TPs or Carb Balance / idle jets

[HydrocarbonPrimate]

I'm having some rough running issues at low speed, it seems to be slowly getting worse the bike is horrible to ride at low speed, jerky. I set the idle speed at 1250ish but after its warm it idles at 2,100 ish, It will stall when warming up sometimes. Is this a TPS issue or a carb balance issue or blocked idle jets?


I had a diversion before this and I spent ages messing around with carbs, only to find it was the ecu and other relay looking thing that has something to do with ignition, that was full of water and corroded inside, It runs sweet now.


I really hate working on bikes, I'm a mechanic all week I don't want to spend my weekends fixing my bike I just want to ride it!!


how do I check TPS do I just unplug it and the rev gauge should move? what should it move to?


I also have what feels like a stiff link in the chain at low speeds, Ive checked the front sprocket is tight and wiggled each link in the chain as I've lubed them but can't feel any stiff, am I just not moving them enough to "feel the stiffness"    or could it be something else?

[His Dudeness]

The bike should be fully warmed up before you adjust the idle that's why it's going to 2100 when it warms up. The throttle position sensor test is on page 6-10 of this manual http://foc-u.co.uk/index.php?action=downloads;sa=view;down=8 Sounds like more than a throttle position sensor issue. Has the bike been parked up for a while? The pilot jets sound like they might need a clean and balance.

If you can feel a repeated clunking through your foot pegs as you're riding there's probably a stiff link in the chain. If you look at the chain the stiff one often sits up more than the others. Check all the links again. You can use two pliers and give them a good wiggle. If the chain is worn or there's a stiff link it's best to replace it.  Have a read through that manual it'll tell you everything you need to know.

[darrsi]

As the Dude says, warm the bike up fully then adjust the idle on the manual screw on the left side of the bike for starters.


With the ignition switched on (not started) unplug the TPS then plug it back in.
Once unplugged you should immediately get a 3000rpm reading on the clock, but when you plug it back in if all's well it should go to 5000rpm.
If it goes to 0rpm or 10,000rpm then undo the TPS screws and physically move it until you hit 5000rpm.
If the needle won't move then you have an iffy TPS.


To be honest if it jumps that high on revs i'd be thinking more about an air leak somewhere.


A carb balance works wonders on these bikes, but a fully functioning TPS and a clean air filter are a must before even considering tampering with the carbs.

[HydrocarbonPrimate]

Thank you both,


I will try the chain links with pliers good idea.


The revs dont jump around like an air leak, I might try some brake cleaner around rubbers to be sure.


The tps tested ok,  did the 3k and 5k thing, Thank you for that I know theirs many threads but not many with the concise info and values it should go to.


So I'll probably run some industrial strength super secret sauce through the fuel then when that fails take it to a garage for carb clean and balance and air filter as I absolutely focing hate removing tanks on bikes, so easy to scratch and all those pipes, After a week on the tools I don't even want to look at a spanner on weekends.


Its been nice here in Shropshire today was riding most of the day, It's a nice bike just need to sort out the low speed stuff as everyone at demon tweeks wrexham was watching me jerkily ride round the carpark like a n00b lol.




Thanks guys
 

[tommyardin]

The bike should be fully warmed up before you adjust the idle that's why it's going to 2100 when it warms up. The throttle position sensor test is on page 6-10 of this manual http://foc-u.co.uk/index.php?action=downloads;sa=view;down=8 Sounds like more than a throttle position sensor issue. Has the bike been parked up for a while? The pilot jets sound like they might need a clean and balance.

If you can feel a repeated clunking through your foot pegs as you're riding there's probably a stiff link in the chain. If you look at the chain the stiff one often sits up more than the others. Check all the links again. You can use two pliers and give them a good wiggle. If the chain is worn or there's a stiff link it's best to replace it.  Have a read through that manual it'll tell you everything you need to know.

Hi His Dudeness,
i have seen the download that you posted the link to, is there do you know a download for the later version of the FZS 600 Foxeye 2002-2003?
I know they are basically the same bike but there are a few differences.
Ie: chain slack, a couple of  carburetor differences, front fork and a few other differences.
Pukka one for the bike would be handy I have a Haynes manual but the real one would be good.

[Gnasher]

It's possibly none of the above, carb bikes running poorly at below 2- 3k is normally and indication there's an issue with the pilot circuit i.e. blocked pilot jet/s. 


Carb balance and TPS's this is a very common mistake in that owners test the TPS position see it's out and move it......wrong!  The TPS is a datum set at the factory unless you move it somehow or it fails it's never going to change, what's moving is the carb butterfly.  The most important thing about carb balance is to get the Hg level correct at idle on No4 which is what the TPS takes it's reading from, this is done not by moving the balance screw but by adjusting the pilot jet.  Then adjust all the other so their Hg is within tollerance, now you balance all the others to No4.


The amount of owners who bring their bikes to me saying the carbs have been balanced by a stealer etc when they are miles out.