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Bikes, Hints'n'Tips => FZS600 Fazer => Topic started by: Anarch on 19 May 2013, 07:19:40 pm

Title: Low revs stuttering
Post by: Anarch on 19 May 2013, 07:19:40 pm
Hi all,
Since last year I've noticed stuttering on the low revs - up to 3/4 000 rpm. When i keep the revs at around 2,500 rpm the engine sounds nearly like an old two stroke.
I've searched for similar threads on this forum, followed the advice there and I've:

- replaced plug caps
- checked spark plugs
- balanced carbs (Autumn)
- I've added some carb cleaner to the fuel (Profi Fuel Max) - didn't seem to help much

I think that there are two possibilities left - either the HT leads (and coils) need replacing or the jets are clogged.
Do you know how can I check whether the HT leads are faulty, and what should I use for cleaning carbs (once I open them up).

Or maybe you have some other ideas ?

Thanks

Title: Re: Low revs stuttering
Post by: ade the blade on 19 May 2013, 09:21:33 pm
Paul.......i think your expertise in this area is needed please !! :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin :rollin
Title: Re: Low revs stuttering
Post by: darrsi on 20 May 2013, 12:01:32 am
anarch try some 99 octane fuel, I noticed an improvement when I had this woe.


He should be able to run on any fuel, higher octane will just make things a bit nippier.



Title: Re: Low revs stuttering
Post by: red98 on 20 May 2013, 09:50:13 am
cheers ade  :lol ....i would go for a carb clean before the coils,they dont fail very often...clean the carbs with a blast of compressed air and plenty of clean cloths  :D
Title: Re: Low revs stuttering
Post by: Anarch on 20 May 2013, 01:13:24 pm
Well I usually put Momentum - so it is 99 octans.
I don't have access to a compressor, and don't really fancy cleaning all the parts at a gas station -> will a compressed air spray do ?

Will there be any seals / orings that I'll most likely have to replace (would prefer to buy some earlier) ?

Thanks
Title: Re: Low revs stuttering
Post by: Dead Eye on 20 May 2013, 02:17:52 pm
I would have thought that a can of compressed air would be good enough. Just check each jet and make sure there is no dirt / obstruction in them. I cleaned mine out with a fine needle and left them in fresh petrol overnight (no idea if this was a good or bad idea though...). There are a few O-rings on some of the jets if memory serves, but I doubt you'd need to replace them - guess it couldn't hurt though. Check out http://www.yamahascooterspares.co.uk (http://www.yamahascooterspares.co.uk) for a full list of genuine OEM parts
Title: Re: Low revs stuttering
Post by: red98 on 20 May 2013, 03:28:16 pm
soaking in petrol is good and then in the morning just blow through them using good old man power....be surprised if the "o" rings need replacing  ;)
Title: Re: Low revs stuttering
Post by: Anarch on 20 May 2013, 04:31:29 pm
Thanks a lot guys :) Will give it a go when I have some spare time (probably early June)
Title: Re: Low revs stuttering
Post by: WookieoToole on 24 May 2013, 08:09:52 pm
clean the idle jet and gallery and while ya on do the main jet and emulsion tube -- u will need a alkaline based cleaner and make it undiluted -- so far since november i have had 4 bikes thru with that same prob
Hope this helps
Title: Re: Low revs stuttering
Post by: caretaker on 24 May 2013, 10:59:37 pm
air filter might need changing?
Title: Re: Low revs stuttering
Post by: Anarch on 15 June 2013, 09:25:38 am
air filter might need changing?
Nope, I've got a new K&N one. WookieoToole - thanks for the advice, will have a look at alkaline carb cleaners,
Should clean the carbs next week.
Title: Re: Low revs stuttering
Post by: Anarch on 16 June 2013, 03:40:20 pm
Update - cleaned the carbs as well as I was able to - but they looked quite clean (no clogged jet screws etc).


Did balancing and replaced spark plugs today  - but I haven't noticed any improvement. The only other idea I have is replacing the HT leads with coils - I checked the spark and its colour was closer to yellow rather than blue (it was blue at the ends).
Title: Re: Low revs stuttering
Post by: Punkstig on 16 June 2013, 03:47:11 pm
While you've got the tank off etc have a go at resetting the pilot screws, screw all the way in then back off (what is it on these 2.5 turns?) won't do any harm and you know in your head its done and they're all the same.


Only mentioned this cause it fixed my issue on the T'cat,  but for that fix I changed the settings to what was mentioned on a forum and not what Haynes said!
Title: Re: Low revs stuttering
Post by: Anarch on 16 June 2013, 03:53:13 pm

 I followed Hayness, and put them in the same position as they were in originally - it ranged from 3.5 to 5.5 turns (by turn i mean 180 degrees).


Going back to garage now to play around with the pilot jets :)

While you've got the tank off etc have a go at resetting the pilot screws, screw all the way in then back off (what is it on these 2.5 turns?) won't do any harm and you know in your head its done and they're all the same.


Only mentioned this cause it fixed my issue on the T'cat,  but for that fix I changed the settings to what was mentioned on a forum and not what Haynes said!
Title: Re: Low revs stuttering
Post by: Punkstig on 16 June 2013, 04:14:22 pm
Best not confuse things, 1 turn = 360 degrees, could easily make mistakes if you treat it any differently!
K&N filter plus aftermarket exhaust and it could probably help to experiment with the screws, probably quarter turn on all at a time!
Title: Re: Low revs stuttering
Post by: Andy FZS on 16 June 2013, 04:56:39 pm
Correct me if I'm wrong (again) but I thought the running mixture was determined by jet and needle size and the mixture screws only set the idle mixture so a stutter at 2.5k wouldn't be effected by these. Anybody agree?
Title: Re: Low revs stuttering
Post by: Punkstig on 16 June 2013, 05:05:38 pm
While you've got the tank off


2 minute job while you're in there!
Title: Re: Low revs stuttering
Post by: Anarch on 16 June 2013, 05:10:42 pm
While you've got the tank off


2 minute job while you're in there!




2 minute job...  I've been trying to figure out for the last 20 minutes how to access pilot jet screw on the 3rd carb and so far no brilliant ideas.
I've got a brand new K&N filter - exhaust is aftermarket (blue flame), but having a tiny leak in one or two places (on one of the joining points near rivets).


P.S. After I readjust the pilot jet screws, should I balance the carbs again ?
Title: Re: Low revs stuttering
Post by: Punkstig on 16 June 2013, 05:22:05 pm
Ha, well typically all photos of carbs in Haynes is of the thundercat carbs, not sure how much difference there is because I haven't had to do this yet, but will be soon!


If it helps '98- '01 is 2 turns out and
'02-'03 is 2.5! (When you get to adjust No. 3 that is!)
Title: Re: Low revs stuttering
Post by: Anarch on 16 June 2013, 05:54:10 pm
Ha, well typically all photos of carbs in Haynes is of the thundercat carbs, not sure how much difference there is because I haven't had to do this yet, but will be soon!


If it helps '98- '01 is 2 turns out and
'02-'03 is 2.5! (When you get to adjust No. 3 that is!)


You're right 2.5 it is - checked in my Hayness as well,
I think bones in my hand shifted after 30 minuts of fidling with it and I've managed to squeeze my hand in there and set the screw on the 3rd cylinder.
Title: Re: Low revs stuttering
Post by: Punkstig on 16 June 2013, 07:26:58 pm
We're they set correctly and equally or did you not count when turning them in?
Title: Re: Low revs stuttering
Post by: Anarch on 17 June 2013, 12:41:01 am
I've counted when dissasembling carbs, now changed all of them to 2.5 turns + balanced carbs and no real change.
Title: Re: Low revs stuttering
Post by: neilavo62 on 17 June 2013, 09:34:27 am
hi,
    i also put a new K&N filter in this year and developed the same problem.
i have since put the baffles back in and it sorted the stutter out.
hope this might help.. :)
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 09:38:54 am
mmmmmmmm...had a scorpion end can on my thou....very lumpy idle and uneaven upto 3/4000 rpm,great at higher revs,put the std can back on and now very smooth,has k+n filter  ;)
Title: Re: Low revs stuttering
Post by: Hedgetrimmer on 17 June 2013, 10:01:11 am
All very interesting - got a similar problem on my thou. Was much worse with open Viper can which was on the bike when I bought it. Changed to standard can, better but not right still. Have just put new Scorpion can on, as good as standard, but still not right. Problem seems to be at worst at about 3k rpm off throttle. Everywhere else, no problem. Can't work on my own bike due to shoulder problem which makes things very awkward, so sooner or later gonna have to take it in somewhere and lay out for someone else to take a look  :(
Pilot circuit problem?
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 10:29:47 am
All very interesting - got a similar problem on my thou. Was much worse with open Viper can which was on the bike when I bought it. Changed to standard can, better but not right still. Have just put new Scorpion can on, as good as standard, but still not right. Problem seems to be at worst at about 3k rpm off throttle. Everywhere else, no problem. Can't work on my own bike due to shoulder problem which makes things very awkward, so sooner or later gonna have to take it in somewhere and lay out for someone else to take a look  :(
Pilot circuit problem?

 
hi nick......baffle,in or out ?
Title: Re: Low revs stuttering
Post by: Hedgetrimmer on 17 June 2013, 10:40:02 am
Baffle in. I've no idea what's in the airbox either.
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 11:36:46 am
Baffle in. I've no idea what's in the airbox either.

 
i would be interested to see what its like if you ever take the baffle out  ;) 
Title: Re: Low revs stuttering
Post by: Hedgetrimmer on 17 June 2013, 11:48:30 am
Red, tbh I don't think the problem is to do with the can, even though it was worse with a straight thru pipe. I've consulted with Mike (Falcon 269) about this, he suggests looking at plugs/plug caps/HT leads first, which I will have checked/changed when I (finally) get round to taking it in. But I've had bikes with those sorts of problems before, and it just doesn't feel like that, you know? Plus, with plugs/coils breaking down, I would've thought the problem would be worse higher up the rev range?
Title: Re: Low revs stuttering
Post by: Hedgetrimmer on 17 June 2013, 11:52:15 am
PS.
I've also run a fuel system treatment through the tank, no change.
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 12:08:57 pm
mmmmmm...sounds like you two have simular problems  :\ ....ANARCH..looks like your carbs are ok then  ;)  iam thinking electrics but not my strongest point  :o  when i first started trying to cure my stutter i bought secondhand ecu,tps and coils and swapped them in turn to see if that was the problem,japanese electrics are very reliable and after 15 yrs and 40,000 miles mine were fine.....looks like mine is a wiring fault (worn through and broken) but not proved yet  :rolleyes
 
i`ll be interested to see what ADE THE BLADE thinks...................
Title: Re: Low revs stuttering
Post by: CRH on 17 June 2013, 02:08:07 pm
mmmmmm...sounds like you two have simular problems  :\ ....ANARCH..looks like your carbs are ok then  ;)  iam thinking electrics but not my strongest point  :o  when i first started trying to cure my stutter i bought secondhand ecu,tps and coils and swapped them in turn to see if that was the problem,japanese electrics are very reliable and after 15 yrs and 40,000 miles mine were fine.....looks like mine is a wiring fault (worn through and broken) but not proved yet  :rolleyes
 
i`ll be interested to see what ADE THE BLADE thinks...................
...no use asking morris paul!!..he,s tooooo loved up with....BAAAAAAAAAAAAAAAAAAAAAAAbra :rolleyes
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 03:30:58 pm
ha ha....MORRIS THE BLADE.....dos`nt roll of the tongue as well as ade,earning a few extra quids and he does get to keep the outfits  :lol :lol :lol ........come on ade put baaaaaaaaabra down and give us your opinion.......
Title: Re: Low revs stuttering
Post by: Anarch on 17 June 2013, 05:31:34 pm
mmmmmm...sounds like you two have simular problems  :\ ....ANARCH..looks like your carbs are ok then  ;)  iam thinking electrics but not my strongest point  :o  when i first started trying to cure my stutter i bought secondhand ecu,tps and coils and swapped them in turn to see if that was the problem,japanese electrics are very reliable and after 15 yrs and 40,000 miles mine were fine.....looks like mine is a wiring fault (worn through and broken) but not proved yet  :rolleyes
 
i`ll be interested to see what ADE THE BLADE thinks...................
...no use asking morris paul!!..he,s tooooo loved up with....BAAAAAAAAAAAAAAAAAAAAAAAbra :rolleyes


I think I'll make a video of the engine running tomorrow - maybe this will give you some ideas - cause I'm clueless at this point :)


Initially I was only able to detect it up to 3k RPM but now I can hear when accelerating up to 6k. Could it have anything to do with exhaust ?
Title: Re: Low revs stuttering
Post by: Hedgetrimmer on 17 June 2013, 05:55:08 pm
Anarch, was your bike laid up for any length of time before you got the symptoms? It's just that Soapy, who's just joined FOC-U, is having similar problem after his bike was laid up for the winter - I bought mine recently from a dealer and suspect it may have sat for a while since last use.
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 08:29:11 pm
video would be good  :) ....my thou is effected by the end can,lumpy tickover and up to 3/4000,great there on,i think its the way the cans are just not my cup of tea.....
Title: Re: Low revs stuttering
Post by: Hedgetrimmer on 17 June 2013, 08:30:55 pm
Except that mine's doing it with standard can too... :\
Title: Re: Low revs stuttering
Post by: red98 on 17 June 2013, 08:52:07 pm
Except that mine's doing it with standard can too... :\






thats blown it  :rolleyes
Title: Re: Low revs stuttering
Post by: Soapy on 18 June 2013, 10:47:32 am
Except that mine's doing it with standard can too... :\
Hi Nick. Looks we are part of a small club with similar issues. Hopefully between us we can get sorted. Cheers John S
Title: Re: Low revs stuttering
Post by: otis on 18 June 2013, 07:10:48 pm
Had a similar problem a few months ago. #1 zorts was not getting as hot as the others. Checked the plug and had not bad spark. Turned out that it was a dodgey plug that would break down as I gave it the beans but ok if I nursed it. I know you have changed the plugs but you get bad ones. Have you tested the headers to see if any are not as hot as the rest ?