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Discussion Starter #1 (Edited)
Forgive the long post but here it goes.
My bike was running great, started and warmed up readily always using the choke for a few seconds to start, ran smooth and then I decided to muddle. I inspected the air filter which hadn't been looked at in years and found it all dried out and partly disintegrated into dust and crud. So I vacuumed and cleaned off the screen, replaced the air filter with a new one, oiled it, worked it in, squeezed out excess oil between 2 rags and reinstalled it. Then the bike wouldn't start as usual. First it wouldn't start at all, then after a while it would run for a second, then restarting it it would run for 2 sec., repeat and it would run for 5 sec, then after multiple attempts it would stay running but not steady, it would miss every once in a while. It also would blow white smoke out of the exhaust 'till it warmed up, which it never did before. I pulled the plug and the electrodes looked dark and I thought it may be running rich, maybe from the new filter restricting airflow, bit it did the same with the filter off and the airbox open for a test. So the next thing I decided to do was to clean the carb. Besides being a PIA to remove it, I did, (with the help of all the info on the forum) and without damaging either of the carb boots which were still reasonable soft and pliable after being 18 yrs. old. There was no debris or dirt in the carb bowl, the float needle is patent (can easily blow through it with the carb upright, can't with the carb inverted) so I did not remove the float and its' needle, but I removed and cleaned out the main and pilot jets (which were both patent). I checked on the pilot screw and it was 2 1/2 turns out and I reset it to the same. I blew carb cleaner through every passage in the carb. The petcock on the tank is not plugged, there is a free flow of fuel with it open and you can easily blow through it. The fuel line is clean and shiny inside. The gas cap vent is not clogged 'cause the bike runs bad with the cap on or off. I also put in a brand new plug with the correct gap. Since I cleaned the carb and reassembled everything, the bike is easier to start but still only runs for 2 sec at first attempt. then 3 sec. then 5 sec, and maybe after 10 tries will stay running. It takes a while to try and push in the choke (enricher) until it will stay running. It responds to the throttle but misses or stumbles at first, then revs up and runs smooth at mid and high rpms. It idles fine but will slowly slow down and then die, but will start in a fraction of a second after that. If the bike sits for a few min it will not start without the choke, even though it is warm. I have no air leak around either airbox or manifold boot as nothing happens to the engine rpm if I spray carb cleaner over them or the carb joints. There is also no smoke from the exhaust now. I had put 1-2 oz Berryman's in the gas tank, which had about 2 - 2 1/2 gal gas in it, ran it for 5 min, let it sit overnight and maybe it runs a tiny bit better, but not much. So this has to be a carb problem, right? Where do I look next, have to do this all over again? I am thinking of dumping another 2 oz Berryman's into the tank to get a decent dose run through the carb and let it sit overnight and see what happens before digging into this again. Any thoughts or suggestions?
 

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Ok – first off, thank you for one of the most informative “”problem” posts on this board – (others take note)

Second up – the initial puffs of white smoke where more than likely due to the freshly oiled air filter settling down – no worries there

The rest of it comes down to some simple things I’m sure you’ve read here before – you’ve been here longer than me – but this still needs saying ….

With carb cleaner, it only takes care of “tar” and other such small stuff that’s dissolvable, and despite a “soaking”, will not yield a result until you actually run it through the carb, rather than simply soak it overnight. On an overnight session, the carb cleaner will reduce most of it to “sludge”, but that sludge still needs to be run through the carb before it can attack the underlying layers

Expect a run of 50 miles to even start to clear it out, then soak, rinse and repeat – carb cleaner is good munchies, but it takes time, and persistence

Next up (and I realise that I’m preaching to the converted here) – just because you think the jet is clean, doesn’t actually mean that it is. These carbs are so small that any small particle (dislodged by the carb cleaner) may still be blocking the jet. New jet is simple five buck fix, which together with the carb cleaner can work wonders

You have very aptly described what you have done already, but I would strongly recommend you do these last two things (at minimal cost and fuss) first

Continue with the carb cleaner, run the bike with the treatment in the tank (for 50 miles), and if that doesn’t do it – change the jet

Good luck …..
 

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Discussion Starter #4
Purple - I did squirt carb cleaner and run a small wire through the jets and hold them up to the light and look through them, and they looked clean. And thanks for the heads up about the oil on the air filter burning through and giving the smoke out the exhaust.
And grewen - yes I did run it without the air filter on and there was no difference.

I also looked closer at the intake boot and it looks almost new but I am going to gob some silicone around the junction with the carb just to make sure there is no air leak coming through that joint, and will put another couple of ounces of Berryman's into the tank and run it all through before taking it apart again.

Anxiously awaiting more suggestions on here.
 

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You mentioned a crumbling air filter so could it have gotten particles in the choke circuit? Did you remove the choke assembly when blowing everything out? There should be a port in the throat of the carb which feeds the choke circuit iirc.
 

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Year and mileage? Always year and mileage, and confirmation on "old" slide carb or "new" cv carb is nice to know. Has the bike been in storage up until now?

If I'm you... I'm looking closer in the air box to make sure some rodent friends didn't make a home in there. Then, I'm looking in the tail end to make sure the spark arrestor is clear. Next, I'm going after the carb. On an 18 year old bike, there is too much risk of frustration, so I'm not dicking around. Things get old, things wear, rubber gets hard and breaks down, so I'm buying any and all replaceable OEM carb parts available... pilot needle set which includes new o-ring, pilot jet, main jet, main jet holder, needle, float needle and seat , bowl gasket, and etc. depending on what style carb it is. If vacuuming off the air filter screen, there is a good chance some debris got sucked in and is blocking the pilot circuit. After it's broken down, I'm soaking it in a simple green solution, ideally running it through a sonic bath, and blowing out those passages with compressed air, then installing all new parts.
 

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Now that's the way ya do it. Right the first time. :headbang:

I remember a sign on the wall in one of the places I worked years ago that said: "If you didn't have time to do it right the first time, where were you planning on finding the time to do it the second time?"
Year and mileage? Always year and mileage, and confirmation on "old" slide carb or "new" cv carb is nice to know. Has the bike been in storage up until now?

If I'm you... I'm looking closer in the air box to make sure some rodent friends didn't make a home in there. Then, I'm looking in the tail end to make sure the spark arrestor is clear. Next, I'm going after the carb. On an 18 year old bike, there is too much risk of frustration, so I'm not dicking around. Things get old, things wear, rubber gets hard and breaks down, so I'm buying any and all replaceable OEM carb parts available... pilot needle set which includes new o-ring, pilot jet, main jet, main jet holder, needle, float needle and seat , bowl gasket, and etc. depending on what style carb it is. If vacuuming off the air filter screen, there is a good chance some debris got sucked in and is blocking the pilot circuit. After it's broken down, I'm soaking it in a simple green solution, ideally running it through a sonic bath, and blowing out those passages with compressed air, then installing all new parts.
 

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Just a suggestion here. It only takes a few minutes and 3 bolts to pull the muffler off. Pull it and stand it on end with the head pipe end facing up. Gently tap the muffler on the sides with a rubber mallet and see what comes out the end while tapping it on the ground. If you see seeds, you may have a mouse nest in there restricting flow. I found one in my 73 RT3 360 pipe. Took forever to clean that thing out of there. :mad:
 

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Here’s one last thing to check. Depending on who or what you believe it may be the first thing to check.

Set your alarm for sometime in the middle of the night. Sneak out to the garage, rush in and flip on the light. Search the garage throughly for the individual I have in the below photo.
I can’t prove it, but I believe he has caused me some difficulties in the past.

 

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Hmm, Seems you've tried about everything. At this point I would try a compression test, (maybe a valve sticking or being held open by something), and like "OlderthanDirt" said, check the exhaust. I've seen everything from critters nesting to the inner wall of double wall exhaust pipe rusting out and blocking exhaust flow.
 

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Discussion Starter #12 (Edited)
With all due respect to Littletommy. I have a better sign for you - "If you didn't fix it and get it right the first time, you probably f'cked up, so do it over".

I took the carb off and apart again (I'm getting really good at that, and much quicker too) and found a small speck of something partially clogging my pilot jet. Cleaned it out as well as the entire carb again, got it back together real quick and it now starts and runs great, altho I still need the choke to start it when cold but that's how it's been since I got it 10 yrs ago. After running 30 sec or so I can turn the choke down and off. When warm it starts b in a fraction of a second, even before I can get my finger off the start button. It runs good, very smooth, accelerates without a hiccup and all's well.

Incidentally, while messing with it, I looked real carefully over the entire exhaust by the front of the bike because I thought I was hearing the whiff of a poot-poot exhaust leak but I couldn't find where it was coming from. I found it after I removed the heat shield on the pipe - there was a 1/8" diameter rusted out hole in the pipe right under the middle of the rear bracket that the heat shield rear screw goes into. Since I didn't have a new exhaust pipe lying around, I fixed it with some high temp exhaust repair compound, then a small piece of aluminum over that, all held in place very well with the heat shield mounting screw over it. So now the noise is gone and the Rube Goldberg/redneck repair is hidden with high temp black paint and the heat shield over it, so all's well for now. If anybody has a similar situation where they can't find a tiny exhaust leak, look under the heat shield.

Thanks everybody, and remember, itr's usually the little things that count the most.:eek:ccasion14:
 
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