Donuts every 500 miles, WTF???

[bigreis]

Agree with the above statements.
You need to go over the sled and check for any worn or loose rivets.
On my sled all the tunnel to bulkhead rivets had be ome loose by 10000 miles.
Digging deeper and looking for potential long term problems will only benefit you in the long run.
Good luck

All of the 8 rivets holding the flimsy upper tunnel piece to the bulkhead under the gas tank were either loose or worn all the way through the thin upper tunnel piece. I drilled a few of the rivets at the vertical tunnel to bulkhead junctions on both the left and right side and didn't find anything suspicious at all. It doesn't make sense to me how the rivets holding the vertical rivets pieces together (which would be where the most force should be due to the constant up and down shearing action) wouldn't wear out first.

When I begin to secure the upper part of the tunnel back to the bulkhead, I am assuming there should not be any gap between them, correct? Before I started digging into this, there was about a 1/8" gap between the tunnel and bulkhead... that isn't normal, right?

 

[yamahatd]

all good advise and considering I have the same sled I read the entire post. These guys on here rule! My doughnuts have never failed in the 10k miles, but have been replaced for preventative purposes only. No one has mentioned the flex pipe, which you may want to inspect. The loose rivets and tunnel are most likely the culprit but worth a look. I taking a close look at my tunnel rivets during pre-season prep that's for sure.

 

[RTX]

All of the 8 rivets holding the flimsy upper tunnel piece to the bulkhead under the gas tank were either loose or worn all the way through the thin upper tunnel piece. I drilled a few of the rivets at the vertical tunnel to bulkhead junctions on both the left and right side and didn't find anything suspicious at all. It doesn't make sense to me how the rivets holding the vertical rivets pieces together (which would be where the most force should be due to the constant up and down shearing action) wouldn't wear out first.

When I begin to secure the upper part of the tunnel back to the bulkhead, I am assuming there should not be any gap between them, correct? Before I started digging into this, there was about a 1/8" gap between the tunnel and bulkhead... that isn't normal, right?

I would think no, its not normal, but i am having a hard time remembering exactly how mine was. That area might be doubled up with layers of metal.cant remember.
Its also possible the metal has burrs between them not allowing them to close up tight
I fixed mine a year or 2 ago
I could not get rivets to pull some of the areas together. The holes were so worn i had to use 1/4-20 button head screws with fender washers and poly locknuts and loctite
Dont just look at the top of the tunnel.
Look at the sides where the tunnel meets the bulkhead, make sure all rivets are good and tight.
If possible put set of pliers on the back side and gently try to turn them.
Any movement at all should be replaced.

 

[RTX]

I am going off memory here. But isn' t the front exhaust hanger mounted to that same joint at the tunnel/bulkhead?
If not. Check the mounting of the exhaust hanger too

 

[maim]

did both brothers 04 and 05 war about 2 years ago and the one with high milage i needed to bolt as the holes where egged out with 1/4" rivits on the top of the tunnel. holding up to sappling killers abuse so all must be good.

 

[Redbeard]

All of the 8 rivets holding the flimsy upper tunnel piece to the bulkhead under the gas tank were either loose or worn all the way through the thin upper tunnel piece. I drilled a few of the rivets at the vertical tunnel to bulkhead junctions on both the left and right side and didn't find anything suspicious at all. It doesn't make sense to me how the rivets holding the vertical rivets pieces together (which would be where the most force should be due to the constant up and down shearing action) wouldn't wear out first.

When I begin to secure the upper part of the tunnel back to the bulkhead, I am assuming there should not be any gap between them, correct? Before I started digging into this, there was about a 1/8" gap between the tunnel and bulkhead... that isn't normal, right?

If your tunnel is getting loose where it attaches to the bulkhead, it could crack the tunnel like my Warrior did. I patched that up, but several rivet holes were egged out. I replaced almost every rivet from the snow flap to the drive axle with stainless bolts.

 

[steiner]

If your tunnel is getting loose where it attaches to the bulkhead, it could crack the tunnel like my Warrior did. I patched that up, but several rivet holes were egged out. I replaced almost every rivet from the snow flap to the drive with stainless bolts.

You call that sled Porcupine now?

 

[Redbeard]

You call that sled Porcupine now?

You forgot, "Just sayin'!"

 

[RTX]

If your tunnel is getting loose where it attaches to the bulkhead, it could crack the tunnel like my Warrior did. I patched that up, but several rivet holes were egged out. I replaced almost every rivet from the snow flap to the drive axle with stainless bolts.

View attachment 123580 View attachment 123581 View attachment 123582

that's what I saw with mine as well.
running down the sides of the bulkhead all the rivets were loose.
just looking at the sled it all looked fine but once you start digging you find more and more problems, lol

 

[steiner]

You forgot, "Just sayin'!"

Ooops. My bad.

 

[Redbeard]

Ooops. My bad.

LMAO

 

[DJ Hennessy]

Anyone have ideas why I am blowing through donuts after 500 to 800 miles? I have tried OEM graphite as well as aftermarket copper and get similar results. On my third set of y-pipes after 8000 miles... love the sled but tired of the constant maintenance.

Like many of the people are talking about on here, anytime I've gone over my sled for any type of repair or maintenance any rivets that have movement I drill out and replace with S/Steel grip rivots. Some that end up with bigger holes, I use 3/16" fender washers on both sides of the rivet for grip. Also, someone mentioned on here already about the flex pipes, I had one broken that unless you pull them off i wouldn't have noticed the crack... I replaced donuts and still heard backfires, so tore it all apart again to find the broken tip on the muffler where it meets the Y pipes and the cracked flex pipe. I replaced the mesh collars that go in the muffler end and wrap around the Y pipes. Have a look at those to, while you're in there, they're not a big expense and might as well change to in case they're allowing air into the system to.

 

[SumpBuster]

Years ago, I used to swap ski doo suspensions, but never riveted. I used button head Allen screws and locknuts, forgot what you call them, but they had the star washer as part of the nut, and you could really tighten the crap out of them and they bit in. Never ever had one loosen up on any of the sleds we used them on. I think I used 10-32 and 1/4-20''s
Mcmaster Carr.

 

[GUKROKIT]

Years ago, I used to swap ski doo suspensions, but never riveted. I used button head Allen screws and locknuts, forgot what you call them, but they had the star washer as part of the nut, and you could really tighten the crap out of them and they bit in. Never ever had one loosen up on any of the sleds we used them on. I think I used 10-32 and 1/4-20''s
Mcmaster Carr.

x2

 

[Goody_1000]

Anytime I had to replace rivets, I used SS bolts, locknuts. Might not be best looking, but never came loose again! On a side note, I checked exhaust on sled I bought from dealer this fall. Put gloved hands over exhaust pipes...started to die out after like 2 seconds...I think my donuts are good for now.