Well, that's not at all what I wanted to hear! I live in Colorado, as most of you know, we have a little drought problem and therefore a fire problem. I am not too worried about getting caught, but as a reponsible ATVer, I think I need to research this a little more, but will likely not do it. So, I will post a couple other questions on another post. Thanks for the quick response.

 

You may want to contact HMF, in Cleveland, OH., and see if they NOW offer an approved arrester, they may. Good luck! HMF has a website, too.

 

I noticed FMF has a few mufflers for the 650. http://www.fmfracing.com Forest service approved.

The Q series looks nice cuz it is supposed to be real quiet.

 

nyroc, you said that you had to rejet your bike after you did the exhaust mod. Did you ride it before you rejetted it to see what it was like ? The reason I ask is I just got my pipe welded back together and took it for a quick spin and there didnt seem to be any mid range power. It seemed to take off fine but it didnt seem to pull very hard once it was moving. I only had a short distance to run before I had to let out of it so I couldnt see what top end was. I was just wondering if this is the way its supposed to feel if I need to rejet it. I didnt expect that much of a difference. Im hoping to rejet this weekend and see if it was the prob or not. Any thoughts ?

 

I rode it a lot before I rejetted it. My needles were on the verge of lean, so when I modded the muffler, I noticed the low to 1/4 throttle being leanest. It became much better after richening the needles.

I noticed the mains being lean up front, and went up one size right after the exhaust mod. If I remember right, it was doing approx what you describe.

 

Thanks for the help and sorry for all the questions but Im new to jetting carbs and such. How exactly will I know what I need to do. I have the DJ kit in there now. I was figuring that I would go up one size on each main jet. Is it possible that I would only have to change the jet in one carb or is it always both ? Also, should I have to change the needle position on either one ? Again, sorry for all the questions. I just donr know enough yet to know what to look for and what it should feel like when it right.

 

You may or may not need to change the jets. There is no hard rule.

However, most people will tell you (I think) that the mains usually need to go up one size with a free flowing exhaust. Once in a while someone says they didn't need to, and another guy says he needs to go up more than one size.

Read up on how to tell if your engine is rich or lean by reading plugs. Stay calm, but don't run it really lean for very long. If it is too rich no big worry.

A good motorcycle tuner can "hear" how rich or lean his machine is. I can get to this point of having my ear tuned to the quad only after owning it and messing with it for a while.

A not so accurate method of determining rich or lean is the tailpipe soot. Black is rich, light or no soot is lean. This takes longer to manifest than a plug reading.

Once you get used to tuning engines, you can also tell if they are rich or lean by how they run from cold engine to hot. If it runs awesone cold, it could be too rich, and may stumble when hot. If it runs pretty crappy cold, and only settles down when the engine is hot, it is lean. It should run reasonably uncrappy when cold, then run fine long before the engine is fully hot. This rule of thumb applies to idle, low throttle, and high throttle. You can tell which way it needs to go. This is an extremely useful method to use, but may not be the right way to go if you are a beginner.

If you aren't very confident with tuning, stick with plugs and follow the plug reading rules exactly. Read it only when hot, and hole the engine at whatever throttle setting you are looking at, then shut it off before coasting to a stop. Take the plug out right there.

 

is this mod for all quads or just 650? what is done?

 

Nyroc's Exhaust Mod