I spent some time looking for this problem on different threads and could not find it; I apologize if it is a repeat. I put my bike on the dyno, and there was a "V" dip in the power. It dropped around 6000 RMPs. You can notice it when you are riding down the freeway; it bucks like it is going to stall, but if you give it some gas it takes off. It is just around when the engine is around those RPM, when it acts up. I replaced the spark plugs, and put in the injector cleaner. I am not sure what it could be, maybe fuel pump? Or fuel filter? If anyone has any suggestions, I would greatly appreciate it. Thanks

 

are you running a pipe and PC3 i assume? If this thing has the same problem as my buddies 929. There is a nasty flat spot around there. With the PC3 we were able to smooth it out, but could never really get rid of it. I guess we just didn't have enough adjustability from the PC3 to correct it. But if it is truely bucking badly then you might have a fuel delivery problem. Hook up a fuel pressure gauge and watch it as you are doing a dyno run. And drop in FP while running would mean either pump or filter. If nothing then your problem is else where.

 

isnt 6000 rpm supposed to be the flapper opening spot? maybe a faulty servo, not opening the flapper, going way rich and losing power? Just taking an alternative guess. Getting any error code??

 

I think the flapper is at 4k.


Sorry dont have anything more to add atm, but i would run with Surfin's idea.

 

The flapper does its thing twice, I know once at 3000 and again at 6 or 7, cant remember, sorry, will try to look around for some answers.

 

mine did this also- it was the fuel pump...

 

Nealio might be on to something. If you gun it(above half throttle) does it cut out on ya?

 

I dont have a Power Commander, The Dyno put out a 134.1 HP stoke (which is actually good acording to records), and the pickup after the 6000 rpm is just fine. The pickup from 2k to 6k could be better. It wont pick up the front end to save its life even if you give it all its got. But after the 7000 RPM it runs great!!!! So I am leaning toward something other then the fuel dilivery system. But it is still in my mind. I put a bolt on can (Yana Shiki). It flattened out the "V", but it still bucks all kinds. The exaust valve was replaced, and adjusted by the dealership. The FI light is NOT on (no codes). If anything the exaust smells like it is running a little ritch. I believe these bikes have a flat spot around 6k to 7k but not this bad. Thanks for all your help, If you have any other ideas I am all ears.

 

heh as a side note doesnt that Yana Shiki sound pretty sweet for, well for what it is, thats what i have on my bike and everyone says it sounds great but they have never heard of it.

hmmmm you have me stumped at the moment, but i would not rule out the fuel pump just yet............ a power commander could deff help a lot, but its not going to fix something thats broken. i keep thinking about it. Mine picks up hard right around 6000-7000 so i dont think its normal.

 

Ya same here. everyone I know tells me it sounds awesome, and no one has heard about it either. I am very happy with it! Thanks for all the info, I am stumped as well. I asked different mechanics at different dealers and they all came back with different ideas, all to get you to buy things... one even said to replace the chain and sprockets.......