HELP!! New 426 owner

Hi everyone. I just picked up a 2001 426 in pristine condition. I have to say that I am pretty pleased with the bike and am going south to warmer weather to ride this weekend (I hear it is in the 40's in Moab, while we are lucky to be above zero in the frozen waste of northern Utah). I just spent three evenings going through the bike and checking the torque specs and getting it ready to go. After an extremely frustrating experience with a fouled plug, I finally got it started. I am a bit concerned about the jetting. Stock main is 162 and I dropped it to a 152. I kept the stock needle but dropped it down to the 3rd position. I changed the pilot from a 42 to a 40. I am really hoping this is the right jetting. Also, I started it tonight to warm it up after changing the oil and was really surprised to see that the headpipe was glowing red!! I have an FMF powerbomb on it and am not sure it is supposed to do that. I mean it was red hot! Please help me out guys!

email me if you can:


I don't know about your jetting changes, but I can tell you the pipe is normal. You can do a search to find out more.

Thanks for the reply. I get really worried about new bikes. I like to know the ins and outs of them and something like the red hot head pipe freaks me out until I find out whether or not it is normal.

Regarding the pipe, just got back from riding, washed down the bike, started it and first portion of the header was glowing red.

Any suggestions on handlebars? Bent mine out of shape today, and would really like some input as to which one and why.

Thanks for the info on the headpipe. I really prefer the Protaper bars. They are a little pricey but the vibration damping and strength make up for it. If you don't want to mess with changing to a 1 1/8" clamp then I would go with Renthals.

Normally, that would be jetted on the lean side. . . but, if you are at altitude, it might be spot on. As a precaution, with that jetting, you might want to be sensitive to the engine's operating temperature and/or whether it pops on decel. Watch for coolant spitting out of the overflow if you run it hard in deep sand or on an extended uphill climb. Even with spot-on jetting, it could still overheat a little on pump fuel. VP MR2 is oxygenated and is a great choice for the 426 at altitude. If you decide to use an oxygenated fuel to compensate for your altitude, you will need richer jetting. This helps to regain a little of the power loss from the thinner air.

I live at sea level (south Fl.) and with the stock jetting it runs great in the summer and on warmer days. I've noticed that as it getts cooler it does start to feel lean. I've ridden in the 60's and it was running well enough that I didn't adjust it (I can't use all this power anyway), but it was definitely starting to feel lean. Some burbling and missing at mid throtttle openings, popping, flat on top, etc.. I am far from a jetting pro but if you're near sea level then you may want to consider taking some jets with you just in case you need to make a trail side swap if you discover that you're too lean.

I will definately take jets with me. Where I am at in Utah we sit just over 4500 feet above sea level. I know I had my KTM 300 EXC jetted down from a 176 stock main to a 158 and had to put a completely new needle in it that was a step leaner. I also leaned out the pilot two steps. If jetting a two stroke is a lot different than a four, please let me know. I just based my jetting on my experience with the KTM. The dealer here is no help since they claim to run stock jetting but I fouled a plug just going up the street and back. I wasn't on it more than 5 minutes and it was all crudded up.

I live in northern CO +-5000ft and fouled plugs like crazy till I swapped the main jet. All i did was switch to a 158 main jet and adjust the pilot screw. It may not be the completely optimum settings, I know a lot of people at my alt switch the pilotjet and move the needle clip, but it works fine and the plug is in great cond after 10+rides.

Originally posted by lco:

Regarding the pipe, just got back from riding, washed down the bike, started it and first portion of the header was glowing red.

Any suggestions on handlebars? Bent mine out of shape today, and would really like some input as to which one and why.

I have Emig triple clamps, renthal fat bar (McGrath bend I think). That set up really opened up the cockpit and gave more leverage to help lean the bike over.

All right. I live in Denver, so my altitude and weather should be near yours. I have done the same leaner main and moved the pilot to a 40. This pilot change has definitly helped me, especially with the colder weather that we get here early on in the season. Work on that fuel screw every ride and the bike will run great.

I just took it out this weekend and everything was great except the main. I went up to a 155 on the main and that helped out. Thanks for all the replies.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now