who can "read" piston tops/combustion chambers ?

[JanBros]

any "experts" here that can "read" piston top's and combustion chambers ?

had my top-end of from my self-tuned engine after a little more than 1000 km's and this is how it looks :







bear in mind that I had a waterleak (probably right cylinder, where the O-ring is broken) and drove home quite slowly for the last 70 km's.

so, does it look ok ? does it need changing ? I'm especialy wondering as there is a lot of carbon deposit on the front of the combustionchambers and almost none at the back, while it is the opposite on the piston top ?

I guess I set my oil-pump a little too rich ?

[headcoats]

Seen this on the RD forums and it was a waterleak

[Luders]

your plugs look fouled, but that could be put down to the water leak/limp home situation.

it certainly looks as Martin suggests, water related though.

[headcoats]

What quality 2 stroke are you using ?
I found Silkolene comp 2 awful for build up

[dave32]

Pretty hard to tell on the jetting front espescially seeing as you may of had a waterleak(did you lose any coolant?), but there is way too much carbon buildup for the amount of miles you've done.
As said it could be the oil pump set too high or the oil youre using.
Also what squish clearence are you running and are they both set the same?
0.7mm is probably about the limit for unleaded,1.00mm is too slack and will give poor combustion resulting in excessive carbon buildup in a short time.
You could run B9EGV on a tuned roadbike rather than the standard 10's,which i feel also cause most of the over oiling/carbon /sludge build up on a road used engine (whatever stock or tuned),you just dont spend that amount of time at high revs too keep them clean,my h***a RS onbly runs a 10 rated plug and thats a tuned race engine.
when the jetting is close to optimum you will see a more pronounced even pattern on the piston crown,regardless of colour,when over rich it tends to coat the whole crown and/or appear uneven from side to side.
So whats the spec and the jetting your using at the moment?
ATB
Dave

[JanBros]

Dave, engine data can be found here : viewtopic.php?t=7529&start=0

the water leak was probably on the right cylinder (the cleanest piston), and it is my believe that when water is entering the cylindre , it kind of "cleans it", maybe that's why there is less carbon deposit on that one ? i noticed temperature was slowly rising when riding, so atr the next gas station I stopt and noticed water had gone (no outside leak). fuilt it up again and after some 100km, started to rise again. so then I decided to go home, not revving too much, not putting too much stress on the engine, just go with the flow.

I'm using putoline RS959 at the mo' , can't be bad oil. no point in trying to save 1 euro per 100km on oil, it's just not worth it

squish is both the same (0.7), but 1 cylindre is 56.50, other is standard but I don't thinck that should make a lot of difference.

I only use the bike for an occasional trackday or a fun day out in the Ardens, and I do keep the rev's up on the roads on secondary roads I ride at an average of about 90km/h and I have trouble not to rev it, too much fun . downside is I consume a lot of fuel (unleaded 98) on a day out , sometimes over 10l/100km ). plugs are B10EG I believe.

My previous engine was done bye a Dutch tuner. just fitted the carbs as they were, and it felt spot on, never changed it. only thing I have is that when running slow for a while, it needs high rev's for one or 2 gears before it set's of again, but it's not problematic and needed to "clean the engine". or maybe my carb's are set up too rich in the lower rev's, which might explain all the deposit's after "limbing home" ?

anyway : my biggest question (maybe I did not make myself clear) isn't about the carb setup, but the drawings on the piston/combustion chamber : do they have the correct form ? deposit's on the right locations, that kind of stuff