97 RM250 doesn't like to start after new pilot jet

drewstair · May 25, 2004

I was fouling plugs after about 1/2 an hour before because I am a new rider and doing a lot of terrain where I am taking it pretty slow. Since I was staying under a quarter throttle for a lot of the riding I switched the pilot jet from a 45 to a 42.

The bike used to start in 2 kicks without a problem, but now it takes 10-20 to get started. This is even after it is hot. I still fouled a plug the other day while riding but it took longer to do so than it did before.

Will changing the pilot jet alone cause this kind of trouble, or is there something else going on. I have taken the carb apart 3 times now without replacing the seals, so I know I need to do that. I am also going to replace the reeds as suggested by a friend. Any other things I should take a look at?

joelyles2004 · May 27, 2004

Here's Some Advice

I Have the same year bike as you do. Instead of going from a 45 to a 42, maybe try a 44. Don't be so drastic with jetting changes. Some jets can change size by a half. Example 45 to 44.5. This should help some. Also change to a hotter plug if youre running a BR8ES or a BR9ES. I use a BR7ES and it helps my bike start easier and run alot better in terms of power. It helps the bike burn the fuel quicker ao it can draw more in quicker. Hence, more snappy response, more power, and in you're case, much less fouling. Reed are also a big thing. At 8000 RPM, dirt bike reeds open & close 133 times a second. No joke, I read that in TransWorld Motocross. If theres any real space between the reed end and the cage than you need new reeds.

Joe Lyles
joelyles2004@yahoo.com
97'RM250

MikeT · May 28, 2004

Good point about the reeds.

97 RM250 doesn't like to start after new pilot jet

drewstair

joelyles2004

MikeT

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