Carb Or Plug Wires?

[dhg]

I'm confused now. When I bought the bike and drove it home I new it had a little miss, and an occasional backfire when going slow just maintaining 15 to 30mph, no acceleration. I'm not sure how long the bike sat, I changed the timing belts, new plugs and synced the carbs, still had the miss. I figured I would ride it and see if fresh gas and running it would clean out the carbs and smooth things out.

The weather finally got to where I could get the bike out last Sunday. I've been riding in temps from upper 30's to 70. Nothing changed with the miss. Then today, riding to work in the afternoon it was 85 and a little humid. After about 6 miles and coming into town, I slowed down and expecting the little miss, it wasn't there. The bike finally ran as smooth as I know it should and for the the next 10 miles to work it was great. When I got off work the temp had dropped to 61 and had rained. Taking off from work the miss was back then I ran into a pretty good rain on the ride home. The bike started running worse that normal by the time I got home.

Anyone have any idea what is going on? Carb, wires, coils???? I have tried to look for sparking when I had the false tank off but didn't see anything. HELP

thanks, Rich

[seabee_]

Sounds like the drain holes for the spark plugs might be clogged. Pull the plug boots off and fish around with a small gauge wire to find the holes and clean them out. A common problem on the Goldwings. When it rains or you wash the bike water fills up in the plug area and causes miss fires. Try the simple fixes first before changing plug wires. Post back with what you find.

[D2D]

Besides the drain holes you could have a plug or some other wire that's shorting out. Try running your bike in a dark place at night and look for an arc on your plug, coil, or ignition wiring.

[virgilmobile]

I removed the rubber holder that keeps the 2 extension caps together then put them back on the plugs.When I started it at night,the Bakelite extensions lit up.Arcing right through the sides.I found replacements and replaced them and the wires to eliminate the problem.

[dhg]

As I was writhing the thread, it sounded more like electrical than carb. One thing I failed to mention is I'm fortunate that I can put the bike in the shop when it starts raining so it wasn't rained on last night while I was at work. It started it's little miss when it was dry and got worse while riding home in the rain.

Thanks for your insite.
'
Rich

[dhg]

From the above posts I started looking for areas where the shorts might be. After the lowers came off I pulled the plugs to see what they looked like.

Below are the plugs as they came out of the bike since my ride home in the rain. It seems the front 2 are running as they should, the back 2 have spark issues.

I also took a look inside the caps and the picture is from the back left cylinder. The rest of the caps looked clean inside.

virgilmobile, did you buy OEM caps or did you find another source for them?

I think I'll continue taking off the false tank & air box to see if I can find other shorting going on as it really started running bad in the rain before I order new caps. I should probably get new wires also while I'm at it. I'll also check the coils. Hope I don't need those.

I'm open to any suggestions. I've got to get the bike back on the road.

Rich

[seabee_]

A trick you can use to find where the short might be is use a spray bottle to wet down the wires and components. Try this when you get everything moved out of the way. Start with the plugs, move to the plug wires, then onto the other ignition components like the coils. If you do have a bad wire or coil the problem should show itself when you wet it down.

[WingAdmin]

A trick you can use to find where the short might be is use a spray bottle to wet down the wires and components. Try this when you get everything moved out of the way. Start with the plugs, move to the plug wires, then onto the other ignition components like the coils. If you do have a bad wire or coil the problem should show itself when you wet it down.

I've done the same thing, but do it in the dark, so any sparks (even weak ones) will be plainly obvious.

[dhg]

Well I just got done doing the watching for sparks in the dark and did the water trick, but no light show. I did pull the back left cap off and had quite a lot of sparking from the side of the cap with very little change in the sound of the motor. It did start running rougher when I sprayed the water, even before I got up to the coils. No change when I hit those.

I guess I'm going to order OEM caps and wires tomorrow unless anyone has a aftermarket source.

Rich

[seabee_]

Yeah, it sounds like the wires are a good start. Once you get the new ones try the water trick again to see if it runs rough. Hopefully the new wires will fix it. Let us know.

[peppilepew]

A little something to think about when diagnosing an engine miss that changes intensity under different conditions. Gasoline is a mixture of compounds. Certain compounds of the fuel burn at colder temperatures and others resist. A chokes purpose is to flood the engine with more fuel and increase the ratio of burnable compounds so the engine will run. Since you were able to sync the carbs we mostly know the idle circuits are clean. As the engine warms and the fuel ratio is adjusted leaner the cylinder develops more heat. Leaning an engine requires more spark. As the spark voltage increases the opportunity for the old rule of least resistance comes into play. A lean running engine will cause spark leakage if your insulation is poor. A cold engine may run fine until warm. We won't get into fouled plugs. You may have more than one problem. It may be fuel and spark.

[virgilmobile]

[quote="dhg"] I did pull the back left cap off and had quite a lot of sparking from the side of the cap

This eliminates the the 2 rear cylinders as having a spark problem.Note that the coil may be cracked tho.
The rear cylinders are fired from the left coil pack.

"occasional backfire when going slow just maintaining 15 to 30mph."
Is it backfiring in the exhaust(too much fuel)or intake(too little fuel)?
Too little fuel by the looks of the plugs.Unless there new,there too white.

" with very little change in the sound of the motor"
It sounds like a lean cylinder.There should be a noticeable drop in rpm when each plug wire is removed from the plug and allowed to arc to the block.
Each cylinder should (in theory)provide 25% of the horsepower and drop the rpm equally.
With all these details,I do think you have a fuel delivery problem.Either plugged jets,stuck slides or a bad sync job.
One quick test please....Start the engine,use as little choke as possible,keep the throttle as low as possible and the rpm below 1500 for 5-10 seconds and shut it down.Lightly tap on each header pipe to test for heat.they should be the same.Obviously a warm pipe is a running cylinder and a cold one is not getting the proper fuel mix.

[dhg]

Ok, I got the new wires and caps on today, it fired right up and all cylinders are hot but it still has a miss/backfire and the backfire is in the carbs. From what I could tell, a small puff of smoke was coming from the area of the #2 cylinder.

It does run better while warming up with the choke on. When I had 3 bars on the temp gage and rev'd it up it would flatten out about 3600rpms.

They are newer plugs, maybe 300 miles on them.

It's just weird that it ran so well when it was hot outside.

Now what to do?????

Thanks, Rich

[virgilmobile]

It's probably time to look at the carbs.That puff of smoke.......Can you explain better..what was it?gas,oil,backfire? where did you see it.?
Will it run better with a half choke?(lean)
Stick a inspection mirror in the plenum and see if all 4 slides jump when you rap the throttle.One can be stuck..
Here's a post about my carb trouble.This may help.
Different atmospheres,temp and humidity affect fuel mixture ratios and some 1200's run a bit lean to start with.
I found a modification to the carbs from Honda that was to cure the carb problems for my 84.I just opted to do it myself....viewtopic.php?f=5&t=9179

[dhg]

virgilmobile,

Just for the heck of it, I checked the carb sync, today and everything was still where they were.

The little puff of smoke that I saw was in the plenum during a backfire happens. The best I can tell is that it's whiteish and hard to see.

It does run better with some choke on, but you can still hear the miss.

I tried looking at the slides with a mirror but I can't see or focus on anything past the screens even putting a small flashlight in the plenum.

[virgilmobile]

This is a guess.
First adjust the valves,mainly for that one cylinder.Also,if the timing belts have been changed,double check the timing on that side.
Check the compression in that cylinder compared to it's mate,looking for a leaking intake valve.
If all is good,it's time to look at the idle jet and mid ports for that carb.

[dhg]

Thanks virgilmobile,

One thing that I keep forgetting to mention is that on the left side, there is a small exhaust leak where the headers and the mufflers connect together. Would the loss of back pressure cause my problem?

I did change the timing belts last month and all timing marks were right on when I put the covers back on. I'll check the other areas that you mentioned.

I'm about ready to pull the trigger and buy one of Randakk's carb kits.

Thanks, Rich

[virgilmobile]

Double check everything that could be free first.....viewtopic.php?f=16&t=11097
And some won't get the "kit" unless the carbs warrant it.Have a read(really long) about this saga.viewtopic.php?f=5&t=10147

[dhg]

Ok, I'm finally able to get back to working on my wing. I've been under a deadline to finish a cabinet side job and couldn't get to the bike, plus It took 3 weeks to get the sparkplug adapter for the compression tester.

The compression in all cylinders is in the 165psi range (warm engine), Number 2 cyl is 160 psi which is the one with the backfire into the carb.
The timing is right on.

I haven't been able to adjust the valves on that cylinder. If there was a problem with the valve adjustment on that cylinder, wouldn't it show up in the compression test?

The engine does run a lot better with about 1/4 choke on.

Time to proceed to the carbs?

[seabee_]

The GL1200 has hydraulic lifters. As far as I know you can't adjust the valves. I have been wondering about the battery. Is it good and fresh? Have a good charge on the battery? I only ask because if voltage gets low, the ignition system will may not have enough juice to provide proper spark. With low voltage, it runs good at idle but starves or runs rough at higher rpms. Something else to offer for a low buck fix is Seafoam. It may or may not fix the issue, but you never know. Normally you run 1/2 a can in the fuel tank, but I would run at least 3/4 of a can. Run or ride the bike long enough to allow the Seafoam to work it's way into the carbs. Let the bike sit for 2 or 3 days to let the Seafoam sit and clean the carbs. Then ride the bike and see if there is a difference. It might take a little time for the Seafoam to work.

[dhg]

Thanks for the reply Paul,

The battery is new. The guy I bought the bike from replaced it the morning I went to look at it. The bike has the problem from idle through about 2500rpm. I can't tell at higher rpm other than I can feel a little tick through the handle bars. I can't tell if it's just a crack in the road or a miss. It does pull pretty good over 2500.
I have put seafoam through it twice. Not quite as rich as you suggested. More like an ounce per gallon, ran it for a while and let it sit like you mentioned. No change was noticed. I also tried some in the crankcase for a few hundred miles and changed the oil with amsoil.

I did talk to a mechanic and he wants $300 to take the carbs off and clean and replace plus parts which as you know can go up pretty high. I've decided to take the carbs off next weekend and clean them myself. I've got to get it running right, my wife is going to want her bike back pretty quick.

[seabee_]

It sounds like the low speed idle jets are clogged and the carbs need a good cleaning.

[peppilepew]

I did my carbs as many others here have done. I took a paper clip and pounded it real thin. I then narrowed it the with a roll lock. You want to unclog, not open the jets larger. Easy job. Getting to the carbs is all the work. All 4 come out in one assy.

[dhg]

A good cleaning and rebuild is the plan. I figured as long as I'm taking them apart I might as well replace the seals so I ordered Randakks kit and Howards book for it. Between the book, Virgelmobiles posts your input and other posts on this site, I should be able to get it done.

[dhg]

Well the fun has started, the carbs are off the engine and separated from the plenum. I did run into a couple of problems however,
1-when I was removing the plastic plenum cover, one of the screws broke off in the plenum with most of the threads still in the plenum. I don't know if it's too small to drill and use a screw extractor. Any ideas?
2-the flange on the choke belcrank bushing broke off (it was brittle). I think I can use another washer in the flanges place and make it work.

Much to my suprise, the factory plugs for the pilot screws have already been removed. I have no idea how long ago this was done, but the o-ring I've seen so far are pretty flattened out.

Tomorrow, the carb cleaning begins.