juttering when pulling away & at low revs

[WhiteRyder]

Hi guys and girls,

i have a p reg yzf1000r thunderace (22500 miles on clock). it starts fine in the mornings maybe a little bit of choke but sounds good and starts well. it does make a noticable clicking sound when ticking over but not sure if this is relevant. i commute everyday at 70mph ( ) in top gear at less than 5k revs, jurney takes about 20 mins one way. the problem occurs when i have been riding atleast afew miles, when i start to go 60mph in top gear and revs are about 4k it really struggles and almost feels like it wants to stall (this problem only happenin over the last 2 months) and/or when i get to a junction and have to stop, pulling away (sometimes) it is really juttery and its embarassing when it sits on the edge of nearly stalling and i have to balance clutch and throttle to keep it going.

i have reported this problem in this forum b4 about 2 months ago and the end result was a suggestion that i should take a look at the ex-up valve. i did take it to the garge and they lubed it and said it seems fine, the next couple hundred miles after that it ran normal and i assumed problem solved. but this problem has started coming back more frequently but is still pretty intermittant (unless how i ride from day to day changes this?).

i am not technically minded but am sensible and have been riding 3 years. bike had a service 1k miles ago (same time as ex-up value was checked). not sure when carbs where last done (more than 5k miles tho). it sits in the cold each night and is now getting freezing cold as im sure u all are aware of.

what is the bikes problem?!

[flipper]

Carb icing possibly? Has the problem started since the cooler damp weather arrived?

[WhiteRyder]

Carb icing possibly? Has the problem started since the cooler damp weather arrived?

 

well it was about 15 degrees ish 2 months ago? (in essex) when it started. it wasnt below 10 degrees weather last month either.

also could it be freezing when it pulls away fine when i first get on the bike in the morning but then once iv been riding 10 mins it seems 2 get worst? (does low rev motorway riding make the engine colder than doing nothing?!)

[flipper]

if it was doing it at 15 degrees then I doubt that's it.

[caretaker]

It might be worth checking and eliminating some of the obvious causes such as condition of the plugs and leads first.

I'd also check that the vacumn pipe from the carb is free and not kinked as well and the same with the tank breather pipe.

Next I dont even know what an ex up valve is..but if lubricating it last time seemed to cure the problem then it could be prone to sticking and need looking at again....is it something that can be serviced/replaced ie given more thorough attention?

[Timmy Tiger]

They might have only lubed the exup valve cables and not really gone to town in cleaning it properly.

[WhiteRyder]

http://www.thunderace.host.sk/thunderac ... owto/exup/

i think those things will have been done its it last service, the plugs where a mess but where changed and should be a problem with them after 2 months?

[caretaker]

http://www.thunderace.host.sk/thunderace_bestanden/howto/exup/

i think those things will have been done its it last service, the plugs where a mess but where changed and should be a problem with them after 2 months?

 

you mentioned that the 'plugs where done when the valve was lubed' so it is still possible that that is also the reason it ran okay for a while too....and still possible your plugs could be getting fouled up due to a over rich mix or some such thing due to doing your steady low revs riding........do things improve if you keep the revs up for a good while? - worth a try as it sounds like it needs the more occasional blast!

[eastanglianbiker]

have you checked condition of air filter and if fitted the fuel filter.also after riding for a while and it stats messing about pull over if you can and open fuel cap,ifyou get a hiss like its drawing air in the the breather hole could be blocked in the cap therefor restricting fuel flow

[flipper]

You now say the plugs were a mess........................... as in sooted up?

Could be that the emulsion tubes in the carbs are worn. This will make the bike run very rich at part throttle and idle. It also makes the bike very easy to start without choke when cold.

[Guest]

all good points above, my first thought was carb icing. Steve (eastanglianbiker) has a good point about the fuel breather too...

And flipper also has a good point.

Gotta start with the easiest and cheapest and go through a process of elimination I'm afraid!!

[WhiteRyder]

some good points there thanks.

plugs where pretty white and not in gr8 nick. can u suggest a new set of plugs to use (i think the garage i use puts cheap plugs in)? what are the super long life ones called and are they worth it?

it does give the feel of wrong mix from the carbs (giving it more throttle when it splutters doesnt help much, pulling clutch works better)

[flipper]

If the plug tips were white then the bike is running lean....... they should be a tan colour.

Iridium plugs last longer, but they won't cure a carburation problem.

If you get engine up to temperature and blip the throttle does the rev counter drop down to a steady idle straight away? Or does it hang up before idling? Or drop down below idle then pick up to idle speed?

Has the bike got the stock exhaust and air filter? Has it ever had a dynojet kit or similar fitted?

[WhiteRyder]

If the plug tips were white then the bike is running lean....... they should be a tan colour.

Iridium plugs last longer, but they won't cure a carburation problem.

If you get engine up to temperature and blip the throttle does the rev counter drop down to a steady idle straight away? Or does it hang up before idling? Or drop down below idle then pick up to idle speed?

Has the bike got the stock exhaust and air filter? Has it ever had a dynojet kit or similar fitted?

 

are you saying if i simply adjust the idle mix it will solve my problem?

i will test the throttle/rev responce on way home.

it has had dynojet (proper job done) with previous owner, since then i have changed the exhaust (and not adjusted anything else) and im guessing airfilter was changed in last service.

------

to: caretaker

i ragged it into work as suggested, in 3rd gear (5 speed) speeds between 70mph (revs 5.5k)-125mph (revs 10.5k), and i didnt get any juttering, but i also didnt need 2 stop at any junctions today as it was clear and only green lights. generally did feel better at lower speeds tho.

[flipper]

you guess the air filter was changed? might be worth checking it.

what have you done exhaustwise? gone back to stock? fitted an aftermarket can?

adjusting the pilot air screws will not cure worn emulsion tubes - the emulsion tubes would need to be replaced. It's possible that the dynojet needles have worn them prematurely - this was an issue with dj kits at one time. But from your description of your plugs the bike is running lean.

was any work done to the bike prior to this problem starting?

[WhiteRyder]

nope, problem just popped up and became more frequent. well i suppose i only had the bike for 1 month then i put the can on then it was about 1-2 months after that that problem showed up.

its an after market can, i took off the stock.

[WhiteRyder]

well this morning when i started it up i realised that it was kicking out quite alot of smoke so it must be running lean. weather is very foggy today so maybe made it show up more.

also i was keeping the revs high and it felt like it was close to juttering when doing 70 in a straight line. i did stop at a junction today on the way to work and it was pretty juttery pulling away.

would you say thats enuf proof that i need someone to check out the plugs and the carbs?

[eastanglianbiker]

if you can put a new set of plugs in it yourself to save on labour costs if that doesnt help then get garage to have a look

[WhiteRyder]

if you can put a new set of plugs in it yourself to save on labour costs if that doesnt help then get garage to have a look

 

good idea, think i should go for the Iridium plugs? or if its the carbs will it ruin these plugs just the same?!

[WhiteRyder]

PROBLEM FIXED

Thanks for all the suggestions & help. the bike really got worst in the last few days, stalling while riding, so i took it into the yamaha dealer and left it with thyem for the day. it was a filthy fuel filter/carbs that was the problem and bike now runs smooth as

did cost me £132 , but atleast i wont stall infront of oncoming traffic now

[WhiteRyder]

PROBLEM RETURNED

But... i am sure it is carb icing as 'pro fst' makes the bike run perfect.

i have found the below links on the subject (just incase anyone wants the answer to carb icing)

http://www.triumphrat.net/hinckley-clas ... ing-2.html

http://www.thunderace.host.sk/thunderac ... arbfreeze/

[Matt Strange]

I don't know a great deal about your bike, but surely it has carb heaters to prevent icing?. Get them checked out if it does

*edit* try running it on super unleaded, pretty much all my carburettor bikes seemed to run better on it when cold. Dunno why?!

[Guest]

hi there,

i seem to have the same problem on my 50cc peugeot jetforce, but it has been since my engine was fixed after it seized. dont know if that makes it any different from this guys problem. It always judders and struggles to go when ive been sitting stationary at traffic lights for a couple of mins, although its fine if i keep giving it revs

[Stu]

I don't know a great deal about your bike, but surely it has carb heaters to prevent icing?. Get them checked out if it does

*edit* try running it on super unleaded, pretty much all my carburettor bikes seemed to run better on it when cold. Dunno why?!

 

carb heaters only help they dont prevent carb icing