YZ250 RB Head Mod

Here is some information for the good of the order. I just had my head examined, I mean modified by RB Designs in Portland, Oregon. I had him lower the squish band to .040-.045 running on high-octane pump gas. I believe stock is about .070.

The modification seems to make the bike run very crisp, with an added bit of punch right off the bottom. As if this bike needed that. The bike seems to run cleaner without all the pinging and detonation I was experiencing before. I think I will need a flywheel weight now, as I ride off-road.

But, I must say that one benifit that almost out-weighs any performance gains, is the lack of spooge running down my silencer at the end of the day.:smirk: Really, the stuff drives me nuts. The rear fender splatter is all but gone too. The pipe showed a 1 1/2" dribble from the outlet, just enough to let me know the motor is safely rich.

Anyway, it was worth it and I would recommend it to anyone who (like me) has not been able to clean up the carburation on their YZ250 through the brass.

The proprieter requires a cashier's check, or money order, which is a bit of a pain but what the heck, it's still a free country. I have no affiliation with RB, and I am not receiving any compensation for this post. I just want to pass on my remedy.:smirk:

Take care and stay safe.

Sounds good :smirk:

How long does it take to get it back once you send it in?

RB turned mine around FAST. It was under a week, including shipping time both ways. I dont see how mine could have sat in his shop for even 24 hours.

I've got to find me a spare head and get this done.


I've gotten heads and cylinders back from him the same day. He hates having work hanging over his head, I think....

I had the same experience as Murphy. This was the ONLY thing that cured my YZ from spooging. That alone was worth the cost and effort.

odd, neither of my YZ's spooge...

it looks like the guy does slide mods also, i was looking into both these mods, funny i live about two hours away, i might stop by there my next time through portland, anyone have his slide mods done to make the stock 7 into an 8 by RB? from the sound of it he does good work

What kind of silencers are you guys running? I just had my head worked on for my altitude and to run on 91 oct, and I still have some poo coming out my fmf q-stealth

its a two smoke, just just like to get a little wet, i haven't ever seen one that didnt spooge a little that wasn't just about to blow up lol

Repack your silencer. I'm sure it was already saturated and is pushing old spooge out the end.

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