Another Wombat 94 Break-In

[Bill2001]

For my Fourth Fire Works I fired up the Wombat. The piston had seized, and now I repaired it with a cylinder hone, new piston and rings, plus much TLC. We suppose that engine ran hot because the stock mixture was too lean. The first thing I'll do is increase the main jet. Stock is 160, and I have 170, 180 and 190 mains on hand. Once i get a couple of heating-cooling cycles bvhind me, I'll start riding 2 or 3 mile easy runs in the pasture. I think I'll use a 180 main for those first runs. After i get a few of those runs behind me I'll go to a long hill about a half-mile away and look closely at mixture/jetting. No repeat of the earlier kerfuffle.

I've a couple of threads on break-in, but don't have a firm 2-stroke plan in mind. Advice is appreciated.

[taber hodaka]

As I remember the main jet tunes the 3/4 to wide open generally. If you do not run in those ranges you may need to jet for the RPM range you ride in. --------Clarence

[Bullfrog]

I would suggest re-reading the tuning process for the VM round slide Mikuni carbs. The very first thing to do is get the pilot jet dialed in. Since I'm not sure which carb you have or the components which are installed in it . . . following proper procedures are advised.
Ed

[Bill2001]

Carb is a new VM24...-83B. Earlier I did set the "idle mixture" with the throttle stop & air screw, but I've since learned how critical that is and I'll recheck it per the Roundslide manual. Feh, I didn't order extra pilot jets so p'haps I can borrow a couple locally. That adjustment is more critical than on my BMW's Bings.

Stock carb, stock air filter (UNI), stock exhaust, even with the spark-arrestor. Dead stock, which is why I didn't think of rejetting before.

[Bill2001]

Just got back from a quick browse of the Wombat dyno thread. After I get the rings seated I wonder if a dyno run to set the mixture would be worthwhile...