Rebuilding an 88 GL1500

[reddeth]

Howdy y'all!

I just picked up this 88 GL1500 over the weekend, the bike is complete and in good shape for it's age, but severely lacking on maintenance. I, naturally, forgot to take any pictures of when I first got it home, but started snapping a few after I began tearing it down:

I still have to pull the carbs, going to wait till I get all my rebuild kits in first before I really tear into that. Here's how she's sitting this morning, tires are on order just waiting for them to show up along with all the other parts!

The current plan is to:

• New tires front and rear
• New fluids
• Timing belts
• Rebuild the carburetors
• Replace as many of the vacuum lines as possible
• Rebuild the brake master cylinders
• Rebuild the clutch master and slave cylinders
• Rebuild the brake calipers

The bike was horribly neglected in terms of maintenance. Look at this air filter!

I'm sure there's more I'm forgetting, but I'll try and drop some updates as I work through it.

I already ran into two things that I'm a bit confused by though, I'm still working on tracking down a factory service manual so apologies for just asking y'all, but hoping someone can at least give me an idea. I have a (I think) vacuum port running under the airbox, this port was open to atmosphere when I pulled the bike apart, what does it go to? At the very least I'll cap it, but should it be running to anything specific?

Additionally on the left side of the bike roughly where the knees land this electrical connector is disconnected, not sure what it goes to:

The bike was missing it's CB radio module and has a bunch of wiring running into a bundle that runs up to an aftermarket potentiometer, no clue what it's for, but if anyone knows what this is supposed to do I appreciate you letting me know lol. The previous owner inherited the bike from his father and didn't recall what it's for. Here's that wiring bundle, apologies for the poor picture quality:

[Rambozo]

The bike was horribly neglected in terms of maintenance. Look at this air filter!

That wouldn't even get a mention in the air filter hall of shame topic.

I bet that rear speakers were added and that pot is the front/rear fader.

The 88-89 is an odd duck and I know the vacuum diagram is different. But I seem to remember that there is an open tee on one variant to vent something. If you search here you can probably locate that topic.

[reddeth]

That wouldn't even get a mention in the air filter hall of shame topic.

Well that makes me feel a lot better at least haha

I bet that rear speakers were added and that pot is the front/rear fader.

Ahhh that would make sense. It's hard for me to trace back where that pot's wires run, once I get the airbox off I think I can trace them back a bit easier, they look to run off to the left side of the bike where the CB unit was (it's either missing or never had one, just an open spot in the body work there now)

The 88-89 is an odd duck and I know the vacuum diagram is different. But I seem to remember that there is an open tee on one variant to vent something. If you search here you can probably locate that topic.

That's super good to know, I'll dig around a bit and see if I can find anything on the 88 in particular. Thanks for the help!

[reddeth]

Making some progress, wrapped up the timing belts, complete with the rebuilt T52015 bearings, thanks to /Docs/GL1500%20 ... ebuild.pdf

Spent some time cleaning up the forks too, not that they won't get dirty again, but it is a lot nicer to work on when clean

Also managed to replace the fuel filter, sub-air and cruise control filters, which all showed up today. Carb rebuild kits came too but I want to fire the bike up again once I get a filter and oil back in it just to quadruple check the timing belt change was right.

Tires became a headache though, I wanted to try a set of the Dunlop Elite-4 on it, and was planning to go to the darkside whenever that wore out, but the shop I ordered from wound up not having the front. Local dealer has a set of Bridgestone Exedras in my size, and they seem reasonably liked, so going to drop off the wheels tomorrow for a tire install.

[reddeth]

Okay question for y'all, I was working to rebuild the petcock today. The rebuild kit went back in, everything went back together just fine and looked how it came out, same size and everything. All looked like I believe it should.

However once assembling it I found that I could blow through the fuel line with ease. Wouldn't that mean the return spring is not exerting enough force on the diaphragm? The petcock should be sealed by the diaphragm (pushed by the return spring) right? Because the fuel shouldn't flow if the bike isn't running, because the vacuum isn't opening the port?

At least I made some other progress getting the new tires installed and remounting them on the bike!

[ct1500]

With no vacuum to the petcock it should be closed. It likely got assembled wrong with the diaphragm. Watch this video for the correct order of things.


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The open metal fitting behind the air cleaner box is as designed and was only attached to a hose if it were a looney left coast CA model for emissions.
The top electrical connector if memory serves correct goes to the cruise control cancel switch located on a bracket at the carburetors. Anyway, it should be connected.

[DenverWinger]

Petcock spring doesn't have to be very robust, it's there to stop any gravity feed that may happen when your fuel tank is full and pump not running with bike parked. The 1500 can run on a dead fuel pump if the fuel tank is completely full- the fuel level in the tank is higher than the carb bowls and will gravity feed if engine is running and petcock is open. Probably wont do much more than idle or putt slowly around the neighborhood though, gravity feed won't deliver much fuel.

The vacuum petcock is there to prevent carb overflow if you have a leaky float needle valve, otherwise an over-flowed carburetor can fill the intake manifold with fuel, resulting in a hydrolock and possibly a bent connecting rod. Also, some fuel vapor pressure can build in the fuel tank on a hot day, the petcock should stop that pressure. Fuel cap should vent any pressure more than a couple PSI.

Petcock valve should be able to stop or seriously slow the fuel pump flow, too, but the fuel pump only outputs around 1-3 psi.... You can probably blow through the petcock harder than that. So gauge how hard it is to blow through the fuel line by that.

[reddeth]

Thank you for the info on the petcock, DenverWinger your explanation is right where my head was. I think the petcock is good, got it reinstalled and fired the bike up, timing belt job was successful and the bike sounds decent! The carbs definitely need attention. I'm not experienced enough to know what exactly is off in their adjustments, but based on the guy I bought the bike from I'm pretty sure they've been "fiddled" with quite a bit. I'm hoping to pull the carbs later this week/weekend.

In the mean time a curse upon the family of the man who designed the rear master cylinder mounting location. Why is that so ridiculously hard to get out of the bike?! I know there's a video of a guy who shows removing it without pulling the headers/collector/etc but I just was not able to get the master cylinder out without risking bending and kinking the hard lines running to it. I did finally manage to get it out of the bike though! Both brake master cylinders and all 3 calipers have now been rebuilt, bled, and I have extremely solid pressure in both the front brakes and rear pedal!

I was swearing at this thing so hard lol.

While obnoxious I am sorta glad I pulled the headers, lead me to discover the oil leak coming from the shift rod on the left side of the bike

Cleaned that up and ordered a new seal as well as a shifter support piece, which should both be getting here this week some time. Hopefully soon so I can start to reassemble everything!

Now just to rebuild the clutch master/slave cylinders and the hydraulics will be done and that'll just leave the carbs themselves! Thanks again all with the advice so far!

[Sassy]

"I was swearing at this thing so hard lol"
Reads like you have things well in hand!
Swearing is usually the sign of a person who has graduated from throwing! LOL
I think youf gonna have a very enjoyable bike when done.

[reddeth]

Thank you! I definitely think it'll be worth it when it's done. I love tinkering on these things, I almost think I enjoy working on the bikes as much as riding them haha.

Got the slave cylinder removed a few days ago, and hoo boy was it crusty too, look at all this junk! I don't think it had ever been flushed.

Rebuilding the brake calipers the pistons were all definitely dirty but the actual corrosion was minimal and I felt good about reusing those pistons. Not the case with the slave cylinder! It's too pitted and already leaking too much for me to feel good about it

So got a new piston ordered, which finally showed up today! Slave cylinder is rebuilt, (clutch) master cylinder is already done and back on the bike. Plan is to get the slave cylinder reinstalled tonight and get the system bled and the hydraulics will all be done!

[reddeth]

One thing I encountered and thought I'd share with y'all is the struggle I had with the heat shield above the exhaust collector, on my '88 there are two bolts that go from the heat shield into the heatsink of what I believe is part of the reverse electrics:

There was no way to reach these from the bottom after getting the collector itself out and it was a big pain point while trying to remove the rear master cylinder. I probably could have gotten them out from the top with a box wrench and a lot of very short turns, but by that point my patience had worn too thin and I just wound up bending the hell out of my original heat shield. I picked up a newer heat shield off eBay that came from (I think) a '95 and lo and behold Honda also realized how big of a pain this was, and dropped those mounting bolts:

My original one on the left shows those two bolt holes and bracket on the top. The newer one even still has the empty space in the sheet metal for the bracket to be spot welded! My point in this is, if you're like me and struggling with this thing, once it's out I think you're safe to not bother reattaching those bolts.

[reddeth]

Carb question for y'all. I've got the carbs rebuilt and super cleaned up. Having an ultrasonic cleaner made quick work of it! I also noticed the carbs were definitely rebuilt at some point, but I'm pressing forward with the rest of my cleaning/rebuilding anyways.

When pulling apart the idle air mix screw (is that the right name? I always mix up the carb part's names) I noticed it was just the needle and spring. No o-ring or washer, which the last time I rebuilt carbs I swear needed to be in there; and the exploded diagram I found for the carb seems to support this:

But I can't quite tell which order they go in. Looks like (from left to right) it should be o-ring, washer, spring, needle/screw. Is that right?

Thanks!

[offcenter]

"I was swearing at this thing so hard lol"
Reads like you have things well in hand!
Swearing is usually the sign of a person who has graduated from throwing! LOL
I think youf gonna have a very enjoyable bike when done.

My general rule of thumb on any repair project is, the project is not complete until I get some blood on it and all the four letter words are installed.

[ct1500]

That is the order of things reddeth. Look inside the mixture screw bore for the old O rings they can get stuck in there.

[reddeth]

My general rule of thumb on any repair project is, the project is not complete until I get some blood on it and all the four letter words are installed.

lol I definitely have installed my entire collection of 4 letter words and even a few extra DLCs worth of curses at this thing but it's worth it!

That is the order of things reddeth. Look inside the mixture screw bore for the old O rings they can get stuck in there.

That's what had me so confused, no trace of the old o-rings or washers down in the bore! Thank you for the confirmation!

On that note I actually forgot to update this thread yesterday, but I got the bike all back together! Fired right up and idles perfectly. I did bench sync the carbs and they feel pretty good by butt-dyno standards so I went ahead and just put the bike back together and went for a ride. Put about 80 miles on it yesterday with fresh gas and did an oil change to try and flush any leftover crud out.

The bike isn't completely flawless, I need to figure out why my neutral light isn't coming on. I've seen people talk about wiggling the reverse lever, and I wiggled for all my worth but nothing. I suspect the bulb _could_ be burnt out. The revere operation and reverse light itself comes on, and the bike will start while the sidestand is down without pulling in the clutch, so I suspect it's just burnt out. Maybe time to fix all the lights in the cluster, some of them are dim. I am also going to give some local upholstery shops a call and see how much it would cost to redo my seat; I've found replacement covers on eBay for $100 but I'd really like to support a local maker if I can.

ANYWAYS! Thank you all very very much for the advice and in general for the forum as a repository of info, I have searched through a ton of threads while doing this and I appreciate all of you. Finally back and together and in her very 80s beige glory

[Sassy]

Congrats!! Enjoy the fruits.

[bellboy40]

If you want to replace the instrument lights with LEDs, there is a good tutorial on this site. I will put the link down below. I did that recently and, man what an improvement. My dash lights were pretty dim and almost unreadable at night. I think some of them must have been burned out. The list that is given for the LEDs to replace the bulbs at the front of the tutorial are no longer available. On the last page, I have listed the bulbs that I used and a picture of the result. I got my bulbs from Superbrightleds.com and the prices are reasonable. BTW, before I started replacing the bulbs, my OD light would not come on when in 5th gear and my bulb was burned out. That is likely what is wrong with your neutral light also.
viewtopic.php?f=14&t=10998

https://www.superbrightleds.com/moreinf ... mens/3305/

https://www.superbrightleds.com/moreinf ... r/197/855/

https://www.superbrightleds.com/moreinf ... /228/1072/

[reddeth]

Nice! Appreciate the superbrightleds link, I've bought from them before. The exact part numbers really helps! I'll order those today and see when I have time to actually disassemble the cluster.

[reddeth]

LED lights ordered for the gauge cluster and finally took the bike out for a ride more than just around town! Hello from the Blue Ridge Parkway!

[bellboy40]

Nice! Been on the Blue Ridge Parkway many times and it never gets old. I've ridden it all the way from Cherokee to Front Royal, VA. Somewhere about half way it changes names to Skyline Drive.
Good to hear your bike is running well after all that work.

[reddeth]

When I bought this bike it did not have the CB radio transponder present. I don't know if it came with one from the factory and was removed, or if it just never came with one, but regardless the small opening above the vents on the left side fairings was just an open spot, so I figured I would 3d print a filler plate to go in it's place and included a spot for a USB charger and the potentiometer that was up by the ignition, but I moved while rebuilding everything! It turned out great!

[Sassy]

Very cool! 3d printing,,, man mskes me wish id a paid more attention to my younger brother in the 70s when he said computers are where its at but he was my "younger" brother,, lol

[reddeth]

Howdy again, y'all! Hope everyone has been well. I've been getting more and more time on the Goldwing and enjoying it, but running into 2 issues I'm hoping to get some thoughts on.

1) I'm getting a heavy clunking from the front right brake while braking. It's definitely connected to the braking, it's rotational based on the speed of the wheel and if I release the brake lever it immediately stops. I can't see any noticeable issues with the rotor. Is there any sort of fault potentially with the anti-dive system? I did re-use the rotors that (I'm pretty sure) were the originals. I might try replacing them, although I don't really have the money to drop on OEM rotors unfortunately, so hoping these Amazon specials might work https://www.amazon.com/dp/B09KN165Z7/?tag=goldwingdocs-20

2) The transmission feels like it's grinding going into 4th and 5th. Going into 5th is worst, by far. I am aware of and have been reading a ton of topics about the 4th/5th issues these bikes, so this definitely could be it, but most of those topics/threads seem to indicate the issue is a noise coming from the transmission while riding in 4th or 5th, not necessarily while in the act of shifting? Perhaps I'm completely misreading the information provided about the known 4th/5th issues.

I have bled out the clutch slave cylinder twice now after it's rebuild, thinking perhaps air got in the system, but that doesn't appear to have had any change in performance. While rebuilding the slave cylinder I could tell it was definitely leaking a bit into the clutch, is it possible my clutch pack is toast and needs replacing? The bike only has 68k-ish miles on it, but I'd far prefer needing a new clutch over the transmission grenading. Again, once the bike is in 4th or 5th gear it runs beautifully and makes no out-of-place noises, it's just the grinding during the shift.

Much appreciated any thoughts on either of those items!

[DenverWinger]

For the shifting have you considered a shifter brace? I think they are still available, and they help shifting immensely..

The 4th/5th shifter fork issue you mention will manifest itself as the transmission will sound like a box of rocks when idling in neutral and front of the bike is pointing slightly downhill.

If your bike isn't doing that I'd say the shifter forks are OK.

[reddeth]

Okay that makes me feel a lot better, then. I have a somewhat steep driveway and the transmission is quiet as could be from level in the garage, a shallow transition out of the garage, and the steep dip at the end. Steep enough at least that the bike wouldn't stay on it's kickstand lol.

I did get a shifter brace during the initial rebuild work, but it was a cheap eBay unit and I couldn't get it aligned properly. I've ordered (what I hope is) a higher quality one from Cyclemax to try out. Thanks for the info, that makes me feel hopeful!