Understanding Warped Head Gasket

[=maz=]

They are hit and miss. Casting quality wise and some other variables...The gaskets are not the problem, it's a casting/material issue.

I dare say you're right Chad but everything, prior to your latest post, from all I have read early on trying to understand why the OEM head-gaskets here were all blowing basically says, "Chads gaskets will fix everything"...your post explains that the gaskets are not the issue or the solution on their own.
My own post was not trying to suggest that your gaskets were/are the problem...but stating for others that they have not been the solution I was looking for to solve the problem my friends and I have encountered here.
The problem is the quality of the original product and the lack of consistency from the factory, if I understand your post correctly, and this has been my argument all along with KTM-Au. Unfortunately they now have more that one bike that has gone in for warranty repairs with blown after-market gaskets(they blew out between the 2-layers of the gasket BTW) and I'm sure they will blame the gaskets rather than their own product.

 

[Deleted member 452]

They are hit and miss. Casting quality wise and some other variables... Regarding my thin gasket set they can be used in any build. If using stock cams with them cylinder pressure is higher due to less overlap/trapped cylinder pressure. Some ignition timing should be pulled out of it a peak torque (where cylinder pressure is highest) to prevent detonation. I pull 4 degrees out a thousand rpm below and above peak torque rpm from 40-100% tps in PCV map. That will fix any potential for detonation. It is not a must on all stock engines but we have seen some cases of detonation with added timing that the stock thickness gaskets like. The squish, cam timing, injector flow, cooling system etc must vary more than I would like on the stock production engines, some are fine with added timing some are not so happy. With that being said you will see clear signs of detonation on the piston if it is occurring. It can lead to blowing out a head gasket for sure. If the gasket has failed and no signs of detonation then it is a material casting issue or workmanship. If the head is not flat or the deck no gasket will seal it up! If the head as had more than .004'' to straighten up "I" wouldn't reuse it. The more material you take off the thinner it gets where the problem occurs (the coolant passage exhaust side), every head gasket that has failed has been there, NO where else by me or KTM. By milling it you loose material there and it will relax/warp again even faster. The gaskets are not the problem, it's a casting/material issue.

Hey Chad- When you pull 4 degrees out, are you're running -2 degrees in these cells since your maps (and Dynojets) show 2 degrees advance?

 

[cjwell]

Hey Chad- When you pull 4 degrees out, are you're running -2 degrees in these cells since your maps (and Dynojets) show 2 degrees advance?

No, back to stock timing in those cells a "0" in them. I also taper it in and out (timing) above and below peak torque rpm. Most of my maps have 4 added in 80 and 100% tps columns, 2 deg in the lowers %'s. So 4 out of big throttle and 2 out of lower, making it 0 back to factory timing in effected area. I should've have clarified before, didn't want to go quite that deep, until someone asked.

 

[Deleted member 452]

No, back to stock timing in those cells a "0" in them. I also taper it in and out (timing) above and below peak torque rpm. Most of my maps have 4 added in 80 and 100% tps columns, 2 deg in the lowers %'s. So 4 out of big throttle and 2 out of lower, making it 0 back to factory timing in effected area. I should've have clarified before, didn't want to go quite that deep, until someone asked.

Thank you.

 

[cjwell]

I dare say you're right Chad but everything, prior to your latest post, from all I have read early on trying to understand why the OEM head-gaskets here were all blowing basically says, "Chads gaskets will fix everything"...your post explains that the gaskets are not the issue or the solution on their own.
My own post was not trying to suggest that your gaskets were/are the problem...but stating for others that they have not been the solution I was looking for to solve the problem my friends and I have encountered here.
The problem is the quality of the original product and the lack of consistency from the factory, if I understand your post correctly, and this has been my argument all along with KTM-Au. Unfortunately they now have more that one bike that has gone in for warranty repairs with blown after-market gaskets(they blew out between the 2-layers of the gasket BTW) and I'm sure they will blame the gaskets rather than their own product.

Took quite sometime to learn and figure out the underlying problem(s). My gaskets are "better" then OEM but can't fix other issues. I think some other folks might have implied my gaskets were a solution and could've mislead you to think that. I apologize if that is the case. That was not our intent, but were working on the problem and still continuing to. I have more stuff in the works too to help! Slow process...

 

[Deleted member 452]

Keep up the good work Chad- Everyone on this forum (and ktmduke390forum.com) appreciates your efforts!

 

[snaggletooth77x]

Took quite sometime to learn and figure out the underlying problem(s). My gaskets are "better" then OEM but can't fix other issues. I think some other folks might have implied my gaskets were a solution and could've mislead you to think that. I apologize if that is the case. That was not our intent, but were working on the problem and still continuing to. I have more stuff in the works too to help! Slow process...

I'm on the fence with replacing my head gasket at the moment. I have put a full season of racing on my Cup bike and haven't had any issues yet. I have a hard time replacing something that is currently working well but I also don't want it to be avoiding the inevitable. Could you give some insight on this as far as when they typically let go and whether I should replace mine or not.

Cheers,
Austin

 

[Deleted member 452]

Mine let go after 4.3K street miles.

 

[cjwell]

I'm on the fence with replacing my head gasket at the moment. I have put a full season of racing on my Cup bike and haven't had any issues yet. I have a hard time replacing something that is currently working well but I also don't want it to be avoiding the inevitable. Could you give some insight on this as far as when they typically let go and whether I should replace mine or not.

Cheers,
Austin

Up to you. You can wait and see if/when it happens or do it now, check for distortion etc and try to prevent. I can't make the decision for you. If it's been good until now you might get lucky

 

[=maz=]

Took quite sometime to learn and figure out the underlying problem(s). My gaskets are "better" then OEM but can't fix other issues. I think some other folks might have implied my gaskets were a solution and could've mislead you to think that. I apologize if that is the case. That was not our intent, but were working on the problem and still continuing to. I have more stuff in the works too to help! Slow process...

Thanks for the reply Chad.
You certainly don't owe me an apology because you have never told me it would fix the problem. You have been a huge help and been more than forthcoming with information and assistance...it's just the nature of things with internet forums and learning about racing from the other side of the world with a bike no one here knows anything about that has QC/QA issues. lol

If any of my posts have implied that you or your product were at fault I apologize because that has not been the case and was not my intention.

 

[wheninrome]

I have an 2015 that I bought in may, has about 6000 miles on it. Oil is on right and left side of engine. More on the left side. My bike is out of warranty. I fear the worst. What is an expected cost to fix the warped issues and get a bike repaired. Very depressing as this is the first bike I ever bought new.

 

[Maddog Reynolds]

I'm also going to stick my neck out, based on general experience of alloy heads :-

I reckon a lot of head gasket problems start with a minor cooling problem, such as the known weak spot on 390s of the water pump seal leaking. The coolant level drops in the radiator and sometimes you won't know, as the coolant may be slow to drop down from the header tank, because it is not pressurised (and any leak may allow air in, without enough pressure drop to pull coolant through the 1-way valve on the radiator cap).

Once the coolant drops too far, there will be air pockets in the head, causing uneven heating and sudden cooling as coolant splashes the overheated areas. This can warp the cylinder head and cause a gasket failure, especially if the head has stresses in the metal from production processes.

Racers tend to take off the radiator cap and check the level directly, while a lot of road riders (including me, until I realised) only check the header tank.

The radiator can block with mud (I would guess this mostly affects road riders, as well) and it can run hot. The radiator is only just big enough for hot climates. Better coolant, or a 1.6 bar pressure cap, can prevent hot spots caused by localised coolant boiling in the hottest parts of the head when the whole system is close to boiling point, and this can reduce the strain on the head and gasket. So modified/racers win here again.

The bike has a high CR and can be close to high speed detonation on regular fuel, which kills gaskets as much as any other part of the engine. Yet again, modified or race bikes win, because mapping the ignition just right and a small excess of fuel stops detonation problems in most cases.

Lastly, using full power before the thermostat opens causes uneven heating on some engines. I don't know how much of a bypass flow the 390 has when the thermostat is closed, so this is a guess, but if it is small, the uneven heating can be enough to warp the head and fail the gasket.

Lastly, if the bike is ridden hard for the last mile, it can blow out coolant when you turn off. Again, losing too much coolant could fail the gasket.

My 2015 has no gasket problems (so far!), I always warm-up gently to full temp before thrashing it, I gently wash mud off the radiator with a car wash brush, and I noticed my coolant leak in the water pump before the coolant level dropped. It may just be good luck/coincidence for me, but I'm not changing my good habits to find out

 

[zaster]

My 2015 bike had the gasket failure issue and I recall that it was due to poor head surface manufacturing. The mating surfaces were not machined smooth enough which caused the gasket failure.
Air was introduced into the cooling system which rendered the water pump useless, hence the over heating.
It is a common RC390 issue and KTM should take care of it regardless of warranty expiration.
If you rode it as designed then you might experience the failure within the warranty period, if you babied it, it might happen later.
I ended up with bent valves, destroyed piston and trashed head since my dealer could not diagnose the issue early on.
The existing warranty took care of it for me.

 

[vanillasoy]

Apologies in advance if i missed it (i skimmed and searched for the answer) but i have a pcv which i have yet to install onto my 2016 390. Would anyone know if it would void warranty on the head gasket?

 

[zaster]

Sorry for the late reply. I had a PCV installed on my bike when the head gasket failed and the extensive repair was covered under warranty.

 

[Mototoro]

I have 2015 and I’m scared this will be an issue is there any way to tell if you have one of the poorly milled heads? Honestly, the last person who owned my bike did some questionable stuff and I’m not sure what damage they did. The bike is running okay now - but if the head gasket does go - does KTM warranty the work because it is their fault? I have 7k on the bike now and so far no oil or coolant issues. I love the bike but I’m also kind of scared of it. Especially in the S. California heat.

 

[john13]

I'm in So Cal too and so far no problems. Still have a year left on my warranty so I need to hit the track to hopefully flush out any issues I might have with my engine.

 

[zaster]

I'm in So Cal too and so far no problems. Still have a year left on my warranty so I need to hit the track to hopefully flush out any issues I might have with my engine.

Yes, you need to ride it hard for the head gasket issue to surface quickly.