I just completed a rebuild on an EVO with 75K on the odometer and have never seen such carbon build-up in the heads, on the valves and piston tops of any engine I have pulled-apart. It was absolutely a mess. I know that driving habits and poor fuel aggravate the problem, but I want to seek some advice on fuel additives and "how to" prevent/minimize this. I have always used the Harley additive (which I adoringly named skunk-pee due to the odor). Years ago, it was available in a concentrated form, but now comes in a bigger container. Obviously diluted and MOCO can charge more for a bigger bottle. Anybody out there have any tips, or a favorite additive? This is a fuel injected bike.

I see folks still using a little Marvel Mystery Oil and Seafoam, but I've been told Seafom doesn't work. The Honda crowd seems to swear by it, but I've never used any.

 

First thing to do would be to make sure your head breathers are in good condition; they are cheap so new ones would be good. Next, vent your crank case breathers to a vented catch can or to the atmosphere and get that nasty crank case oil/water/uncombusted fuel vapor out of the intake track. This will go a long way toward minimizing the problem. The last step would be to run some Sea Foam mist through the carb once a season to break up any carbon that may be building up; there won't be much if you do the above. Running some MMO or Seafoam through a tank of fuel occasionally certainly won't hurt.

 

tagged for reference,,,,,More comments on MMO is appreciated

 

MMO....Marvel Mystery Oil. Been around since about 1928 I think. Some people swear by it for just about any automotive use as an additive in the oil and the fuel system. I'd Google-up Marvel Mystery Oil and you'll find lots of information concerning the product, including it's ingredients' and uses.

 

That Sea-Foam does work well.
Scott

 

Polishing the heads will help.

 

Did that by default ohio. They were so blamed cruddy....by the time I had cleaned them up they were pretty well polished.

 

Another vote for Sea foam. Use it in everything lawn mower, snow blower, generator you name it. Also works pretty good on the new direct injection cars. You ain't see carbon till you work on some of those.

 

Ride it like you stole it.

 

Back-in-the-day we called that blowing the soot out of the engine. I'm a believer in that to some degree....I think she needs to be s t r e t c h e d every now and then. This particular example was a "city bike" and likely saw a lot of putting from one traffic stop to another.