When accelerating hard, I've notice that from about 4200-5000 RPM my bike accelerates weird. The engine sounds like it's revving up, but the bike feels like it's not really going much faster, then once the rpms get past 5000, the bike suddenly grows balls and starts hauling ass like it should. I have a feeling this is related to the exhaust/lunchbox/rejet I did a few months back. I never really put any effort into tuning the carbs, I just used the standard 40/150/1washer/3 turns that seemed to be what everyone used. I'm thinking about changing the plugs and doing a plug chop, but I'm not sure if I would know what the hell I'm looking at.
Quote from: 007brendan on August 18, 2010, 11:55:32 PM
When accelerating hard, I've notice that from about 4200-5000 RPM my bike accelerates weird. The engine sounds like it's revving up, but the bike feels like it's not really going much faster, then once the rpms get past 5000, the bike suddenly grows balls and starts hauling ass like it should.
Sounds like you've got clutch slip. When it sounds like its revving up, is the tach actually showing more rpm, ie more than you should get for the speed you're doing?
I wanna say the rpms just go up slower, but the engine, or at least the exhaust, sounds like the engine is working harder. It's more like the rpms climb steadily, while the exhaust gets louder, then somewhere around the 4-5 rpm mark, it doesn't seem to accelerate as much and the rpms climb more slowly, but the exhaust sounds like the engine is working away. I'll need to go check it again to get a better description.
I have the same set-up as you. 150/40 jets, lunch box, drilled exhaust though. Mine feels the same way. I just got the bike and am working out a few kinks. I notice that the throttle position is what is going on with mine. You're cruising at 5000 rpms, but you give it alittle throttle and the bike sounds like it's revving up, but you go nowhere(seemingly), then you move the throttle a bit more and it starts to pull pretty hard. I think it is just the nature of the Jet kit, or maybe the bike. I never rode it while it was stock (it's a 1997 btw).
I also only did 2 tuns and 1 washer on mine. It had no washers and ran like crap, then the one washer really made it smooth.
Just tested it over lunch. It's definitely related to throttle position and not the RPMs. There's like a "dead spot" between casual cruising acceleration and balls to the wall acceleration.
i notice it too. i think it's just the flat-spot in the power band. jardine, lunchbox, 40/150 etc. when cruising at 4 or 5, youre not in the main powerband yet. so when you pull the throttle, more fuel is flowing in making the engine louder, but there's not enough torque to get the engine going until you pass about 5k to 5.5k rpm. i wouldnt know how to explain it. i have an analogy in mind but it's longwinded and probly wont make sense to anyone else =P