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Burn Down

2914 Views 24 Replies 16 Participants Last post by  hawk
Just thought I would post a little info on my burn down in case any one else is running or thinking of running a similar set up to mine. This happened last weekend on the lake. Had made one 1/2 mile pass at about 3/4 throttle, turned around for another run and shut down have way. My set up is Speedwerx single, reeds, spacers, headcut, airbox mod, D&D Y-Pipe, injector perfector with 290 main, 93 octane gas. Also running 22/40 gears. PUt the Y-Pipe on late last season and had probably 200 trail miles on it, no long hard runs. Plugged looked fine then. Obviously at 3/4 to top end with the 290 and the Y-Pipe I was on the lean side. Was about 33 degrees out at the time of the burn down. Also an issue I discovered at the time of tear down, pipe had come loose on the can, how the *uck that happened, no clue. Well motor is back together with fresh pistons, however I will be running the stock y-pipe. I have not had my sled dynoed but by reading various posts have heard Speedwerx pipe and D&D Y-Pipe not a good combo. Anyone have dyno info on this combo? Bottom line, error is on me for being too lean. Just a heads up for anyone else out there with a similar setup. Pistons will be added to the wall of shame!
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D&D Y-Pipe designed to flow more air. More air (Y-Pipe) + leaned out top end (290 main jet) = detonation. This is why the boondockers are used. To add / lessen fuel where needed. The injector perfector is effective, however limits you to topend and not as precise.
My 04 has the updated ECU which mirrors the 05 and 06's. Your Lite probably flows differant from the Speedwerx. Great post! THanks for the info. Looking for more posts.
Headcut possibly sounds like your problem. Head cuts are so tempermental and from what I know of, the F7 is one of them...or quite simply, you had bad gas. Happened to me last year on my zrt600.
ahhhh the price we pay to play. im sure people will appreciate the info :beerchug:
I have been running my whole setup, other than the y-pipe and gearing, for 5000 miles. No problems, plugs always looked great. 22/40 setup worked great for trails. Not a top end setup. Sled would pull 8050 on top right where the Speedwerx likes it. The part about the gas is also a possibility. Sometimes, the 93 octane gas in early season has been sitting for an extended period of time. Could have been bad.
I had pretty much the same set-up last season, dyno tuned it with my boondocker and had to add fuel all the way through out the prm range. When i was all done trouble free 152 hp all day long.....................Johnny
Johnny, Are we saying that the speedwerx pipe needs fuel? Or which mod does? Thanks
Could be some bad gas, but I will go out on a limb here and say the head cut is your problem, center of the piston looks like it ran very hot with detonation at the edges of the pistons.
Cutting the heads will make the motor act as though the ignition timing was advanced because it increases combustion flame speed.
Advanced ignition or to fast of flame speed for a "factory" timing curve will raise combustion chamber temps.
If you have ever ran EGT gauges with a motor that has ignition timing that you can adjust, you will see that exhaust gas temps will go down if you advance the motor or will go up if you retard the ignition timing.
Why? because with advanced ignition the cylinder, piston & head has more time to absorb heat from combustion where retarded has less time and some of the mixture may even burn in the pipe thus raising exhaust gas temps.
The increased compression will also add heat to the motor, and with the motor leaned down the combustion chamber is just to hot.
Also worn pistons with excessive cylinder wall clearance will not transfer the heat as effeicently as a tight tolerance also adding to a heat problem.
It has also been argued running lean oil mixtures hurts heat transfer from the piston to cylinder wall.

Just something to think about
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Good info. I will state again, that I have run the Speedwerx pipe, with reeds, spacers, head cut, airbox mod, stock 24/39 gearing, reflashed 04 ECU, and always 93 octane for 5000 miles, never a hint of a problem, plugs always looked fine. Last March, added the y-pipe and 22/40 gearing. Last weekend was the first 3/4 to wide open testing I have done with the Y-Pipe on. So, yes, I believe that more fuel probably was the ticket with the y-pipe. I guess when I look at it, and the Speedwerx guys can comment, there is a reason why Speedwerx doesn't offer a Y-Pipe for the F7. There single probably works best and makes the most HP with the stock y-pipe flow. Just my 2cents.
I don't think is was just the y-pipe that caused your burn down. I think you were running on the lean side before the addition of the y-pipe and the addition of the y-pipe was the straw that broke the camels back. I wouldn't just blame the addition of the y-pipe in this situation. I know you said it was fine before the y-pipe but we have to look at your overall setup here. Maybe the thing was ready to burn down before you put the y-pipe on, how many miles did you have on the setup before you put the y on? Oh well at least you have it put back together and ready to go. Thanks for the heads up though!!!
Adding gear is adding load, and adding load then making long runs" witch you haven't done yet" change everthing. My boondocker numbers were like 10's at 7800 10's at 8250 so you need fuel with these mods.....................Johnny
I'd say head mod also. Everything else contributed, but lean would have eroded the exhaust edge more IMO.
I'll vote on head mod too.
You have to much compression for 93 octane by looking at those pistons. Its not severe deto as it didn't blow the exhuast side of the piston clean off, but it slowly evenly ate away at it. You could either ditch the heads for lower compression heads(best idea), run a 50/50 c12/93 octane mix(pretty retarded on a single pipe trail sled) or get a boondocker and really fatten it up. Problem is you will likely have to run overly rich to be safe, which reduces power which was the hole point to begin with right? This is one of those examples of to many mods that turn out to be incompatible. You can keep the heads around, run them with twins and use the 50/50 fuel mix with a boondocker, then you will fly.
If it ran good for 5000 miles then why is everyone telling him to ditch the head? Put the stock Y-pipe back on and run it for another 5000 miles!
Johnnys point about the gearing is on target also I believe. I had planned on originally putting in the sno pro setup 23/40 but didn't have the 23. Thats the setup I will go with and put in a 300 or 310 main for a little more fuel. By the way Y-Pipe is for sale if anyone is interested. PM me.
Keep the y-pipe, add the 310main jet watch your plugs for a few passes and have fun. The D&D y-pipe is not at fault, when you tighten up the head and add more ait flow you need to add fuel. m2c Johnny
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