Odd behavior - fixed itself?

[StatDoc]

Keep in mind I own a 1984 FJ1100 with only 14,000 miles on the clock when considering this behavior.  Before being sold the carbs were rebuilt and were synchronized - all hoses were replaced as were the plugs, wires and battery.  Oil and filter changed and there is zero rust in the tank.

Running down route ** at about 85MPH for about 10 miles (seemed reasonable) the bike started to surge - steady hand on the throttle but it felt like power was coming and going.  Pulled in the clutch and she died.  Let out the clutch (slowly) and she caught - pulled off on the first exit - had to gas the bike to keep it alive - made a left (to head North on the route I'd just pulled off of) and all was well - pulled steady and strong, no surge, idle around 1K.

So I figure that I passed a bit of crap through one of the carbs and that is that - last time I experienced this was an XS750 - I never found the cause and in a few thousand miles the problem never re-surfaced - what are the odds that I'm correct a second time?  Anything to look for or test?

Cheers
StatDoc

[yarin]

Strange.  Ive had this happeb also. exactly how you described it.  A couple things i did when i got home.  i found the one battery post was not quite tight clean and tighten both of them,  also i found cold solder joints on the coild.  clean and tighten the ground wire to the chassi from the coil and resolder with new all the leads to your coils.  you can tell the difference right away !  that solder is 20 years old its gets heated and reheated every time you run the bike

Tom

[StatDoc]

Tom -

good thinking - I'll check the battery connections - especially since it's a new battery!  Maybe the hard left turn back onto the highway shifted things enough to correct them!

Cheers

Steve

[StatDoc]

Problem came back today - after a 70 mile interstate drone.  Sat by the side of the road thinking through the problem and it struck me that I'd experienced this before - opened the fuel cap and hear a woosh - cranked her over and she was running great - turns out that the vent in the fuel cap is knackered - going to have a look at it later (once the rain quits) -

[rktmanfj]

http://www.fjowners.com/index.php?topic=3982.0

http://www.fjowners.com/index.php?topic=4149.0

http://www.fjowners.com/index.php?topic=3791.0

[E Double]

Keep in mind I own a 1984 FJ1100 with only 14,000 miles on the clock when considering this behavior.  Before being sold the carbs were rebuilt and were synchronized - all hoses were replaced as were the plugs, wires and battery.  Oil and filter changed and there is zero rust in the tank.

Running down route ** at about 85MPH for about 10 miles (seemed reasonable) the bike started to surge - steady hand on the throttle but it felt like power was coming and going.  Pulled in the clutch and she died.  Let out the clutch (slowly) and she caught - pulled off on the first exit - had to gas the bike to keep it alive - made a left (to head North on the route I'd just pulled off of) and all was well - pulled steady and strong, no surge, idle around 1K.

So I figure that I passed a bit of crap through one of the carbs and that is that - last time I experienced this was an XS750 - I never found the cause and in a few thousand miles the problem never re-surfaced - what are the odds that I'm correct a second time?  Anything to look for or test?

Cheers
StatDoc

I've had that happen a few times with my '84 FJ.  Mind you, mine has 78K miles on it, but is in top tune.  In the past, when I've had that sort of thing happen on other carbed bikes I've owned it turned out that it was a random bit of crap that makes its way to one of the carbs.  The three times it happened on my FJ I was able to "blow it out" after a few miles and everything went back to normal.  I would definitely eliminate any loose  electrical connections or what have you, but as shitty as fuel is nowadays I'm surprised that it doesn't happen more frequently.

[StatDoc]

Seems that it was a faulty tank vent - took her for a ride - left the key in the cap  while bombing along at super-legal speed for 50 or so miles the bike starts running on 2 cylinders - I turn the key - pop the cap - close it and it's running like a top.  Looks like I'll be taking the danged cap apart this weekend to solve the problem (or adding an atmospheric vent AKA 1986 GSX-R750! - little hole, little tube, tiny weld and some rubber hose - problem solved!)