[MotoDuc]

Now that spring is almost here I'm thinking of tuning up the M900 for the new riding season. During my random thoughts of what to do first I keep thinking "MORE POWER" The bike is a 99' M900 whic I bought at the beginning of last season with under 10K on it. THe bike was is in unbelievable condition with a bunch of bolt-on mods. On top of that the original owner was a 50 something year old guy who used it for leisurly highway rides. I can't help thinking that this bike is not tuned correctly since it seems low on power for a 900. I've never ridden a 900 monster other than this one, but it seems like it should have some more. I would think that the bike could at least get it's front wheel off the ground without too much effort, but my attempts have produced nothing but extending the forks : I'm not a wheelie person, but my 18 years of moto-x have gotten me used to have the front wheel in the air. My R6 could pull wheelies, although too quickly at times, without much trouble. I even went to a 14T front sprocket on my M900 to see if it would help, but still not enough.

The bike is a B#@ch to start in cold weather, and the last time I pulled the plugs I noticed they were black. So I know it's running rich, but don't know what jet kit the guy put in it. Does anyone have the baseline jetting specs for a 99' M900, and possibly some input as to what jetting works for your bike?

Much Thanks

 

[CRASH!]

Sounds like your bike is in the state of tune mine was in when I got it (used also).

I had black plugs and poor gas mileage. I thought it might be overjetted. But I had BCM check it out and they were ok with the setup (Dynojet Stage 1).

I ended up pulling the snorkel tubes off (it already had Termi pipes on it). But I found the best thing for the bike is to REV IT! The bike runs much better when you keep it simmering at about 5k and make sure it gets frequent blasts up to 8k. Doodling around at 3.5-4k caused it to load up.

Now this says to me that my idle or low-speed setup is not right, whereas my mid and high speed are good. So I'd say me needles, clips and needle jet are all good. Too bad I can't actually tell you what the sizes or settings are though. I got in there once and when I couldn't make it any better, I handed it over to the pros.

I'm not putting any more energy into the carbs 'cause I'm just waiting to get FCRs ;D

 

[Norm]

Try replacing your emulsion tubes, they get worn & cause an overly rich condition at low RPMs. What state is your airbox in?

 

[ScottRNelson]

The jetting FAQ on this site lists what worked for my 1997 M900. It would easily wheelie with just a sudden application of throttle in first gear (okay, that and a 14-tooth front sprocket together with the original 39-tooth rear).

The 97 was different from all of the other M900's because it had smaller valves. That supposedly gave more midrange at the expense of the loss of a little top end. I'm starting to believe the midrange part, because it clearly had more midrange than my fuel injected 944cc ST2 motor, but the ST2 clearly has at least 5 more horsepower on the top end plus pulls stronger above 8000, all the way to the 9500 rpm rev limiter.

I rode a 99 M900 once with high compression pistons and FCR carburetors. I couldn't give that thing full throttle in first gear without the front end coming up, even when leaning my head over the headlight. I definitely couldn't give it full throttle in first gear throughout the full rpm range. That one was scary to ride.

If you're going to rejet, I believe you'll find Factory Pro easier to install than Dynojet, and one Factory Pro jet kit generally works for whatever you have without the need to worry about stage 1, stage 2, or stage 3.

As for the hard starting problem, mine was always hard to start if it had sat for more than 3 days with the temperature under 50 degrees. If it had sat for a week or more I didn't even try until I could find a warm afternoon.

However, you can turn the idle mixture screws out half a turn to 4 turns and it will help cold starting, cold idling, and the off-throttle to part throttle transitions when it's warm. That's independent of any jet kit.