VF1000R: Strange power loss

Hopefully all you gurus can shed some light on a new issue that just popped up tonight with my bike.

I have put 600-700 miles on it since I bought it (85 VF1000R) and everything has seemed to be fine until tonight.

I just helped my friend do a few things to his '90 GSX-R 750 and we went out for a quick ride. I snapped the throttle open in 1st gear and the bike had virtually NO power...almost felt like when you hit the rev limiter. I closed the throttle, shifted to 2nd, and got back on the throttle and the bike SPRANG to life, front tire skipped off the pavement for a second and I was off like a rocket! I figured, OK, no big deal, I just started the engine and it's bogging a bit on me. Then it did it several more times, usually only in 1st gear, except for right after I got gas, it was bad in 1st and 2nd. I found that if it acted up and I closed the throttle, then snapped it open again once or twice it would come out of it and pull great.

It wouldn't surprise me if the carbs needed to be gone through, but I haven't seen any signs of issues until tonight. I've been getting 32 mpg pretty consistently and power has seemed good, so any ideas on what may have suddenly sprung up to cause this issue? I will admit that the times it happened seemed to be the first time or two I ripped on it after starting the engine (engine already warm), but I've never noticed this to be a problem before.

Any thoughts and/or suggestions are much appreciated!

Thanks in advance!!

-Paul

 

always go for sparkplugs FIRST!

remove, inspect, clean, gap.....note any difference in appearance.

 

Yep, was going to take a peek at them as soon as I got a chance, probably this weekend.

I gapped and installed a brand new set when I bought the bike as it had been sitting for a while and was only started and run for brief periods of time, never fully warmed up. The plugs I replaced were a bit fuel fouled, but pretty even across all cylinders...


-Paul

 

Check the float level and float needle rubber tips for deformity or a ring that won't wipe off.

Also, did you get gas at a different gas station than usual? Maybe as simple as water in the gas...

 

Actually that's a good point. In fact I got gas in a totally different town than I would normally get it. I know it can't help that we're stuck with 10% Ethanol in our fuel up here now. It wreaks havoc on fuel systems in older vehicles. I just filled the tank with fresh 91 octane (figured I'd try it, been running fine on 87, but it can't hurt to try) so I'll try running it some more before I tear too much apart.

Thanks for all the help so far!

-Paul

 

UPDATE: As it turns out this problem seems to have been caused by a dying/dead regulator/rectifier. The next time I rode the bike I ended up stranded with a dead battery and no charging capability when I jump started it.

I have since replaced the regulator/rectifier (if you haven't seen my other thread) and took my first ride tonight. NIGHT and DAY difference! The bike runs 100% better on top end, it really RIPS now! I think this has been at least a slight issue since I bought the bike because it has never made power like I experienced on my ride tonight!

Moral of the story: You need a hot fire to light the fuel!!

Thanks to everyone for their help on this one!

-Paul