Super hot!

[matt75]

Riding home last night i noticed the pipe got red hot, it was actually glowing in the dark. Now its discolored from the heat. Its a FMF fatty. Anyways went to fire it up today. It fires right up and runs good in neutral. When i put it in gear theres no power. A little but not much... Any ideas on what to look at? I might tear into tommorow. Thanks in advance.

 

[Blasterdude27]

air leak ?

 

[Awk08]

check for a clogged silencer, maybe just pull it off and see if it has power

 

[brandoz28]

yeah man sounds like you might have something clogged up or you're running lean! check for air leaks too

 

[yb200]

lean check the plug check compression

 

[matt75]

check for a clogged silencer, maybe just pull it off and see if it has power

Im pretty positive the silencer isnt clogged, it doesnt even have packing in it. Where to check for air leaks? Would a leak where the FMF fatty connects to the flange cause it? Also is it possible it got so hot it deformed the reeds?

 

[matt75]

No air leaks unless around the fatty flange counts? , no clogged silencer, reeds are fine and new, any other suggestions? Coil, carb? It just runs hot as hell and has no power when put into gear. Compression seems really good...

 

[stephen12091985]

do a compression test and maybe you have weak spark

 

[rideyamaha09]

I'd say do a compression test and try to seal the pipe up around the flange if you can. Make sure the gas is mixed if you run premix, or if you have the injection i'd definitely check that. You might want to also take a peek at your piston through the intake or exhaust for scarring, that excess heat could have caused some problems.

 

[matt75]

Riding home last night i noticed the pipe got red hot, it was actually glowing in the dark. Now its discolored from the heat. Its a FMF fatty. Anyways went to fire it up today. It fires right up and runs good in neutral. When i put it in gear theres no power. A little but not much... Any ideas on what to look at? I might tear into tommorow. Thanks in advance.

Okay i finally got a chance to tear into the blasty this morning. I found out what the problem is. Freaking sheared woodruff key again.... Luckily an easy fix. Sheared woodruff key screws the timing causing it to run hot in this instance. In my other experience the sheared woodruff key was enough to run the timing backwards and make the blasty run in reverse in every gear. So anyways thought i would say what the problem was incase someone else had a similar problem. Thanks for yalls help on this.....

 

[blasterfreek30]

wow bro, i wouldve thought it was airleak.....good job finding the prob and thanx for the headsup on it.....im sure someone else will have this prob again lol

 

[Blasterdude27]

Weird.. Glad you found the problem, never would have thought of a sheered woodruff key doing that.

 

[doc_speeder]

Yes, that's right. It most likely would have retarded the timing. That will cause excess heat and loss of power. Nice diagnostic work!

 

[super noober]

so you put a new key in and now it runs good again?

 

[Brainmatter]

What is causing the key to shear? The crank and flywheel are tapered... once you have that thing torqued down, there should be no pressure to speak of on that key, it really just lines everything up for installation. once it's torqued, there is a sufficient interference fit to keep it from spinning. Make sure the flywheel is not cracked right along the key way, and make sure it's torqued to spec. I've seen the flywheel crack from being overtorqued right alongside the keyway groove, if its cracked, it will always be loose. The crack can be really hard to see, so look close!