Well, can't say that I'm new to this forum...you guys have helped out tremendously in the past...but I just signed up to ask:
My bike rode funny a couple weeks ago. I thought, "maybe slightly low battery"? I only had to ride about 5 miles and the bike rode fine on the road, but when I would go to leave a stop, it just felt...off. Not as much power in the take off, ya know? Anyhow, after parking it a couple hours, I went to start it and it cranked, cranked, cranked then backfired...I eventually gave up hope and loaded it in the bed of a truck and proceeded home to tear it apart. The plugs were fouled...easy enough, I replaced them...but that didn't solve it and now those are fouled too. I cleaned them, propane torched them and put them in the wires with them grounded to the casing and the spark is very, very weak...I'd guess .003, the thickness of paper.
Carbs are CLEAN. I tear carbs apart all the time, so trust me here. Not just Seafoam cleaned, lol! Anyhow, any thoughts? I want to eventually post a solved here since I could not for the life of me find a post that relevantly had to do with weak spark. I've got the bike torn pretty much all the way down so everything is accessible...shoot me some ideas and tests, please!!! If you could include a link to a walk-through of your suggestion - you rock! If not, I will by all means do the foot work.

 

Not to sure about your problem but the Mods should move this to the "General Tech" Section as you will get more help there.

 

Thanks Jeff, I reposted in the General Forum....thanks for heads up!

 

Not sure why you strip your carbs so often? Once they are set up it's best to leave the alone. Your weak spark could be due to a low battery state. If the bike is cranking, but not spinning fast enough, your spark to the plugs will be weak. All the battery power will be used up mainly trying to spin the engine. Charge the battery overnight or if you think it is time, get a new one. Before you do that though, using a mulitmeter and the engine running, check that the voltage increases across the battery terminals with the revs over 3500 rpm. You should see a rise in voltage to at least 13.5-14.5 volts at these revs. Any lower and your voltage regulator/rectifier may be shot. The rectifier changes alternating current to direct current to charge the battery and if it is faulty it won't do this. I had a problem with my cbr 600 and a good overnight battery charge cured it. Hope it cures your problem!

 

No highwaypatrol, I work on bikes all the time so I am well versed in carb teardown and cleaning.
Anyhow, thank you for the info on the r/r, that's the first time I've heard of the voltage increase while cranking....makes sense. Mine does dip to 10v, so I'll go ahead and replace that...here's hoping. The battery is brand new and has a trickle charger on it.

 

The rectifier was the problem. Tossed the new mosfet style r/r on and it fired right up!

 

u need to replace the stator when u replace the R/R cause the rectifier is gonna get break again.

 

not neccesarily, the f2 rectifiers are total cheap POS. i am amazed the one on my f2 made it 50k miles.