'84 1200 engine for a '82 GW

[dan filipi]

I must be missing something. I don't see how a valve could leave a mark like that on the cylinder :headscratch: especially not that far in.

 

[Denver]

Valve on the opposite side shoving it over??? :headscratch:

 

[slabghost]

No way it's a valve.

 

[joedrum]

well on hooch ..i had one head on with oldgasket and other head off ...its starts to hit with arly cams when valve is extended ..them piston is pusing the valve home ...marks are in that zone not saying for sure its that ...but the pisto dose try and push valve to edge as it id dome top..then it actually get caught some in the stock cut outs in the piston just before top with early cams ....duration being shorter on 1100 cams makes this action slighter id say ...to the point the other pistons are not showing signs ....

good thing your going 1200 heads in my opinion ...to think the clearence is there to do 1200 modded motor with no piston work and 1000 or 1100 heads is not something to push at all ....

good check is to see if this is where intake valve is on head ..if its exhaust then its something else for sure

 

[canuckxxxx]

Pretty sure it's not the valve hitting :nea: . It's more of a localized wear. Besides the valves in that head look fine. Post #126 has a pic of that same cylinder and no wear in that spot.

You can see along the top edge where the surface has flaked off. You can feel it.

Could it be some issue with the rings? :head bang:

Brian

 

[slabghost]

Look close at the full size picture that is a stain.

 

[Denver]

Water making its way down spark plug threads & laying on bottom of bore will form a rust spot & stop motor from rotating past it. :roll: Have a parts motor that suffered this fate, :sensored: so a stain happens before rust, just may be a stain. :beg:

 

[canuckxxxx]

But this bike has not been sitting around, I 've been riding it pretty regular until a couple of weeks ago. :moped:

 

[slabghost]

condensation maybe pooled there and caused a little rust which would lift the glaze. Then combustion and piston rings removed the rust leaving just a stain.

 

[canuckxxxx]

Could be, Slab. Makes sense; on left side, with bike on side stand, water would pool there. When I took head off #2 was all the way out and #4 was in.

I'm going to look at it again with a strong light and magnifying glass. There seems to be some damage to the surface.

Thanks
Brian

 

[ekvh]

Joe, you looking at the piston? Something looks funny there from what I remember of 1200 pistons. It should show valve reliefs and no groove out as far as that piston. Exhaust valve is on the other side of the groove in the pic, but something looks funny, unless it's optical delusion.

 

[joedrum]

yes im sure its not valve hitting i dont know i was thinking last night ....seems like something is falling there and getting in the piston crack .....and taking out the cylinder wall some ...the scratching has about taken the ring groove out ...could be the black gunk on pistons .....i have diffidently seen stains there before ...but not the wear you can see ....seems piston tops need good cleaning ....maybe this will help figure whats up brian ....i notice in one pic you can see the black in the lines running strait up and down around the edges of the stain ....

quite a wear spot for such little time the motor has been running ...and on SCC...hmmm maybe something is not good in the set up there ....

if i remember you said your plugs look light tan ...piston top dont look that great on that cylinder at all ...what do the others look like ?.....

 

[ekvh]

It almost looks like the edge of the piston is coming off. Looks like a chunk missing in the bottom of that groove. If so, this is bad news. Hope I'm wrong.

 

[dan filipi]

Easy to see that's a stain.
Burning some oil too.

 

[canuckxxxx]

Dan,

Yes, it does use some oil.

BTW, here is a picture of #4 cylinder that I posted when I first go this engine. No signs of this staining or corrosion or unusual wear. I've put about 3000 miles on the engine since installing it...mostly highway.

1100 cylinder walls 1

• canuckxxxx
• Jul 5, 2015

Starting to feel like :deadhorse: :deadhorse: :deadhorse:

Brian

 

[dan filipi]

Well, you asked opinions.

I wouldn't even pay any attention to the stain and move forward with whatever you're doing.

 

[ekvh]

Now I see the valve reliefs, they look normal. I was thinking this was more towards 4 o'clock.

 

[joedrum]

me too....i personally think the carb is dumpimg gas in cylinders at low rpm running ...the before pic shows decent piston ...the after seems wet nasty black and collecting in bottom and also marking up the cylinder by sanding it with the black gunk ...is my guess .....

after my work on dft carb i cant see a stock carb ever doing right ..in my opinion

 

[canuckxxxx]

Joe, do you think black gunk is due to over-rich gas or burning oil?

 

[slabghost]

Way over rich.