I'm new to the forum, but am looking forward to hearing from you folks! I have a 1990 GL1500 that I picked up as a basket case of sorts. I've been restoring it over the last couple months and have actually put 1000 miles on it (mostly without any body parts lol).
It's had a sort of misfire from the start and is consistant as far as sound goes. I recently synced the carbs and now, when cold (well, in between cold and operating temperature), it runs very well, could not be better. After it gets closer to operating temperature, it starts to develope a mis. Seems like always the same cylinder (though I don't know which one it is). There is also notable lifter noise, seemingly from one or two lifters that gets louder when it heats up.
Things I have checked... First thing was changing the plugs, made no difference and they all looked good. I did a compression check of sorts with the throttle closed. All cylinders were within 2 lbs of eachother at 120 lbs (WOT would make that higher I'm sure, but they were consistant, so no big leaks and that's what I was after at the time). Changed oil to Rotella 15W40.
It does not appear to be a hard mis, as if I remove the plug wires one at a time, the bike runs different with each wire removed. I ran a very small amount of Seafoam in the oil and have considered running a larger amount... I run Seafoam in the fuel regularly and have run high octane and low octane fuels.
To my knowledge the choke is shutting off completely, but I suppose there could be some leakage... The plugs are anice tan color. They look picture perfect. Until I synced the carbs, one side was just a tad on the rich side (more blackish in color), but is more even now.
as all looks ok what you can try when the bike warms up under the right intake manafold is a termo valve about 3ins long gold and silver it conects to the heat exchanger on the bottom of the carbs if you have a small long nose visegrips clamp one of the hoses just to stop the water flow and see if the symptons go away
Interesting, I'll give that a shot this evening. Seems to me it didn't always have this problem, well at least not that I noticed. When I first put it together I had that hose blocked off, as the radiators are from a different year and did not have the inlet at the bottom to receive the bypass hose coming from the carbs. I made some mods to the hoses to accomodate the change. I'll get back to you with results.
I tried choking of the coolant to the carbs on my ride in this morning. I choked it off near the radiator, as I have free access there. No real notable difference... Any other thoughts?
Oh, one other notable thing... I did notice that since syncronizing the carbs I tend to stall after a long deceleration (coming off the highway or down a steep hill). Starts right back up and idles fine at 800 RPM... Wierd!
hi lorne check the sub air filter on the right hand side it may have disinagrated and been sucked into the carb lines also you will need to see if you have a small vacume leak spray a little wd40 around the bottom of the carbs on the islators when the bike is ideling see if it smooths out
Well, all seems to be in tact there and the WD40 made no difference. It all seems to be related to one cylinder, every revolution. It appearently fires, but not like the rest. You can hear it in the gear noise and exhaust and lightly feel the vibration in the ride... Lower ambient temperature seems to make it take longer to fail. At 53 degrees F (11.66 C) it took 20 minutes "after" reaching operating temp to fail. On a really hot day, it's within a couple minutes of starting.
i changed mine last week. it was old but intact until i touched it. its a very easy job. thats the first time i replaced it and it took abot 20 minutes. have you re checked the sync and vacuum hoses. from most of the posts here that is one of the biggest problems these tanks have.
I synced the carbs last week. It was out a little. It runs much better than itused to before it gets up to running temp, but it seems to have exaggurated the problem when hot. Near as I can tell the vacuum hoses are OK. The one on the left side between the plugs was shot, so I replaced it.
hi lorne the answer is no from what you have discribed with the warm up i would say you have some thing expanding with the heat and causing a vacume leak prob in the intake manafold just on that cylinder may be it has a small crack closed when cold and open when hot try all the bolts holding them to the heads also you need to check the camshaft bolts on that side as the lifter noise may be that also
Well, I did some vacuum checks and wasn't able to find any real issues. I ended up contacting agenlteman that used to own a bike shop and specialized in Goldwings of all types. He took it for a spin and immediately went to lifters. He said it sounded like there were maybe two of them that were leaking. When the oil's cold it's thick and pumps up the lifter OK. When it heats up and the oil thins out it leaks around the lifter body and doesn't open the valve all the way, just like a car. Anyway, I'm picking up a used head this eveningand will play with the lifters, see what happens. Will keep you posted!