Help with 1993 RM250 PWK Carb Upgrade
Thread Starter
|
Junior Member
Joined: Apr 2024
Posts: 3
Help with 1993 RM250 PWK Carb Upgrade
Hello, I have a 1993 Suzuki RM250, fresh rebuild and have updated to a PWK38. I am trying to get the jetting correct and are hoping someone may have done the same upgrade, or at least point me in the right direction?
My original settings in the original PJ38 were PJ-40, Main-195 and R1471N needle (3rd clip).
My first disaster occurred after my first test after a full top and bottom rebuild with the PWK. I fitted PJ-52, Main-180 with the R1471N (3rd), the bike seemed to go very well for 2 hours until the new piston decided to burn a hole through it!!, during this disaster I was running 91 octane, with Castrol 2T std oil (for the run-in) @ 32.1. Now I do not know if this assisted in the failure.
I have now rebuild the top end again, this time I also pressure tested engine, it did have leaks evident on the RH cover gasket only, resealed, all the replaced oil seals from the lower build still held vacuum. 5psi for 10 min, no drop.
Back to the track, changing settings as what I was recommended, I tried the original PWK needle (DDJ) PJ-45 and Main-205, bike ran flat, and hesitated.
DDJ, PJ-52, Main-205. Better, hesitation mid-range, flat spot for seconds and then power…
DDJ, PJ-55, Main-205 Better again, hesitation still evident, however doing the air needle it was 3 ¼ out indicating PJ to rich.
Dropping DDJ needle down to 5, improves but not enough….
Using the DDJ needle creates this flat hesitation, like I turn fuel off?
Refitted the R1471N needle, played with Pilot jets (I have a 40,42,45,52,55), (and also have Mains 155-210 available) but only the two needles mentioned.
Finally finished up with PJ-45. Main-210 R1471N (4th) bike ran ok, no hesitation and pulled ok.
I have gone back to 98 Octane using Castrol synthetic oil @ 32.1 again, but I lack the confidence and money to again ring the neck out of the machine.
I am open up to suggestions and jetting recommendations as when I think I am heading in the right direction, I get a curve ball. My location is South Australia, 0-300 metres elevation, 20-40 deg Celsius. For those who like fine tuning….
Sorry to be long winded but trying to get as much info to you.
I would appreciate any feedback…. Cheers
My original settings in the original PJ38 were PJ-40, Main-195 and R1471N needle (3rd clip).
My first disaster occurred after my first test after a full top and bottom rebuild with the PWK. I fitted PJ-52, Main-180 with the R1471N (3rd), the bike seemed to go very well for 2 hours until the new piston decided to burn a hole through it!!, during this disaster I was running 91 octane, with Castrol 2T std oil (for the run-in) @ 32.1. Now I do not know if this assisted in the failure.
I have now rebuild the top end again, this time I also pressure tested engine, it did have leaks evident on the RH cover gasket only, resealed, all the replaced oil seals from the lower build still held vacuum. 5psi for 10 min, no drop.
Back to the track, changing settings as what I was recommended, I tried the original PWK needle (DDJ) PJ-45 and Main-205, bike ran flat, and hesitated.
DDJ, PJ-52, Main-205. Better, hesitation mid-range, flat spot for seconds and then power…
DDJ, PJ-55, Main-205 Better again, hesitation still evident, however doing the air needle it was 3 ¼ out indicating PJ to rich.
Dropping DDJ needle down to 5, improves but not enough….
Using the DDJ needle creates this flat hesitation, like I turn fuel off?
Refitted the R1471N needle, played with Pilot jets (I have a 40,42,45,52,55), (and also have Mains 155-210 available) but only the two needles mentioned.
Finally finished up with PJ-45. Main-210 R1471N (4th) bike ran ok, no hesitation and pulled ok.
I have gone back to 98 Octane using Castrol synthetic oil @ 32.1 again, but I lack the confidence and money to again ring the neck out of the machine.
I am open up to suggestions and jetting recommendations as when I think I am heading in the right direction, I get a curve ball. My location is South Australia, 0-300 metres elevation, 20-40 deg Celsius. For those who like fine tuning….
Sorry to be long winded but trying to get as much info to you.
I would appreciate any feedback…. Cheers
Thread
Thread Starter
Forum
Replies
Last Post