Bike is running like a dog, help!!

[Jay]

First a bit of history:

Some twot sided me and I took a spill, so the bike has been on a paddock stand for about a month. Tank repaired no major damage, cosmetic really.

Did an oil change, started it, but didn't take very well, the plugs were very oily, oil level was fine, so perhaps this oily residue was from when bike was on it's side after car hit me?

Anyway, changed plugs, starts better, new plugs look pretty okay on a second look, perhaps a little black, the electrode looks fine though, after the short run I've just done. but idles like a pig (shudders at about 1k), each time I rev it from idle (even when throttled very gently as well) it doesn't seem to take initially and then springs into life.

Test ride: Same thing, have to keep the revs real high when I pull off otherwise it just shudders about, have to blip it into life. It seems slightly better right after a good thrashing, but soon goes back to shuddering, that could be my imagination though.

Basically sounds like a bad air/fuel mix, but I haven't been buggering about with that at all, unless a dirty jet causes a similar problem, or the spill botched it!?

Occasional sound when I try and pull away: a wet pop, possibly from the carbs but also exhaust.

Been using the standard cans, so I can hear things better. When I changed cans over I didn't dyno it or anything, everything else is standard.

So: are my jets dirty or sumfink?? Any ideas?

Ta ever so...

J

[Dave in USA]

Did you use fresh fuel when you fired it up? Modern gas is crap & doesn't take to being left standing too long, I would start with that & check all your lines are flowing freely (not trapped anywhere)

:)

[Jay]

Yup, fresh fuel, pipes all okay, none of them constricted... did amend my post above, had a second look at plugs, they look perhaps a little black, I'm no expert though. The low rev running sounds typical of a bad air/fuel mix, but only from what I've read, never actually experienced it before. But I haven't been touching the mix or carbs.

aaargh!

[grunter]

the vacuum pipes some times they go soft and cause fuel starvation?
or put it on a lead and give it some chum?

[spacemonkey]

...but you have admitted putting the standard, restrictive, pipes back on. Have you had it jetted for the loud 'uns? If so you are now running rich and this will blacken the plugs, cause it to cough like a sixty-a-day miner, and fart like a dog that's eaten the Christmas leftovers. It might also experience bore wash which is when surplus unburned petrol washes the protective oil off the bore. This promotes early wear and also blackens the plugs.

I'd suggest putting the loud pipes on and see if all is ok. Clean the plugs again. I use a wire brush and carb cleaner. Give it some beans to burn off any excess oil etc from the cylinder and see if all is well again.

[Jay]

Thanks for replies, sorry I wasn't clear. The bike hasn't been dyno'ed at all, pipes were just swapped for loud ones a little while after buying it, and then I put the standard ones back on for the purposes of testing the bike today.

I'll try loud pipes and see what happens, but seems a little odd, unless of course On Yer Bike, who serviced it last adjusted things?

If it doesn't work, I suppose a trip to the dealer... arse!

[CK & AK]

Jay - just a possible idea.

The fuel that sat in the carbs - since your off, could have varnished up the slow running jet - causing a restriction - so would cause bad running at slow RPM.

If you have the knowledge to take the carbs off - it might be worth dropping the fuel bowls - and checking none of the jets are blocked - but they are very small - and require close inspection.
Crap could have also been dislodged from the bottom of the float bowl & got sucked into the jets.

Had the same prob with another (non duke) whilst standing.

Or, poss even water in the bottom of the float bowl - which will sit in the bottom of the float bowl (water is heavier than petrol) which you can drain off through the bottom of the float bowl as a quick check. Then re-fuel.

Just a few ideas for you - sorry not to live nearer.

Alan

[kriss]

pilot jet or jets blocked, piece of p-ss to do just drop float bowels off and their they are, dont poke them out try and blow them clear, good luck mate.

[Jay]

Thanks both, don't really know my way round the carbs, although I sort of know the theory.

Dropping and draining the Float Bowls sounds easy enough, is it? Do I have to drain the fuel tank (no tap to isolate the tank), and remove the carb unit from the bike . Looked in the Haynes Manual and can't find a mention of it. Is it easy to explain or should I plod along lé dealer?

I have no garage which a real arse, so have to wait for decent weather each time I do something... London ... sigh

J

[kriss]

hi jay, dont think tank is your problem, if your getting enough fuel when you cain it then forget the tank. the carbs are p-ss easy to do, if you lived by me id do them for you in 15 mins. the bowels are only held in place by 4 little screws and once you undo these the bowel will come away and expose your jets. if you want to ring me at home ill go through it with you, just let me know and ill pm you my home number but it reall y is easy peasey, let me know jay, kriss.

[Jay]

Cheers Kriss, that's very kind of you... I'm gonna have one final check at the new plugs to see oif the gap is correct, cos I didn't check that after my run (doh!), so perhaps it is something as simple as that, otherwise I may need you to just point me to the correct screws, cheers for that, I am away till Monday or so, but will let ya know either way via a reply message, thanks

J

[CK & AK]

Jay - if you are still stuck by next weekend (Sunday) - and if you can get it over to me mid morning - I will be able to have a look for you, as I have some nutters coming to have a look at the monster & collect some of the 'spares' I am selling.
Could have a 'group diagnosis'!!!
Shouldnt take too long (I hope)

Alan

[spacemonkey]

Good point about water in carbs. Try Motorex Motoplus. This absorbs the water and makes it miscible with the petrol and hence can be 'burned'. Very good to chuck in a tank after a lay up. You could try a blast of carb cleaner down the carb throats with the throttles fully open.

[kriss]

if you have water in the carbs its just as easy to drain them same as the tank. instead of all these substancies they come out with id rather invest in a repair manual and learn about my bike, ( im not getting at you jay) just dont agree with quick fixes as they dont always work in the long run. a little time and learning never hurt anyone and we all have to learn in the end or keep paying some-one else for something 99% of us are capable of doing. end of my sunday morning lecture, let me know if you need help jay, good luck mate.

[spacemonkey]

I don't know jack about the 600, but on my 900 only one of the drain screws is accessable, the other has a carb in the way. Good 'ol Italian design. Unless someone knows a way around this?

[kriss]

loosen first carb and twist then you get to other, easy peesy.

[Jay]

Well, the saga continues... checked gaps on plugs, all fine, drained float bowls (which was surprisingly easy), but now it dawns on me it could well be Carb Iceing (stop groaning at my stupidity), but it may not be, will let you know, cos I know you're very excited to discover what is actually wrong, ha!

So, in goes the Pro FST tonight, and I'll give her some welly, and we'll see. If still not too good, will put on race cans again and see of the extra freedom does anything, and if still nothing, then it looks like a bit of removing carbs and blowing out jets and all that malarky...sigh!

J

[spacemonkey]

Ah, Kriss-san, you help me on the road to enlightenment!

[spacemonkey]

Oh I forgot: I took my dog out for a run at the weekend and he ran just fine! What's all the trouble about?

[Jay]

I'll have your dog then!

Well apart from scaring the sh*t out of myself while going round rondabouts with a bike that farts and splutters all the way round I had a very nice ride in the p*ssing rain! T'was fine when all I needed to do was open up the throttle and go straight ahead....! When I stopped anywhere she just spluttered while idling... arse!

Ran her for about 20 mins, oil temp was about 80 Degrees.

I'm not so sure it's carb ice'ing cos it's not that cold tonight, and I've ridden in colder weather (freeze hands off type weather) this year, and she's been fine, but will try other cans tomorrow and see what's what. That FST stuff did f*ck all.

J (disillusioned) I may buy a Harley .. jokes!!! :p

[CK & AK]

Jay - get your arris over (with your bike:D) on Sunday - and I will have a look for you. Come about 10ish, and should have time before the others come over. 5 mins Jct 11 M25.

Hope its not too far for you to splutter!

Alan

[spacemonkey]

Use about 160-200mils per tankful. If no joy howsabout an air leak? Failing that when a dog is sick a shotgun is the best remedy. Wanna borrow??

[Jay]

Thanks Alan, will do, I fancy a squiz at your fabbo creation. Could you give me some basic directions? Just from the the junction... I'm coming from Greenwich, I'll probably do M25 so I don't have to stop!! :burnout:

Spacemonkey: bring your gun!

J

[brixtonjacks]

Ooooohhh. I wanna know what happens! I wanna know what happens!!!

[CK & AK]

You can come too - its an open invite to UKMOC!

C

[spacemonkey]

I'll bring the guns...

[Bunny]

Have you tried riding it with the fuel cap open ?
My ZZ-R tank came back from the sprayers with the breather blocked, did the same as yours, wouldn't suck the fuel through until high revs - good for wheelies though

[Jay]

Hey Bunny, yeah I'd thought of that, or been pointed in that direction, can't remember which. I started it for a bit with it open, but didn't ride with it open!!! Anyway.. it didn't make any difference.. also the latest development is when blatting off at 60/70mph if I change to a too high gear and slow down, it does a bit of a splutter as well, arses!!!

The plugs tend to be a bit charcoaled, so I thought it was running with too little fuel not air. Could be wrong cos I don't really know what I'm doing, clearly!