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 Post subject: Head Gasket Leak
PostPosted: Tue Jun 04, 2019 11:11 am 
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Still in the Driveway

Joined: Tue Jun 12, 2012 1:26 pm
Posts: 8
Country: usa
Bikes owned: T500 Titan
Hello All. Cannot get my left side head to seal and I'm out of ideas. The bike had a stripped head bolt when purchased and I helicoiled it no problem. I don't think it was leaking prior to teardown but the center main seal was which has since been repaired.

The leak is occurring in the same general area as the broken bolt. Relapped the head and jug, fresh gasket, still leaking. No cracks found, bolts are not bottoming out, torque is correct. In my frustration I even tried Permatex Copper Spray - still nada.

The sleeve is slightly higher than the casting but as I recall so was the right side. This is something I have never seen on any of my 2 strokes but this is my first Suzuki. Should it be higher or could the sleeve have slipped?


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 Post subject: Re: Head Gasket Leak
PostPosted: Wed Jun 12, 2019 9:57 am 
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Expert racer

Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1035
Country: England, UK
Bikes owned: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
Suggest you skim the block (with liners fitted). Be cautious doing this. You will need to check deck height to ensure piston will not hit head afterwards. If it is too high, you will need to get the squish band re-cut. Chris Applebee did this on a GT250 for me a while back.


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 Post subject: Re: Head Gasket Leak
PostPosted: Tue Jul 23, 2019 8:10 am 
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Still in the Driveway

Joined: Tue Jun 12, 2012 1:26 pm
Posts: 8
Country: usa
Bikes owned: T500 Titan
The leak is occurring between the 2 bolts nearest the opposite cylinder, one of which had been broken when I bought the bike. Base gasket is sealing well I believe.

For some reason the head is bowing in this area when torqued down. Both surfaces are flat, fresh aluminum gasket. I am at the point where I am going to buy another head to see if it would make a difference. Possibly from having that broken bolt there and having been run that way for however long the metal has just fatigued too much? Really have no other explanation.


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 Post subject: Re: Head Gasket Leak
PostPosted: Fri Jul 26, 2019 4:25 pm 
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Expert racer

Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1035
Country: England, UK
Bikes owned: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
I'm confused; in one post you say the sleeve is slightly higher than the casting, but in another you say both surfaces are flat. Which is correct?


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 Post subject: Re: Head Gasket Leak
PostPosted: Tue Oct 08, 2019 8:57 am 
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Still in the Driveway

Joined: Tue Jun 12, 2012 1:26 pm
Posts: 8
Country: usa
Bikes owned: T500 Titan
The head surface and the sleeve surface are flat but the sleeve is slightly higher than the casting, probably less than 0.1mm but not evenly around. The worst / highest section is nearest to where the head bolts were broken and it is causing the head to bow out of shape when the bolts are tightened down.

I tried another head that I bought off ebay to eliminate it being just a head issue and now its actually leaking back up thru one of the bolt holes.

I assume my only recourse is to have both jugs machined flat to get the sleeves back down flush to the casting. Any suggestions on who is best qualified to do this would be appreciated.


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 Post subject: Re: Head Gasket Leak
PostPosted: Tue Oct 08, 2019 12:11 pm 
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Still in the Driveway

Joined: Tue Jun 12, 2012 1:26 pm
Posts: 8
Country: usa
Bikes owned: T500 Titan
Is it safe to assume the sleeve and casting / bolt surface should be on the same plane and flat? As I said, I've never seen otherwise but since both sets were the same (sleeve surface slightly higher) I thought this may be normal for Suzukis of this era.

If I had them re-decked, could I double up the base gasket to avoid re-cutting the squish band? Looks like there would not be enough piston clearance as is and it will be in need of a re-bore soon (.005" clearance at present). Ultimately maybe better to find another set of jugs?


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 Post subject: Re: Head Gasket Leak
PostPosted: Wed Nov 27, 2019 11:47 am 
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Expert racer

Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1035
Country: England, UK
Bikes owned: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
Your best bet would be to get the barrels and the head skimmed and assembled at the same place. A good 2-stroke specialist machine shop should be able to check the protrusion of the piston crown and establish if your squish band needs re-cutting, while reassembling. The only guy I know of is Chris Applebee in the UK. But I would very much be surprised it there are not a few racing engine specialists of similar calibre in the USA. Sadly I don't have any first hand knowledge of them. Ask around a few local classic bike restorers who they would use.


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