Hunting between 4000 - 6000 rpm

[fugly]

Hi guys, Im new to the site but have riden an FJ1100 for years, there has been some mods to it which I will post later, my problem that I need help with at the moment is as follows. I thought that I filled up with some bad fuel as she started to miss or hunt particulary between 4 and 6000 RPM, took her to my mechanic and had a good service done but still hunting, we have checked spark, carbs all is good the only thing we can come up with is that it is the TCI unit vacumn that is playing up, has anyone else had this problem or any sugestions will be welcome. Speak soon.

[andyb]

Not enough information to really help there.

New problem?  Mods are what again? Problem under what throttle conditions?  What's a "good service" involve?

[Dan Filetti]

Guessing: vacuum leak, check the intake boots for cracks.  With the bike idling, spray WD40 in and around the boots, if the engine surges, you have a leak.

But without more, this is just a guess.

Dan

[Mark Olson]

Mice in the airbox.

[fugly]

Not enough information to really help there.

New problem?  Mods are what again? Problem under what throttle conditions?  What's a "good service" involve?

Yes it is a new problem never happened in the last 10 years. Mods are modifications, there was nothing done to the engine itself, just rims (17inch) and a few other cosmetic changers for looks(willpost picture). The problem occurs under normal throttle conditions going through the gears changing up at about 5 to 6000 rpm no matter what gear you are in this hunting happens between 4 and 6 000 rpm. A good service is change oil, oil filter, air filter,clean and calabrate carbs, check and adjust chain and a general check on lights, electrics, etc. hope this is more help. 

[Mark Olson]

Is it a wide open throttle problem? or just half throttle , normal ride going thru the gears thing.....meaning hard acceleration or cruising?

[fugly]

Is it a wide open throttle problem? or just half throttle , normal ride going thru the gears thing.....meaning hard acceleration or cruising?

Normal going thru the gears not hard acceleration just taking the revs up( cruising) and the hunting starts at 4000

[weymouth399]

Just for shit & giggles, try adding choke when it happens.

That should tell you if it is jetting? and which way to go.

As long as your tune up is good, it should be a good place to start.

Bob

[Mark Olson]

pull the carbs and clean them , check diaphragms for pin holes. you have a transition problem between the circuits in the carbs.

[fugly]

pull the carbs and clean them , check diaphragms for pin holes. you have a transition problem between the circuits in the carbs.

Thanks, Will check for pin holes, my mechanic recons that it may be a TCI problem to do with the vacumn pipe, have you heard of this or is it a known fault of the FJs, I think it is something simple well I hope it is as parts in South Africa are hell of an expensive, it will be cheaper to fly them in from US, The local dealer quoted me R 6500, 00 ( about $1000)for a CDI unit.

[weymouth399]

I doubt it's that, but I have 3 or 4 so don't buy a new one.

Bob W

[bluedirtydigit]

Just a thought have you checked the side stand switch mine did exactly that! did you use the side stand when you filled up with fuel before it started? just a thought as its a common fault.

[Dan Filetti]

Just a thought have you checked the side stand switch mine did exactly that! did you use the side stand when you filled up with fuel before it started? just a thought as its a common fault.

Really?  I thought the side stand switch was a binary fault.  The bike starts or not.  You actually had hunting symptoms from a side stand switch problem??!!??

Dan

[andyb]

Any mechanical switch that controls the ignition can become a very strange misfire if it resonates and goes bad at a certain frequency.

<edited to be nicer to original poster>

[fugly]

Thanks for all the help, looks like it was a voltage thing after all, when the lights are on she hunts way more than when the lights are turned off, read about putting the relay into the curcuit so will be doing it this weekend and seeing if that solves it, will keep you posted, Once again thanks for all the input.

Keep the rubber side down