Dano
TY 4 Stroke Master
I agree with the others that its most likely the donuts, but I would also check and see if the airbox boots are all in place.dave_dj1 said:
Dan
Len Todd
TY 4 Stroke God
dave_dj1 said:
Given the symptoms you describe, I would say you had a cylinder not firing correctly and fuel was forced out into the pipe. Then when you "blipped" it, it fired and consequently the excess fuel fired. It is also possible that a coil may not have been making good contact with the plug or may be going bad. But, with the problem not returning, the likelihood of this is low.
This could have been a plug starting to fowl.
KevinS
Expert
I just replaced mine this fall. I had the sled out today for the first time. On one long run after letting off the throttle I noticed some backfiring. I tried to see if I could get it to happen again but I couldn't. Not sure if I should take it apart again and check it. I didn't have any issue with the clamps being loose. I was able to re-tighten them.
Kevin
Kevin
Len Todd
TY 4 Stroke God
Just maybe, .... when you let off on the gas, there is some raw fuel ejected into the muffler, and then you get a backfire. That could be happening if the fuel injection was to rich for the particular conditions or not working 100% up to par. This would especially show up, if you are choppin' the throttle right after a WOT condition.
I am not saying anyone needs to remap the fuel or make computer fuel adjustments. Just for particular conditions, the fuel system may be lagging or not changing state quick enough. Even carbed sleds have been known to do this. Or, ...
Maybe an injector is dirty or dealing with fuel contaminates? One of my ZRs backfired a couple times just before an injector fully failed open. The thinking was it was not closing fully. The root case pointed towards containated fuel.
There are a lot of things other than Exhasut Gaskets that can make a sled backfire. Fuel delivery is one. Timing is another. And, so is exhast system intergrity. But, if you really think about it, maybe the backfiring is casuing the exhaust gasket failure (What comes first; The chicken or the egg?) A backfire in a car, and you on your way to the muffler shop. After all, a backfire is an explosion. Just food for thought.
I am not saying anyone needs to remap the fuel or make computer fuel adjustments. Just for particular conditions, the fuel system may be lagging or not changing state quick enough. Even carbed sleds have been known to do this. Or, ...
Maybe an injector is dirty or dealing with fuel contaminates? One of my ZRs backfired a couple times just before an injector fully failed open. The thinking was it was not closing fully. The root case pointed towards containated fuel.
There are a lot of things other than Exhasut Gaskets that can make a sled backfire. Fuel delivery is one. Timing is another. And, so is exhast system intergrity. But, if you really think about it, maybe the backfiring is casuing the exhaust gasket failure (What comes first; The chicken or the egg?) A backfire in a car, and you on your way to the muffler shop. After all, a backfire is an explosion. Just food for thought.
SumpBuster
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I let mine sit outside in 0 temps all day, and plugged the exhaust...no sounds, and almost stalled. Then, after blipping the throttle several times, as we all like to do, it backfired. This was from a not fully warmed up sled. Once hot, the throttle response and sounds were all normal.
My question is, do the donuts go more quickly with guys who do lots of wide open runs (heat), or guys that beat them up on the bumps (me)? I seldom do long pulls more than a mile, the only time maybe a full throttle for 6.5 miles across Salmon river reservoir, but that's not too often. There seems to be a big discrepancy on mileage..anywhere from 2000 to 8000..thats a big difference.
My question is, do the donuts go more quickly with guys who do lots of wide open runs (heat), or guys that beat them up on the bumps (me)? I seldom do long pulls more than a mile, the only time maybe a full throttle for 6.5 miles across Salmon river reservoir, but that's not too often. There seems to be a big discrepancy on mileage..anywhere from 2000 to 8000..thats a big difference.
phantomrt
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Its an old thread, but I was doing some research on when I should start looking at the donuts on my '05 RX1 with about 4500 miles on it now.
Are you guys with the exhaust backfire noise sure that the backfire isn't related to the throttle override system? I used to have such a spooky backfire out the exhaust, most prominently when the weather was around zero or below, and yes, it was after releasing the throttle such as when engine braking down a hill or after having some fun with my right thumb. This was often accompanied by the loss of throttle response resulting from the TORS system, but not always.
I once had to clean up the carburetors, and upon re-assembly, I made some throttle cable adjustments which likely affected the throttle override system and the backfire never returned since.
If your throttle override system has been bypassed, then, I guess that can't be the problem.
I may tear it apart for an inspection this spring so that I am surely ready to rock and roll next winter.
Are you guys with the exhaust backfire noise sure that the backfire isn't related to the throttle override system? I used to have such a spooky backfire out the exhaust, most prominently when the weather was around zero or below, and yes, it was after releasing the throttle such as when engine braking down a hill or after having some fun with my right thumb. This was often accompanied by the loss of throttle response resulting from the TORS system, but not always.
I once had to clean up the carburetors, and upon re-assembly, I made some throttle cable adjustments which likely affected the throttle override system and the backfire never returned since.
If your throttle override system has been bypassed, then, I guess that can't be the problem.
I may tear it apart for an inspection this spring so that I am surely ready to rock and roll next winter.
gitrdun
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I am not familiar with the RX1 but if the exhaust is the same as the early Apex and suffers the same fate, then 4500 moderate miles is probably getting close to when the clamps start to turn and the donuts lose volume. If you pay attention to your exhaust noise, you will notice it will very gradually get slightly louder. At this point you will probably have grooves in your flanges on the clamp that is turning the worst. If you let it go much longer, I am guessing maybe 1000 -1500 miles, obviously could vary, your donut will likely disintegrate and parts of your flange will disappear either from the clamp spinning freely or the exhaust flowing through the opening, or combination of both. So it would probably be a good time to catch it now and put the copper donuts in, but a lot of this membership advises to change the two pipes to stainless while you are in there anyway. They are saying that it is just a matter of time and those brittle titanium pipes will give you trouble.
phantomrt
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I think that is a good idea. I am going to do it. I see the copper Donuts available on eBay. Are those the ones we want to use? I bought the sled with 3300 miles on it. They are probably original.
I'm not a hardcore sledder, and I have no biased opinions on what is good, but from what I can tell so far, the Yamaha is superior over the other brands in build quality. They may cost more upfront, but it does not take long before that money pays for itself.
I'm not a hardcore sledder, and I have no biased opinions on what is good, but from what I can tell so far, the Yamaha is superior over the other brands in build quality. They may cost more upfront, but it does not take long before that money pays for itself.
gitrdun
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Copper donuts are recommended for long life, maybe forever. I am not sure where you are located, you should add that to your profile, but there are vendors on this site that will have them for your particular sled. I got mine from Crewchief47(sledtoyz.com) who has them manufactured a smidgen thicker so that the clamps tighten up nicely on them.
Last edited:
Winderallday!
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x2 on sledtoyz.com, good quality stuff.
fwiw, there are different grades of copper, some of the others come from asia, could be very low grade copper with no alloy.
Cheers.
thor452
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also fwiw if you plug the exhaust and it almost dies there is a leak I like to use two tennis balls and it should die almost immediately not almost die if it stays running it is leaking.
Rich Kay
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Since I dont think it was mentioned I would look closely at the bellows (flex pipes at the head) last time mine started making that sound like the donuts where shot it was one of my flex pipe joints.... the donuts where perfect. While it was apart I threw in the copper donuts for hopefully a improvement. It was hard to find but # 2 pipe was cracked and missing a small folded section.
