Mine was doing the same thing last fall. It would accelerate just fine, but (especially after it warmed up) it would die suddenly under deceleration. I couldn't figure it out. Put in a new Lithium battery and new R/R this spring... same thing.

I finally went through my stick coil loom and found a loose wire that turned out to be the problem! Worth a shot - your problem sounds exactly like mine. Good luck!

 

I'll definitely be checking the wiring today. Funny thing is I've run stick coils occasionally and with the two sets of coils/harnesses I have I always get horrid misfiring/dieing after it warms up. I'm running the stock coils now. I want to get this thing running correctly with the stock parts before I switch coils.

 

Ok now the problem is back. Filled up and as soon as the fuel hit the carbs, trouble started. While sitting at traffic lights it idles fine and then dies like someone hit the kill switch. Fires right up and then tach needle jumps from 1,200 down to 800 back to 1,200 and then bike dies. I have to rev up to 3,500 to take off. The bike sputters and pops during down shifts.

This is the effects of ethanol separation or to much ethanol in the fuel. I just have to get through this tank of fuel and I am 100% sure my problem will vanish. I absolutely hate that chit. With my rich jetting at least the bike gets me home. With factory jetting and this particular tank of gas, it would have left me sitting roadside. The fuel in my area, for some reason, really really really sucks.

 

I hear ya TimBucTwo, but my only response is why does my wife's Ninja run so great on the same fuel? My buddy's old cb750? My other buddy's old Triumph? All are carb'd, I understand ethanol is bad but I'm jetted appropriately. I'm not ruling it out but why is this the one bike I've had that has this much trouble with it?

You very well may be right but I'm going to be looking for a bad ground tomorrow and eliminating a bad clutch/kill/sidestand switch as the potential problem. Can't hurt to check. After looking for carb problems for the past couple weeks the bike's pulling scary fast! At least I have my carbs sparkly clean and my jetting spot on.

 

I had an idle problem last month after doing a rejet, idle was up and down, had to keep revs up at lights etc. couldn't figure it out so I tried swapping the floats and needles out of another set of carbs and it's been idling fine ever since. I have a choke issue now but I can live with that till I can afford some new needles. Mine is a 600f though.

 

Well, so far it appears amacadams is the winner of this round! I made an all new wiring harness from scratch for a new set of stick coils I had on my workbench (after finding nothing wrong with anything else on the bike!) and so far all is smooth. I haven't had any stuttering or unintentional shut offs, we'll see how everything goes over the next few days. I really wanted to get this fixed with the stock parts but it could be that my old coils waited until now to start giving up... it certainly seems that way anyhow. Who knows, maybe I'll be worry-free for another few rides

 

Man I got all the problems back with a vengeance, shutting off all the time in traffic, cutting out on decel, even had it die and lost all power to everything for a few minutes. Super weird stuff.

Finally started re-re-testing my new parts including my Yuassa battery, stator and r/r (all replaced last year). Battery was good but it's getting tired now after all this, r/r tested fine, three yellow wires on the stator are all good. Then my mechanic buddy told me to test the black to white wire out of the stator (4 to 6 ohm spec) and there it was: super low resistance if not continuity.

So I can do another stator on her but I'm surprised it went out this quick. It had a new regulator and battery at the time of replacement so I don't really think it was getting beat up by old parts.

At this point I'm just going to replace what it needs and see what $$ I can get for it. Hate to do it but my wife doesn't trust riding on it. Shame too as I suspect I'd be good to go after this. My buddy (Honda tech) had it for a week trying to figure it out and he couldn't believe how solid the engine was, he just suggested a valve adjustment after I replace the stator. Oh well, I guess I'll keep plugging away! It sure is fun when it's running right

 

Hi, I had a similar problem on my CBR 1000f. I have made quite a few modifications and it's always a worry that something I have done to 'improve' the bike is causing the problem. Anyway, I think my problem is slightly different to yours, though. Fine running, and fine idling until it gets really hot in stop start traffic with the fan working a lot. Then, the idle will start hesitating, revs dropping to about 500 from 1000 before picking up again, and eventually just dying. It starts up again instantly, but will stall again after a few seconds.

After checking all of the electrical systems (several times) and the carbs (several times) and still having the problem, I was out of ideas. Then, last weekend I did a routine service and found that on one cylinder the exhaust valve clearances had closed almost right up. Suddenly it all made sense - fine when the engine is cold or warm, but when everything gets really hot the exhaust valves are being held open, engine loses compression on that cylinder, engine stalls,

Proof of the pudding - now it get get as hot as it likes in traffic and the idle stays rock steady.

Hope that helps you and others having similar problems!

 

Do you have a fuel filter in line? If so, is it old? Since the problem reoccurs, and then goes away when you clean the carbs it sounds like you may be picking up crud from your fuel tank. It doesn't take much to plug things up.

As for valves and carb sync, I doubt that's the cause of your troubles, but it's a good idea to check both anyway. On the other hand, it's amazing the number of odd noises and gremlins out of sync carbs can cause.

 

I think snotter may be correct with the valves. The more I've thought about it and discussed with my mechanic buddy the more I think I'll find some clearances out of check when I get in there. I've had no time to look into it lately though. I'm losing my evening daylight now that summer is ending but good news is I will have a garage up in a couple weeks! I'm holding off until then.

There are a few things that need attention anyway... I finally got back to getting my black tank sanded down and polished so I should be color matching before long too.

EDIT: not to ignore your comment dram! Although I do not have an inline fuel filter. You could still be right on it being a fuel delivery problem.