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Is this normal? (big dirty mark on cylinder). it is coming from the decomp fitting, its all over the fitting's vent hole as well.

not normal.... you must be running service honda jetting

I'm not sure - I've never used those types, but it looks like far to much, and it's 'projected' quite a distance.

It looks like it may be staying on, for too long, and being a Second Exhaust Port. It's like a 'burn' mark, to me, in this picture. Not Effing Good!

At the most, I'd expect a tiny bit of 'wetness', at the decomp. itself, and perhaps a tiny drip onto whatever is directly below. It should only be open till the engine turns over a very, very few times, and fires - well, probably before it fires. Even after a few weeks of riding, I'll just have a dust/ fuel spot that barely gets to the top of my cylinder head - which can be wiped of with my finger.

Get off the bike, and check it out whilst it's running - and if it's got 2 ports, have a Bloody Good Look too see if it's firing at the plastic tank......................

That, looks Bloody Scary


If I used one of those, I'd probably block one of the 2 ports (if there were 2), and put a fitting to take a hose, to get the wetness of what should be unburnt fuel, away from the unit. That would also help with any fears of dirt getting into the decomp. valve, that another bloke raised as a concern a couple of weeks ago. I'd go as far as putting a bit of foam in / a RC car airfilter on the hose end. And have the end up high. The Works Honda Decomps, used a 'drain hose'.

The jetting seems fine. minimal smoke, no blubbering, even when idling through tight singletrack for a half hour.

I will check and see if it has two vent holes, but I am pretty sure it only has one.

It doesnt feel like it is leaking while it is closed, might be taking a while to close. The spot doesnt just wipe off like its a fuel/dust mix, it is definitely more of a burn mark.

put the motor under water and run it. If it's bubbling get some valve lapping compound and get busy.

BRILLANT!!!

LMFAO. Or perhaps just build a little fitting to thread the Decomp into and test it with compressed air? Just throwin that out there.

too much work, just dump it in the pool with a snorkle

Freaking bonus is you get to see if your exhaust manifold it leakin too.

seanmx57 wrote:put the motor under water and run it. If it's bubbling get some valve lapping compound and get busy.

LOL.....

You think I'm joking.......

I've got pics of one leaking under water somwhere. Dude pulled the head to check it under water. Needed a quick lapping session.

Mix up some soap and water if your scared of getting wet

I like the soapy water idea better something about water finding its way into every bearing on this thing doesnt sound like fun. Plus, finding a puddle deep enough around here could be difficult.

1/ Put a ribbed condom over it (for traction in the mud)
1/ Start the engine.
3/ If it inflates-you've got a horny engine