2006 EC 300 - Looking for some Cylinder Expertise

[bje]

I've just pulled off my cylinder to do a top end job and noticed that the lip of two of the coolant ports adjacent to the outer cylinder head O-ring have small pieces of the cast missing!!

When I removed the Cylinder head, the O ring was still intact in these areas and I've had no exterior coolant seepage whatsoever.

You can note the pieces missing on the bottom left and bottom right coolant paths.

The question I have for the cylinder experts here is simply, do I need to send the cylinder in to have those lips welded back on, given that I have experienced no external coolant seepage and there is no compromise to the internal o ring?

Looking forward to your thoughts.

Thanks!

 

[gasgasman]

Looks like a casting flaw.

It could be a problem.
As the cylinder and head expands and contracts with the heat cycles, the o-ring could "roll" into the cavity and leak.

Trying to weld that and machine a new groove may be a problem.
You can buy a replated cylinder for $200. Might be an option for you.

 

[blitz11]

I don't think it will be a problem.

When the bike is running the cooling system is pressurized, which would tend to push the O-ring out. that won't happen, though, as the O-ring is held (squeezed) in by the compression created by the head and cylinder.

If it doesn't leak now, it won't leak later.

i have just spent 2 weeks trying to chase a coolant leak on my daughter's "new" KMT 200. Ended up having a porous casting which was blowing coolant into the exhaust/power valve cavity. I had to make a pressure testing rig to find the pinhole leak. Fixed it with JB weld as there was no room to actually TIG up the hole. Just finished a second thermal cycle as it is 32 degrees in MN right now. Seems to have fixed it.

(Actually, you probably don't care, but the anecdote might provide me with a bit of credibility).

good luck.

blitz

 

[GMP]

I agree with Blitz, under pressure the o-ring is forced to the outside (good side) of the groove. Plus, the areas of concern are short, and it would be difficult for the o-ring to flex that much in the wrong direction.

Blitz, if the JB Weld should fail, try the HTS-2000 alloy brazing rod. Amazing stuff for fixing aluminum. TIG won't work well anyway if the casting is porous and contaminated.

 

[blitz11]

Hi Glen,

The passage which has the porosity is REALLY tight. I could barely get in there with the small screw-driver with the JB weld on it. Really a weird place. Right above the one of the two rotary power valve valves.

Thanks for the tip on the HTS-2000 alloy brazing rod. I have read your posts about that before. I am going to order some Monday to be ready if the JB weld doesn't work.

However, i think the JB Weld will be OK. about 5 years ago, i bought a set of heads for my old bmw off of the interlink. The knucklehead who sold them did a horrible job of packing them, and during shipping, the cylinder studs from one head beat up the area where the head gasket seals at the lip of the head. Beat up to the point where the metal on the head gasket had nothing to push against. Well, I JB welded (is that a verb?) that area, "fine machined" with my dremel tool, and 5 years later, no cylinder head gasket failures. No pinging from hot spots where the stud beat into the other parts of the combustion chamber. (I filled those in, too).

JB Weld is pretty amazing stuff.

I'll keep you posted. Thanks again for the HTS-2000 tip. I need to get some.

blitz

 

[bje]

Thanks everyone!

I'm going to drop a new piston in the freshly honed cylinder and simply keep an eye out for any coolant leaking.

 

[iancp5]

Blitz, if the JB Weld should fail, try the HTS-2000 alloy brazing rod. Amazing stuff for fixing aluminum. TIG won't work well anyway if the casting is porous and contaminated.

I find that stuff quite hard to use even on clean, new metal but it looks so easy in the videos.

You have to get exactly the right heat and that always seems difficult on aluminium because it conducts so well. I find MAPP is about best. Tried it once with a welding torch - lots of molten aluminium! Luckily it was just an experiment and I'm probably the world's worst welder.

Talking of which, I just made a horrible mess of my 4T exhaust. What's the can made of? I assumed Stainless but I guess it could be aluminium. It looks as if the pipe has been welded in the end piece so I assumed it was SS. Anyway I made a complete mess of it with a MIG because there's a nice thick weld and very thin sheet which I always find impossible to get the power right. The thin end piece was cracking around the weld to the pipe because it was mounted under stress and I was trying to stitch it back up. Any tips for MIG welding a thin to thick bit? How do they do it professionally - there's a massive neat weld on thin material.

 

[nick790]

I find that stuff quite hard to use even on clean, new metal but it looks so easy in the videos.

You have to get exactly the right heat and that always seems difficult on aluminium because it conducts so well. I find MAPP is about best. Tried it once with a welding torch - lots of molten aluminium! Luckily it was just an experiment and I'm probably the world's worst welder.

Talking of which, I just made a horrible mess of my 4T exhaust. What's the can made of? I assumed Stainless but I guess it could be aluminium. It looks as if the pipe has been welded in the end piece so I assumed it was SS. Anyway I made a complete mess of it with a MIG because there's a nice thick weld and very thin sheet which I always find impossible to get the power right. The thin end piece was cracking around the weld to the pipe because it was mounted under stress and I was trying to stitch it back up. Any tips for MIG welding a thin to thick bit? How do they do it professionally - there's a massive neat weld on thin material.

Have you got SS wire in your mig?
Your better off TIG welding it realy, is it just for repair?

 

[iancp5]

Have you got SS wire in your mig?
Your better off TIG welding it realy, is it just for repair?

No it's normal steel wire - thought that works ok on SS except it rusts of course. I just couldn't get the power right. If it was enough to heat up the thick existing weld it just blew through the thin end cap. I'd like to get some SS and Aluminium wire but my welder takes the big reels and they cost a fortune.

 

[nick790]

No it's normal steel wire - thought that works ok on SS except it rusts of course. I just couldn't get the power right. If it was enough to heat up the thick existing weld it just blew through the thin end cap. I'd like to get some SS and Aluminium wire but my welder takes the big reels and they cost a fortune.

You can get smaller reals and make a small mod on your welder?

 

[iancp5]

You can get smaller reals and make a small mod on your welder?

Found an adapter for small reels so next time I can do it properly. Might even try aluminium but seeing as I struggle with HTS / Lumiweld I may find that a tad tricky. The problem is it's almost impossible to similar find test pieces to practice on so if you're not a pro with years of experience it's hard to set the MIG correctly. Mind you even a pro told me it sometimes goes wrong on new pieces they haven't done before. Last time I welded the footrest back on and by pure luck got the power right first time so I guess this balances it out.

 

[GMP]

I find that stuff quite hard to use even on clean, new metal but it looks so easy in the videos.

It works as advertised with practice. You need MAPP and patience, Oxy/Acet only for BIG parts that suck heat, like a bellhousing, and then a lot of care! Fixing a porous casting would be easy if you could access the hole.

Talk to any welder who has tried to TIG repair an oil soaked sand casting, not fun in most cases.