine was too loose in the frame which is hard on the chain and the motor mount bolts.

In the future, I plan to perfect my rubber motor mounts by using rubber cones from an anti-vibration steering stem in the motor mounts.

oh yeah, and your quadracer is SUPER nice!

 

Thanks! Yours is sharp as well! The black wheels toughen it up cinsiderably. Do you know Mark from HSD? He should try the RM set up with his IRS.

 

That would definitely be very interesting for me to see Mark try out an RM250 motor in his IRS quad!! I've considered the idea a few times of doing IRS on my quad, but I think some people would get my quad confused with Mark's seeing as we're both in Manitoba. Still, I think that the advantages of IRS are very considerable, and if one were ever to build an IRS quad, they would have a lot of info to draw on, just by looking at Mark's machine one can see what works well and what doesn't work well. I'm sure that when mark builds his next IRS quad it'll be a much lighter, simpler beast.

FTZLT250R, I'll probably be coming down to Minnesota a couple times this year to race my LT in Staples although I'm not sure what weekends I'll go. Are you planning to go there any more times this year?

 

I am wondering if the IRS would absorb a little of the vibration. They say the forks absorbs it all on a dirt bike.

I am somewhat trying to sell my LT. There isn't enough track time in our dirt track series to make it worth racing. I am spending way too much time and money on it to be satisfied with 5 minute races. We have no place to practice without paying for the track and for an ambulance to be there. I could get more track time by racing more classes, but that's just more money......

The Moto Dome is a 3 hour drive for me, and I've only raced there once. If I can't sell my LT, I may be there for one of our spring races. I am in the process of moving, and don't plan on attending any of the winter races.

 

I've wondered about how IRS and other suspension ideas would absorb vibration, too. I think it would probably help out just a little, since most of the vibration is directly up and down along the same axis as the cylinder where the vibration originates.

I think that the key to bringing the chassis's frequency back to comfortable levels would be to soften up the suspension A LOT, whether it be solid rear or IRS. But then your suspension performance would obviously suck.