Carb problems again !

[Guest]

I'm finally recovered enought to get back to wrenching and am trying to finish off the Kat project.

When I was last on the project back in May she was ready for the road but on my initial road test I couldn't get it to shift up from first. I parked it then and got caught up in other things.

I think I now have the tranny/shifter issue figured and was about to retry the road test but I couldn't get the bike to run off of choke.

Back at the begining of the year, I had cleaned and rebuilt the carbs ( exactly as per the tutorial, strip dip and new o-rings), adjusted the valves and did the coil mod. Despite these, the bike was hard to start and there was a really long thread on that back then. It finally did start and after a synch it idled perfectly at around 1100 rpm.

Now after sitting, it will start and run on choke but won't idle. I notice also that cylinders 3 and 4 don't get hot and are likely not firing due to lack of gas since when I blow into the overflow tube the revs go way up but then quickly drop.

As it seems the problem is with carbs 3 and 4, I pulled the rack today and recleaned them ( didn't dip but sprayed and blew out all ports and ran a wire through the jets). Sadly no change and I still can't achieve idle.

I'm sure gas is getting to the carbs as I can blow it out via the overflow tube and it does drain from the bowls when the drains are open. I can feel engine vacuum too but the gas is only getting in when I blow through the overflow. I'm very confused now and research throught the archives didn't turn up anything.

Has anyone experienced anything like this?

As always all input is greatly appreciated.

[bobthebiker88]

clogged pilot jets. remove carbs and clear all jets so you can visibly see light through them.

[tom203]

clogged pilot jets. remove carbs and clear all jets so you can visibly see light through them.

Yeah, very logical. When you blow into overflow hose, fuel is pushed up any openning (choke tube, main jet ) and compensates briefly for clogged pilot jets. My son's ninja can't sit for two months without clogging these tiny jets!

[spyug]

Thanks guys but I guess I didn't make myself clear. I did pull the 3 and 4 carbs completely apart and removed all jets. I did blow them clear and stuck the wire in every hole. I also sprayed and blew out all passages.

As the tank had been cleaned and sealed, the petcock cleaned and rebuilt and fresh hoses, I didn't expect any gunge or crap and didn't find any. I always run Seafoam in every tank as a stabilizer and I put a 1/4 can in this tank of fresh gas.

This is a baffler as the carbs are clean and getting gas, the engine vacuum is pulling and there is spark.

Any more thoughts folks?

Cheers,
spyug

[KiwiGS]

Ok, so just spit balling here

So for combustion you need, fuel, air, compression and a spark.

Fuel: You say the carbs are clean and getting fuel, and I believe you have done them properly.

Air: IIRC you have pods on this bike, try changing them around I don't expect there to be a change, but it is better to eliminate the air side of things. No sneaky leaks around the head?

Compression: I seem to remember you checked it, and you say the tappet clearances are done. So is the timing ok? On the surface it would appear that the timing isn't an issue because the fault is on 3 and 4, but better to eliminate it.

Lastly: Spark, you did the coil mod, everything ok after that? Leads on the right pot etc etc.

Ok those are the steps I would do. Others who know more than me will no doubt chip in.
On a side note, my little car had a similar fault, I checked and checked everything, followed the steps above. Still no joy, turns out I had water in my fuel, which then hid in the filter and the bottom of the carb bowl waiting to catch me out....like I said just spit balling....
Cheers man

[spyug]

Thanks Kiwi.

I was thinking back to the original trials I had to get it going back in the spring. It was a bugger. Nothing I seemed to do would get any fire in the hole. Tons of help from the fellas but nothing until someone suggested putting "clingfilm" over the mouths and poking a tiny hole in the film. Worked like a charm.

I hadn't tried that today but I guess its worth a go. Maybe I'll get a chance to do that tomorrow.

Its an odd situation that's for sure.

Thanks for input. I'll let you know when I get it sorted.

Cheers,
spyug