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Down on power at top end?
Ok, I used Berryman's B12 Chemtool to clean the grime off the outside and to clean out the non-removable pilot jets, then followed up with compressed air. Did this at least 5 times on each pilot jet, letting the Berryman's soak for a good 30 minutes a few times.

I used my Dremel to cut slots in all of the diaphragm cover screws and then just unscrewed them with a flat-head screwdriver. I verified that the diaphragms were not cracked, torn or folded over. The diaphragms had swollen up like balloons from using the Berryman's, so I wiped them off and let them dry out overnight. They shrunk back up nicely. I used petroleum jelly to hold the diaphragms in place for re-assembly. I replaced the diaphragm screws with M4x16 stainless allen head cap screws, being careful not to over-tighten, and using anti-seize.

I replaced all of the vacuum hoses with 5/32" vacuum hose, and replaced the vacuum tee. I think the vacuum advance hose was pinched by the front of the airbox or plenum before. That is corrected now.

I pulled the mains and the 2nd screw-in jets (mid-range?) and ensured all the holes were clear. I blew out all passages with compressed air. I pulled each float, checked the float valve needle for cleanliness, shook each float to check for fuel inside, and re-installed, adjusting their heights.

I pulled the anti-afterburn & slow air cutoff valves and checked that the diaphragms looked good.

So, then I reassembled the whole she-bang. I found two problems. Two of the M4x16mm screws rubbed against the choke linkage, causing it to bind. I loosened those two up a bit and then the linkage was fine. I'll replace those with M4x12 when Sears Hardware is open. Throttle cables were incredibly difficult to re-install, especially the return cable. If the bars are turned all the way to the right, the throttle binds. I'll have to look at this again. Maybe I'll just replace the cables with new ones from mother Honda, since I got stuck with a broken throttle cable on another bike last year and it basically ruined my ride that day.

So, once I got the carbs back on the bike, I couldn't wait until I got the airbox back on before trying to start her up. She did eventually start, but it was not easy, and she ran like crap. Idle was too low, engine made lots of low frequency intake growl (sounds kinda cool, but louder than the exhaust), but ran poorly. I finally reinstalled the air cleaner and filter, and restarted again. She ran beautifully! She idled at about 1200rpm, rising to 1500 when warm. Seems like I must have had a miss at idle before, because now she idles beautifully, with almost no vibration.

Then, I took her out on the road. She seems peppier, but it was late, and I was (am) pretty tired, so I took it pretty easy. I couldn't find anyplace safe to attempt a top-end run, but I got her up to about 85 in third gear. There is still a vibration at higher RPM. Now the idle doesn't return right away, either. I'm pretty sure that these are symptoms of a synchronization issue, so I'll try that next.

Thank you,

Ed
1986 Honda GL1200 Interstate
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#16 03-30-2009, 10:12 PM,
Sounds like you're making progress in the right direction but I still would have liked to see you boil the carbs in water as an extra measure of ridding any blockage. Sticky throttle cables could be messing up your idle return as well as the synchronyzation.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

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#17 03-31-2009, 09:13 AM,
To be honest, I just didn't want to disturb o-rings and seals/etc. and have to go buy rebuild kits. I'd assess how much work is involved while tearing it down and if it was significant, then I'd weigh the risk of still having a blocked jet and tearing down again vs. boiling. Luckily, teardown really wasn't all that much work. It took me less than an hour to get the carbs on the bench, and about an hour to put them back in.

First thing I'm gonna do is try adjusting the throttle cables. If that doesn't help, then I'll try dri-slide, then new cables from mother Honda. Routing hasn't changed significantly from the way they were installed (outside the frame), but the ends may have been over/under each other differently.

Once that is ironed out, I'll synchronize.

Then I'll look at timing belts.

Thank you,

Ed
1986 Honda GL1200 Interstate
Reply
#18 03-31-2009, 11:47 AM,
Why not disconnect the cables, start the engine & see if they still are slow about coming back to idle.

Poorboy
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#19 03-31-2009, 02:58 PM,
One thing I forgot to mention is that sometimes the cables can become caught under the left lower lip of the false tank shell and that can cause the cables to bind. The cables must be pushed up and inside the false tank shell.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

Reply
#20 03-31-2009, 03:51 PM,
This seems like the most likely possibility. Any chance you could post a picture of this area on the left side of the bike for me? I tried to put 'em back as closely to the way they came off as I could, and I even took a picture, but unfortunately that was after I had already gotten the carbs off to the left side by about 3 inches and moved the cables, so I don't know the original routing around the plenum.

admin Wrote:One thing I forgot to mention is that sometimes the cables can become caught under the left lower lip of the false tank shell and that can cause the cables to bind. The cables must be pushed up and inside the false tank shell.
1986 Honda GL1200 Interstate
Reply
#21 04-01-2009, 01:15 PM,
Actually, all you need to is look or feel at the lower left side of the tank and if you see or feel the cables they are out of place. If they are sticking out just lift the false tank and push them up inside the false tank and then lower the false tank back into place.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

Reply
#22 04-01-2009, 01:45 PM,
I'll give it a gander when I get home from work tonight.

Thank you Vic!

admin Wrote:Actually, all you need to is look or feel at the lower left side of the tank and if you see or feel the cables they are out of place. If they are sticking out just lift the false tank and push them up inside the false tank and then lower the false tank back into place.
1986 Honda GL1200 Interstate
Reply
#23 04-01-2009, 01:53 PM,
This is the cable routing now. It binds only when I turn the bars all the way to the right. I've read elsewhere how the cables must be routed outside the frame, and I'm pretty sure they were outside the frame when I started. I don't remember the cables binding when the bars were turned all the way right before I started, but I guess it is possible.

Any thoughts?

Thank you,

Ed


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1986 Honda GL1200 Interstate
Reply
#24 04-01-2009, 08:21 PM,
I just did the carbs on one of my 84 "Standards" & the cables were inside the frame. I did the same on one of my other bikes, couldn't remember how they were routed. So I put them on the outside of the frame, don't feel right.

Poorboy
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#25 04-01-2009, 08:35 PM,
In you picture it looks like the bottom cable is twisted over the top cable. This can make a difference. You want the cables to run as straight and free as possible. Inside or outside the frame doesn't matter as long as they don't bind anywhere.

I suggest that you remove the false tank completely to see if the cables still bind or not. If they still bind with the false tank off then you will have to look elsewhere for the binding problem. Perhaps they are not routed correctly elsewhere. If the engine RPM rises when you turn the bars to the left or right at full lock then the cables are not routed correctly. If you can't see the binding spot anywhere then slack off the cable adjuster a little and rotate the bars left and right and watch the outer cables loosen and tighten or move in their sockets. If the outer cable maves back and forth as you move the bars back and forth you have a bind and you will have to physically feel for the tightness in the outer cable with your fingers feeling for any spots where the cable might be binding against the frame or other components. Without seeing your bike I can't tell you exactly where the cable should go but you want the cables so that they are easy to move back and forth when the bars are at lock extremes.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

Reply
#26 04-02-2009, 10:01 AM,
I removed the false tank tonight, but the throttle still sticks when the bars are turned to full lock all the way to the right, same as before. So, the faux tank isn't the problem.

I disconnected the return cable from the bracket, and sure enough, the throttle stopped sticking. So, I've tried re-arranging the cable in various positions, but whenever it is in the bracket, it makes the throttle stick. While there are two adjusters on the main throttle cable, it looks like there is no way to adjust the slack on the return cable. Is that correct?

I guess the next step is to lube the cable. Any suggestions as to what lube to use? I've heard that dri-slide is the best for other Hondas with teflon-lined cables. Does anyone know if GL1200 Interstate cables are teflon-lined?

Thank you,

Edward
1986 Honda GL1200 Interstate
Reply
#27 04-02-2009, 10:15 PM,
Although there is no way to adjust the push cable, you might try adjusting the pull cable turnbuckle. It will affect the "slack" in the push cable. Double check the fitment of the cables at the throttle housing at the handle bars as well. Make sure the cable hasn't "jumped" the guide at that housing.
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#28 04-02-2009, 10:24 PM,
I synchronized the carbs yesterday, and it really smoothed out the idle (at about 950RPM), and got rid of the excessive vibration at higher RPM.

Still has no power up top though.

My buddy rode it, and he still thinks it is a fuel delivery issue. Basically, if you are crusing along at say 4K RPM in OD, and open the throttle, the bike doesn't respond much at all. I rode his Ducati 900, and it was QUITE a contrast. In fact, even my old two-valve 600cc and even smaller engines had significantly more power than my Gold Wing at higher RPM in this condition.

Since it is easy, I'll try the flow test on the fuel pump tonight, and if that is good, then I'll go buy the timing belts and radiator hose.

I talked to my buddy who I got the bike from. He says the prior owner "dumped money into it" right before he sold it. I'm thinking that since every maintenance item on the bike has been basically brand-new, he probably had the timing belts replaced, too, but the mechanic may not have aligned the marks right (yes, GLHonda and Vic both alluded to this MUCH earlier -- I guess sometimes you just have to go through the process yourself, ya know?).

Thank you,

Ed
1986 Honda GL1200 Interstate
Reply
#29 04-06-2009, 01:40 PM,
GL1200's are not famous for their bottom and mid range torque. Next time your at 4K RPM in OD try shifting down to 3rd and spin the engine up to 7500 RPM and see if your acceleration is any more impressive. These engines don't even start making any serious power until about 3000 RPM.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

Reply
#30 04-06-2009, 04:23 PM,


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