Head Gasket Problems

[Bri Lewis]

Hi all, running a 2014 390 as a race/track bike only and having head gasket problems, just had the head machined due to normal warp issues with early models. Just been to a track day and the head went again in the last session, no noticeable overheating issues after doing cooling mods, ( better coolant, 1.6rad cap, motor heat shroud removed, radiator cowling fins removed, etc) missing the start of the racing series , not happy. Running Akar exhaust, Athena GET mapping, K & N and a few air box mods.

Any ideas, noticed only two cooling ways in the barrel with one restricted by the head gasket, has any one made this small hole in the gasket bigger?

Thanks in advance.

Bri, Australia

 

[Deleted member 452]

Just looked at pictures of my blown head gasket & ruined cylinder from last month and I see what you mean. The hole on the intake side if the cylinder is much larger than the hole in the gasket. I'll be curious to see what this thread turns out...

 

[Rcdan]

Seems like a lot of restriction. Especially given the size of the coolant port. Maybe they had a reason to restrict flow.

 

[Maddog Reynolds]

Is the gasket different on the RC Cup bikes, or any of the engine kits available?

I've seen restrictions used to balance flow to avoid over-cooling one side of the barrel, but that looks very small to me.

 

[=maz=]

How much was machined off the head?

 

[Deleted member 452]

Is the gasket different on the RC Cup bikes, or any of the engine kits available?

I've seen restrictions used to balance flow to avoid over-cooling one side of the barrel, but that looks very small to me.

The picture that I posted is of a Cometic gasket. I don't have any pictures of the OEM gasket.

 

[Deleted member 452]

Just figured it out. I Googled a picture of our head and the coolant passage is a small circular hole that lines up with the hole on the gasket. Doesn't seem like the smoothest transition for coolant flow going from a rectangular port in the cylinder to a small round hole in the head but I also found similar layouts in other KTM engines when Googling.

 

[Bri Lewis]

How much was machined off the head?

Hi Maz, not sure hom much was machined off, I'll find out this week, a bit risky skimming the barrel in case it nicks the coating in the barrel.
Planing to do away with the thermostat and getting it looked at on a dyno in case it's running lean at the high end of the revs.
Last resort is to try and source a later model motor.
Pain in the Ass!!!