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Running on 3 cylinders
steve8274 - 8/6/14 at 09:37 AM

Hi all
My car appears to be running on 3 cylinders. Sounds lumpy and 1 off the exhaust manifolds doesn't warm up.
I replaced the spark plugs since it was a job I was planning anyway but still no joy. Checked to see if I was getting a spark and I am so it must be fuel.
Problem is it's running on motorbike carbs and I not sure how to check/fix it. Is it possible that 3 carbs can be working and 1 not? I sprayed carb cleaner in all carbs. 3 of the times, engine changed note, almost stalling. On the one that wasn't working, when sprayed, the engine didn't change much.
Engine is a 1.8cvh with I believe zx6r motorbike carbs. The carbs were set up by Gbs and have been fine on the car for 3 years.
Any ideas? Please keep it simple because I unsure on working on bike carbs.
Regards
Steve

madteg - 8/6/14 at 10:19 AM

Sound to me like the float is stuck, try tapping the float bowl. should strip really.

steve8274 - 8/6/14 at 11:17 AM

I was thinking something like that but as I say I am unfamiliar with bike carbs. Is the float bowl the black cover on top? Looks like it has a screw in each corner. If I tap with hammer, anywhere in particular? Top, side?
If I undo the screws, are springs etc gonna go everywhere?
Thanks

[Edited on 8/6/14 by steve8274]

owelly - 8/6/14 at 11:58 AM

Float bowls are on the bottom of the carbs. Be carefull you don't ruin the gasket as you drop the bowl.

philhoward - 8/6/14 at 02:06 PM

Have you checked to see if you have an air leek on the manifold gasket?

davidimurray - 8/6/14 at 02:15 PM

First check - are they balanced? Mine starts to misfire as the balance drifts.

steve8274 - 8/6/14 at 04:00 PM

Don't think there is a leak. Can't feel anything and the engine doesn't change note if I spray the manifold. Not sure if they have lost balance. Car was running fine. Stopped off for short while and when I restarted, it was on 3 cylinders. Carbs hadn't been touched.

Dingz - 8/6/14 at 05:33 PM

Could be just a stuck needle valve in that carb or dirt in the main jet, you need to take the float bowl off to have a look.

19sac65 - 8/6/14 at 07:41 PM

No need to drop the bowl
Theres a drain screw on each bowl
Undo it and see if fuel comes out , if it doesnt then take the bowl off
If it does ide do a compression test

steve8274 - 8/6/14 at 09:04 PM

quote:
Originally posted by 19sac65
No need to drop the bowl
Theres a drain screw on each bowl
Undo it and see if fuel comes out , if it doesnt then take the bowl off
If it does ide do a compression test


Ok will try and find drain screw. If fuel does come out, then what? Not got a congressional tester so will have to take to garage for that.
Really hope it's an easy fix. Only just starting to get some enjoyment out of it.
Thanks
Steve

rusty nuts - 9/6/14 at 06:42 PM

Might be worth checking the compressions,I've had rockers come loose on the CVH engines in the past which result in the valve not opening

02GF74 - 9/6/14 at 07:08 PM

Stick your hand over the intake of each carb. You shoukd be zble to feel air drawn in, more noticeabke if yku fingers are danp.

steve8274 - 9/6/14 at 07:35 PM

Didn't have a chance to look at car today 😟. With regards to rocker covers loose, I would have thought the spark plugs would still get wet with fuel even if the rockers weren't lifting. My spark plugs where dry and all looked normal. Will check it out tho.
Also, I did put my hands over intakes and I could feel air moving. You could also hear the sucking. Putting hand over any if them didn't alter engine sound