Reply To: Wisconsin M RBM poppet valve carb

[PM T2]

I’ve reviewed your 2 minute video and have come to the conclusion that its your choice of radio station that is screwing up your motor. Seriously. Play some classic rock before your motor barfs on you…..

I’ll repeat that I agree with Harry that it sounds like a fuel supply issue but add that I do not believe it is poppet valve related. Continue with the valve stem refurb, but even as sloppy as you describe it (and 15 thou clearance is not out of the ordinary for something that old) it shouldn’t cause your engine to start, run briefly, then lean out and quit. Dunno where your needle is being set at and what condition it is in, so maybe fill us in on that part and I may have further opinions to add/subtract. The needle profile and fit in the orifice is as important as any other factor in getting a motor to run its best.

Like I wrote earlier, I made a new poppet for a Blakely gearless because the old one was so sloppy. The new one didn’t solve my non-start issue that was compression-related, but once the compression leakage issue was rectified, the new one didn’t make the motor run any better or worse than the old one. I’ve reverted to running the old one with its 0.030″ clearance between the stem and casting and the motor runs fabulously well.

Hope it helps.

Best,
PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...