Running Issue, Holding Back @ Speed

[sirloveyou]

Hi Guys & Girls,

I have a issue with the Storms running ...

Basically when riding around normally under say 60mph or accelerating hard or gradual she runs fine,

But when going down a dual carriage way at 70-80mph on a constant / steady throttle she keeps missing, it feels like she's holding back then surging forward and occasionally you can here it can back through the carbs :/
Give her a handful and takes off like a rocket but return to a steady throttle she is does it again, it really is very annoying.

Like I say at lower speeds going round town on a constant throttle & country roads its fine, maybe the very odd occasional cough.

She's had new NGK Iridium plugs, I took off the carbs checked them & took off the bowls to see if there was any dirt, but the where clean. Also checked the filter inside the tank and that's OK as well.

Could anyone give me any tips or suggestions, am I missing something very obvious or is this a common fault

All feedback will be much appreciated

Thank you

[Z28DUNC]

Hmm I had a similar issue when I took the tank off to change the air filter. Are you sure the pipes are on the right way round under the tank?

[sirloveyou]

Im pretty sure they are, the hoses are preformed and sit alongside the airbox so wont go into the fuel tap any other way

[Da Lipper]

Cheap fuel?

[VTRDark]

It's no good looking at the jets for dirt. LOL Take them out including the emulsion tubes, check what they are and make sure they are correct, remove fuel mixture screws (watch out for springs and rubber O rings ) and give everything a blast through with carb cleaning spray. Wear gloves and watch your eyes, carb cleaning spray is nasty stuff. That last one is a do as I say and not as I do comment. Is the jetting standard?

If there is not an electrical fault, for example, coils, then It sounds to me like your bike needs a good tune up. Sounds like you have some sh1t in the carbs blocking one of the passageways or maybe some crap is getting down through the fuel filter/tank. I wouldn't rule out the petcock diaphragm though.

Personally I would start with giving the carbs a strip down and thorough clean with carb cleaning spray. Get it in every passageway you can see/get to. Whilst in there check what jetting set up you have and adjust/change if necessary. TPS would be another one to check and adjust. Also what air filter are you running and is it clean. While carbs are off it's a good time to fit a front vacuum take off for carb sync/balancing which can work wonders and should be done every time carbs are removed though that makes little difference but it should definitely be done after any jetting changes carb adjustments or periodic maintenance.

You may even be running a little lean. Try pulling the choke out a tad to see if things improve, and I mean a small amount or it will just flood. The choke is actually an enricher so adds fuel when pulled out so you can use this to determine if lean or rich.

Hows the bikes idle speed and does the rev needle fluctuate at all at idle or after giving a quick flick of the throttle?

A QUICK OVERVIEW ON OPENING THE CARBS
AND MAKING CHANGES

Vacuum pipe is what I think Z28DUNC is referring to.



(:-})

[Mav617]

Help!!

Connected like the picture shown, but the bike doesn't even try to fire. If I put the vacuum pipe where the breather is, it tries to run? The vacuum pipe seems to connect to a blanked off spigot - wtf am I doing wrong here??

[VTRDark]

The vacuum pipe seems to connect to a blanked off spigot - wtf am I doing wrong here??

Have you got a front vacuum take off for carb balancing or maybe a scottoiler. Sounds like you have the wrong pipe.

The vacuum for fuel flow should run from the rear cylinder to the tank. If you look on the left hand side down near the rear carb inlet rubber you should see the vacuum pipe. This should run to the tank.

Any other pipes you may have like front vacuum take off should be run separately and capped off and for rear vacuum take off should be taken from a T Piece off the rear vacuum pipe and capped off.

Right hand side in the following pic.



(:-})

[Mav617]

Okay, thanks - doesn't help me though. Where on the petcock does the vacuum pipe fit? I have a breather and a drain connected to the tank and two petrol pipes connected to the petcock - am left with a thinnish tube but can't find where to fit it other than a seemingly blanked off takeoff on the left hand side of the petcock behind the left hand fuel pipe? The manual is fookin useless also.

Wish I'd taken photos when I took the fooker to bits.

Looks like the pipe on the photo above sitting behind the petrol pipe. Maybe it's been sat too long and the carbs need cleaning - which is beyond me so it needs a new home

[tony.mon]

The rear cylinder avc line, the one on the right in Carl's photo, goes onto the small spigot on the side of the petcock. NOT the one at the bottom pointing vertically down.

[Mav617]

The rear cylinder avc line, the one on the right in Carl's photo, goes onto the small spigot on the side of the petcock. NOT the one at the bottom pointing vertically down.

Wonder if mine is blocked or something got blocked when the tank was resprayed (took petcock off first). Fed up now, been f0cking around for months, it can be someone else's problem.

[VTRDark]

which is beyond me so it needs a new home

No it's not...I could easily talk you through it with mu eyes closed. Their nothing to fear!!! Anyhow get the vacuum connected in the right place and it should run. You wouldn't believe how many people make a mistake over reconnecting the vacuum.

Wonder if mine is blocked or something got blocked when the tank was resprayed (took petcock off first).

Have you connected up in the right place and tried starting again then. Sounds to me like your getting frustrated with it. Time to take a breather and walk away and come back to it with a clear head maybe. Go and have a pint and things will feel so much better.

(:-})

[Mav617]

The rear cylinder avc line, the one on the right in Carl's photo, goes onto the small spigot on the side of the petcock. NOT the one at the bottom pointing vertically down.

Okay, looking at pictures of petcocks on eBay it's obvious where the pipe fits. The fact it won't run must be something else I'll have a go at the carbs following Carl's guide.

[tony.mon]

The rear cylinder vac line, the one on the right in Carl's photo, goes onto the small spigot on the side of the petcock. NOT the one at the bottom pointing vertically down.

That spigot seems to be blanked off?

Look at Carl's picture of the tap, fourth post down this thread.
You can see the two large diameter petrol pipes, where the fuel comes out and goes to the carbs.
Behind the one on the right in the picture (on the left on the bike) you can see a smaller diameter pipe entering the petcock. The small diameter line coming form the vacuum take-off point on the rear cylinder, which is already pointed out for you earlier in this thread, pushes onto a small metal pipe that exits from the side of the petcock at the rear of the larger fuel outlet pipe.

You must not connect the vacuum line to the vent pipe that exits the tap and pints directly down.

The fuel tap is operated by the engine vacuum, so will only allow fuel to flow if the engine is sucking air in at the carb throat, the vacuum it produces sucking when the valves are closed pulls on a diaphragm in the tap and allows fuel to flow.
If you haven't got any vacuum going to the tap it won't allow fuel to get the the carbs.

Please, can someone local just go round a stick the pipe onto the right place for him?

Mav, could you just take a picture and post it of the "blanked" petcock so we can see what you're on about?

[Mav617]

Thanks Tony. I took the tank off, checked all the pipes, refitted, with that thin pipe on the spigot on the rear of the petcock, turned the juice on - and she fired up. Still not sure what the problem was but thanks for all the help, she's running again now