Super Jet 61x sleeves dropping = blown o-rings

[D-Roc]

i am blowing o-rings again on my 83mm 61x cylinder. I had this problem a few seasons ago so i decked the cylinder minimal amount as possible. i checked my squish and gave my machinist the max spec for decking he could go and he did about 1/2. so i could redeck, but on 83mm bore and two seasons i am thinking not. how do you keep the sleeves from dropping. if i get a BB sleeves done am i going to have this issue again.

I guess what i am asking is what are my options with my cylinder, it runs at 190 psi, sport ported(freestyle version, exhaust port timing unchanged) and decked minimal amounts. I want at least 85mm flattops or bigger with room for a few bores. my cases can accept BB sleeves already and have been ported. Any engine builders think they can build me something with my current cylinder or should i be looking for a completly un molested 61x jug?

non engine builders need not respond.

 

[waxhead]

I find all or at least most 61x cylinders will settle there sleeves. Im not sure if the sleeves isnt home from the factory or if the cylinders move a little.
Its not normal that they continue to drop as your are doing.
I did have a cylinder do that before and after it had be machined twice I instructed the person to get a different cylinder. Which they didnt and last I heard they were pulling the cylinder to get it machined again.
I can only think it was an issue with the cylinder as the sleeves are cast iron and couldn't collapse to this point. as well as both dropping it didnt make sense.

 

[D-Roc]

well it is the front cylinder and yesterday i blew two o-rings. usually right on start up. sometimes if i ride it out and let the motor get hot the pisser stops spitting and sounds/flows normal. so anyways after the first blew i swapped domes from front to back to see if the problem followed the domes. it did not. i can acutally see a gap (in the spot where the o-ring blows) between the sleeve and cylinder casting. would a gasket type head seal that up and stay sealed or will it blow out the gasket too? i am not against getting a different jug but if this one can be used i would just as much rather use it and have the work done in the off season. what do you suggest, is the fact that the my cylinder has been decked and previously lightly ported not make it a good donor jug for a BB build?

 

[waxhead]

The o-ring seals on the sleeve so the gap while it doenst look good is not an issue unless its sitting higher then the sleeve.

 

[D-Roc]

yeah it just wierd that in that area is the only visible gap and although i can't feel any height difference (on the beach with my finger) it is where the oring keeps breaking. would a sleeve drop in one spot like that or is it usually the entire sleeve?

 

[waxhead]

I have never seen a sleeve drop in one spot and I cant imagine how it would.
have you used a straight edge on the top of the cylinder to check it

 

[D-Roc]

no not yet.
thats what i thought about sleeves dropping maybe i have a high spot from the bolts? do the sleeves press down onto a lip when seated properly or do they float?

 

[waxhead]

There is a lip in there and the sleeves seat on it . The cylinder head holds the sleeves in place as the engine is running. You can heat the cylinder up and remove the sleeves so it makes sense that when the engine is running the sleeves could actually come out or at least move.
If you have a streched thread it may be sitting proud and reducing the clamping force of the head on the cylinder

 

[Moto360]

Hey D- Roc,
How old is your head shell? I have a ADA head shell that is wore out. It did not clamp the domes evenly. Tried another shell and no problem. Then bought a new shell for that ski. No problem since!
You could see in the shell were the dome contacts and the metal was worn. Anyways an Idea.

I did a BB with a clean unmolested cylinder. Check with the builder about over all deck height before you decide and I had to sink by BB sleeves into my OEM cylinder to get the port timing that my Builder wanted.

Moto360

 

[D-Roc]

i guess i will have to check it and see. i gotta do something, i am running out of orings and my season isn;t supposed to be quite over yet. if its a high spot i think i can figure 8 it on some glass and grit maybe get it to hold on a bit longer but if the sleeve has dropped again i am going to go for BB. the cylinder is like 15 years old, i don't want to drop $ and sleeves into it if it i the cylinder causing the problem.

 

[Watty]

Are the head bolts bottoming out in the threads before the head is fully torqued done by any chance? If they do bottom out, obviously you are going to get a false torque setting and the o-rings will be eaten out and blow.

Usually happens when you use aftermarket heads with fastener shop stainless bolts. Even though the bolts seem perfect, they won't quite pull the head down enough.

P.S...I'm not an engine builder, so my response may hold no credibility at all.

* Disclamier: I may have no idea what I'm talking about *

 

[D-Roc]

thought about the headshell too, inspected it by eye on the beach, that was why i swapped domes front to back but maybe i will turn the head around and see if i can get it too blow the ring on the back cylinder instead. that would indeed suggest the headshell is toast and maybe not clamping that part of the dome.

 

[D-Roc]

i am not 100 percent sure the bolts are seating all the way but your not an engine builder so i doubt thats it. lol. it blows the oring on the rear of the front cylinder where the two middle bolts are. i guess with the cylinder decked that could be an issue but i chased them and had it decked and don't use loctite (i know what ever) they turn in nice, everytime and have alway held and sealed. After i had the cylinder decked (two seasons ago) it has been perfect. 2 months ago the o ring blew and i replaced and ran until just recently. yesterday i blew two but still rode for a long time and right now it is holding. i gotta check into it before i ride again because like i said i only got two orings left.

 

[waxhead]

The head is not able to be rotated. The two bolts on each end of the head are not symetrical. watty brings up a good point and its an easy check. Some times engine builder look to hard and miss the real easy stuff

 

[D-Roc]

i have used my head backward for an entire year. not a proud moment of discovery but its the truth.

 

[waxhead]

opps, how did you go putting it on. They do go on but its not an easy fit. last one i saw had done some damage from them wrestling it on

 

[D-Roc]

to tell ya i can't remember installing it because i bought the motor from a buddy and bought him a new ada and gave it to him in the box and kept the old head already installed on this motor. i was probably in the garage when the head got installed but i don't remember doing it so it was probably steve that did it, haha yeah thats my story, and he also gave me the motor with br8hs plugs in it which i ran for a embarrasingly long time. yeah it was free hp on that spark plug change.

 

[SUPERTUNE]

Measure the head depth for the domes, needs to be .499-.500. (new .499)
If over .500 replace the head shell.
Measure overall dome thickness need to be .502-.501, (new .502) if under .501 replace domes.
In order for ADA heads to work successfully they need to achieve about .003 crush at the dome o-ring.

 

[waterfreak]

Hey D- Roc,
How old is your head shell? I have a ADA head shell that is wore out. It did not clamp the domes evenly. Tried another shell and no problem. Then bought a new shell for that ski. No problem since!
You could see in the shell were the dome contacts and the metal was worn. Anyways an Idea.

I did a BB with a clean unmolested cylinder. Check with the builder about over all deck height before you decide and I had to sink by BB sleeves into my OEM cylinder to get the port timing that my Builder wanted.

Moto360

I had the same problem with one of my ADA head shells about 4 years ago. I could'nt figure out why I was blowing o-rings only in the front cylinder. it turned out that the dome was spinning and kinda machined itself further into the head shell (you should be able to see the wear from the top of the dome on the head shell).
I replaced the head shell and the problem was solved
hope this helps!

 

[D-Roc]

thanks for the all the info guys, i measured with my tools the best i could and my domes are reading 0.501 and the shell is reading .502 on spot i am blowing out and the opposite side is 0.499. the shell is at least 5 seasons old now. Great direction on the problem solving as well as the specs to check against. Is there any better heads out then the ada or is this still the best one piece shell out there.