Idling @ 8000 rpm

[cbfb]

Hi, some of you might remember my previous posts about the partial rebuild I've done of my GSF250 Bandit. The good news is that I fired it up the other day and it starts easily (far better than before the rebuild) and ticks over smoothly. The bad news is that it is idling at 8000rpm!

Some other KBers have very kindly given some advice about this already, but we're still a bit stuck so I thought I'd see if anyone had experienced this issue before.

The first thing I thought was idle speed screw - I had removed and refitted this and possibly got it wrong. So I adjusted the idle screw so far that it was no longer opening the throttle at all, this had no effect.

Next I loosened the throttle off completely so that the throttle was completely shut when closed - there is even slack in the cable confirming that the cable isn't stuck somewhere or has been incorrectly routed. No difference.

Also checked that the slides move correctly and throttle butterflies open/close correctly.

BTW I have been firing it up then killing it after just a few seconds so can't say what happens if it is allowed to run. Not keen on thrashing the nuts off a cold engine that has just been rebuilt.

Apparently an air leak can cause a high idle, but I would have thought that firstly, it's unlikely that I would get a leak in more than one carb and secondly, assuming that only one carb was faulty, I wouldn't think that the engine would run at a smooth, high idle. I would have thought it would be a bit rough?

Now if it is an air leak, trying to find it could prove to be a bit of a bitch - can anyone recommend a good method? I've been advised that an ether spray can be used to find leaks. Sounds good but as mentioned above I don't want to leave the engine running, I need something I can try with the engine off.

Having said that, am I barking up the wrong tree thinking air leak? Maybe it's something else completely?

[White trash]

It's almost impossible totell with them fitted, but are the carb slides in backwards? I know Drew's discussed the possibility but to me, that's the most likely culpret.

[cbfb]

It's almost impossible totell with them fitted, but are the carb slides in backwards? I know Drew's discussed the possibility but to me, that's the most likely culpret.

Hi thanks for the reply. Yeah I did have a chat with Drew earlier and he mentioned the slides, we checked that they were dropping back down into place properly. Bit confused about how they could be in backwards though. Am I right in thinking that the slides are the bits I've highlighted in red on the attached parts diagram? If so as far as I can tell they can only fit in one way? Wouldn't take too long to have a look I guess, just couldn't figure it out from memory of what the carbs look like inside and the parts diag. Cheers.

228930

[NAR RG500]

Hi all

Just a funny story I thought id add, when I was young and dumb ( still might be) I did the carb on a bike and it wouldnt start so I push started it down my drive way and it started right up on full power !! Threw me right off the back and ended with wrecked skin and a bike lying there doing 10,000 rpm, morale of the story for me was to make sure the carb needle was in the hole!! Ahh memories :weird:

[Drew]

Am I right in thinking that the slides are the bits I've highlighted in red on the attached parts diagram?

228930

Yep, them's the slides.

I've just had another thought, did you put the needles back in the slides in the right order of clips, washers, and spacers? If you had them out of course.

To start it up and leave it running, drain the coolant and pour in hot water. With the wires off the coil turn it over for a little while to pump the oil to the top and circulate the water a bit. Then fire it up.

Those motors are screamers so it wont harm it to have it running that high for a couple minutes while you try a few things. Give it a blip on the throttle and see how quickly the revs drop back to 8000.

Also, with the butterflies totally closed like they are with the idle screw out, it souldn't run at all for a near total lack of air. I think no matter what the issue is, the mounting blocks/rubbers that the carbs clamp into need to come off again and be sealed.

[cbfb]

Hi all

Just a funny story I thought id add, when I was young and dumb ( still might be) I did the carb on a bike and it wouldnt start so I push started it down my drive way and it started right up on full power !! Threw me right off the back and ended with wrecked skin and a bike lying there doing 10,000 rpm, morale of the story for me was to make sure the carb needle was in the hole!! Ahh memories :weird:

Ouch!


I've just had another thought, did you put the needles back in the slides in the right order of clips, washers, and spacers? If you had them out of course.

I was pretty methodical when I had them apart, lining the parts up on the bench in the right order and putting them back in reverse, so I would be suprised if I messed it up.


To start it up and leave it running, drain the coolant and pour in hot water. With the wires off the coil turn it over for a little while to pump the oil to the top and circulate the water a bit. Then fire it up. Those motors are screamers so it wont harm it to have it running that high for a couple minutes while you try a few things. Give it a blip on the throttle and see how quickly the revs drop back to 8000.

Useful tip! Might have to do that, but your last paragraph is probably what I'll try first...


Also, with the butterflies totally closed like they are with the idle screw out, it souldn't run at all for a near total lack of air. I think no matter what the issue is, the mounting blocks/rubbers that the carbs clamp into need to come off again and be sealed.

I think you're right, there should be bugger all air getting in there with the slides down and the throttles fully shut. I will pull the carbs off and remount them. Did you mention using gasket sealant or something on them yesterday?

Also can I ask a slightly embarassing question - I am pretty sure about this but sometimes the dumbest things can turn out to be the problem... On the picture below, the hoses I have highlighted don't appear to go anywhere, I assume that's OK?

228978

[MSTRS]

Based on their position, I would have said those are your incoming fuel hoses, from the tank tap....or some sort of rebreather from the rocker cover.

[FJRider]

Based on their position, I would have said those are your incoming fuel hoses, from the tank tap....or some sort of rebreather from the rocker cover.

Vaccum hoses ... ???

[MSTRS]

Usually only one of those. And a slightly smaller gauge than the fuel hoses.

[cbfb]

Based on their position, I would have said those are your incoming fuel hoses, from the tank tap....or some sort of rebreather from the rocker cover.

Maybe I've got them confused on the diagram... but the fuel and vacuum hoses are quite distinctive so I'm confident they're correct. And the breathers coming off the rocker cover are much bigger and short so they can only fit in one place.

These hoses are quite long (a perfect length for sitting at the front of the subframe right where the airbox oil drain hose sits) and show no sign of stretching at the end and no sign of hose clips, so I doubt they've been connected to anything. Also I made notes of where everything went when I removed the carbs and these weren't mentioned, so I'm assuming they're some sort of air vent hose that just stays open? I ruled out overflow because the overflow pipes clearly come off the bottom of the float chamber. Unfortunately I've only seen a limited number of carbs and can't remember seeing these before.

[cbfb]

Vaccum hoses ... ???


Usually only one of those. And a slightly smaller gauge than the fuel hoses.

Yep there is a vacuum hose and a fuel hose (the fuel hose as you say being larger diameter). But it's obvious where these come from and go to. Also the diameter of these hoses match the fuel tap connectors. The mystery hoses are too wide to go on the vacuum hose connector.

[MSTRS]

Best be id-ing what they do then.
Carbs only need fuel and airflow. The fuel is supplied to the bowl/s to feed the various jets inside, and the air comes in through the throat/s attached to the airfilter box.

[cbfb]

Best be id-ing what they do then.
Carbs only need fuel and airflow. The fuel is supplied to the bowl/s to feed the various jets inside, and the air comes in through the throat/s attached to the airfilter box.

Yeah I agree, trying to do just that. Of course things are complicated a bit by rebreathers and fuel overflow but nah I can't figure what the hell these random hoses are for. Will do more Googling...

[White trash]

Yeah I agree, trying to do just that. Of course things are complicated a bit by rebreathers and fuel overflow but nah I can't figure what the hell these random hoses are for. Will do more Googling...

I've got two breather hoses similar off the carbs on the GSX. They go nowhere. Never have, never will. Tried blanking them off as I thought they should be capped but the bike ran worse. I can only assume their something to do with the CV carbs.

[cbfb]

I've got two breather hoses similar off the carbs on the GSX. They go nowhere. Never have, never will. Tried blanking them off as I thought they should be capped but the bike ran worse. I can only assume their something to do with the CV carbs.

Thanks you just answered my next question! Reading up on the interweb I have discovered that these buggers seem to be air vent hoses. A good description of their purpose that I found:


That is what makes carbs work. That hose provides the atmospheric pressure reference signal to the fuel in the float chamber. The difference in pressure between atmospheric and the lower pressure of the air flowing thru the carb moves the fuel from the float chamber to the air stream where it accelerates, bursts into a fine spray, mixes with air and vaporizes so it can burn in the combustion chamber. For an experiment, put your finger over the end of the hose and see what happens. Nothing bad, just try it.

So I was gonna ask if anyone had tried blocking these off, expecting the engine to run badly or idle - which you've just confirmed. Apparently it's a problem with dirt bikes going through deep water.

So looks like that was a bit of a red herring, but at least we've ruled it out.

Going back to thinking about the inlet manifold now....?

[Drew]

I think you're right, there should be bugger all air getting in there with the slides down and the throttles fully shut. I will pull the carbs off and remount them. Did you mention using gasket sealant or something on them yesterday?


Yep, use a gasket sealant to be sure they seal.

But here's the thing about that stuff. You dont need fuck all of it...EVER. There should never be great gobs of the shit being squashed out around the surfaces when you do bolts up. Apply it so thinly it is near transparent as it is not the seal itself, just there to fill tiny imperfections.

You might wanna go to a seal merchant and replace the "O rings" too if you wanna be totally sure.

[The Pastor]

I would check the internals of the carb are installed correctly. and that the carbs are attached to the bike correctly.

[JMemonic]

Umm you had the carbs how far apart? Did you have the butterflys and shafts out? If so did you install back the correct way?

I ask because I have seen someone put them in such a way that air flow past the butterfly will allow them to open, some how they appeared to be working fine until we realised they were operating in reverse once the throttle was connected.

The needles as suggested would be a good starting point as well.

[cbfb]

Thanks all for your replies.


Yep, use a gasket sealant to be sure they seal.

But here's the thing about that stuff. You dont need fuck all of it...EVER. There should never be great gobs of the shit being squashed out around the surfaces when you do bolts up. Apply it so thinly it is near transparent as it is not the seal itself, just there to fill tiny imperfections.

You might wanna go to a seal merchant and replace the "O rings" too if you wanna be totally sure.

Agreed, I've never used it before. Certainly wouldn't use it in engine.


I would check the internals of the carb are installed correctly. and that the carbs are attached to the bike correctly.

Pretty sure the internals went back OK, suspect it might be the latter (see below).


Umm you had the carbs how far apart? Did you have the butterflys and shafts out? If so did you install back the correct way?

I ask because I have seen someone put them in such a way that air flow past the butterfly will allow them to open, some how they appeared to be working fine until we realised they were operating in reverse once the throttle was connected.

The needles as suggested would be a good starting point as well.

I didn't have the butterflys and shafts out, just the float, needle, jets, diaphragm, slide etc.

I pulled the carbs off this evening and one thing I did notice that one of the hose clips on No 1 Cyl appeared to be done up tight, but it had actually reached its minimum diameter before makiing contact with the inlet manifold, so the seal would have been poor. Unfortunately I missed it first time round when installing the carbs because the screw goes tight indicating that the hose clip has tightened up but it hasn't really. Will go get a hose clip that fits tomorrow and see how that goes.

That means on one cylinder there may be an air leak. Still I would expect it to idle rough, not idle at a constant high rpm? Although I have read that it will idle high then die off (I didn't give it chance to die off I hit the kill switch).

[jonbuoy]

Have you tried restricting or blocking the carb mouth/s themselves maybe some helping hands covering the mouths or something solid that won´t get sucked in by them. You could pull some of the plugs out of the engine run on one or more cylinder at a time - cup your hand over the inlet to restrict the air flow and see which ones are causing greif. Are the inlet rubbers still rubber and pliable or have they turned to plastic with age?

[cbfb]

Have you tried restricting or blocking the carb mouth/s themselves maybe some helping hands covering the mouths or something solid that won´t get sucked in by them. You could pull some of the plugs out of the engine run on one or more cylinder at a time - cup your hand over the inlet to restrict the air flow and see which ones are causing greif. Are the inlet rubbers still rubber and pliable or have they turned to plastic with age?


No I haven't tried that, thanks. If the new hose clip doesn't fix it will give that a go.

Yeah the inlet rubbers are mint actually, no cracking and still 'rubbery'.

[MSTRS]

Exposing (and covering) the inlet/s may not be helpful. CV carbs do not behave right without the still air of an attached airbox to draw on.

[Camshaft]

take it too a doctor

[cbfb]

Exposing (and covering) the inlet/s may not be helpful. CV carbs do not behave right without the still air of an attached airbox to draw on.

Right-o, that makes sense. Praying that the hose fixes it, gonna pop down to Steelmasters at lunchtime and get a nice new shiny one.

[cbfb]

take it too a doctor
:killingme

[ducatilover]

Fuck, replied before I saw page two.

Fail.


Get the hammer.

[cbfb]

They aren't for the slides are they? :wait:

Are the what for the slides sorry? The hose clamp? If so no, it's for fastening down the rubber hose that goes from the inlet manifold on the head to the outlet of the carb.

Unfortunately though so far unsuccessful finding a suitable hose clamp, all ~12mm instead of 8.6mm as required.

[ducatilover]

Are the what for the slides sorry? The hose clamp? If so no, it's for fastening down the rubber hose that goes from the inlet manifold on the head to the outlet of the carb.

Unfortunately though so far unsuccessful finding a suitable hose clamp, all ~12mm instead of 8.6mm as required.

I may have one that fits. What diameter is the intake? 40mm external diameter? I'll go have a hunt in the shed :niceone:

[cbfb]

I may have one that fits. What diameter is the intake? 40mm external diameter? I'll go have a hunt in the shed :niceone:

That would be awesome. But to save you the fuss I'll pop into Manawatu Motorcycles (breakers, don't know if you've heard of them) on the way home from work and see if they've got one. If I don't have any joy I'll let you know.

It needs to be min 49mm when fully open, and max 44mm when fully closed. Width of the clamp is 8.6mm (maybe +.2mm wider would be OK, narrower is fine).

[ducatilover]

It needs to be min 49mm when fully open, and max 44mm when fully closed. Width of the clamp is 8.6mm (maybe +.2mm wider would be OK, narrower is fine).

I've only got a 16-29mm dia one :weird: My toolbox with all my bits and bobs isn't here at home.

[Katman]

Check the positioning of the manifold clamps. Sometimes the screw piece can foul with the throttle actuator possibly stopping it returning to the idle screw.

[cbfb]

I've only got a 16-29mm dia one :weird: My toolbox with all my bits and bobs isn't here at home.

Ah well no worries, thanks for looking.

Must say I was a bit disappointed with Freedom Suzuki (who have otherwise been generally great in the past if a bit pricey), not much help there. City Honda (who couldn't help) led me on a bit of a wild goose chase (although they had the right intentions) by giving me the wrong directions to Manawatu Motorcycles; turns out it was nowhere near where they said, so didn't get there today. Anza did their best but nothing doing, although they said ring back if I really struggle and they would dig around.

Who would have thought it would be this bloody hard!!!

Anyway if anyone's interested in where to find stainless hose clamps:
Ullrich Aluminium (http://www.ullrich-aluminium.co.nz/fastenings/23_hose_clamps_SS.php) - dealt with these guys before, very helpful
HCD Flowtech (http://www.hcdflowtech.co.nz/documents/Mikalornarrowclip.pdf)
Steve's Marine (http://www.stevesmarine.co.nz/Online-Shop/Hoseclamps/12906/)

So good news is I can get one, bad news is not before the long weekend :(

[cbfb]

Get the hammer.

Tried that, bashed me thumb :niceone:


Check the positioning of the manifold clamps. Sometimes the screw piece can foul with the throttle actuator possibly stopping it returning to the idle screw.

Unfortunately I've pulled the carbs off now so can't tell if this was the issue. But having said that will definitely watch out for that when I'm putting everything back together, cheers.

[jonbuoy]

Exposing (and covering) the inlet/s may not be helpful. CV carbs do not behave right without the still air of an attached airbox to draw on.

Its idling in the driveway - don´t think moving air turbulence will be too much of an issue to prove an 8000 RPM idle problem.

[MSTRS]

Check the positioning of the manifold clamps. Sometimes the screw piece can foul with the throttle actuator possibly stopping it returning to the idle screw.
Good point. Idling at 8000 suggests a bit more than just the mixture being out of whack.


Its idling in the driveway - don´t think moving air turbulence will be too much of an issue to prove an 8000 RPM idle problem.
You'd be surprised.

[cbfb]

Its idling in the driveway - don´t think moving air turbulence will be too much of an issue to prove an 8000 RPM idle problem.

I'd always thought that the air filter was necessary to regulate the air getting into the carbs even at standstill? I seem to remember a few engines I've played with that didn't run right with no filter on. Not something I usually do reguarly for obvious reasons.

[jonbuoy]

Yes it does have an effect but at standstill/idle its marginal, your not fine tuning the mixture or adjusting the carb balances - your engines revving its tits off with a closed throttle. It was a suggestion to prove which if any of the carbs are causing the fault. Pod filters, airbox, velocity stacks pair of nylon tights - whatever is on the carb mouth - the engine shouldn't be "idling" at 8000 RPM. Plenty of cars run with pod filters/velocity stacks on CV carbs. Theorising on the interweb and wishing it isn´t the part you´ve already stripped down three times causing the problem won´t fix it.

[MSTRS]

I'd always thought that the air filter was necessary to regulate the air getting into the carbs even at standstill? I seem to remember a few engines I've played with that didn't run right with no filter on. Not something I usually do reguarly for obvious reasons.

Probably CV type.
I may not have this quite right, but all carbs operate by way of a vacuum. Disturbing the 'constant' vacuum upsets their performance. But since CV carbs rely on that vacuum to lift the slide/needle as well, it is critical that airflow/vacuum is just right.

[jonbuoy]

Good point. Idling at 8000 suggests a bit more than just the mixture being out of whack.


You'd be surprised.

No I wouldn´t - I would however be very surprised if I took the airbox/filter off and the engine revved to 8,000 RPM. Maybe a rise of 250-500 RPM not 7,000 RPM

[jonbuoy]

I'd always thought that the air filter was necessary to regulate the air getting into the carbs even at standstill? I seem to remember a few engines I've played with that didn't run right with no filter on. Not something I usually do reguarly for obvious reasons.

Airfilter stops dirt getting into the engine, nothing more. It will run better without an airfilter (if the mixture is adjusted), your engine won´t last long sucking in dirt and crap off the road.

[cbfb]

Yes it does have an effect but at standstill/idle its marginal, your not fine tuning the mixture or adjusting the carb balances - your engines revving its tits off with a closed throttle. It was a suggestion to prove which if any of the carbs are causing the fault. Pod filters, airbox, velocity stacks pair of nylon tights - whatever is on the carb mouth - the engine shouldn't be "idling" at 8000 RPM. Plenty of cars run with pod filters/velocity stacks on CV carbs. Theorising on the interweb and wishing it isn´t the part you´ve already stripped down three times causing the problem won´t fix it.

Ah OK, cheers for the explanation.

[MSTRS]

No I wouldn´t - I would however be very surprised if I took the airbox/filter off and the engine revved to 8,000 RPM. Maybe a rise of 250-500 RPM not 7,000 RPM

Diagnosing the problem wouldn't necessarily be helped by removing the airbox. In saying that, if the inlets are exposed, then at least one could see if the slides were all level with each other.
An air leak around the manifold on one, or even all, of the carbs doesn't explain 'idling' at 8000rpm.
I think KM is on to it, with his suggestion of something interferring with the butterflies.

[cbfb]

Diagnosing the problem wouldn't necessarily be helped by removing the airbox. In saying that, if the inlets are exposed, then at least one could see if the slides were all level with each other.
An air leak around the manifold on one, or even all, of the carbs doesn't explain 'idling' at 8000rpm.
I think KM is on to it, with his suggestion of something interferring with the butterflies.

Have checked that the slides are all returning to bottom, not checked what they are doing when the engine's running though.

Bit of a bugger if the manifold seal doesn't explain it, was hoping the new hose clamp would fix it.

Well hopefully KM IS right then (Edit: of course KM is right, could well be caused by that - I mean I hope that is what the problem was), will check very carefully that nothing is jamming open the throttles, but I am pretty certain it was OK before, we will see!

[MSTRS]

If you re-install everything, then before your fire her up, see how much play there is at the grip. There should be a small amount anyway, but it should be easy to ascertain whether it is excessive. If there is a lot of play, chances are those butterflies are somewhat open. Which would explain everything.
Of course, then you'd have to figure out just what is holding them open.
One thing at a time...

[cbfb]

If you re-install everything, then before your fire her up, see how much play there is at the grip. There should be a small amount anyway, but it should be easy to ascertain whether it is excessive. If there is a lot of play, chances are those butterflies are somewhat open. Which would explain everything.
Of course, then you'd have to figure out just what is holding them open.
One thing at a time...

There is quite a bit of play at the grip, problem is I had the bike apart so the throttle adjustment has changed. However I have checked that the butterflies are fully closed with the throttle shut, which they are. Is this what you mean?

[jonbuoy]

There is quite a bit of play at the grip, problem is I had the bike apart so the throttle adjustment has changed. However I have checked that the butterflies are fully closed with the throttle shut, which they are. Is this what you mean?

If the slides are shut then it can't be being fouled by the hose clip, are you sure they are shut completely? The idle screw is backed off completely? they don't have to be cracked open much. If you have them off you can check if you shine a torch in a darkened room - shine it in from the engine inlet side through to the airfilter side - might need to lift the slide to get the torch in. I "rough" balanced my carbs this way before I fitted them, fairly accurate - get the same amount of light from each carb gets you pretty close.

[MSTRS]

There is quite a bit of play at the grip, problem is I had the bike apart so the throttle adjustment has changed. However I have checked that the butterflies are fully closed with the throttle shut, which they are. Is this what you mean?

It is. If the excess play wasn't there before, then I'd be questioning the butterflies being FULLY closed. It doesn't take a lot to run an unloaded engine at 8000rpm.
A similar effect could be caused by the slides not being bottomed out either. That is possibly something you'd have to look at with the engine going, however.

[cbfb]

If the slides are shut then it can't be being fouled by the hose clip, are you sure they are shut completely? The idle screw is backed off completely? they don't have to be cracked open much. If you have them off you can check if you shine a torch in a darkened room - shine it in from the engine inlet side through to the airfilter side - might need to lift the slide to get the torch in. I "rough" balanced my carbs this way before I fitted them, fairly accurate - get the same amount of light from each carb gets you pretty close.

Idle screw is completely out, no way that is affecting anything.

Slides are shut in as much as they reach the bottom of the groove they slide in, although they don't reach right to the bottom of the manifold, there is a slight gap (see attached pic, not my carbs found the pic on the internet but similar). I think that's right, what do you reckon?

229118

[Katman]

If the slides are shut then it can't be being fouled by the hose clip,

You're getting confused between the slides and the butterflies. They're two separate things.

[cbfb]

It is. If the excess play wasn't there before, then I'd be questioning the butterflies being FULLY closed. It doesn't take a lot to run an unloaded engine at 8000rpm.
A similar effect could be caused by the slides not being bottomed out either. That is possibly something you'd have to look at with the engine going, however.

OK I will double-check this tonight, won't hurt to check again but I am fairly certain they were fully closed.

[Katman]

(see attached pic, not my carbs found the pic on the internet but similar)

They are slide carbs not CV carbs.

[TimeOut]

Is there supposed to be a spring above the slide? If so and it's not there vacuum could suck the slide up.

Just a thought

[cbfb]

They are slide carbs not CV carbs.

:facepalm: Sorry man I'm confusing things even further eh. Was just trying to show the gap between the bottom of the slide and the manifold.



Is there supposed to be a spring above the slide? If so and it's not there vacuum could suck the slide up.

Just a thought

From memory no I don't think there shuld be a spring above the slide, can't see one on parts diag anyway.

[Katman]

If you now have excessive freeplay at the throttle that you didn't have before it's most likely because the throttle butterflies are not being allowed to fully close.

[cbfb]

If you now have excessive freeplay at the throttle that you didn't have before it's most likely because the throttle butterflies are not being allowed to fully close.

Nah it's cause I had to loosen the throttle adjuster to get the cable end out, it was an absolute bastard to release. Need to tighten the throttle up once the bike is running normally.

[MSTRS]

From memory no I don't think there shuld be a spring above the slide, can't see one on parts diag anyway.

Hmmmm....

<img src=http://www.battlescooter.com/resources/Battlescooter+Carb+Tech+9.jpg>

[jonbuoy]

You're getting confused between the slides and the butterflies. They're two separate things.

No only terminology, I meant the slide/butterfly controlled by the throttle cable - not the internal slide.

CBFB good luck with the fix, sure you will suss it out in the end.

[Katman]

From memory no I don't think there shuld be a spring above the slide, can't see one on parts diag anyway.

Number 22.

[Katman]

No only terminology, I meant the slide/butterfly controlled by the throttle cable - not the internal slide.

On a slide carb the throttle is mechanically connected to the slide. There is no throttle butterfly.

On a CV carb the throttle is mechanically connected to the throttle butterflies.

[cbfb]

Hmmmm....

<img src=http://www.battlescooter.com/resources/Battlescooter+Carb+Tech+9.jpg>


Number 22.

:facepalm: Twice in one day, sorry you're right, was a while since I did the carbs. I was pretty methodical when I did them so am confident they have gone back right but will check tonight against the parts diag.

[Katman]

On a CV carb, with it's throttle butterfly fully closed, manually lifting the slide won't increase the revs as the closed butterfly isn't allowing sufficient airflow. That cylinder will just run rich and bog down.

[jonbuoy]

On a slide carb the throttle is mechanically connected to the slide. There is no throttle butterfly.

On a CV carb the throttle is mechanically connected to the throttle butterflies.

I know! I have them on my car.

[MSTRS]

On a CV carb, with it's throttle butterfly fully closed, manually lifting the slide won't increase the revs as the closed butterfly isn't allowing sufficient airflow. That cylinder will just run rich and bog down.

Hence 'our' supposition that there is something interfering with the butterflies...
An airleak or lack of spring holding slide/s down just isn't going to cause the engine to race.

[cbfb]

OK so what I'm gonna do, I'm gonna get me a nice shiny new hose clamp so we can rule that out. Then I'm gonna give the carb insides a quick check. Then I'm gonna bung the carbs back on and without the airbox on, try and turn it over to see where the butterflies and slides are sitting. Hopefully that will tell us something.

[ducatilover]

On a CV carb, with it's throttle butterfly fully closed, manually lifting the slide won't increase the revs as the closed butterfly isn't allowing sufficient airflow. That cylinder will just run rich and bog down.

This is very true.


CBFB, if it's not sorted I can drop in on Saturday? Maybe sooner if need be.
I really doubt it's an air leak after the butterflies, I would assume it's an issue with the butterflies, have you set their clearance according to fact. specs?
The slides will only affect it, if the butterflies are open, the lifting slides will just lift the needles, opening the main jet, hence the rich running.
Also may be worth a peek at the plugs, but, I imagine you will find them as white as hell, indicating being lean.

[cbfb]

This is very true.


CBFB, if it's not sorted I can drop in on Saturday? Maybe sooner if need be.
I really doubt it's an air leak after the butterflies, I would assume it's an issue with the butterflies, have you set their clearance according to fact. specs?
The slides will only affect it, if the butterflies are open, the lifting slides will just lift the needles, opening the main jet, hence the rich running.
Also may be worth a peek at the plugs, but, I imagine you will find them as white as hell, indicating being lean.

Mate that would be awesome if you could. Will see how I go with her tonight and if still no joy I'll be in touch.

Good news is Manawatu Motorcycles had a used hose clamp (exact match of existing ones). Bloody good wee shop that, they break bikes, didn't know they were there till now.

I didn't touch the flutterbys when I took the carbs apart so I assumed they would be OK having not been changed? The service manual says this:

229123

But wtf is the 'foremost bypass'? How do I set the clearance otherwise?

Plugs are brand new and have about 10 secs of running time on them.

[ducatilover]

Mate that would be awesome if you could. Will see how I go with her tonight and if still no joy I'll be in touch.

Good news is Manawatu Motorcycles had a used hose clamp (exact match of existing ones). Bloody good wee shop that, they break bikes, didn't know they were there till now.

I didn't touch the flutterbys when I took the carbs apart so I assumed they would be OK having not been changed? The service manual says this:

229123

But wtf is the 'foremost bypass'? How do I set the clearance otherwise?

Plugs are brand new and have about 10 secs of running time on them.

Something may be interfering with the flutterbies...but wel shall see.
The foremost bypass may be the idle circuit, or the flutterby air gaps. I haven't played with CV carbs for a while, but, they are piss easy to figure out.
That attachment isn't working dude

[cbfb]

Something may be interfering with the flutterbies...but wel shall see.
The foremost bypass may be the idle circuit, or the flutterby air gaps. I haven't played with CV carbs for a while, but, they are piss easy to figure out.
That attachment isn't working dude

Don't think it's the idle circuit intake ports (assuming that's what you mean) cause they're a bit further forward.

Try it now:
229124

[ducatilover]

Don't think it's the idle circuit intake ports (assuming that's what you mean) cause they're a bit further forward.

Try it now:
229124

Is there a small bypass groove where (8) is positioned on the diagram?

[cbfb]

Is there a small bypass groove where (8) is positioned on the diagram?

Hmmm not sure from memory. You reckon that's a factor?

[ducatilover]

Hmmm not sure from memory. You reckon that's a factor?

Could be. It may help to check, but, I doubt a bypass port is enough to make it sit at 8000rpm.
:weird:

[cbfb]

Could be. It may help to check, but, I doubt a bypass port is enough to make it sit at 8000rpm.
:weird:

Yeah that's what I can't figure, there's got to be a lot of air getting in there somehow :confused:

[ducatilover]

Yeah that's what I can't figure, there's got to be a lot of air getting in there somehow :confused:

It's really all pointing to interference with the flutterbies.

[cbfb]

It's really all pointing to interference with the flutterbies.

Roger that. Will report back my findings later on.

[Drew]

Airfilter stops dirt getting into the engine, nothing more. It will run better without an airfilter (if the mixture is adjusted), your engine won´t last long sucking in dirt and crap off the road.Wasn't gonna call you on this, but I will cos your attitude bugs me.

Run a bike with CV carbs without a filter and it will idle fine, but run like a sack of shit when you are on the throttle. Because there is a delicate balance of spring tension versus air flow to be maintained in order for the slides to sit at correct levels for the engine speed.


Roger that. Will report back my findings later on.

When we spoke on the phone I could hear the butterflies slamming home when you shut the throttle I thought. Would be funny if that was infact a linkage hitting a hose clamp.

[cbfb]

When we spoke on the phone I could hear the butterflies slamming home when you shut the throttle I thought. Would be funny if that was infact a linkage hitting a hose clamp.

Aye that's right you did, I remember now. Althought by then I had taken the airbox off so still can't rule out that something was catching (although less likely to be something from there).

[jonbuoy]

Wasn't gonna call you on this, but I will cos your attitude bugs me.

Run a bike with CV carbs without a filter and it will idle fine, but run like a sack of shit when you are on the throttle. Because there is a delicate balance of spring tension versus air flow to be maintained in order for the slides to sit at correct levels for the engine speed.



When we spoke on the phone I could hear the butterflies slamming home when you shut the throttle I thought. Would be funny if that was infact a linkage hitting a hose clamp.

Wow I feel so shamed - I couldn´t care less if my attitude bugs you, I´m amazed you can tell what my attitude is through the interweb. My point was to try and help the guy identify if one or more carbs was causing the issue and maybe let him run the engine for more than a couple of seconds to ID the vacuum leak if there was any. There wasn´t much in occurring in the thread. I didn´t suggest he run full time without filters - No attempt at a good deed goes unpunished on KB.

[cbfb]

OK well I checked the carbs tonight (by that I mean the top; diaphragm, slides, butterflies etc). All looking good.

Next I reassembled everything. Put fuel tap on 'prime' and turned it over a couple of times, nothing. Switched to 'on', started with a bit of help from the throttle. Adjusted idle screw to rev around 2000rpm (although a little erratic). Holy shit, fuel pissing out of overflow hoses and smoke coming from front of engine (near rocker cover). Appears to be some coolant around, but could be a red herring - recently refilled radiator. Rad is still full. Oil level seems OK. Suspect fuel overflow due to me turning it over on 'Prime'? Cause of smoke unknown, thought maybe fuel burning off?

Let engine dry and used compressed air to blast away as much gunk as possible (concerned about residue from CRC, oil etc smoking)?

Started up again. Carbs not leaking but smoke definitely coming from centre of rocker cover (front), smell is like burning rubber. Wonder if it's possibly the rubber grease I used on the rocker cover seal?

Checked oil level - oil may have gone down marginally, possible oil leak around rocker cover gasket? If this was true would expect oil residue but it looks fairly clean. Would leaking oil smoke like that? Would oil smoke smell like burning rubber?

Rad has gone down slightly, but maybe expected seeing as though bike has only run for a few minutes since refilling coolant?

I degreased the engine, carbs, rad, exhaust and have left it out in the shed to dry off overnight.

So worse case scenario, losing oil and coolant but where's it going? Head gasket could be an explanation but I've just replaced the head gasket. Hmmm.

Anyway the only idea I can come up with is fill the oil and coolant up tomorrow then let it idle for a couple of minutes, just long enough to heat up. If the smoke is just crap burning off, hopefully it will stop. And if there is an oil/coolant leak somewhere hopefully it will give me some clues.

And as for the carbs, I am hoping that is all OK now... fingers crossed...

Any ideas/suggestions more welcome than ever!

p.s. sorry for being a bit of a hopeless mechanic so far, it's a steep learning curve unfortunately i've got more enthusiasm than ability at the moment...

[Katman]

Checked oil level - oil may have gone down marginally, possible oil leak around rocker cover gasket? If this was true would expect oil residue but it looks fairly clean. Would leaking oil smoke like that? Would oil smoke smell like burning rubber?

It takes a while for all the oil to drain back into the sump - particularly when it's still relatively cold. If the level is only down slightly then there is nothing to worry about.

[cbfb]

It takes a while for all the oil to drain back into the sump - particularly when it's still relatively cold. If the level is only down slightly then there is nothing to worry about.

True, however I just went back out to the shed and it hasn't gone up again yet.

Worse still, I noticed that there is a slight greeny colour to the oil. Drained some off, the oil is black but yeah it definitely has a green tint. I'm assuming coolant has got in there?

May not be so bad as I haven't changed the oil since refitting the head & block so maybe some coolant got in there then... was gonna change the oil after I'd got it running. Will do it immediately.

[Katman]

True, however I just went back out to the shed and it hasn't gone up again yet.

Worse still, I noticed that there is a slight greeny colour to the oil. Drained some off, the oil is black but yeah it definitely has a green tint. I'm assuming coolant has got in there?

May not be so bad as I haven't changed the oil since refitting the head & block so maybe some coolant got in there then... was gonna change the oil after I'd got it running. Will do it immediately.

If you fitted a new oil filter when you reassembled the engine that may well explain the drop in the oil level. The oil capacity cast into the engine casing is usually the amount needed without the oil filter being changed. You need to add some oil once the oil has been pumped into the filter.

[cbfb]

If you fitted a new oil filter when you reassembled the engine that may well explain the drop in the oil level. The oil capacity cast into the engine casing is usually the amount needed without the oil filter being changed. You need to add some oil once the oil has been pumped into the filter.

Nope I left the old filter in there, was being a cheapskate. Only had the motor apart because I had stripped one of the cam journal bolts and needed to take the head off to sort that out. :facepalm:

I'm getting a bit concerned that the oil is getting pumped up into the rocker cover and there's some sort of obstruction preventing it from getting back down to the crankcase? That would suck.

[FJRider]

I'm assuming coolant has got in there?



If water gets into the oil ... it goes white ...

[cbfb]

If water gets into the oil ... it goes white ...

Aye, I agree with that. Just thought coolant is green therefore oil + coolant = green.

Have read on t'interweb though that some bike oils are green??? News to me but maybe that's what it is.

Won't hurt to do an oil and filter change tho, was gonna do it anyway.

[FJRider]

Aye, I agree with that. Just thought coolant is green therefore oil + coolant = green.

Have read on t'interweb though that some bike oils are green??? News to me but maybe that's what it is.

Won't hurt to do an oil and filter change tho, was gonna do it anyway.

Finish what you started already ...

[cbfb]

Finish what you started already ...

Sorry don't understand?

[FJRider]

Sorry don't understand?

AFTER you know it's running smoothly, with no issues. (NO leaks of anything)

A short run if it seems ok ... with a clean engine to start with. Leaks then become obvious.

[FJRider]

Nope I left the old filter in there, was being a cheapskate. Only had the motor apart because I had stripped one of the cam journal bolts and needed to take the head off to sort that out. :facepalm:

I'm getting a bit concerned that the oil is getting pumped up into the rocker cover and there's some sort of obstruction preventing it from getting back down to the crankcase? That would suck.

The oil channels to the crankcase are not that big ... and it is usual to expect a drop in oil level if checked cold then run for a bit. The oil has spread itself around the engine ... as it is supposed to. It will drain down again ...

[Drew]

Don't over think stuff too much. The smoke is probably residue burning off, but a leaky rocker cover gasket is easy to fix.

I'm with FJrider, get it running and go for a short buzz down the road.

[cbfb]

AFTER you know it's running smoothly, with no issues. (NO leaks of anything)

A short run if it seems ok ... with a clean engine to start with. Leaks then become obvious.

Good point, yep will do that.


The oil channels to the crankcase are not that big ... and it is usual to expect a drop in oil level if checked cold then run for a bit. The oil has spread itself around the engine ... as it is supposed to. It will drain down again ...

You're right, they're not very big, that's why I was concerned about them getting blocked up. But yep it makes sense about the oil getting spread around, would be a bit buggered if it didn't!


Don't over think stuff too much. The smoke is probably residue burning off, but a leaky rocker cover gasket is easy to fix.

I'm with FJrider, get it running and go for a short buzz down the road.

I can't help it, that's my job!

OK I'll give it another crack tonight.

[MSTRS]

Glad to hear the 'idle' issue has been resolved. Probably was the butterflies being held open, eh?
As for the rest...after a semi-major strip down, it is common to experience odd bits of fluid/smoke in the initial few minutes after startup.
Change that old oil now. Filter too. You don't know what might be lurking in there...

[cbfb]

Glad to hear the 'idle' issue has been resolved. Probably was the butterflies being held open, eh?
As for the rest...after a semi-major strip down, it is common to experience odd bits of fluid/smoke in the initial few minutes after startup.
Change that old oil now. Filter too. You don't know what might be lurking in there...

Yeah could well have been that, one of those annoying things we'll never find out for sure now it's stopped. Also the inlet manifold might not have helped.

You reckon I should change my oil before starting her up again? Was gonna fire her up again for a few minutes first to see if I could get more clues to go on.

[Katman]

Yeah could well have been that, one of those annoying things we'll never find out for sure now it's stopped.

Don't worry - I know for sure.

[cbfb]

Don't worry - I know for sure.

Aye well you know better than I do, will go with that :niceone:

[MSTRS]

You reckon I should change my oil before starting her up again? Was gonna fire her up again for a few minutes first to see if I could get more clues to go on.

A prudent person would. Then change oil and filter again once 'happy' with the way the engine is running etc. That way you're not running old crap through, the first lot picks up anything that might have got in there during the stripdown/rebuild and you know you have fresh oil when you start riding it.

[cbfb]

A prudent person would. Then change oil and filter again once 'happy' with the way the engine is running etc. That way you're not running old crap through, the first lot picks up anything that might have got in there during the stripdown/rebuild and you know you have fresh oil when you start riding it.

Hmmm, bugger that's gonna cost a bit. But hell yeah I deinitiely agree it needs doing pretty soonish, prob heaps of dust and shit got in there, was careful but just dust floatin around in atmosphere will get in.

[pete376403]

I'm getting a bit concerned that the oil is getting pumped up into the rocker cover and there's some sort of obstruction preventing it from getting back down to the crankcase? That would suck.

Oil drains back via the cam chain tunnel - a pretty big hole and about the only way you'd ever obstruct that would be to leave cleaning rags inside the cam cover.

[cbfb]

Oil drains back via the cam chain tunnel - a pretty big hole and about the only way you'd ever obstruct that would be to leave cleaning rags inside the cam cover.

OK, nope definitely no rags left in there.

Started her up again tonight and left running for around 5 mins. Smoke from around rocker cover seemed to decrease quite a bit to barely anything now.

There is a fair bit of white smoke from the exhaust though. Did not decrease as engine warmed up and does not decrease when the throttle is opened up.

Idle is somewhat erratic (varies by +/- 500 rpm).

Most worringly, there is STILL fuel coming from the fekkin overflow pipes on the carbs. I have checked the needle valves and floats, I am at a bloody loss as to what is wrong with it.

Beginning to think it's time I admit defeat and take it to a mechanic but of course I can't ride it with fuel pissing out and I don't have a trailer :facepalm:

Anyway I've been consistently wrong with my assumptions so far so not even gonna try and explain this one, but if anyone has any idea what's going on please let me know ...

And again many many thanks for all your help.

[pete376403]

tap against the float bowls (screwdriver or whatever you can get in there) while the motor is running. Might help seat a sticking float valve. (obviously, don't bash the shit out of them)
The excess fuel *might* be the source of the exhaust smoke.

[Katman]

Most worringly, there is STILL fuel coming from the fekkin overflow pipes on the carbs. I have checked the needle valves and floats, I am at a bloody loss as to what is wrong with it.



Possibly leaking past the o rings on the needle valve bodies.

[Max Preload]

Possibly leaking past the o rings on the needle valve bodies.Yeah, the float valve seat o-rings. The valve may well be closed, but it's going around that and overfilling the float bowl...

Replace the o-rings with VITON. Nitrile doesn't cut it.

[MSTRS]

Erratic idle prolly due to overfull float bowls. As others have said, the needle cutoff valve/s may not be sealing. But ALL of them at the same time seems a little unlikely. Did you dick with the float height tabs when you had the carbs apart?
White smoke from the exhaust is water vapour. Could have several causes...
either condensation in the pipe which will fix itself, or you have a leak between the water jacket and (a) cylinder.
If it's a leak, a falling water level and/or milky oil will confirm.

[cbfb]

tap against the float bowls (screwdriver or whatever you can get in there) while the motor is running. Might help seat a sticking float valve. (obviously, don't bash the shit out of them)
The excess fuel *might* be the source of the exhaust smoke.

Yep will give that a crack (although still would prob try and fix permanently but that would tell me more). There are pipes linking each bowl's overflow, will rip them off so I can see which carb(s) leak(s).

You reckon excess fuel would be white though?


Possibly leaking past the o rings on the needle valve bodies.

That sounds logical, thanks.


Yeah, the float valve seat o-rings. The valve may well be closed, but it's going around that and overfilling the float bowl...

Replace the o-rings with VITON. Nitrile doesn't cut it.

Sounds good, what is Viton? Will I find it at Ripco or Supercrap? Is it a sealant? I have some rubber grease but don't know about using that??


Erratic idle prolly due to overfull float bowls. As others have said, the needle cutoff valve/s may not be sealing. But ALL of them at the same time seems a little unlikely. Did you dick with the float height tabs when you had the carbs apart?
White smoke from the exhaust is water vapour. Could have several causes...
either condensation in the pipe which will fix itself, or you have a leak between the water jacket and (a) cylinder.
If it's a leak, a falling water level and/or milky oil will confirm.

Ah, the overflow pipes are joined so that might have been a bit misleading. I suspect in reality only one carb is leaking (hopefully).
Nope, measured float height and they were all OK.
Yeah that doesn't sound too good. I took the rad cap off last night and what I did notice was a fair bit of pressure. Level had gone up slightly instead of down. Engine was hot tho but I remember when I had a leaky head gasket on my car it blew the crap out of my cooling system...
In the process of changing the oil as you suggested, we'll see if that changes colour (bloody hope not it's not cheap).



THANKS AGAIN ALL .... !

[cbfb]

Erratic idle prolly due to overfull float bowls. As others have said, the needle cutoff valve/s may not be sealing. But ALL of them at the same time seems a little unlikely. Did you dick with the float height tabs when you had the carbs apart?
White smoke from the exhaust is water vapour. Could have several causes...
either condensation in the pipe which will fix itself, or you have a leak between the water jacket and (a) cylinder.
If it's a leak, a falling water level and/or milky oil will confirm.

p.s. MSTRS, you don't reckon the white smoke could be excess fuel from the leaky carb or oil I used on the pistons/bore/just about everywhere when I reassembled the block?

[MSTRS]

Excess fuel (rich) burns black. Excess oil burns blue.
As a rule.

[cbfb]

Excess fuel (rich) burns black. Excess oil burns blue.
As a rule.

Thanks, as I thought but was trying to persuade myself all that white shit is just fuel :crybaby:

Ah could be nothing, won't panic too soon will check the needle valve o-rings and go from there.

Cheers :)

[RDjase]

Sounds good, what is Viton? Will I find it at Ripco or Supercrap? Is it a sealant? I have some rubber grease but don't know about using that??





Nitrile and Viton are types of material the O Rings are made from,

If they are stuffed you will notice they float valves will come out on the carbs easy and the o ring wont be sticking out from the outside of the float valve and the fuel will bypass and overflow your bowls.

Take the Orings ,carb and float valve to Saeco or SKF (if you have one where you live, look under bearings suppliers in the Yellow Pages) They will be able to figure out what section and diameter size O Rings you need,

I think Nitrile Viton O Rings are orange, the origianls might still be black

Dont put rubber grease in there, It dont like fuel, some oil will be fine to lube the o rings

[cbfb]

Nitrile and Viton are types of material the O Rings are made from,

If they are stuffed you will notice they float valves will come out on the carbs easy and the o ring wont be sticking out from the outside of the float valve and the fuel will bypass and overflow your bowls.

Take the Orings ,carb and float valve to Saeco or SKF (if you have one where you live, look under bearings suppliers in the Yellow Pages) They will be able to figure out what section and diameter size O Rings you need,

I think Nitrile Viton O Rings are orange, the origianls might still be black

Dont put rubber grease in there, It dont like fuel, some oil will be fine to lube the o rings

Ah OK. Well rather than bugger about figuring out which bowl is leaking might as well just change all the o-rings, doubt they are too expensive? Save finding another leak in a few months'.

Yep got Saeco and SKF here.

Cheers :)

[RDjase]

Ah OK. Well rather than bugger about figuring out which bowl is leaking might as well just change all the o-rings, doubt they are too expensive? Save finding another leak in a few months'.

Yep got Saeco and SKF here.

Cheers :)

Yep, do all 4, they dry out and shrink/crack when sitting.

I got a couple of dozen O rings for VM and TM Mikunis as most of my bikes use them.

You must be at the end of your problems now aye :niceone:

[cbfb]

Yep, do all 4, they dry out and shrink/crack when sitting.

I got a couple of dozen O rings for VM and TM Mikunis as most of my bikes use them.

You must be at the end of your problems now aye :niceone:

Good stuff will do that.

Yeah man it's looking like I'm getting there, still shitting myself about that white smoke though. Pray to fuck it's nothing serious. Will get the carbs right then go for a ride see if it clears up.

[Max Preload]

Nitrile and Viton are types of material the O Rings are made from, What he said.


If they are stuffed you will notice they float valves will come out on the carbs easy and the o ring wont be sticking out from the outside of the float valve and the fuel will bypass and overflow your bowls. Just to clarify for cbfb - it's the valve seat bodies. They're normally recessed into the carb body and held by a small machine screw (that's just a bolt that is fully threaded).


Take the Orings ,carb and float valve to Saeco or SKF (if you have one where you live, look under bearings suppliers in the Yellow Pages) They will be able to figure out what section and diameter size O Rings you need, Not sure they'll have them - I've struggled to get anything but nitrile there in the past so I just go straight to Seal House (http://www.sealhouse.co.nz/) or Seal Imports (http://www.sealimports.co.nz/).


I think Nitrile Viton O Rings are orange, the origianls might still be blackI've never seen viton in anything other than black.


Dont put rubber grease in there, It dont like fuel, some oil will be fine to lube the o ringsCorrect.

HERE (http://www.kiwibiker.co.nz/forums/showthread.php/57946-O-ring-gasket-fitting) is why you don't use nitrile (NBR) in contact with fuel (even vapour).

[cbfb]

Just to clarify for cbfb - it's the valve seat bodies. They're normally recessed into the carb body and held by a small machine screw (that's just a bolt that is fully threaded).

Hmmm, not held in place by a machine screw, if it's the right bit I'm looking at it's just pushed into place and held by the friction of the o-ring. Ducatilover is popping over later to take a look, and I can stick some photos up if we still can't figure it.


Not sure they'll have them - I've struggled to get anything but nitrile there in the past so I just go straight to Seal House (http://www.sealhouse.co.nz/) or Seal Imports (http://www.sealimports.co.nz/).

Cool they've got one in Palmy too!

Thanks :)

[Max Preload]

Hmmm, not held in place by a machine screw, if it's the right bit I'm looking at it's just pushed into place and held by the friction of the o-ring. Ducatilover is popping over later to take a look, and I can stick some photos up if we still can't figure it.It'll be held there mechancially somehow - it won't be relying on o-ring force.

It's the bit that the float valve taper end goes into. Normally has a strainer on the top of it that you can't see until it's removed.

[RDjase]

Hmmm, not held in place by a machine screw, if it's the right bit I'm looking at it's just pushed into place and held by the friction of the o-ring. Ducatilover is popping over later to take a look, and I can stick some photos up if we still can't figure it.



Cool they've got one in Palmy too!

Thanks :)

All will be sorted once Dukelover gets there :niceone:

Your bike is putting up a great fight but the Might of KB will fix.............eventually:msn-wink:

[RDjase]

What he said.


Not sure they'll have them - I've struggled to get anything but nitrile there in the past so I just go straight to Seal House (http://www.sealhouse.co.nz/) or Seal Imports (http://www.sealimports.co.nz/).

I've never seen viton in anything other than black.


HERE (http://www.kiwibiker.co.nz/forums/showthread.php/57946-O-ring-gasket-fitting) is why you don't use nitrile (NBR) in contact with fuel (even vapour).

I forgot about Seal Imports, get stuff from them for work sometimes, Seaco is across the road tho and I am usually getting bearings too and let them sort out odd ball parts. Seal Imports have got so many differnet types of seals, Handy having one local

I get bright orange O rings that may be a Gunuine part for some of the machines I work on, Cant remeber if after market are Black or Orange or what type they even are

Nordson glue machine O rings are a dull orange, Hi Temp (200 Deegree C)

[cbfb]

It'll be held there mechancially somehow - it won't be relying on o-ring force.

It's the bit that the float valve taper end goes into. Normally has a strainer on the top of it that you can't see until it's removed.

Yep there is a strainer but it seems a bit different to what you've described, better get some pictures...


All will be sorted once Dukelover gets there :niceone:

Your bike is putting up a great fight but the Might of KB will fix.............eventually:msn-wink:

Hopefully! Yeah she's really trying hard to piss me off :angry:

Yeah dunno what I would have done without KB... have a permanently broken bike probably :facepalm:

[cbfb]

Well a bit of an update... Ducatilover came over yesterday to have a look at it, we got the fuel leak sorted I think, needed the float height adjusting on one of the carbs. Bit strange as it was only out on one carb, but anyway it doesn't seem to be leaking anymore.

Last remaining issue is that once the bike is warmed up, the white exhaust appears (doesn't do it when cold) and the idle gradually increases on its own from around 1500 to around 2500. We were thinking it might be an air leak, the carb rubbers look mint but I'm gonna replace them with a thin layer of sealant to see if that helps.

[MSTRS]

Last remaining issue is that once the bike is warmed up, the white exhaust appears (doesn't do it when cold) and the idle gradually increases on its own from around 1500 to around 2500. We were thinking it might be an air leak, the carb rubbers look mint but I'm gonna replace them with a thin layer of sealant to see if that helps.

White exhaust...you mean white smoke? Suggestive of a water leak into a cylinder.

Possible airleak...got a can of ether? StartYaBastard is essentially that. A very short squirt onto each inlet rubber (do one, then allow to disperse, then the next etc) will tell you if there is a leak.

[cbfb]

White exhaust...you mean white smoke? Suggestive of a water leak into a cylinder.

Possible airleak...got a can of ether? StartYaBastard is essentially that. A very short squirt onto each inlet rubber (do one, then allow to disperse, then the next etc) will tell you if there is a leak.

White smoke yup. And yup I'm hoping that's not what it is. Checked the head/block wasn't warped/damaged and replaced the gaskets so dunno how that could be happening, would be a pain in the arse if so. Will deal with the rough idle first.

Not got a can of ether, saw the price of it and thought I'd see if using sealant on the inlet rubber fixes it first. If that doesn't work I'll get some ether.

[RDjase]

White smoke yup. And yup I'm hoping that's not what it is. Checked the head/block wasn't warped/damaged and replaced the gaskets so dunno how that could be happening, would be a pain in the arse if so. Will deal with the rough idle first.

Not got a can of ether, saw the price of it and thought I'd see if using sealant on the inlet rubber fixes it first. If that doesn't work I'll get some ether.

CRC or WD40 sort of does the same job as Ether, it just seals the air leaks when it is sprayed on and sucks it thru the vacuum leak/leaks.

Ether does work better and wont make the manifolds slippery as you want to seal them with RTV

Getting closer mate :msn-wink:

[cbfb]

CRC or WD40 sort of does the same job as Ether, it just seals the air leaks when it is sprayed on and sucks it thru the vacuum leak/leaks.

Ether does work better and wont make the manifolds slippery as you want to seal them with RTV

Getting closer mate :msn-wink:

Ah OK, yeah Ducatilover gave the inlet manifolds a liberal soaking with CRC, didn't make any difference.

Have degreased the rubbers and manifolds, all shiny smooth and good as new.

Yup getting there! Will report back after I've tried the carbs with a bit of sealant.

Cheers all!

[ducatilover]

:niceone: It was worth the beer.
I'll give my brain a bit more of a work out and see if anything pops into my mind.
Thankfully there wasn't any sign of condensation in the oil cbfb has dropped out of the bike. I couldn't find any signs of a decent air leak. Carb #4 had the float level set as high as fuck, which seemed to indicate why it would piss out of number four.
I'll bring the hammer next time, I have to use it on the CB tomorrow, it's decided to start missing like a pig.

[Max Preload]

Well a bit of an update... Ducatilover came over yesterday to have a look at it, we got the fuel leak sorted I think, needed the float height adjusting on one of the carbs. Bit strange as it was only out on one carb, but anyway it doesn't seem to be leaking anymore.So you didn't check the float levels after you reassembled the carbs? That's a fundamental error. Any time you disturb them even by just removing the float bowl they MUST be checked. For the high fuel level to have been a cause of the overflowing fuel, the float would have to have contacted the carb body before the float valve seated. That's a LONG way out. Methinks you've not seen the last of that issue.


Last remaining issue is that once the bike is warmed up, the white exhaust appears (doesn't do it when cold) and the idle gradually increases on its own from around 1500 to around 2500. We were thinking it might be an air leak, the carb rubbers look mint but I'm gonna replace them with a thin layer of sealant to see if that helps.An idle speed of that magnitude if the butterflies are indeed closed does indicate an air leak, unlike 8000rpm.

[cbfb]

:niceone: It was worth the beer.
I'll give my brain a bit more of a work out and see if anything pops into my mind.
Thankfully there wasn't any sign of condensation in the oil cbfb has dropped out of the bike. I couldn't find any signs of a decent air leak. Carb #4 had the float level set as high as fuck, which seemed to indicate why it would piss out of number four.
I'll bring the hammer next time, I have to use it on the CB tomorrow, it's decided to start missing like a pig.

I have a fine selection of hammers, 8 at the last count ;)


So you didn't check the float levels after you reassembled the carbs? That's a fundamental error. Any time you disturb them even by just removing the float bowl they MUST be checked. For the high fuel level to have been a cause of the overflowing fuel, the float would have to have contacted the carb body before the float valve seated. That's a LONG way out. Methinks you've not seen the last of that issue.

An idle speed of that magnitude if the butterflies are indeed closed does indicate an air leak, unlike 8000rpm.

Ah, the tab was only slightly bent, I didn't realise they were that sensitive. Another lesson learnt. What makes you say it will be coming back? I do wonder about that carb maybe I need to replace it.

Good, will see how I get on with the sealant.

[Max Preload]

Ah, the tab was only slightly bent, I didn't realise they were that sensitive. Another lesson learnt. What makes you say it will be coming back? I do wonder about that carb maybe I need to replace it.

Good, will see how I get on with the sealant.They're sensitive in that a lot of float movement is required in order to move the float valve a little because of the distance from the pivot of the float compared to the distance to the valve. This is to some degree done to damp the float movement due to the fuel movement and also to centralise the floats forward and aft at a point at which the fuel level doesn't particularly vary. But I digress.

All I'm saying is that I doubt the float level was the real reason for the overflowing fuel because it has to be a long way out to do that.

I'm not sure where you're planning on using the sealant exactly, so I'll say this: Go very easy on the sealant.

Given the very nature of the carbs going inside the rubbers any sealant you were to use there (which I simply wouldn't - ever) is unlikely to make any difference anyway - sealant works on face-to-face contact - just fitting the carbs into the rubbers will remove most of it.

Using sealant on the face of the rubbers where they connect to the head will really be masking the fault and it will come back so if successful you still need to find where the air leak actually is because it will grow if it's a crack in the rubbers. So largely that would be a wasted effort.

I take it you've actually checked all the rubbers where they connect to the head for leaks on that face?

[cbfb]

They're sensitive in that a lot of float movement is required in order to move the float valve a little because of the distance from the pivot of the float compared to the distance to the valve. This is to some degree done to damp the float movement due to the fuel movement and also to centralise the floats forward and aft at a point at which the fuel level doesn't particularly vary. But I digress.

All I'm saying is that I doubt the float level was the real reason for the overflowing fuel because it has to be a long way out to do that.

Go very easy on the sealant. Given the very nature of the carbs going inside the rubbers it's unlikely to make any difference anyway - sealant works on face-to-face contact - just fitting the carbs into the rubbers will remove most of it.

I take it you've actually checked all the rubbers where they connect to the head for leaks on that face?

Ah OK. It seems that whoever owned the bike previously had set the float on this one carb way high; Ducatilover & I set it back to normal, still overflowing so went a bit the other way so floats are sitting low in order for the needle to close earlier.

Yep I will use the sealant sparingly.

We sprayed CRC around but didn't notice anything. I haven't got a can of ether, could go buy some, any other method you could recommend?

[Max Preload]

Ah OK. It seems that whoever owned the bike previously had set the float on this one carb way high; Ducatilover & I set it back to normal, still overflowing so went a bit the other way so floats are sitting low in order for the needle to close earlier.In what way were they set to 'normal' - just a measurement from the bottom of the float to the carb body float bowl base? Have you also verified the actual fuel levels in the bowls are correct?

At the end of the day if it's overflowing you have either a leaking float valve or the float valve seat body o-ring (the one where Viton was discussed). There's no other way for the fuel to enter the float bowl.


We sprayed CRC around but didn't notice anything. I haven't got a can of ether, could go buy some, any other method you could recommend?We used to use an 9kg LPG bottle with a hose off a regulator and a copper rigid end to poke around and accurately locate vacuum leaks. Just do it in a well ventilated area like outside so the gas concentration doesn't build up and get to potentially explosive concentrations.

[ducatilover]

We used to use an 9kg LPG bottle with a hose off a regulator and a copper rigid end to poke around and accurately locate vacuum leaks. Just do it in a well ventilated area like outside so the gas concentration doesn't build up and get to potentially explosive concentrations.

That's a neat idea.
Before the cabs go on, perhaps you should do the float height cbfb?
http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html
This may help a wee bit. :niceone:

[cbfb]

In what way were they set to 'normal' - just a measurement from the bottom of the float to the carb body float bowl base? Have you also verified the actual fuel levels in the bowls are correct?

At the end of the day if it's overflowing you have either a leaking float valve or the float valve seat body o-ring (the one where Viton was discussed). There's no other way for the fuel to enter the float bowl.

We used to use an 9kg LPG bottle with a hose off a regulator and a copper rigid end to poke around and accurately locate vacuum leaks. Just do it in a well ventilated area like outside so the gas concentration doesn't build up and get to potentially explosive concentrations.

Yes that is how I checked float height and no I havent checked actual levels as I didn't know how.


That's a neat idea.
Before the cabs go on, perhaps you should do the float height cbfb?
http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html
This may help a wee bit. :niceone:

OK will do...

[disorderly]

are the slide diaphrams in the carbs in good condition? have you checked if they have a hole or a small tear? with regards to idling?

[cbfb]

are the slide diaphrams in the carbs in good condition? have you checked if they have a hole or a small tear? with regards to idling?

I gave the diaphragms a visual check when I had them out. Slide/diaphragm operation looks/sounds as you'd hope - Ducatilover will agree with me there I'm sure.

Well I've decided this has gone on long enough, I want to ride the bloody thing while it's still summer! So will:

- Check/adjust float height
- Refit carbs with sealant
- Warm up
- Use ether to check for leaks if still idling funny

If none of that gets me anywhere, and if this white smoke persists, I think I'm gonna have to take it down the road to the garage :(. Should be OK to ride that short distance as is...

[Gibbo89]

I gave the diaphragms a visual check when I had them out. Slide/diaphragm operation looks/sounds as you'd hope - Ducatilover will agree with me there I'm sure.

Well I've decided this has gone on long enough, I want to ride the bloody thing while it's still summer! So will:

- Check/adjust float height
- Refit carbs with sealant
- Warm up
- Use ether to check for leaks if still idling funny

If none of that gets me anywhere, and if this white smoke persists, I think I'm gonna have to take it down the road to the garage :(. Should be OK to ride that short distance as is...

You've given her a great crack by the looks of things, even if it doesn't work you've learned about your bandit and how it works. I have no idea about how my bike works... :facepalm:

[cbfb]

You've given her a great crack by the looks of things, even if it doesn't work you've learned about your bandit and how it works. I have no idea about how my bike works... :facepalm:

Yeah mate, it's been a learning experience but sometimes you've got to admit you're out yer depth!! Could probably sort it out eventually but too much on atm, just want to ride. Plan is to buy another machine eventually, one to tinker with and one that's working.

Cheers :niceone:

[Gibbo89]

Yeah mate, it's been a learning experience but sometimes you've got to admit you're out yer depth!! Could probably sort it out eventually but too much on atm, just want to ride. Plan is to buy another machine eventually, one to tinker with and one that's working.

Cheers :niceone:

What was you previous experience with small engines?

[ducatilover]

Get into it man! Take it up the road anyway.
A compression check may be in order if there's still a gay idle, but, setting the floats could have something to do with it too.

[cbfb]

What was you previous experience with small engines?

Had a few bikes over in the UK but this was the biggest job I'd done on one. Had rebuilt a GS550 with a friend but we didn't touch the engine much as it was running OK. So a bit of experience and OK with maintenance etc but just find troubleshooting a bit tricky.


Get into it man! Take it up the road anyway.
A compression check may be in order if there's still a gay idle, but, setting the floats could have something to do with it too.

Easy for you to say you know what you're doing ;)

But yeah will run it up and take it up the road. Just really running out of time at the moment and want it done so might have to spend a few $$$s at Simon's...

Yeah the compression check is a bastard on these things, need a special adapter that I don't have to get down into the plug holes, otherwise with my socket-on-a-hose style guage its impossible to get a good seal.

[ducatilover]

I've forgotten, did you set all the pilot screw to fact. specs?

[cbfb]

I've forgotten, did you set all the pilot screw to fact. specs?

Nope haven't done that, you reckon it's worth a go?

Not sure what I'm doing mind you, the carbs in the GSX manual are totally different. Do have what is apparently the factory specs for these BDST30s tho, what do you reckon I go off?

229969

[ducatilover]

Nope haven't done that, you reckon it's worth a go?

Not sure what I'm doing mind you, the carbs in the GSX manual are totally different. Do have what is apparently the factory specs for these BDST30s tho, what do you reckon I go off?

229969
Give one full turn a go, have you got a vacuum gauge?
Wind the screws in 'till they stop (gently) then back 'em off a whole turn. Will be interesting to see where they are currently set.

[MSTRS]

Might be wrong for your bike, but rule of thumb was always 1 and a half turns

[cbfb]

Give one full turn a go, have you got a vacuum gauge?
Wind the screws in 'till they stop (gently) then back 'em off a whole turn. Will be interesting to see where they are currently set.

OK all good will have a crack at that.

Not got a vacuum gauge no, our vacuum was brand new at Xmas so it should be fine ;)


Might be wrong for your bike, but rule of thumb was always 1 and a half turns

OK will give it a try at 1 then wind it out a bit more. Found a handy site about it earlier (and now lost it again will check later when not bogged down @ work).

[ducatilover]

Might be wrong for your bike, but rule of thumb was always 1 and a half turns

That seems to be true, but, my (crap) eyes see 1 turn on the sheet below that cbfb posted up.
That reminds me, I better do mine whilst the carbs are off (I think I already have, but, it can't hurt)

[cbfb]

That seems to be true, but, my (crap) eyes see 1 turn on the sheet below that cbfb posted up.
That reminds me, I better do mine whilst the carbs are off (I think I already have, but, it can't hurt)

Ah that's what it means! got you now. Get a bit lost without the manual.

[Katman]

Have the carbs been balanced?

[cbfb]

Have the carbs been balanced?

Nah not yet, didn't think there was much point while we're dicking around changing things and pulling bits apart. Was going to be a winter project.

You reckon that could be contributing?

[Katman]

Nah not yet, didn't think there was much point while we're dicking around changing things and pulling bits apart. Was going to be a winter project.

You reckon that could be contributing?

Balancing the carbs needs to be the last step in the 'tune-up' process. Valve clearances need to be right first but I'm assuming that you set them in the process of refitting the head.

Yes, unbalanced carbs will most certainly contribute to an uneven idle.

[cbfb]

Balancing the carbs needs to be the last step in the 'tune-up' process. Valve clearances need to be right first but I'm assuming that you set them in the process of refitting the head.

Yes, unbalanced carbs will most certainly contribute to an uneven idle.

Aye valve clearances are spot on. Will get these other things ticked off first before doing the balancing like you say. Cheers.

[cbfb]

Aye valve clearances are spot on. Will get these other things ticked off first before doing the balancing like you say. Cheers.

Um turned out valve clearances were NOT spot on, apparently I'd set them too loose. However in the end I took it down to a mechanics and got that and the carbs sorted properly, runs like a beauty now.