CBR carb probs...

[veefer400]

Am having a few issues with the carbs on my recently aquired CBR6 jellymould of 1990 vintage - the bike has been sat for 6 years in the last owners garage & needless to say - the carbs are full of Übergak.







The carbs are CV type, very similar to Triarm carbs etc - a LOT of stripping and scrubbing later & the bike runs on one/two cylinders, all four when revved, hinting the remaining pilot jets /pilot circuits are blocked (again...)

I have ordered at reasonable expense 4 NEW pilot jets from DSS - my main concern is that the actual pilot circuit itself could be blocked with the nasty gorilla snot gummy sh!te...

How easy would it be to clear this out? Im thinking compressed air wouldnt be enough, could I push a hole thro with say fishing reel wire?

Carbs are back on the bike at the mo so I'm unable to see any detail? Am waiting for the jets to turn up before they come off again.

[Wozza]

Could just be balancing. When my NC23 ran on three cylinders at tickover, balancing was the cure.

[veefer400]

Could just be balancing. When my NC23 ran on three cylinders at tickover, balancing was the cure.

Have had a look down the end of the bellmouths and all the slides look to be the same height so I doubt its balancing TBH??





(Just joking - I hate CV carbs for their lack of workability - I can handbalance my 400/4 carbs in 20 minutes by removing the pod filters and checking the relative slide heights. )

[The Novice]

to it could be balancing from my experience.

after i cleaned out the carbs....twice.....my triarm ran on 3 cylinders at tickover, all 4 when revs applied, as soon as i bit the bullet, bought a set of guages and balanced the bike it idles on all 4 cylinders again and runs a lot sweeter. *although i did have to clean up the plug first as all that running only at revs meant it was all wet.

[Wozza]

If you want to get busy you can do all the following in this order:

Check/adjust valve clearances
Check/adjust float heights
Balance carbs
Tune pilot screws
Tune needle heights
Tune main jet sizes

Although obviously if it's all standard you shouldn't need to change the needle heights or main jet sizes.

I wouldn't put much faith in balancing carbs 'by sight' - can't be very accurate! However I will admit to having balanced my carbs by header temperatures before I had gauges. Not accurate either, but it did get me from 3 to 4 cylinders firing at tickover!

[Cammo]

How easy would it be to clear this out? Im thinking compressed air wouldnt be enough, could I push a hole thro with say fishing reel wire?

The most effective way is to get them ultrasonically cleaned, you may need to separate them depending on the size of the cleaning tank.

[veefer400]

How easy would it be to clear this out? Im thinking compressed air wouldnt be enough, could I push a hole thro with say fishing reel wire?

The most effective way is to get them ultrasonically cleaned, you may need to separate them depending on the size of the cleaning tank.

Granted - havnt the money for this tho as have just lost my job...

Waiting for the new jets to show up, are on special order from Honda - as soon as they get in it will all get another strip & scrub...

Modern petrol is shite, my 400/4's carbs wernt half as bad as this & the bike had been standing for 10 years?? What the hell are they putting in it??

[veefer400]

SORTED.

Stripped the carbs off, removed the pilot jets, held them in longnose pliers -

and blowtorched them.

The nasty goo that was trapped in the chambers either side of the hole itself got turned to ash and was easily removed...

Bike now running good - will finish fitting the bodywork tomoz and see if I can get it in for MOT.