How many RPMs on full choke? ZL600 1997

[Davidtrom]

It use to be about 5000rpm when cool and climb up to 5500 in about 30-40 sec them
on half-choke about 3000rpm
and idle at about 1000rpm

The thing is, the other morning I went to start the bike and on full choke went only to 3000rpm and when I took the choke off it just dies.

I put some Gummout in the tank and now it runs with not choke, but on full choke only goes to 3000rpm.
When I ride it with no choke it has no power, any ideas?

I just clean the carbs about 3 moths ago, it was riding great and the next morning this.

[shiftless]

Originally Posted by Davidtrom

It use to be about 5000rpm when cool and climb up to 5500 in about 30-40 sec them
on half-choke about 3000rpm
and idle at about 1000rpm

The thing is, the other morning I went to start the bike and on full choke went only to 3000rpm and when I took the choke off it just dies.

I put some Gummout in the tank and now it runs with not choke, but on full choke only goes to 3000rpm.
When I ride it with no choke it has no power, any ideas?

I just clean the carbs about 3 moths ago, it was riding great and the next morning this.

When I first purchased my bike in '99 it was a 2 year hold-over bike (i.e. a '97 model new, never sold, although it did have just a few miles on it) and I had a tough time getting it started and keeping it going (it even had a tendency to stall while on the move - never a good thing). The dealer it seems had left gas in the bike for those two years and that gummed up the carbs pretty bad. I had the carbs cleaned by a dependable shop and it ran fine after that. Until a couple years later when dirt got into the carbs (mentioned in the other post re: an the inlet stack on the fuel tap decided to go AWOL) and played havoc with the fueling (talk about rough running!). The carbs were cleaned again and I fixed the fuel tap and it's been running fine ever since.

Carbs can be finicky little devils. They do not like dirt at all as dirt can plug up the various small fuel passages, that can cause fueling problems. There are other issues too, i.e. a bad diaphragm, or vacuum leak, or a mal-adjusted metering needle can also cause fueling problems. In these cases the engine may be hard to start and will tend to run rather rough.

Unless the weather is rather cold, 40's or below, I don't need to use full choke at all. I just use partial choke and the bike starts right up. After a minute or so of warm up I'm on the road with partial choke still on but only for another minute or so, then I take it off choke. I have my idle at about 1,200 rpm. You might want to bump up the idle on that puppy just a bit (although that's probably not the issue). The book says 1,000 to 1,100, but I find that 1,200 works better.

Other possibilities are that the vent tube to the fuel tank could be plugged or kinked. If this happens a vacuum builds up in the tank as fuel is drawn from it and at some point the vacuum is sufficient to prevent fuel from reaching the carbs. Also the fuel tap could be the problem, it works off a vacuum and if the vacuum line is detached or plugged the fuel tap will not let fuel flow, or if the diaphragm inside is worn then again no fuel flow. Actually the fuel tap can also fail in the other direction, i.e. always letting fuel flow even with the engine off, but that's probably not your situation.

To make an unnecessarily long story short, do the easy stuff first and check the tank vent tube (attached to the underside of the tank) and maybe remove the fuel tap and do a refurbish of that (they sell a rebuild kit for that with the few replacable parts you need, it's simple DIY job).

Just curious, can you get the bike running at some point? If so does it run smoothly?