I just installed a HMF s/o on my 300, but their reccomended baseline jetting (125, up from the stock 122 and 1/4 turn further out on the pilot from the stock 2 1/4 turns) appears to be way too lean. Started with my aftermarket UNI filter, airbox lid cut alot, the slip-on, and the 125 jet. WAY too lean. The plug showed no carbon anywhere after a half hour. Ok ok. I put my stock filter back in and duct-taped the airbox hole. No difference. Ripped my gas tank out, rejetted up to a 135 (the biggest jet HMF gave me) and backed the pilot out even more. I still have to drive it around with the choke 1/4 on to get any carbon on the base ring (porcelain still white) and make me feel a little safer. My bike was like this when I got it, and even with the stock pipe, jetting, and intake it would get so hot it would start to puff blue smoke occasionally. If you ask me, thats a wee bit lean. (this goes back to my previous post, 'new 300ex smoking') In the manual it says that honda utilizes lean carburator settings, but I didn't know it was this bad. Will someone enlighten me? What jets are other people running with their HMF's?

 

With a good muffler, air filter and box opened, you should run a 40 pilot and about a 132 main. Try a bigger pilot and raise your needle up atleast one notch. That should get you pretty close.

 

i know this is off topic but im buying a new exhaust for my quad and i was just wondering how loud the hmf s/o was

 

Not as bad as an HMF on a 400. buy the quiet core if you're worried about noise. it works. I think people get all weirded out about noise because they hear those big name pipes on bigger bikes, and they're loud. I've run mine alot lately and my neighbor hasn't even called the cops on me yet. He would have if it was really bad. With the Quiet Core, I think it's quieter than stock at idle and starts getting louder as you rev. Without it, it has a nice deep put-put at idle and just plain yells when it's wide open. Its a good loud, though.

(p.s. HMF claims 100-102 db without the QC and 92-96 db with the QC installed. There's a limit to how much noise a 281cc engine can produce.)

 

Even though something is way off fuel wise, (or maybe it's just me not knowing how to read a spark plug and freaking out) me and my impartial dad who doesn't put much stock in upgrades both agree that it produces way more power, most notably on the bottom. I can clutch into second from a dead stop and lift the front end up for quite a ways. If someone feels the urge to explain how to adjust a pilot screw WHILE your bike is running without ripping all the plastic off to get the carb out lemme know.