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i need help with HMF pipe

2545 Views 12 Replies 5 Participants Last post by  marcust
i have a 06 foreman 500 es everything is stock besides 12 inch rims and 26 inch tires and i put a HMF pipe and a 170 main jet on it and it blew the first one out in like one hour so i took it to the honda dealer got the pipe replaced and adjusted the fuel screw and everything and it ran perfect. i ran it for about another hour and it blew another hole in it again. does anyone have a clue what might be wrong?
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Hole in what the pipe?
in the muffler. the canister

its on the canister the the end close to where it meets the pipe
We are just trying to figure out why this mans pipe burned out twice.

He is running the 170 oem jet and adjusted his fuel screw yet he burned up two mufflers.

I see that the majority of 500 owners are running a 170 or a dynojet kit.
If this is correct then why is this mans pipe burning out when everyone else is running the same jet and not burning up.
We ran the 500 on the dyno and found the 170 to be a good baseline jet and 2.0 out on the fuel screw.

Please post what main jet you are running OR if you are running a dynojet kit so we can help this guy out.

[email protected]
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Try taking the jet kit off, had it on mine when I got the HMF and it was making it pop really bad, took it off and made it run fine. The guy told me that the jet kit does little or no good (horsepower) try that, unless you just want a jet kit.
you got to have the whole dyno jet kit you cant just run with a main jet. the jet kit was supposed to come with the pipe. thats why its blowing im sure. ive never put one one without the dyno kit. i know that will fix it
Thanks everyone.

We only sell OEM type jets because that is what we test with.
Typically, when we get machines for testing there is no jet kit available.
We do not sell a "jet kit" we only sell OEM type jets.

We found the 170 and 2.0 on the fuel screw to be in acceptable ranges air fuel ratio wise. External exhaust temperature testing lowered stock vs recalibrated as much as 45 degree at the muffler inlet.

BUT you guys are the ones out there running them day in and day all have the "in the field" answers.

Maybe this man needs a dynojet kit.
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I have a 165 jet on mine 2.75 turns out.
The man just sent us back his pipe all I can say is WOW the inlet to the muffler is BLUE to the can and the can has a big hole in it. The muffler packing is turned to chunks of rock. I know our packing is good to 1200 degrees so something got really hot in there...NOT NORMAL HOT !!

I run the dyno here and do all the fuel recalibration and EFI mapping, to be honest with you all I could NOT begin to think how I would go about re creating this issue if I had to.

The stock 162 main, needle taper and fuel screw setting did not show up as seriously lean in our testing of this machine, no where even cloe to cause the damage of his muffler.

I'm sure if you all or even one of you had this problem with your 500's you would be letting us know on this forum.
So far not much BAD info on this subject.
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If it got that hot wouldn't the oil temp light come on?
I do not have a 500, so I cannot give you any pro's or con's. all the guys that I know of running the oem 170 jet and aftermarket exhaust are also running a snorkel. .
Before I put on my snorkel and got the dynojet jet kit I was running an oem 170 jet and stock setting on A/F screw with k&n filter and had no problems.
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