Late 90's Yamaha YZ's

[dingoe]

Anyone out there riding an older YZ with the PWM carb? I've got a 1999 yz250 and it has the PWM carb and the choke is the idle adjustment as far as I can tell. To make a long story short, I got the bike, took most of it apart (as I do with any bike I buy) replaced jets, carb lines, reed block, packing, filter, etc. and I can't seem to keep the bike running once I start it. I did dial (turn) the choke all the way closed and do not if the turning of the choke will set the idle after all. If it does, is there a magic setting. I'm trying, but I haven't found it. I'm at approx 700' and it's 50-70 degrees most of the time around here. Ride slow trails and wide open desert trails.

Thanks for any input.

Also, anyone know the torque on the countershaft sprocket nut. What about the chain adjustment, is it 3 fingers like most bikes?

Sorry for the dumb questions, but I do not have a service manual yet. With Huskys you could download one for free, but I've yet to find free manuals online for Yamahas. They sell them for 60.00 or so. Good christmas gift idea I guess.

Thanks ed

 

[gowen]

Ed, maybe your carb is in need of a rebuild or good cleanin'. I bet the pilot jet is just too fat (rich). What is your jetting like? Does it smoke alot?

 

[dingoe]

Gowen, I was told the bike was jetted for desert racing. I got it from one of the other AMA D37 members out here in Southern California. We race in the high deserts, elevation 1200-3500' or so. I went into the bike when I picked it up last Thursday night, cleaned the carb and replaced all lines, swapped the stock reed block for a V-force Delta2, and changed the pilot from a 52 (rich) to a 50 (48 is stock as far as I know). The bike was jetted funny in my opinion. For desert racing, it's best to run rich to keep the motor tight after holding the gas wide-open all day. This is how I found the carb, Pilot 52, stock needle clip position 2 from top and a 172 main. So he had it rich on the bottom, and lean on top. Just didn't add up. Plus when I tested the bike at sea-level it had that typical Lean Bog. The guy was running about 55:1, making the air/fuel mix rich. I guess that's how he could run 2 slot (clip). I like to run 40:1 in my sons bikes, a Polini X-3 Works bike and Planto CR125 Honda race bike. Knowing that I was going to lean the air/fuel going to 40:1, I figured I'd drop the clip to 3rd slot to make the main a hair richer and lean the pilot to 50 from 52, because I race more of the enduros than the open desert races out here. Didn't want the plug to load up so much when dinking around in 2nd and 3rd all day. Overall the bike doesn't smoke and I'd say that's because he had it mixed 55 (plus):1, I dumped that and I'm starting over. Changed the plug too to get a fresh start in the morning. I may just go back to stock 48,2nd clip slot, and 172 and go from there. Was hoping to run in some of the 1000-2000 foot mountain trails this weekend to get the bugs worked out, plus I installed a 9oz flywheel weight and I need to get the bike dialed in with that.


On another note; How's things out in the Triangle these days. My familys from Spring Hope area, Nash County. I use to work with the USACE down in Wilmington, and was looking to get a job up at Falls or Jordan, but it never happened. So we move out here to SoCal after 13 years in and around Wrightsville beach and lastly south down in Long Beach. Ended up moving down on to Long Beach before we moved. It was quieter and cost of living was easier. Plus I could surf with my son right out in front of the house with no crowds. I do miss it up around Spring Hope though, wooded trails, rolling hills, and real dirt (Raleigh Red Clay). One day I hope to get back, I think the wife and kids are getting to adjusted to SoCal living though. Plus my wife make twice teaching in the schools out here. I took my wife by our family farm in Martin County last year, she just sat there looked around and said, "there's nothing here for me it's all trees and dirt, nothing". I guess she and I have different ideas about what constitutes nothing. I don't call 300 acres of prime hunting and riding land nothing. Heck, out here in Southern California all I could afford was a 1 acre Avocado property. People out here call it a ranch, I guess it is when you pay over 500k for a 1200sqft house on less than 1/4 acre.
Man I miss it back there. Ride some real trails for me. Do you get out to run the GNCC races at all?

Keep the rubber side down and in the clay.

Thanks for letting me blab.
Ed