cracked cyclinder head

[jmw76]

Hi Guys,

Has anyone had an experience with cracked cylinder heads on the oil burners?

My son has a GSXR750 head on a bike that he is planning on running as a weekend track bike. The head has a number of cracks around the spark plug holes. It doesn't look like these have migrated into the ports at all. We are tempted to just clean up the head and run it as it is in the short term.

Maybe we will look for another and rebuild for installation later.

Are we likely to see any real issues? The engine was running pretty well prior to strip down (for a general freshen up). If we hadn't stripped it, we probably would have just run it until it broke anyway.

Has anyone else run GSXR oil cooled heads with cracks? What are the risks?

Peter.

[pav69]

can they be welded

[jmw76]

I thought about welding it, but to be honest without removing the valve seats I believe it would be a bit of a hit and miss process. To do it properly would be expensive. The valve seats look quite deep and the cracks would have to progress a long way before going into the port area. I guess this might not happen for many years by which time we will probably have rebuilt the engine or moved on to another bike.

[03gixxerpilot]

only going on what i have been told, most dont even worry about them, as you said they dont go far and dont go into anything like ports or water jackets.

i personally dont have any experience with this problem, this i just what i have herd from others.

Clive

[jmw76]

Thanks Clive.

Yep.No water jackets on the oil cooled machines and there is a lot of metal to crack before any oil is likely to get in to the cylinder. Extremely unlikely I would believe.
Any other thoughts/experience from anyone?

[Booster]

Sounds like the old xl hondas they used to crack out of the plugs, its fine for a while but if it gets too big , worst case senario is dropping the valve seat

[Dynomutt]

Depending on how deep the cracks are, if you have the plug holes opened out an dfitted with Timesert thread repairs that should take care of the cracks. It is a known problem with the old Zed heads which crack between the plug hole and exhaust valve seat. I've repaired some by using a Timesert sparkplug thread repair with great success, can you post up some photos of the offending plug holes?

[jmw76]

Here are some pics of the cracks in the head.

All chambers have cracks.
The pics are of the worst 2 chambers.
One has a small pice of metal missing at the top of the spark plug thread (it looks worse than it actually is).
I believe a combination of design/production issues and poor quality fuel (low octane) has contributed to this.

We plan to clean up the area around the cracks (remove sharp edges) and lightly peen around the top of the valve seats to assist to keep them in place.

Any other ideas on this issue would be appreciated.

Peter.

http://i1085.photobucket.com/albums/j427/pwstone/gsxr750/crack-head1.jpg


http://i1085.photobucket.com/albums/j427/pwstone/gsxr750/crack-head2.jpg

[Dynomutt]

Bin it, that is too far gone, and risks a major failure. I personally wouldn't run it, even Timeserts won't save it. You may be able to drp the seats out and have it welded and machined and new seats fitted but it is not a cost effective option, when you can pick a head up fairly cheap.

[03gixxerpilot]

i agree with dyno.

[jmw76]

Anyone got another head kicking about?

[03gixxerpilot]

long stroke or short stroke

[jmw76]

short stroke

[03gixxerpilot]

might have one spare, i will have a look around the workshop this week, nothing garenteed,

Clive

[jmw76]

Thanks Clive.

[DCRacing]

Hey Clive, If you have a spare 195hp flowed head available....... ;)

[03gixxerpilot]

hey Peter only got 1 long stroke head, and 2 1100 heads spare, sorry cant help you.

DC sorry i cant help you either, i actually do have a 1100 head flowed to number close to that by stone brothers racing, but alass
it is not spare :-)

[jmw76]

Thanks guys.
I will keep looking.