Jump to content
Sign in to follow this  

Stock Header Pipes Collapsing - WHY? (PICS.)

Recommended Posts

This first picture shows my original stock header pipe that I used for about 3 and a half years. You would think with a pipe as deformed as that, a crash was to blame for it. I can assure everyone that this is not the case, and the sole reason that I seek some answers.

1-4.jpg

This next photo presents the evidence that I have two header pipes (both stock) and that I just didn't simply swap the cage out to hide a crash and stir up suspicion that I am making this all up. The new header pipe is present in the left side of the photo and will be present in the next two photos.

2-4.jpg

O.K. - with that out of the way, this next photo shows my new header pipe (stock also) that I have been using for about 4 months. Take particular notice of the header pipe section that I have enclosed in the red rectangular area. The header pipe is starting to collapse in on itself in much the same way as the original stock header pipe did in my first photo. That section of the header pipe was almost perfectly round 4 months ago, and now it is starting to deform. Sure it may take almost three years until it collapses almost completely flat like my first one did; but my question is: WHY IS THAT HAPPENING AND IS IT NORMAL?

3-4.jpg

This next photo shows that the header pipe even has that nice bluish-purple hue to it that I have read is an indication that the bike is jetted pretty close to where it needs to be in relation to running temperatures.

4-4.jpg

If the bike is running too hot, I would understand why it is doing that; but take into account that if it were, that first header pipe wouldn't have lasted as long as it did - which was 3 and a half years, plus the bike isn't overheating and runs impeccable. Should the header pipe be changed out before it reaches three years old? I figure that if one doesn't bang it up from a crash, why should it be replaced.....right???

I will admit truthfully, that the bike did fall on its right side one time with the first header pipe because it got a rear flat tire while on the triangle stand after I broke my collar bone and is a possible reason for the header pipe deformation in the first photo. The crash was on the left side of the bike though, and the cage presents no evidence from when the bike fell on its right side, that it was the reason for the header pipe to collapse in on itself, because my second pipe is starting to show the identical signs of deformation.

Now I may just be jumping the gun here because the second header pipe is by far, in way better shape; but I am seeing an identical pattern develop here, and I am completely at a loss as to why a header pipe that is only four months old, would start to display signs of deformation (collapsing in on itself) already only from heat. The header pipe fits perfectly into the mid-pipe and isn't under any stress when assembling it - that is why I cannot trace the cause as to what is causing premature deformation...............Any Ideas, because me :lol::):banghead::cheers:

Share this post


Link to post
Share on other sites

Check the engine mounts especially the 2 between the head & frame...there may be movement somewhere.

Share this post


Link to post
Share on other sites
Check the engine mounts especially the 2 between the head & frame...there may be movement somewhere.

Good thinking, that was my first suspicion as well - no rocking engine though - anything else I can check dgcars?

Share this post


Link to post
Share on other sites
Motor may move when under load and be solid, well more solid on stand.

Is there a certain amount of "engine rock" that can be associated with aluminum frames flexing that would cause this?

Share this post


Link to post
Share on other sites

The engine mounts being loose is a possibility I suppose. Everytime I have seen a header squished by the flange like that it has been from being bent in a crash, it tends to try to rotate near the head and results in a flattened out pipe. How did you ride for 3-1/2 years without ever crashing on the right side?

Share this post


Link to post
Share on other sites
The engine mounts being loose is a possibility I suppose. Everytime I have seen a header squished by the flange like that it has been from being bent in a crash, it tends to try to rotate near the head and results in a flattened out pipe. How did you ride for 3-1/2 years without ever crashing on the right side?

You asked me that before already KJ - I guess being in TN too long has made me more apt to making left hand turns :lol:

I have no real answer as to why I have never crashed on the right side, and until I do, I won't know why I haven't.

I understand the reasoning behind the pipe flattening out like that from a crash, and was hoping you would see this thread, because I wanted to show you that it is happening to a new pipe also without the bike falling over off of the stand.

Personally, I think that it is frame flex, and it takes about three years until it finally flattens a pipe out from gentle motor rocking caused by frame flexing.

Share this post


Link to post
Share on other sites

You are running way to lean, that's melting from the heat the exhaust is giving off. Does your pipe glow cherry red?

Share this post


Link to post
Share on other sites

No, not normally. I have seen in non-bike applications that motor mounts loosen and create header/exhaust issues. In these cases the motor appeared to be tight and under load it moved. How does the rest of exhaust system look? Mounting bolts on sub frame tight?

Share this post


Link to post
Share on other sites
No, not normally. I have seen in non-bike applications that motor mounts loosen and create header/exhaust issues. In these cases the motor appeared to be tight and under load it moved. How does the rest of exhaust system look? Mounting bolts on sub frame tight?

I just did a full make over this past June, and everything that needed replaced got replaced. Yes, sub frame bolts are good to go - I check em almost every outing if not every time I ride.

I'm still leaning towards a combination of engine rock and frame flex combined.

You are running way to lean, that's melting from the heat the exhaust is giving off. Does your pipe glow cherry red?

Every YZ250F owner on here with F1 motors will tell you their header glows cherry red - it is normal.

I'm not lean.

Share this post


Link to post
Share on other sites

Lean or not, its to much heat for the pipe to take, I see no kinks indicative of pinching or bending...looks like a glass tube does when its heated.

Share this post


Link to post
Share on other sites
Lean or not, its to much heat for the pipe to take, I see no kinks indicative of pinching or bending...looks like a glass tube does when its heated.

Exactly - That is why I don't understand what precisely is causing these pipes to collapse other than too much heat with a combination of frame flex and motor rock.

Share this post


Link to post
Share on other sites
My guess would be the gauge of the oem pipe is to thin

Yes, I intend to draft a strongly worded letter towards Yamaha Motor Corp. for taking shortcuts on certain pieces for weight savings :lol:

I guess that is the price I pay for having the lightest 250F water cooled, five valve made at that time from what I hear.

Share this post


Link to post
Share on other sites

If it was a thin material condition you would hear alot more about it. That said, you should not write the letter. Step up and buy MRD header and recheck jetting. 4T will run with lean jetting for ever. Have you added fuel to the system where you ride at (rpm's range)?

Share this post


Link to post
Share on other sites
If it was a thin material condition you would hear alot more about it. That said, you should not write the letter. Step up and buy MRD header and recheck jetting. 4T will run with lean jetting for ever. Have you added fuel to the system where you ride at (rpm's range)?

I was just kidding about the letter, didn't you see the little smirk icon behind the statement?

I'm always thinking about that MRD header I should've gotten a long time ago. Could you elaborate please, as to the second part of your post, I don't understand what you are asking. I understand the 4T will run lean forever; but at a cost - what is your question about added fuel - an octane booster? - No, I buy the highest quality premium fuel I can get - No race fuel for me :)

Plus, the motor is all stock anyway. No high compression piston either, just bare bones and knuckles boys - :lol:

Share this post


Link to post
Share on other sites
My guess would be the gauge of the oem pipe is to thin

Yep...the oem pipe is thin, but it is also titanium. It should be able to withstand any amount of low/high temp changes. I have not seen this particular problem on a stock YZ before. Abnormal flex or movement would still be at the top of my probable cause list.

Share this post


Link to post
Share on other sites

Shouldn't the header only glow red when sitting still for a while? At least that's what I've heard. I don't know about when riding fast as the header temp is pretty low on my mental list! Usually when I stop though it isn't red at all and the only time I've ever seen it actually glow was at night but I usually turn it off when I have to sit for a while.

The thin Ti header will heat up fast, but it also sheds heat really fast so a little cool air flow can keep it cool.

Share this post


Link to post
Share on other sites
I was just kidding about the letter, didn't you see the little smirk icon behind the statement?

I'm always thinking about that MRD header I should've gotten a long time ago. Could you elaborate please, as to the second part of your post, I don't understand what you are asking. I understand the 4T will run lean forever; but at a cost - what is your question about added fuel - an octane booster? - No, I buy the highest quality premium fuel I can get - No race fuel for me :)

Plus, the motor is all stock anyway. No high compression piston either, just bare bones and knuckles boys - :lol:

Adding fuel to the system by changing around your jetting. Move the needle, change main/pilot items like this. A 4t can run lean for years putting out low HP without any motor damage. Light material thickness as in this header maybe telling you to check jetting. Several riders (no dis-respect) I came accross in the past several years had great running bikes. After re-thinking jetting, found more power and cooler running bikes solving issues that pleg them for some time.

MRD are amoung the best headers built. They are not the lightest but will last a life time. If not they will fix or replace it!

Share this post


Link to post
Share on other sites
Adding fuel to the system by changing around your jetting. Move the needle, change main/pilot items like this. A 4t can run lean for years putting out low HP without any motor damage. Light material thickness as in this header maybe telling you to check jetting. Several riders (no dis-respect) I came accross in the past several years had great running bikes. After re-thinking jetting, found more power and cooler running bikes solving issues that pleg them for some time.

MRD are amoung the best headers built. They are not the lightest but will last a life time. If not they will fix or replace it!

I have quite a few jetting maps that I run through each year. Stock seems to handle every season except for the rare occasions where a different leak jet comes into play because I want my AP to either deliver more or less fuel depending on the circumstances. My riding elevation stays the same all year typically, and the only real jetting I have needed to do were for air density and temperature changes in regards to starting issues, which the bike rarely has. I have never had to use my hot start lever either, which kind of surprises me because the carburetor (FCR-MX37) is rather known to be a finicky carburetor to tune if using the incorrect main needle to begin with which currently I'm running the stock needle and will probably switch it to the blue needle from the JD kit. Just depends on how much cooler it gets here this winter. It has been very mild so far. Have to wait until after the 21st anyways to see real temperature changes around here.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×