1990 600f Idle Trouble

[ridingthe603]

My recently bought katana is having some idle trouble. I start the machine up and after turning off the choke the bike idles at 4000. The guy I bought it from is an older certified moto mechanic. He said that he had cleaned the carbs 3 days before selling it. I dont think the throttle or choke is sticking but not 100%. The previous owner said that the owner prior to him had placed aftermarket jets in the bike and had done no other work. Would installing the stock jets fix my problem? I also tried adjusting the idle screw, it would get down to around 3500 then with the slightest turn shoot down to 1100 and the machine would die. I also put 93 ocatane in, dont know if thats a problem? If anyone could help me trouble shoot this problem before I start digging into my wallet that would be great.

[Kreylyn]

My recently bought katana is having some idle trouble. I start the machine up and after turning off the choke the bike idles at 4000. The guy I bought it from is an older certified moto mechanic. He said that he had cleaned the carbs 3 days before selling it. I dont think the throttle or choke is sticking but not 100%. The previous owner said that the owner prior to him had placed aftermarket jets in the bike and had done no other work. Would installing the stock jets fix my problem? I also tried adjusting the idle screw, it would get down to around 3500 then with the slightest turn shoot down to 1100 and the machine would die. I also put 93 ocatane in, dont know if thats a problem? If anyone could help me trouble shoot this problem before I start digging into my wallet that would be great.

The "Stock Jets" and "Aftermarket Jets" are all refering to the main jets. Those will really have no effect on your idle, so they are not the issue here. (they may be a seperate issue, but not related to idle at this time).

So, no... changing them will not solve your issue at the moment.

Your bike has an idle circuit. This circuit is not clean. Yes, a claimed certified mechanic can half azz it to sell it quick without actually doing the job right.

Cleaning the carbs are simple. There is a full walkthru on the website (carbs 101, search in the wiki... link at top of page). To truely clean the carbs, you must remove all jets and soak/dip the carb bodies.

If the guy just opened them up and blew around some carb cleaner spray... he definatley didn't "clean" the carbs... That's like taking a dirty rag, spitting on it... and wiping your window to clean it.

See this recent thread for some more info on how your CV carbs work.

http://katriders.com/vb/showthread.php?t=110522

Krey

[ridingthe603]

Thanks Krey,

I read through that Carbs 101 bit. I believe I could do this im just worried about syncing the carbs, I hear its difficult and I dont have a meter. I really want to do this but I have limited time. How long does this usually take?

[Kreylyn]

Thanks Krey,

I read through that Carbs 101 bit. I believe I could do this im just worried about syncing the carbs, I hear its difficult and I dont have a meter. I really want to do this but I have limited time. How long does this usually take?

Plan on 1 hour per carb body. Generally the dip can only holds 1 at a time. I suggest 12 hours soak per body.

If your doing it casually, 4 days... (30 mins to dis-assemble, soak it 12 hours, 30 mins to reassemble).

Sync is actually very very simple to do, and a sync tool can be made for less than $10.

krey

[ridingthe603]

You can make a sync tool!!?? Where can I find directions on how to do that? I also read that the idling problem can come from the throttle/choke cables and vaccuum seals. How do I test to make sure these arent the problems before I take out the carbs?

[Kreylyn]

You can make a sync tool!!?? Where can I find directions on how to do that? I also read that the idling problem can come from the throttle/choke cables and vaccuum seals. How do I test to make sure these arent the problems before I take out the carbs?

http://katriders.com/vb/showthread.php?t=92640 for the sync tool info...

For the cables, just make sure they are loose and not binding... if no differnece, then it's not the cables.

For the vaccuum seals/leaks... with the bike running, spray a lightly flamable liquid around the various boots spots and listen for the RPMs to pick up. If they do, you found a spot that has a vaccuum leak.

Krey

[ridingthe603]

hey thanks for all the help, i ran some checks on the bike this weekend and discovered i had a couple bad seals that were causing the erratic idling. Runs great now, i do however plan on taking apart the carbs and cleaning them this winter.