400ex cylinder problems HELP

[markvette]

a while back we blew the head gasket on this sparks 440. it had pulled 2 head studs. sparks racing says this is common when you run the 12.5 to 1 piston. i had all 4 head studs heli coiled and new honda studs put in. we blew a head gasket last week. the shop i took it t says the left stud was put in crooked by the machine shop and pulled again. the shop says the cylinder cant be fixed now since it was already heli coiled once. i got a ton of money tied up in the top end of this quad. anyone know of another permanent fix for this. if not anyone got a 440 cylinder they want to sell.

Mark

[Colby@C&DRacing]

My fix would be to run an oversized head stud. Many of the builders like sparks a FST use them when they build a motor that is 12:1 or higher. If you use an over sized stud this will allow you to drill and tap out the holes that are not stripped and to use a larger heli coil in the one that is. The larger studs should keep the motor from pulling studs. Hope this helps and if you have any questions you can give me a call:)

[skemp]

That is what I would do. I am surprised Sparks didn't suggest it to you already.

[jerry-89-250R]

there was a 440 cylinder in the for sale section a week 2 ago, i have a stock 400 if your interested

[markvette]

yes im interested. pm me a price and phone number. we have decided to build a 426.

Mark

[tprender]

I tried the heli coil on the front and back stud but it still came out. got a set of 12mm studs from TC racing. Just ran the tap for them in the holes that had the heli coils and then pu the studs in. That was 3 months ago and it has not leaked any.

[markvette]

how did you run the tap in the holes with the heli coils in hem ? wont the heli coils need to come out first. also will the 12mm studs fit through the holes in the head without drilling them bigger.

Mark

[jerry-89-250R]

you have a pm

[markvette]

you have one too

Mark