Head gasket replacement?

[Quimrider]

Thought I'd post an update to let you guys know how things turned out. I had my local shop fix it. Turns out I must have slightly overheated the cylinder head as it had slightly warped contributing to the head gasket leak. $330 later they had machined the head flat and replaced all the gaskets from the cylinder up. She purrs nicely again.

With that $330 lesson in mind, I guess it really isn't a good idea to ride WOT for extended periods of time.

[alanmcorcoran]

Thanks for the update Quim. That happens to be how I ride the GZ. Do you think that's really what caused it? I thought as long as you don't redline, it's okay.

[Water Warrior 2]

At wide open throttle you are asking the bike to make maximum power all the time. Maximum power equals maximum heat generated regardless of RPM.

[Quimrider]

Originally Posted by alanmcorcoran

Thanks for the update Quim. That happens to be how I ride the GZ. Do you think that's really what caused it? I thought as long as you don't redline, it's okay.

The damage was probably cause by a combination of things. I ride WOT with a 16T front sprocket averaging just under 7000 rpm. There also was a fairly large carbon build up on the top of the piston. The head mechanic I talked to (whom I got the impression he knew what he was talking about) asked if I had ridden on the freeway a lot and if I used the low grade gas. He said something about the alcohol blended with the cheap gas was bad for the engine. I'm not sure why a small amount of alcohol would be bad for the engine. Other than throwing the air - fuel ratio being different for alcohol, I thought alcohol burns cooler and would be better for the engine?

About a year ago I experimented using various amounts of alcohol and gasoline (blending E-85 with gas at various ratios) for $hits and giggles. I was curious what would happen. I quickly learned that without major carb adjustments alcohol made it run like $hit!

I also fiddled around trying to tune the carb for a K&N filter and to compensate for the holes drilled in my exhaust. For a couple tanks of gas I was extremely rich. I attribute the excess carbon on the piston to this. I found the intake noise annoying and there really wasn't much of a noticeable difference. I could make it really rich and gain ~5mph top end and sacrafice 15-20mpg. This wasn't wort it to me so I went back the stock filter with the diverter removed and Plugged 3 of the 4 holes drilled in the exhaust. I don't know if it's true or not, but I read somewhere that without the restriction in the exhaust, the momentum of the exhaust gases will pull some of the incoming air/gas mixture into the exhaust pipe during the brief moment the intake and exhaust valves are open at the same time. This air/gas would then burn in the exhaust pipe overheating it and causing the chrome to blue.

I rode 2 up on a 120 mi trip 1/3 to 1/2 of which was WOT. Another time I was in a hurry to get home and rode 163 mi all WOT.

I think the damage to my engine was mainly due to the two trips that I took with the alcohol and carb tuning as contributing factors. I also have over revved the engine a couple times down shifting which couldn't have helped. The mechanic said that riding on the freeway was ok, but that I should back off the throttle every now and then to let the engine cool. He also suggested mid grade or higher gas since it resists pinging/detonation in a hot engine better.

I'm toying with the idea of adding a cylinder head temp sensor monitoring the temps for a while and then trying to figure out how to add an oil cooler to see if that helps cool the engine. I'm also going to adjust my riding habits so that I'm not as hard on the engine.

[alanmcorcoran]

Thanks for the background Quim. The Strat asks on the 91 octane on the tank, and I've obliged except for one tank when I forgot. Previous threads on here have not felt that higher octane is of benefit to the GZ, but those discussions were focused on power, not heat, so perhaps that could be revisited. I'm not sure we even have an ethanol option out here...

I solved my freeway/power/climbing issues by buying another bike. So far, that seems to be the option that provides the most trouble free solution. The GZ is still a great option for getting around town and relaxed (no high speed, steep hills) touring.

[Easy Rider]

Originally Posted by Quimrider

The mechanic said that riding on the freeway was ok, but that I should back off the throttle every now and then to let the engine cool. He also suggested mid grade or higher gas since it resists pinging/detonation in a hot engine better.

I'm sorry but that "mechanic" is a total putz.

You would KNOW it if your engine was knocking or pinging; if not, higher octane is a waste of money.

It is not the position of the throtle that is important but how fast the engine is turning.......so, with a 16T front, it is highly doubtful that whatever you did in 5th gear would hurt the engine any......unless you lug it or go screaming down the side of a mountain at 95 mph.

So the question then is: How did you ride it in the lower gears ?? If you were in the habit of winding it out as far as it would go, then that might be a factor. The other experiments that you tried might be factors too. Sometimes, however, heads just warp and sometimes they are not perfect when new and the gasket just finally gives out.

I think you are just wasting your time trying to pinpoint the cause and would be much happier just riding a tiny bit easier getting up to 70. You haven't done anything to the front of the bike that would cut down on the air flow across the engine, have you ??

One final thought: It is good to give the engine a short "cool down" period before shutting off. That is, don't go racing home at WOT, whip it into the driveway and shut it off; instead reduce your speed a bit for those last few miles before reaching your destination. Not working the engine as hard while still moving at a good clip will cool it down some.

[Water Warrior 2]

Originally Posted by Easy Rider

I'm sorry but that "mechanic" is a total putz.

You would KNOW it if your engine was knocking or pinging; if not, higher octane is a waste of money.

It is not the position of the throtle that is important but how fast the engine is turning.......so, with a 16T front, it is highly doubtful that whatever you did in 5th gear would hurt the engine any......unless you lug it or go screaming down the side of a mountain at 95 mph.

So the question then is: How did you ride it in the lower gears ?? If you were in the habit of winding it out as far as it would go, then that might be a factor. The other experiments that you tried might be factors too. Sometimes, however, heads just warp and sometimes they are not perfect when new and the gasket just finally gives out.

I think you are just wasting your time trying to pinpoint the cause and would be much happier just riding a tiny bit easier getting up to 70. You haven't done anything to the front of the bike that would cut down on the air flow across the engine, have you ??

One final thought: It is good to give the engine a short "cool down" period before shutting off. That is, don't go racing home at WOT, whip it into the driveway and shut it off; instead reduce your speed a bit for those last few miles before reaching your destination. Not working the engine as hard while still moving at a good clip will cool it down some.

The cool down idea is well worth it. Just ask any trucker about shutting off a real hot engine. Big $ signs ring up sooner than later.
As for higher octane I will agree to disagree with Easy. Higher octane gas is slower burning and more controlled which lowers detonation and pinging in engines. It is primarily used in higher compression engines which need more controls but it may help a lower compression engine is some cases.

[Water Warrior 2]

Originally Posted by Easy Rider

I'm sorry but that "mechanic" is a total putz.

You would KNOW it if your engine was knocking or pinging; if not, higher octane is a waste of money.

It is not the position of the throtle that is important but how fast the engine is turning.......so, with a 16T front, it is highly doubtful that whatever you did in 5th gear would hurt the engine any......unless you lug it or go screaming down the side of a mountain at 95 mph.

So the question then is: How did you ride it in the lower gears ?? If you were in the habit of winding it out as far as it would go, then that might be a factor. The other experiments that you tried might be factors too. Sometimes, however, heads just warp and sometimes they are not perfect when new and the gasket just finally gives out.

I think you are just wasting your time trying to pinpoint the cause and would be much happier just riding a tiny bit easier getting up to 70. You haven't done anything to the front of the bike that would cut down on the air flow across the engine, have you ??

One final thought: It is good to give the engine a short "cool down" period before shutting off. That is, don't go racing home at WOT, whip it into the driveway and shut it off; instead reduce your speed a bit for those last few miles before reaching your destination. Not working the engine as hard while still moving at a good clip will cool it down some.

The cool down idea is well worth it. Just ask any trucker about shutting off a real hot engine. Big $ signs ring up sooner than later.
As for higher octane I will agree to disagree with Easy. Higher octane gas is slower burning and more controlled which lowers detonation and pinging in engines. It is primarily used in higher compression engines which need more controls but it may help a lower compression engine is some cases.

[Easy Rider]

Originally Posted by Water Warrior

Higher octane gas is slower burning and more controlled which lowers detonation and pinging in engines.

That is true but you can't get it any lower than ZERO! :poke2: :biggrin:

I think everybody should try a couple of tankfulls of mid-grade gas. Premium is just foolish in a low compression engine but some people swear that the GZ and other similar bikes run better on 89. Maybe so, maybe not, but the cost difference is minimal and even if it IS all just in your head, feeling good about what you are doing is priceless.

[dan_]

So what about race fuel in the GZ? We sell 110 octane where I work. Crotch rockets and Harleys use it all the time. I'd consider putting a little in with my tank of 89 to clean the carb but i'd figure it would explode if i put in a full tank of 110.