Hi again guys

I though my bike sounded a bit rough and I have now discovered that it was only firing on 2 cylinders.

I have had to bite the bullet and take my carbs off again (AAARGH!!)

Stripped down the bowls and cleaned up the slow jet and the main jet. However the 'third' nozzle (no screwdriver slot) which i don't see as a spare part. 2 points.

1. Can it be removed or is it an integral part of the carb?
2. Is the best way to clean it just with a bit of wire as shown in this excellent post; https://cbrforum.com/forum/how-tos-8...ll-gas-104182/

Excuse my ignorance but can someone explain the slow jet/main jet set up to me. The slow jets were most definitely blocked but the main jets were clear. Bike was not firing at both idle and fast revs. Does the slow jet need to function fro the main jet to work. I thought that if the slow jet was blocked then I would have still been able to get fuel through the main jet at fast revs.

I have checked the ignition and I am getting a spark OK.

Anything else that may stop the fuel getting to the carb, float valve?

 

The slow or pilot jet works at lower RPM. The mains take over when the needle is lifted at higher RPM allowing more fuel as needed.

I think the third one you were asking about is a breather tube that balances outside air pressure to the bowl. It should be clear or fuel won't enter the bowl as pressure would build and flow would stop.

If #2 and #3 aren't getting fuel, sounds like both needles are stuck with gunk. You would need to pull the carbs and check.

 

No gunk on the needles on 2 and 3. Funny thing is there was a small amount of gunk on 1 and 4 needles!!

I will check the breather tube tomorrow and see if any blockage.

 

Slow (Pilot) Jet needles are out front on the motor side of the carb unit
when you pull the carbs to clean again

pull the needles and clean (there's a washer , spring and oring in there too)

pull the pilot jets (slow jets) and clean - the top of each of those has a microscopic
hole that should be clear - almost need a magnifying glass to see it - use solvent
and compressed air- don't run wire or an anything through----- it's there trust me !

Usually they get get caked up with brown crap and are impossible to see

 

No offence, but I've gotta wonder about two cylinders that share the same coil that aren't working.

 

and each float valve has a fine screen that sometimes needs cleaning

 

Yep i saw that in the service manual. I have a 1997 model where the seat is part of the carb (non-removable)

Going to run some fuel from a funnel with the carbs off to see if the bowls fill up!!

 

I am getting a spark at the plugs. Is that sufficeient to confirm the coil is working OK?

It is really weird numbers 2 and 3 (the non runners) are really clean inside (pilot jet, main jet). Numbers 1 and 4 (the runners) the main and pilot jets are mostly clogged.

It is almost as if someone has cleaned the carbs at some point and numbers 2 and 3 have never seen fuel since. The needle valves on 2 and 3 are like new, brightly polished silver.

??

 

^ The thing is, fuel can only enter the bowl by way of the needle and seat.
Something have to be clogged there.

 

Fuel getting to bowls OK. Just done a bench test all clear

I have come up with another potential issue. On my bike cylinders 2 and 3 have a rubber cap and spring clip to blank off the tap of points for the vacuum gauges for carb balancing. The rubber blanks are rock hard (more like plastic) and I can pull them on and off with my fingertips. The rubber is so hard that the spring clips are not even making an impression in the caps.

Could it be that these are passing and not allowing enough vacuum to pull the fuel out of the bowls? That would certainly explain why number 2 and 3 carbs are as clean as a whistle (never seen fuel) and numbers 1 and 4 are really dirty.

Can any member confirm whether the rubber caps on their bike are hard or soft. I have ordered the parts from Honda anyhow, only cost £5

Thanks again for all your feedback