April 30, 201214 yr How else can you create more bottom end on a 250 apart from changing the rear sprocket size?
April 30, 201214 yr How else can you create more bottom end on a 250 apart from changing the rear sprocket size? What year and type 250 do you have? Jon
April 30, 201214 yr 2012 250 pro A higher compression insert in the head can help. Boyesen dual-stage reeds are a little more sensitive at low RPMs and time spent getting the carb off-idle response clean will be rewarded. A heavier flywheel will cut down on engine response a little but comes in real handy when you spool up and use clutch and engine momentum for a quick shot up obstacles and it reduces traction problems in iffy terrain. Jon
May 1, 201214 yr MORE BOTTOM END? Not too many ask for more grunt from a decent 250 unless they are upper class riders! One place to start may be your jetting! If this is a standard dellorto in stock form, it may be quite lean in the pilot jet. My bike came accross the pond with a #30 pilot, and while it ran smooth, it would not lift the front wheel off idle. Change from a #30-33 range to a #35-36 range would seem normal from what I hear based upon current UK fuels as I understand.
May 1, 201214 yr I have a 011 250 having come from a 300. The issue I have is it's very snappy off bottom end unlike 300, so I put a flywheel weight on and that has smoothed of the bottom end and I riders alo better. A different carb would alter power I guess , but I wished I'd gone for 300
May 1, 201214 yr Cope is right on, The Dellorto PHBL makes alot more power off the bottom when on the rich side. When the pilot is too lean, it becomes a nice running 200. A high comp head will give you more punch. However, there are tradeoffs. I found the HC head was the biggest shot in the arm on my 250's, but the biggest gain was to the midrange and it became harder to ride on the low end as it lost its nice smooth delivery, so I added a FWW. Jon was right on about adjusting your technique with the clutch to spin her up. While the FWW helped smooth out the big pulses from the HC head and provided torque for slow, controlled hill climbs, One thing I didnt like about the FWW is that the bike now wanted to over run everything. Get all that mass spinning for the hit and it wants to keep spinning! Again, use of the clutch provided a solution - but it took me several rides to get my throttle/clutch timing set. I will say that the best mod I did to my bike was to switch to a 26mm VHST carb. It provides cleaner - crisper power down low. (not really any more - just more responsive) and I would mount it as close the the airbox as possible (1/2" makes a noticeable difference to bottom end response) I never tried a long head pipe, but my buddy with a 280 has one and his bike runs sweet off the bottom. All that said - a stock (properly jetted) 250 with the correct use of the clutch can do very well.
May 1, 201214 yr Just wondering if it was from running no stop rules. We forget how easy a 5 can be with all our messing with the clutch nowadays. Since we started stop and hop with always on the clutch the bikes just do not have the same tractor pulling grunt they used too.
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