JohnnyL's 1980 GS550L Cafe Build

[93Bandit]

Too bad it doesn't run worth a shyte. I pulled the carbs off and meticulously rebuilt them in the course of about four hours. Found a small tear in one of the diaphragms. Replaced it with one of the eBay carbs that had a good one. Checked all float heights meticulously. Thoroughly looked at all the jets. New o-rings everywhere....Put carbs back on bike and #1 burps through the carb. #2 isn't running. I left the pods off just to be able to watch the needles. It won't start unless choke is on and I put my hand over 3 & 4 carbs to suck fuel. Then it runs with the choke on but at about 4000 rpm. Fudge! I am about to throw this motherfudger in the trash. I don't know what else to do. I give up. I'm at a total loss.

Hey man, don't give up yet. You've come too far. You're fortunate to have bwinger near by to help. Between you two guys and the wealth of knowledge here, you'll get it sorted out eventually. Just be patient. There's likely something small that's causing this.

Idk if it's your problem, but I know several have mentioned that these carbs are very sensitive to types of air filters. Are the filters you're using part of the issue?

Also, for what it's worth, my bone stock GS850 won't cold start without the choke. As far as I'm aware, no GS will cold start without the choke.

[Steve]

I'll neeed to ammend your statement a bit.

Also, for what it's worth, my bone stock GS850 won't cold start without the choke. As far as I'm aware, no properly set up GS will cold start without the choke.

There are some that brag about not needing the "choke", but I find that the mixture screws are WAY out or they have upped the pilot jet size, both of which richen up the mixture to the point of not needing the "choke".

.

[93Bandit]

I'll neeed to ammend your statement a bit.

There are some that brag about not needing the "choke", but I find that the mixture screws are WAY out or they have upped the pilot jet size, both of which richen up the mixture to the point of not needing the "choke".

.

Would doing this only affect fuel mixture at idle, or would it be rich throughout the throttle range?

[Steve]

That would depend a bit on how the carbs are set up. If you have larger pilot jets or have the pilot (mixture) screws turned out too far, only the pilot circuit is affected. The pilot is the primary supplier of fuel up through 1/4 throttle. Above that, the needle and main jets feed fuel all through the range, but they provide quite a bit more than the pilot jet.

However, if you have your float level too high (smaller numbers when setting it), ALL of your circuits will run richer.

.

[93Bandit]

That would depend a bit on how the carbs are set up. If you have larger pilot jets or have the pilot (mixture) screws turned out too far, only the pilot circuit is affected. The pilot is the primary supplier of fuel up through 1/4 throttle. Above that, the needle and main jets feed fuel all through the range, but they provide quite a bit more than the pilot jet.

However, if you have your float level too high (smaller numbers when setting it), ALL of your circuits will run richer.

.

OK, that makes sense. I work with a guy who's somewhat familiar with GS's and knew a few guys who bought them new and would richen the idle mixture since "they are too lean from the factory for emissions reasons." They claimed they ran better and were much easier to start. I must admit, I would rather not have to wait 10 min before I can ride it on a nice 75 degree day. But I understand that older bikes aren't "turn key" like new stuff.

I don't see any negative affects on the engine if it idles a bit rich though, right? Other than maybe reduced fuel economy.

[JohnnyL]

So here is a little update to where I am with the bike:

About a week ago, I had BWringer over to help me diagnose what was going on with the bike. The bike was running like poo backfiring from the tail pipe and #1 carb. Five minutes prior to Brian arriving at my house, I decided to run a compression test on all cylinders. #1 had only 15 psi while 2,3 & 4 had 145 psi. Ding ding ding...found the problem. Brian arrived and I told him what I had just found out and he replied with "that's not good." We proceeded to remove the valve cover and check valve clearances. Valves on 1 and 4 were way off on the intake and exhaust. Intake was too tight and exhaust was a little loose. We fixed those issues and ran a compression test again. Still only 15 psi on #1.

This meant the problem was deeper in the motor...like a ring problem. We proceeded to remove the head. Oh we're getting closer to the problem(wait for it). We noticed 2 & 3 looked good but the black line where the rings come to the top of the piston was lower on #1 than 2,3 & 4. Cylinder walls looked good though. Time to remove the jugs.

Doh! Found the issue! Oh my...this is embarrassing... It seems that I must have gotten distracted when putting the rings on. All rings were on 2,3 & 4 but someone forgot to put the middle and top ring on #1 piston. Whoever did this managed to put the oil rings on but not the middle or top ring. I looked at Brian and said "what the hell?" I think we found the problem. Haha....Well now we know the oil rings are good for 15 psi.

That same day, I ordered new factory gaskets, found the rings that I forgot to put on and waited for the new parts to come in.

On Thursday last week, the parts arrived at my local dealership and I immediately ran up there and picked them up. I can attest that the factory gaskets are much better quality than any aftermarket gaskets. Before, I was having a problem with a few oil leaks. I'll talk more about that later. Thursday afternoon and evening I rebuilt the motor again(this time with all the rings on #1 piston) and fired the bike up. EUREKA! The bike sat there and ran like a champ! No more backfiring. The bike was good running condition just in time for a sunny and 50 degree weekend.

Prior to rebuilding the engine again, I had gone through the carbs with the advice of Steve and swapped out the 42.5 pilot I had in there for a stock 40 pilot. I also removed the nylon spacer from the needle and raised the needle by two washers. I started at 3 turns out on the mixture screw and put in a 110 main. I then synced the carbs on the bike with my new Morgan Carbtune and adjusted the mixture screws to 3-1/2 turns out. The bike sits there and idles nicely, revs out nicely and returns to idle nicely. Time to take it for it's first test ride.

Holy smokes! This bike is incredible. I took it down the street in front of my house and hit 80 mph. I couldn't help myself. The bike just wanted to be free and get up and go like a wild horse! It shifted through the gears perfectly, revved out perfectly and put a HUGE smile on my face. Success...finally!

I put about 80 miles on it this weekend and man I love this bike. It sounds SO good and rides SO nice! It also tends to turn a LOT of heads. Pretty much all bugs are worked out. I just have a few minor things to tweak. The M-Unit is connected to my speedometer and I am still trying to figure out all the capabilities of the M.Ride app. The speedometer is all setup and has been trained to show what gear I'm in. I put a new factory petcock on the tank but it seems to be leaking gas ever so slightly around the bolts. I'm put nylon washers under the bolts but that didn't seem to resolve the problem completely. I was having a problem with some minor oil leaks before with the aftermarket gaskets but with the new factory gaskets, no oil leaks.

I can't wait to bring this bike to the midwest gathering and show it off to you all. Here are some pics from this weekend. Some of the photos are of my son on the bike. Here is a link to a video of the first test ride: https://youtu.be/ZAZeQ2DqRpM

[Rich82GS750TZ]

Great work Johnny. I've really enjoyed following the progress on your build.

[Grimly]

Excellent work.
As for the rings - well, as you say, that kind of thing happens when you get interrupted.

[93Bandit]

Looks amazing! I'm glad you got the motor sorted out. See, aren't you glad you didn't give up?

Also, I don't claim to be an expert and I wish had said something sooner, but last week I was thinking about the issue you were having and was going over things you had already addressed: spark and fuel. I couldn't remember if you had done a compression test and was going to suggest it, but it was a hectic week and I never had the chance to post. Finally had a moment this morning to check progress, and what do you know?! Compression! Glad it's all worked out now!

[dorkburger]

Problem with the nut holding the wrench.... been there.
The bike is looking great, nice job.

[bwringer]

Yeah, one of our topics of conversation last week was how and when to confess...


Honestly, it could have been much worse -- if the rings had been broken or bent, it could have badly scored the cylinder wall.

Other than time, money, and a large chunk of sanity, leaving the rings out didn't cause any permanent damage. We've all probably made worse mechanical mistakes.

And I gotta say it was a pleasure to be involved in a frame-up project like this. I learned a lot -- that m-Unit is amazing. And I know John learned a lot.

And that matte paint looks good in photos, but it's mind-bending in person; the parts don't quite look real.

So often the focus around here is on getting a "cheap" bike running without spending any money or time, never mind making it safe, reliable, and looking decent. I've seen far too many riders who refuse to replace 25 cent crush washers or spend $5 on a valve shim. We've also seen a lot of folks give up prematurely in the face of the multiple overlapping issues so often found in vintage vehicles, especially when they're customizing. You can't deny John's commitment of time, effort, and cash, and it's been well-rewarded.

Here's to many happy miles -- this bike is built to ride, not sit around!

Just thought about this when I saw this photo: does the rear tire hit the frame when the suspension compresses? I don't remember if you limited shock travel or have taller spacers, etc.

[JohnnyL]

Yeah, one of our topics of conversation last week was how and when to confess...


Honestly, it could have been much worse -- if the rings had been broken or bent, it could have badly scored the cylinder wall.

Other than time, money, and a large chunk of sanity, leaving the rings out didn't cause any permanent damage. We've all probably made worse mechanical mistakes.

And I gotta say it was a pleasure to be involved in a frame-up project like this. I learned a lot -- that m-Unit is amazing. And I know John learned a lot.

And that matte paint looks good in photos, but it's mind-bending in person; the parts don't quite look real.

So often the focus around here is on getting a "cheap" bike running without spending any money or time, never mind making it safe, reliable, and looking decent. I've seen far too many riders who refuse to replace 25 cent crush washers or spend $5 on a valve shim. We've also seen a lot of folks give up prematurely in the face of the multiple overlapping issues so often found in vintage vehicles, especially when they're customizing. You can't deny John's commitment of time, effort, and cash, and it's been well-rewarded.

Here's to many happy miles -- this bike is built to ride, not sit around!






Just thought about this when I saw this photo: does the rear tire hit the frame when the suspension compresses? I don't remember if you limited shock travel or have taller spacers, etc.

Yep. I just looked at the bike underside and apparently the tire hit the back fender/frame at some point. I don't remember it doing that but yes, I am going to have to limit the travel somehow. I could extend the shocks a little bit but I like the height of it now. I currently have 280mm shocks on there but I do have some 320mm shocks on hand I could put on but again...I like the height where it is. Any suggestions?

I am still debating if I want to share how much money I have in the bike. Spending got a little out of control and I'd probably be lucky to sell it for what I have in it. Good thing I don't plan on selling it. Anyhoo....I looked over my spreadsheet and most of the purchases were necessary and had I not purchased them, and the ones that weren't necessary would have made for a totally different looking bike without some options that I really wanted. Would I recommend to anyone to do what I did? Not unless you have the funds to spend on a toy that you will probably never recoup the cost on other than fun factor.

[Spyder]

That was the first thing I thought of when I saw that picture. I figured that HAD to rub. Just my thoughts, 40mm is only an inch and a half. With the shock angle, I'm thinking it will only raise it about an inch, maybe a touch more. Swap the shocks, and raise the forks a bit, I bet you hardly notice. Might even like it more?

[Spyder]

OH ! ! ! AND CONGRATS ! ! ! It looks AMAZING ! Can't wait to see it in person come June !


Is it June yet ? ! ?

[93Bandit]

I am still debating if I want to share how much money I have in the bike. Spending got a little out of control and I'd probably be lucky to sell it for what I have in it. Good thing I don't plan on selling it. Anyhoo....I looked over my spreadsheet and most of the purchases were necessary and had I not purchased them, and the ones that weren't necessary would have made for a totally different looking bike without some options that I really wanted. Would I recommend to anyone to do what I did? Not unless you have the funds to spend on a toy that you will probably never recoup the cost on other than fun factor.

Hey, don't worry about sharing what you spent on it. I don't remember who requested that info, but I'm of the opinion that a person's finances are their business only, unless they want to share. I've never been one to ask others about their finances, and I don't share my info with others. This is just my opinion though, I don't mean offense to anyone.

But I'm sure most people here who have spent any amount of time wrenching is aware that the money spent will never be recuperated. The money shouldn't matter. We should just enjoy the experience and the bikes, and just understand that if you have to sell, you'll take a financial loss.