Idling @ 8000 rpm

**Drew** · 17th January 2011, 16:12

Originally Posted by cbfb

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** · 17th January 2011, 17:10

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

**JMemonic** · 17th January 2011, 18:26

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** · 17th January 2011, 19:28

Thanks all for your replies.

Originally Posted by Drew

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.

Originally Posted by renegade master

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).

Originally Posted by 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.

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** · 18th January 2011, 02:37

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** · 18th January 2011, 08:18

Originally Posted by 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?

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:Me** · 18th January 2011, 10:39

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** · 18th January 2011, 10:40

take it too a doctor

**cbfb** · 18th January 2011, 11:06

Originally Posted by 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.

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** · 18th January 2011, 11:08

Originally Posted by Camshaft

take it too a doctor

**ducatilover** · 18th January 2011, 15:23

Fuck, replied before I saw page two.

Fail.

Get the hammer.

**cbfb** · 18th January 2011, 15:30

Originally Posted by ducatilover

They aren't for the slides are they?

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** · 18th January 2011, 15:33

Originally Posted by cbfb

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

**cbfb** · 18th January 2011, 15:41

Originally Posted by ducatilover

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

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** · 18th January 2011, 15:46

Originally Posted by cbfb

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

My toolbox with all my bits and bobs isn't here at home.