Idling @ 8000 rpm

[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

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]

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]

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/carbt...m_engines.html
This may help a wee bit.

[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/carbt...m_engines.html
This may help a wee bit.

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...

[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...

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

[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

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.