Recently bought an 02 with 17k miles and have been chasing problems on it ever since.
When I got it it refused to idle steady when cold, choke hardly helped, I had to give it throttle to keep it going. Later it developed issues resembling a vaccum leak and I found that the intake boots were leaking so I changed the o rings. So far I've adjusted the valves, installed k and N lunch box, rejetted for the lunchbox based on wiki recommendations, cleaned the carbs, new plugs, and changed intake o rings. It's definetly better now but still acts funny when cold, I can now get it to shoot up to the high idle when cold with the full choke, but I have to help it get there, once I rev it up a bit it will hold it like it should. If it's idling while cold it seems to run better at half choke. It will idle like you'd expect with half choke (around 2-2.5k) with half choke, but if I go from half to full it will drop idle and want to die. Once it's warm the full choke will idle its self up fine.

I've done a warm compression test, they tested both 110 psi, which I know is low, but there was no variance across each cylinder , and adding oil didn't change the readings more than 5 psi or so, so I think either a weak battery or my shitty tester may be to blame for that low reading, so I don't think that's the cause of the problem.

I haven't syncd the carbs yet but I don't think that's the issue and I want to correct whatever this is before I do. Any suggestions will be appreciated, I'm really starting to reach my wits end with this thing.

I know you said that you cleaned the carbs, but it sounds to me like the choke (enrichening) circuit is still a little dirty. How did you clean them?

Did you mess with the air/ fuel mixture screws? Just a long shot, but a faulty oring around the screws or even a broken mixture screw needle can mess with idle.

Just curious - did you do the compression test with the throttle wide open?

I didn't actually disassemble the enrichment circuit to clean it I just shot some carb cleaner thru, so I should probly take that apart to clean it.
I actually replaced both mixture screw orings to rule that out.

I did the test with throttle wide open but thinking about it since these are cv carbs the  slides were still choking air so maybe I should do it again with carbs off.

Just recalled a potentially relevant piece of info, the choke mechanism it's self squeaks a little bit when being actuated, I wonder if that could indicate an issue within it.

Sounds to me like the idle mixture is too rich.

Any chance you didn't get the old o-ring out when changing the pilot needle o-rings?

Anyway, I'd say just turn the idle mixture screws in each 1/2 turn and see what happens. If the situation improves and you don't have hanging idle, then go another 1/4 turn, test, ride, repeat, etc. until you get the idle mixture as lean as you can without having hanging idle.

I definitely got the old o ring out, but now I have discovered the issue is larger. Took it for a ride and after rejetting and installing the K and N lunchbox, it compleatly falls on its face around 6 k, good power to that point bit then it just drops off, also sounds like it starts to spark knock. Seems like the o rings on the intake were still leaking with a carb cleaner test so I rtv'd them, also I  went ahead and blew in the vaccum line  after taking a puff off an e cig and noticed that a little vapor was coming out around the circlip that holds the throttle assembly in on the outside of the carb. I'd imagine that shouldn't happen, but couldn't find any o ring or such that would control it or could be replaced on any parts diagrams. Any thoughts?

I think you're saying it runs OK when it's warm, and it stars OK on half choke. If so, just use half choke when starting and call it good.

Quote from: jamesf on June 28, 2017, 03:45:09 PM
after rejetting and installing the K and N lunchbox, it compleatly falls on its face around 6 k, good power to that point bit then it just drops off, also sounds like it starts to spark knock. Seems like the o rings on the intake were still leaking with a carb cleaner test so I rtv'd them

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The problem you are describing sounds like the slides are not coming up or he main jet is way too small. Many reasons for this but make sure you are not spraying carb cleaner into an assembled carb since it can literally melt the rubber diaphragms, which could cause the exact behavior you describe.

Pull the carbs and inspect the rubber diaphragms for tears and holes. Verify the slides move freely and needles are moving smoothly through the main jet. While you have it apart makes sense to verify float height just in case but I really doubt it is the cause of this problem. My money would be on a damaged rubber diaphragm or entirely too small jets.

What size main jet did you put with the lunchbox?

Obvious is to return to stock air box and jets then make it run right stock before making mods.

BTW rtv is not needed or recommended for the intake boot o rings. If they were new and leaking then there is some other problem.

also I  went ahead and blew in the vaccum line  after taking a puff off an e cig and noticed that a little vapor was coming out around the circlip that holds the throttle assembly in on the outside of the carb. I'd imagine that shouldn't happen, but couldn't find any o ring or such that would control it or could be replaced on any parts diagrams. Any thoughts?
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The diaphragms are in good shape so far as I can tell, no tears or holes. I didn't spray carb cleaner in an assembled carb, only with all the rubber including diaphragms removed, what I meant with the carb cleaner test was spraying it around the boots to look for leaks.

I verified that the slides were functioning earlier by running it with the filter off and observed the slides going up with throttle as they should. They did jump around at low rpm wjen being revved but I've read that's normal.

I used a 140 sized main, 65 mid, and 20 pilot.

Alright then maybe it's float height is way too low?

Is it literally 6K rpm and won't rev past that even in neutral on the side stand? Or do you mean, under load and WOT in some gear it hits 6K rpm and refuses to rev beyond that? This makes a difference, so trying to clarify.

Someone that knows much more than me about issues with the three-stage carbs running on the main jet will have to chime in to sort this problem out. I just think your idle mixture is too rich which is causing your choke/warm-up behavior.

It revs fine in neutral, it's only when loaded. It just feels like it hits a wall, it's not exactly 6k, varies between like 6 and 7 where it craps out, it will continue to climb in revs but it has absolutely minimal power as it does, also makes an arythimic clanking noise right when it hits the wall which I assume is after firing or spark knock from it leaning out.

Maybe someone who also has the lunchbox can chime in, but did anyone else notice that the boots on the lunchbox are a larger diameter than the factory airbox? They seem to be tight once the clamps are tightened but it's a VERY loose fit when the clamps aren't tightened, I'm talking gravity makes it fall off, maybe amazon sent me the wrong part or something, I haven't checked to see if it's leaking from there or not, but I'd imagine if it is that could totally cause this.

Correction to previous post, I said after fire but I meant backfire

Problem solved, I'm a complete moron, took right side bowl off and the main jet was just sitting there. Must not have tightened it enough. Runs like a champ now. Cold idle still a little funny but I think it just needs carbs balence at this point.

Quote from: jamesf on June 30, 2017, 11:50:59 AM
Problem solved, I'm a complete moron, took right side bowl off and the main jet was just sitting there. Must not have tightened it enough. Runs like a champ now.

Great! love it when it's that easy. I knew it was a main jet issue, good that it was so obvious.

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Cold idle still a little funny but I think it just needs carbs balence at this point.

I still think you have the pilot mixture set too rich.

Certainly could be, but leaning it out actually makes the revs take a while to drop down, maybe that's a separate issue that I'm just covering up by over richening it, although I've found and fixed several vaccum leaks and none are present now. Maybe the rev hang is caused by the lack of carb sync and the idle issues are caused by it being too rich.

Yeah the hanging idle probably means one of TWO things (in combination, generally):

1. idle set too lean
2. idle speed set too high

If I were you from your description I'd set the idle 1/4 turn more lean (mixture screw 1/4 turn in) on both carbs and then make sure you are setting the idle speed with the bike FULLY WARM. Ride it on the road 20 minutes then set idle speed for like 1200 rpm. See if you can get the idle to behave correctly on cold start with choke and also get rid of the hanging idle. Set it as lean as you can with no hanging idle. With the bike fully warmed up you can then tweak the idle mixture 1/4 turn at a time until there is no sign of hanging idle, use the idle speed to keep it where it belongs.

Bear in mind you may very well have to let the bike warm up on choke or nurse the throttle for a long time when it's cold once the idle mix/speed is set correctly.