Pop goes the head gasket

[400exBRAAP]

I gotta start by saying I already had a really big detailed post typed up but I tried attaching a picture that was too big So when I hit the back button it sent me to the forums. Not my new thread I had spent half hour typing up the whole life story is of my Wheeler so we could really get to the bottom of my problem. So as I'm bringing this post I'm extra heated now.

Anyways the thing blew another head gasket
We had the head and cylinder lapped and trued so everything was starting fresh and flat. I had new stock head studs installed and i believe my machinest helicoiled them. I trust his decision as he has 30 years exp doing machine work.

I had a well known shop assemble my engine so it could get put together "right".

Here's the details on my unit
440 big bore sleeve kit, 10:1 piston, stage 2 cam , pretty significant head porting, 450r carb with a 175 main and geared up. I ride on tug hill not sure of elevation. Most of my riding is 5th gear cranking down roads.

My head gasket was cometic kit for the big bore. There's a cheap one and an expensive one. Naturally I spent the money for the quality. The little clips holding the metal pieces were gone. Idk if they melted away or what. Something is going on here.

If he helicoiled into the cylinder will I no longer be able to install HD studs? I never wanted to before because I run low comp pistons. However if I get the studs I will probably install a higher comp. Most likely 12.5:1. I mean why not of Im going to build it heavy duty might as well have a reason to do so.

[Blodg]

According to the GT Thunder website the HD studs can not be used on a cylinder with helicoils installed. But you may want to call them to find out if there are any other options.

Hind sight is 20-20 but I think it was a mistake going with a helicoil in the first place. I just built a 416 with a 10.8:1 piston and had the HD head studs installed even though they may not be needed.

I wonder if you could be running hot due to jetting? A 175 main sounds small for a 440, have you tried going higher or how did you end up at 175? You also may want to look into extra cooling with a fan or an extra cooler if you don't have either yet.

[CJM]

Did it fail on the side the exhaust mounts? if so you needed the HD studs, not helicoiled stock studs.

Your machinist might have all the experience in the world-but you DO NOT helicoil 400ex head studs. I keep telling everyone: AL on these things is to soft and they will pull out.

[400exBRAAP]

I had dropped it down from 180 to 175 but I am putting the bigger in when i reassemble tomorrow. I never wanted a 440 but had some.oil blockage issues we.didn't get figured out.until I was on my final bore. So the next option is going to be a new cylinder and that will solve all problems.

I took the head and cylinder to have cleaned and decked again. I'm going to double stack base gaskets to compensate for the 3 times things have been machined now.

I really don't see the need for fan because most of my riding I'm going 75 mph or better.

[400exBRAAP]

And it failed on the left side. I put my hand down on it and felt it blowing compression.

But you guys are telling me I should start saving for a new cylinder?

Anyone have a used one that's still close to stock bore? IMA have HD studs installed from the get go on the next one

[CJM]

Wait they decked it? how much did they take off? If they decked it, you possible raised the comp ratio up higher than expected. Could be 11:1 or could be 12:1, at 12:1 you need to run 100 octane or better. 10:1-11:1 needs 93 or better

Id say at this point new and or good used jug would be your best bet.

keep stock bore, do the studs and do 11:1.

How much did you torque it down to and did you do it in a pattern? 33 ft-lbs is the spec for both the jug and head.

[Zakradu398]

Ever have your spark plug come loose?

[400exBRAAP]

Haha no my plug has not come loose. I have heard of that tho. The cure there is a helicoil I believe.

I don't remember how much he took off. Not much. .001 on one part and .002 on the other I am thinking tho. I already ordered a gasket set and he's gonna shine stuff up and check it for flatness.

I have a ride on Sunday I'm gonna throw it together for. Plus i might as well get as much use out of the parts I've put in such as the 440 piston, sleeve and new stock studs. And quite a few gasket sets.

but i already have my eye on a used jug on flea bay. I think I'll most likely get a higher comp piston since I'll be boring it regardless as long as its used just so I know whats going on with it.

Is it worth it to have my flywheel lightened? What are some.details on that

[CJM]

Dont overbore like crazy, do an 85.5mm piston aka 402. Power comes from the compression not the bore size.

[400exBRAAP]

Yea the power on my current build comes from.significantly upgrading the airflow. Instead of bumping compression.

This was the whole idea so I wouldn't be blowing head gaskets..but that's still happening so I gotta come at this engine from a different angle and a different attitide for it.

[Zakradu398]

I asked if you were losing plugs because that is a sign of detonation.

[Blodg]

Originally posted by 400exBRAAP

I really don't see the need for fan because most of my riding I'm going 75 mph or better.
The need for a fan or additional cooling is evident because you keep blowing head gaskets from running hot regardless of how fast you are going. Although making sure you have proper jetting is definitely the first thing and more important than adding cooling or a fan.

[cheater13]

My fourwheeler runs super hot too for some reason. I have a good bit of stuff done (no boring) and a 200 main jet. I have a 12.5:1 piston and I don't run any lower than 93 octane. (112 when i drag race)

Mine leaks oil out of the head gasket and the cylinder head gasket only on the right corner. More coming from the cylinder head gasket though. It's like a seeping oil and it actually drips onto my right engine case. All cause a stupid head bolt i think broke off.

But i think i need some type of extra cooling because sometimes i can actually see that "heat wave" kind of effect when i look down near my engine near the header area. Just like you see when rain hits a hot blacktop.

It could be just cause i been running it hard on a pretty warm/humid day too. It still runs like a champ though, but some type of extra cooling would be nice.

[CJM]

You cannot run 93 pump on anything higher than 11:1. 11:1 is the limit b/c the 400 is aircooled. DETONATION is occurring!

[cheater13]

Originally posted by CJM
You cannot run 93 pump on anything higher than 11:1. 11:1 is the limit b/c the 400 is aircooled. DETONATION is occurring!
Been occurring for 2 years then I guess. What's some signs of detonation?

[2001400exrida]

You can't make a claim that 93 won't work with 11:1. THere are many factors that influence this. Basically it's just safe to recommend a higher octane in order to avoid catastrophic failure. You can run the risk or you can play it safe, but some people are just fine with 11:1 and 93, it just does not come recommended. Usually when detonation occurrs, it goes boom, 2 years of detonation is highly unlikely, i'm guessing you either ran into a poor quality fuel or you finally pushed the envelope.

A good sign of detonation is motor pinging, knocking, a sharp metal ringing. Usually if you hear detonation in the engine, you won't hear it for long, because failure comes shortly after.

[cheater13]

Originally posted by 2001400exrida
You can't make a claim that 93 won't work with 11:1. THere are many factors that influence this. Basically it's just safe to recommend a higher octane in order to avoid catastrophic failure. You can run the risk or you can play it safe, but some people are just fine with 11:1 and 93, it just does not come recommended. Usually when detonation occurrs, it goes boom, 2 years of detonation is highly unlikely, i'm guessing you either ran into a poor quality fuel or you finally pushed the envelope.

A good sign of detonation is motor pinging, knocking, a sharp metal ringing. Usually if you hear detonation in the engine, you won't hear it for long, because failure comes shortly after.
Well it makes a pinging noise all the time. Definitely not a knocking. I heard it's cause of the Hotcam because a lot of people on here reported more pinging with a different cam.

But am I fine then? I had it built two summers ago and they said they put the 12.5:1 piston in it. I always been running 93, nothing less. 112 on races all the time.

[2001400exrida]

that sounds like the good old 400ex valve tick that you're referring too. pinging (the deep metallic ringing noise) in any case is not good and it won't do it for long because detonation occurs and leads to problems rather quickly

if you're running 12.5:1 in a 400ex you definitely need high octane, that's not even on the line, that's a most definite there!

i would say you have been lucky for the last 2 years, maybe you were keeping a high enough mix in there with the racing fuel during races, because 12.5:1 won't run long on a 400ex on 93 octane.

[cheater13]

Yeah oh well I guess. It runs strong so I'm just going to run it with 93. I might put some octane booster in once in awhile even though it don't do too much.

At least their isn't any metal shaving anywhere in the oil. :p

And yeah that pinging is similar to all the other 400exs that I run with so I'm not worrying too much until I see a sign of some problem.

[Zakradu398]

Originally posted by 2001400exrida
that sounds like the good old 400ex valve tick that you're referring too. pinging (the deep metallic ringing noise) in any case is not good and it won't do it for long because detonation occurs and leads to problems rather quickly

if you're running 12.5:1 in a 400ex you definitely need high octane, that's not even on the line, that's a most definite there!

i would say you have been lucky for the last 2 years, maybe you were keeping a high enough mix in there with the racing fuel during races, because 12.5:1 won't run long on a 400ex on 93 octane.

I know of quote a few running QUALITY 93 with a 12.5 no prob..


Also OP octane booster does nothing. It raises octane by maybe .1-.2 . That's one tenth .

[2001400exrida]

You can run pump gas on 12.5:1 if its a liquid cooled machine but the 400exaccount requires high octane anything above 11:1.

You're playing with fire running 12.5:1 on 93 pump with the 400

[Zakradu398]

A friend of mines 400 has been running strong on 93 with head studs, 12.5:1 and stage 2 cam.. Jetting is key

[cheater13]

Originally posted by Zakradu398
A friend of mines 400 has been running strong on 93 with head studs, 12.5:1 and stage 2 cam.. Jetting is key
Sounds about similar to mine then. My next step is getting them gtthunder studs too.

[CJM]

Originally posted by Zakradu398
A friend of mines 400 has been running strong on 93 with head studs, 12.5:1 and stage 2 cam.. Jetting is key

Depending on elevation it will also allow you to run higher comp b/c your getting less air into the mix. Air is less dense higher up you go and more dense lower you go.

IE a member here can run 13:1 on 93 in there 450r at a higher elevation but at sea level where I am it cant be done.

[Zakradu398]

Porting is another factor. There is most of the time some compression loss with a ported head. This could effectively allow a lower octane for a higher compression. Not recommended lol

[Zakradu398]

Here's a question I have that I'm not sure of. Could you use a lower octane if you jet richer?

[CJM]

Originally posted by Zakradu398
Here's a question I have that I'm not sure of. Could you use a lower octane if you jet richer?

very much doubt this, I dont have a definitive answer but I did have the following happen:

Buddy did up his 450 (13:1, ported, 490 kit, etc), was running 93 and we jetted it good (or so we thought). Bike ran ok, but def had signs of detonation. Switched to 100 and dropped the jet 1-2 sizes and no more problems. Again tho, we are at very close to sea level here.

[Zakradu398]

I suppose it doesn't make sense that would work.

[DragonGunner]

Originally posted by Zakradu398
Here's a question I have that I'm not sure of. Could you use a lower octane if you jet richer?

Its not the richness so it wouldn't work. Higher Octane is harder to ignite, its made that way to prevent pre detonation....running richer lower octane wouldn't prevent that. Wish it did, we could save some money!!!

[Blodg]

Originally posted by Zakradu398
Porting is another factor. There is most of the time some compression loss with a ported head. This could effectively allow a lower octane for a higher compression. Not recommended lol
How do you figure there is some compression loss with a ported head? Porting does have an effect on compression on a 2-stroke engine but has no effect on a 4-stroke.

The style of cam, however, does effect dynamic compression on a 4-stroke with a longer duration on the intake. The longer intake duration holds the intake valve open longer before the compression stroke starts therefore lowering compression.

[Zakradu398]

Originally posted by Blodg
How do you figure there is some compression loss with a ported head? Porting does have an effect on compression on a 2-stroke engine but has no effect on a 4-stroke.

The style of cam, however, does effect dynamic compression on a 4-stroke with a longer duration on the intake. The longer intake duration holds the intake valve open longer before the compression stroke starts therefore lowering compression.

I think I may be getting my banshee info mixed around lol

[cheater13]

Well I was cleaning up my 400ex parts and I came across the wiseco box which had my stock piston in since I switched them out when I had it built. And lookey there.

http://i396.photobucket.com/albums/pp47/cheater13_photos/null.jpg


It's a freakin 11:1 compression piston. Thank god. I coulda swore that he said it had a 12.5:1 piston in it, but at least I know for sure what's in it now.

[Blodg]

Well obviously that explains a lot on how you were able to get away with running pump gas. Some others may have gotten away with 93 on a 12.5:1 but most of the time that will just ruin your motor.

Thanks for sharing.