1986 XC 500 - 38mm mikuni flatslide.

Hello,

ls anyone here running a mikuni 38mm flatslide on a 500, ive read somewhere they work well, and improve starting, whats your experience?

l have one on a XC400 that ive got to work very well, i dont know about improvement over the stock roundslide as the org was totaly shagged, and i rebuilt/refreshed the engine at the same time. lt would interesting to have a good round slide to do side by side testing with.

Thanks

I've run the Keihin PWK 38mm flat slide and it's much cleaner than the round mik.

Yes I have grafted the carb (good condition) which came on a 2002 wr360 onto my air cooled 500. I assume this is like the carb you are asking. It is just a little big for the carb boot to the reed cage for a 38mm round slide and quite a bit small for the rubber boot for the 40mm round slide. I fixed this by building up the carb with epoxey gas tank repair paste and turning the hardened epoxey on a lathe to mimic the 40 mm round slide profile. In my application the length also needed stretched and made to accomidate the air cleaner boot. Just guessing you would switch to an air boot for a 38 of that vintage or sleeve that bigger which allows you to go longer if necessary. I have a pwk 39 but have yet to install that one which is planned on for a 430 and cost much more. I got the biggest pilot jet I think a 50 instead of the 35 which was in it, the main jets are the same as the round slide ones. When the bike with the 40 mm carb was new and for a long time it started wonderfully, eventually the carb got pretty worn out, the threads for the idle screw failed. It starts pretty good now but different and I am not sure I remember or have figured out what order to pull the knob or twist the throttle. I may not be done jetting it but it certainly was/is a low $ improvement from where I was. It starts wonderfully when warm. As for the water cooled 500 models I havn't had good experiences starting them but didn't tamper with anything from the previous owner. I am pretty sure Honda cr500 and kx500 used keihin pwk39. I also notice by 1988 husqvarna seems to have gone to a 38mm on the xc500 and only 40 for the cr version If I recall the parts sheet correctly. I also see the 44 mm version of the bored out 40 they started with in 1982 or so didn't last long.

Fran

Thanks for the input guys.

Picklito, what do you mean by 'cleaner'?



Fran, lm going to put a XC500 LC mill into a XC400 LC.

l got a new 38mm flatslide of evilbay that came with; #22.5 pilot jet, 6FJ41 jet needle and #280 main jet.
My XC400 ended up with #45 pilot, 6FJ40 jet needle,#380 main and dial a jet. Runs very well, starts 1st or 2nd kick, after 3 gentle strokes on the kill switch from cold, when warm, 1st prod with a blip of gas.

The LC reed block, mainfold etc will swap straight accross from the 400 to 500, lm thinking of leaving the pilot, 6DP4 jet needle, and start with #460 main.............................

Failing that i have one of those HUGE 42mm mikunis!

Cheers

Bike seems to run smoother. It always felt a bit "gritty" with the round slide, no matter how I jetted it. I could get it to where the plug was clean, no spooge out the back, no fouling, easy starting, good power everywhere, but running just seemed sort of rough. Put the PWK on there and it's snappier, sharper, crisper.

North Husky, look into a PWK air striker 38mm carb.

Available from J.D.Jetting.com for only $239
comes complete with a J.D. Jetting jet kit (a $70 kit)

Front spigot is 3 mm larger (but fits snugly) and the rear air bell is the same diameter.

overall carb lenght is 1/4" shorter so i made a 1/4" phenolic spacer to put the filter air boot overlap back to stock.

Also J.D. will custom make the jet kit for your bike,alt., and temp!
Awesome carb and tech support.

........Thanks,