Just Burned The Head Gasket

[hendrixgr]

Well it was about time to get bitten by the only thing i didn't changed when i was building my bike, the head studs.
When i understood that this is a must it was too late so the only thing i could do is wait.
The funny thing is that the engine kept working fine and the power was great with no overheating up to the time i parked her outside my house, that's when i heard a boiling sound and saw the water coming out from the overflow tank looking very oily.
Just for the record the head gasket with the stock head bolts lasted 12000 km at 280 hp
Chris

 

[turbobusa2000]

What did you do when you rebuilt? Head surfacing? What type of gasket?

 

[hendrixgr]

Hi.
When i was converting my bike to turbo i knew nothing about head studs so i used the stock head bolts.
The gasket was the Cometic std 81mm and i also used a 0.080 base gasket to lower compression.
The bike was found in perfect condition during the conversion from normally aspirated to turbo so head surfacing was not needed.
Chris

 

[hendrixgr]

Update:
I just got bad news, the pistons are burned and the cylinders are damaged.
It looks like my turbo "kit" might be up for sale as i am considering not repairing it at all.
It is an Mc Express mc400 with water intercooler + 4 injectors with all the parts needed like a full stainless exhaust, Power commander etc.
Chris

 

[hendrixgr]

Ok i decided to go and fix it, reduce the boost and be happy with stock compression (almost) and 220 hp.
After all that's why there are boost controllers...
It looks like the inlet side of the pistons was burned (not much but fairly visible) and cylinder #3 and the gasket was burned near the very top and underneath the inlet valve.
It looks like i went too far lean at low rpm ( 3-6 K rpm) because after 6Krpm the mixture was a flat 11.5:1 but below that it was near 13.8 to 14.7 :1.
If i could describe the engine usage using numbers i would say that the bike was operating 90% at 3-4 K rpm, 8% up to 7000 rpm and the rest 2% up to 10000 rpm but after 6Krpm the mixture was a flat 11.5:1 so no problem there...
Chris

 

[dadofthree]

Best of luck on the rebuild

 

[hendrixgr]

Thank you very much.
After some thinking i came to the conclusion that either an injector was clogged (something not visible with an AFR meter that uses one sensor)
because only one cylinder was slightly damaged or i went too lean on lower gears.
Looking my logs i found that while the bike was running fine at 6th, it was running somewhat lean up to the 4th gear (13.8:1 @ 6000 rpm)
I decided to repair it, improve it by fitting those APE studs and then use her for occasional rides only.
Chris

 

[Kevin Jones]

I am in the same boat, detonation damaged head and block, but in 2 cylinders. I bought a bare head off the bay ($200) and someone is helping me with a block.

 

[hendrixgr]

Hi.
I really wish you the best of luck as i know how it feels....
Chris

 

[hendrixgr]

Update:
I installed Wiseco turbo pistons and APE studs, going for the rods now.
Don't ask why Wiseco, i wanted Wossner but my builder insisted on Wiseco's
Now i have an all build up motor but i will set it at 250 HP and leave it there for life.
Chris

 

[shade]

#1 - you aint gonna leave it at 250hp, especially now you are building it correctly.
#2 you are smart to also do rods at the same time (see #1)
#3 not sure if you tuned it yourself when it blew up. If you did reconsider doing it again, if it was someone else take it somewhere else.
#4 intercooled - yes please. Might as well knock this off the list as well.
#5 - take pictures cant wait to see the build! Good luck!

 

[hendrixgr]

Hi.
I did tuned it my self but the engine was never lean (i have a logger), the leaner it got was 11.5:1 past 6000 rpm.
I also have a liquid to air intercooler with 4 extra injectors installed so the intake temperature was not high.
Now either the fuel was bad and caused detonation or the stock head bolts simply flexed and allowed gases to blow by.
I also plan to use bigger injectors and use the 4 extra plenum injectors for methanol/water injections as an extra detonation prevention method ( i have heard that water can remove carbon deposits also)
The head needed 0.18 mm (0,007 inch) shaving.
Here is a picture of the new pistons.

 

[hendrixgr]

Update 2:
After showing my old pistons and cylinder block to experts here, 90% the light but expensive damage was due to blown cylinder head gasket.
This means that the stock head bolts simply flexed under power (280 hp).
It is my fault but i couldn't do anything else than wait for it to happen in order to justify the repair cost.
I will post pictures of the damaged part this Friday when i will pick up my brand new bike.
Now i will have to break it in for 1000 miles i guess, if anyone more knowledgeable suggest a lengthier break in please do tell me.
Chris

 

[shade]

Ah that sucks that it was the head gasket but you got it done right. As for break in - I did the warm up and run under X rpm's for like 20 minutes. put about 200 miles on like that.
Then hit the street for normal riding. What really sealed the motor was 500 miles after the build getting it dyno tuned. The hard pulls helped the rings seal nice and tight. Just my experience.
I also have the head studs - I went ARP though. They held no problem @ several 400hp dyno pulls.

 

[hendrixgr]

I will follow your advice with X = 4000 rpm max or should i use a lower rpm limit?
Chris

 

[hendrixgr]

Here are the pistons.
Unlike the cylinder block which had very light but visible damage, i can't identify any damage on the pistons...
Chris

 

[hendrixgr]

here are some more.
The wrist pins are immaculate, in fact there is not a single scratch on the skirts, everything is super clean and smooth.
Please remember that those are 61000 km (40 K miles) pistons.
Of course the fact that i can't find anything wrong with the pistons does not mean that there isn't any, it simply means that i don't know what the damage looks like.
One thing i noticed with the new pistons is that the engine now seems to have more power on the low rpm range
Chris

 

[GNBRETT]

Wiseco over Wossner? who is ur builder and tuner? lotta wannabes out there.....

 

[oldgixxer]

I will follow your advice with X = 4000 rpm max or should i use a lower rpm limit?
Chris

IMO,you need to vary the load and never maintain a set rpm;loading and unloading the engine basically heats it up briefly and then lets it cool. I wouldn't keep 4k rpm as a max,you can safely run higher rpm then that. I'll let the builders who are more knowledgeable then I am give their suggestions. You can also break the engine in on a dyno;which I have done successfully in the past as well. Lotta different theories on the proper way to break an engine in.

 

[hendrixgr]

Wiseco over Wossner? who is ur builder and tuner? lotta wannabes out there.....

I would like the Wossners which also have the skirts coated but my builder insisted so it is his responsibility.
Chris