Fluctuating rev needle..

[threepot]

And a noticeable hesitation. Noticed this on a ride today. Most of the time the bike ran OK,but....
Bad coil?? Noticed the rev needle fluctuating up and down by a few hundred revs?
I fitted a set of tt600 coils last year.

[Bixxer Bob]

Are the revs going up and down with the needle???

[Sin_Tiger]

If the TT600 coils were new ones then it's not so likely, if the revs were steady I can think of only one other thing  Mustang's the expert on the igniter.

[threepot]

Not noticed them rise Bob,just seems like a slight miss/hesitation? I did notice th e needle drop a little when I kept it at a constant speed. I remember reading somewhere what a fluctuating rev needle indicates,but I can't remember if it was coils,ECU,or something else??

[threepot]

If the TT600 coils were new ones then it's not so likely, if the revs were steady I can think of only one other thing  Mustang's the expert on the igniter.

They were 'used' ,not new ST.

[ssevy]

Do a search for "the little fucker"😆

[threepot]

Do a search for "the little fucker"😆

I did think that was the problem,but bike didn't cut out. Ran OK mostly.
Have noticed that when I start from cold,it seems like its 'missing',but when I shut the chokes off,it settles to a nice idle,and rides away nicely.

[ssevy]

Water in the gas? Worth a bottle of Star Tron or some Sea Foam, as it won't hurt anything.

[threepot]

Water in the gas? Worth a bottle of Star Tron or some Sea Foam, as it won't hurt anything.

That wouldn't cause the needle to fluctuate? ? At first I thought it was the fuel tap? I've been having an issue with that. But not noticed the needle fluctuating before.

[GavD]

If you haven't heard the engine revs fluctuate as well, it's gotta be an electrical gremlin right? If I remember right, the rev counter is fed from the cdi unit.

Got an old rev counter that was working OK when I got it hanging around if ya wanna try that?

[ssevy]

That wouldn't cause the needle to fluctuate? ? At first I thought it was the fuel tap? I've been having an issue with that. But not noticed the needle fluctuating before.

If the engine is running roughly, the tach needle would fluctuate with the changing revs. Sorry if I am misunderstanding the symptoms☺️

[threepot]

If the engine is running roughly, the tach needle would fluctuate with the changing revs. Sorry if I am misunderstanding the symptoms☺️

It's only slight . Just like its not quite getting enough fuel? I did think it was that,because the tap plays up now and again. But the needle fluctuation seems an electrical issue.
I've just ordered a 'new' set of Gill coils on eBay for £30 each!

[threepot]

If you haven't heard the engine revs fluctuate as well, it's gotta be an electrical gremlin right? If I remember right, the rev counter is fed from the cdi unit.

Got an old rev counter that was working OK when I got it hanging around if ya wanna try that?

Thanks Gav. I've got a spare set . I'll try the new coils first. It only happened a few times during the ride. The bike ran really well.......95% of the time!! :icon_wink: It is 20 yrs old after all.
I was out with a friend on his wee strom 650,and he's always telling me what a good bike it is! I've ridden it,and it's OK,but not as involving as the steamer. So I was telling it..'don't break down,don't break down'!! But it didnt

[Sin_Tiger]

I've got a spare igniter box if you want to try that.

[threepot]

I've got a spare igniter box if you want to try that.

Thanks ST. If the coils don't sort it,I'll try the one off my Super3. I have before,and it runs OK with it. Failing that,a new crank pickup? Worth carrying a spare anyway.