porting & piston wash pictures..

[Dski]

alright guys.. my SJ was running crappy as i posted last week(one of the cylinders seemed to be not running).. so i pulled the plugs and pulled the head off and here is what i found... still 195psi in each cylinder

questions:
whats the deal with that porting??
why is only half the plug burning and how can i fix it? what caused it?
are those aftermarket pistons?

 

[Dski]

here are the pistons:

 

[Matt_E]

Edit: Never mind about the eight port. It looks like the transfers were cleaned up nicely while the exhaust port was widened in a very narrow area.
Interesting.

 

[waxhead]

whats with the exhaust port
i dont like the look of that at all
the port pushes the ring in and then lest it out again just before is shoves it back in again
look like you are going to get twich the ring groove wear than a normal port shape

 

[Dski]

yeah definitly differnt than i've see on these boards.. how bout any comments on why one of those plugs is half burnt? and how does the piston wash look? i gotta get this thing running right by next weekend.. one of the cylinders seems to be not tuned right.. any suggestions?

 

[sflsurfrider]

dual carbs or single?

it looks like its not to late to fix those exhaust ports. it doesnt look like too much material was taken away from anywhere. just remove some more metal, right?

 

[sflsurfrider]

also, the plug on the right looks .... rusty?

 

[SkiDaddy]

yeah definitly differnt than i've see on these boards.. how bout any comments on why one of those plugs is half burnt? and how does the piston wash look? i gotta get this thing running right by next weekend.. one of the cylinders seems to be not tuned right.. any suggestions?

It's normal on a 2 stroke to have uneven looking plugs. As to the piston wash, I'm no expert, but the jetting looks ~OK~ to me with some imbalance, maybe from the porting.

 

[Dski]

its running dual buckshots with race gas. the plug wasnt like that until after it started sputtering last weekend.. so you guys dont think the posting is too radical to run pump gas if i drop the compression to ~180psi and set the TL timing to a normal degree?

 

[douglee25]

I've never seen that type of port job, but my guess is that porting is to increase the exhaust velocity to help with the scavenging effect?

The cylinders actually look like you may have had some water ingestion issues? The vertical lines don't appear to be that of a ring snagging on the port either. I gather this because I see vertical lines even where the port isn't present.

Doug

 

[douglee25]

whats with the exhaust port
i dont like the look of that at all
the port pushes the ring in and then lest it out again just before is shoves it back in again
look like you are going to get twich the ring groove wear than a normal port shape

I would disagree.:smile: The contact portion on the ring extends all the way around the cylinder. When the ring crosses over the first lip of that exhaust port, the ring should not come out of it's groove whatsoever. The rest of the cylinder should be holding it in. Also, the ports look to be chamfered quite nicely. I don't think it's a ring snagging issue.

Doug

 

[Dski]

hmmmm the inside of those cylinders are extremly smooth.. yeah actuallu cant feel any of the lines in the picture and compression is where is should be at 195psi per cylinder.. water ingestion huh?? interesting.. how would i find out if that is the case and how would i fix it? thanks for the ideas.. i am brand new to fixing skis and dont really know where to begin..

 

[Dski]

heres the initials of whoever did the porting.. anyone know it??

 

[waxhead]

protec
it doesnt look like a protec port job to me

 

[douglee25]

hmmmm the inside of those cylinders are extremly smooth.. yeah actuallu cant feel any of the lines in the picture and compression is where is should be at 195psi per cylinder.. water ingestion huh?? interesting.. how would i find out if that is the case and how would i fix it? thanks for the ideas.. i am brand new to fixing skis and dont really know where to begin..

Well looking at the pics again, it def. looks like it could be a combination of water ingestion/running lean. If others agree with that, set your carbs up a little richer, lower your compression to around 180ish, and run a set of stock flame arrestors to avoid water ingestion.

I would hone out the cylinder and see how the bore diameter and piston to cylinder wall clearance are compared to the spec limit. If those things look good, chamfer the ports again, slap in some new pistons and rings, and ride it.

Edit: I just saw the pic of the cylinder with the initials. To the left I see a 'K&N type' air filter. That's how water ingestion happens easily.

Doug

 

[waxhead]

I would disagree.:smile: The contact portion on the ring extends all the way around the cylinder. When the ring crosses over the first lip of that exhaust port, the ring should not come out of it's groove whatsoever. The rest of the cylinder should be holding it in. Also, the ports look to be chamfered quite nicely. I don't think it's a ring snagging issue.

Doug

i dont think the problem he is having is a ring snagging issure ethier
but i dont like the port shape
it the amount of movement of the ring on the land over the port will create massive ring land wear in comparison to the more conventinal port job in my op
the ring always bulges into the exhaust port even on a stock port

just the way this is doing it its inand out real fast at the small point
and i dont like it
if you were going to do it then you would have been better off having it wider at the top where the gases are still holding more pressure
plus its quite likely that as it goes over that round bit that it creates another even though softer sonic wave that confuses the pipe

 

[waxhead]

one thing is for sure you need to helicoil those head bolts

 

[Flash-FX]

How about cleaning up the head/deck surfaces and replacing the shot-out
o-rings? Looks like some leakage there.That allways makes things run like crap.
Did it ever run really good?

 

[cookerq62]

could that porting be to get a second pulse going to the pipe???

 

[keefer]

I have seen several cylinders from Protec that had the exhaust shaped like that. I think they were offering that porting style starting back in the mid 90s. It is odd looking and seems like it would produce an unusual exhaust sonic wave. But then again I am no expert either.

I agree that you should have that cylinder honed and measured along with the pistons. If things are within specs you might just be able to install new rings, gaskets & O-rings for the head. Pressure test the engine for air leaks before you start it. Check the internal carb filters and replace the external fuel filters. Make sure the carbs are popping at the same pressure and take a look at the jetting to get it tuned properly. Those Buckshot carbs usually work better with higher compression engines due to their lower signal. The Buckshots I had were kind of picky on the low end and were better for mid top RPM style riding. Good luck!