I just got an 02 CR250 and have been working on the jetting, so far I have not run an idle, but I have also stalled it a couple times when I've jumped on the brakes. I have read that running an idle does not give you good jetting. Why is this? Does it only effect low speed jetting? Can I get away with running any kind of idle at all ?
Why aren't race bikes meant to idle?
- Thread starter cr-man
- Start date
Setting your bike to not idle does not affect the jetting, it affects the response when snapping the throttle open from fully closed. Personally, I haven't found any advantage to setting the idle screw that low, so I set my idle speed so that the engine will just barely idle.
EricGorr
Super Power AssClown
- Aug 24, 2000
- 708
- 1
Hi Joe,
the problem has to be with designing a carb for fast response. The slide and needle jet hood area produce a strong fuel signal. If you raise the idle it could lower the plug temperature with too rich a mixture and wet-foul the plug. Back in the old days we had big round slide Mikuni carbs that idled great but had sloppy response.
I'm sure we can dig around in the attic and find an old Bing carb from a Maico that would be fitted to your new CR!
the problem has to be with designing a carb for fast response. The slide and needle jet hood area produce a strong fuel signal. If you raise the idle it could lower the plug temperature with too rich a mixture and wet-foul the plug. Back in the old days we had big round slide Mikuni carbs that idled great but had sloppy response.
I'm sure we can dig around in the attic and find an old Bing carb from a Maico that would be fitted to your new CR!
Guaryzzzpode
Member
- Feb 25, 2000
- 66
- 0
As Buzz said, having the bike to not idle offers some sort of "engine brake" on 2 strokes. I prefer having perfect idle, so I don't lock the rear wheel (and shutting the motor) quite as often.
FMX_novice
Member
- Jan 5, 2001
- 161
- 0
When braking hard use the clutch! When you do some serious braking your motor will die without the clutch! I set my bike to a real low idle as well, When i brake i pull the clutch and i put enough pressure so that the wheels are about to lock up, i stay in this pressure unless the bike is about to flip over, i try to keep the bike level by shifting my weight. I shift down with about 1 second inbetween each shift and when im ready to get on the gas i nail the gas as im popping the clutch and stay on through the corner.
What works for me
CR Man,
I've set my bike all 3 ways, strong idle, weak dying idle, and no idle at all.
I found the weak dying idle works best for me. The throttle response was right there as opposed to having the screw all the way out, and the engine doesn't fire unexpectedly when I'm going downhill (set at a strong idle).
Joe Chief
CR Man,
I've set my bike all 3 ways, strong idle, weak dying idle, and no idle at all.
I found the weak dying idle works best for me. The throttle response was right there as opposed to having the screw all the way out, and the engine doesn't fire unexpectedly when I'm going downhill (set at a strong idle).
Joe Chief
You guys have my vote on setting it so it either just barely idles, or idles for a while then dies.
When I lean my bike against the truck (idling), get out my ramp, then ride it into the truck, I get some strange looks and comments from time to time. The trend with many mxers is to copy some pro racer who sets up the bike without an idle.
I have had bikes that would load up like Eric mentioned, I just make sure I don't let them idle long enough for this to happen.
When I lean my bike against the truck (idling), get out my ramp, then ride it into the truck, I get some strange looks and comments from time to time. The trend with many mxers is to copy some pro racer who sets up the bike without an idle.
I have had bikes that would load up like Eric mentioned, I just make sure I don't let them idle long enough for this to happen.
Ha! That might explain the funny looks I get when I am leting my bike idle for a while to warm it up before I go ride.
It is a YZ 125 and it idles and has plenty of throttle response...
Of course, the fatty pipe, carbon reeds, spot-on jetting, and exhaust porting help out a bit too ;)
-jeffd