JohnnyL's 1980 GS550L Cafe Build

[Spyder]

Going all the way down to #100 jets seems WAY too low. I am thinking the stock jet is around #112 (look it up because I don't know for sure). With pods, and a free flowing pipe, you'll need to go at least one size up from stock, possibly 2 sizes. Also will need to raise your needles at least one notch. Granted, you don't have an airbox in your way, and it's easy to remove them, but why do more work than you have too. LOL

[Rich82GS750TZ]

Agree. And at that price, if most the parts of ebay carb rack you bought are in decent shape, than you'll have lots of spare carb parts on hand, just in case you ever need anything else.

[JohnnyL]

Johnny, I've seen threads here of people repairing broken carb float post like yours. Hope is not lost. Do a little searching..

Thanks! I didn't realize this was a common problem. I read about the suggested repairs. Since I'd rather not have any janky repairs on this bike, I decided to purchase a set of carbs off of eBay for $138 and free shipping. The price didn't seem too bad since I've seen them sell over $450 for a set. I'll pull #3 off of the eBay set and clean it up and replace my #3 with it.

I'm going to bet money that this is why the bike ran poorly. While I'm in the carbs though, I am going to change out the 117.5 main jets for 100s and set the float heights to where they're supposed to be.

eBay set for $138

[Rich82GS750TZ]

Johnny, I've seen threads here of people repairing broken carb float post like yours. Hope is not lost. Do a little searching..

[JohnnyL]

Brian came over last night to help me tune the bike. We first synced the carbs with his syncing tool. The engine had to be idling pretty high(about 4000 rpm) to even get the vacuum carbs to register on the gauges. Once the carbs were synced, we were able to set the idle to about 1200 RPM. The bike would sit and idle fairly well but would pop every once and awhile. As soon as you crack the throttle up to about 5000 RPM, the revs would run away and stay at 5-6000 RPM. We checked for air leaks and didn't find any. Brian thinks maybe the main jets are too large and that I may have the float heights off.

So this morning I took the carbs off of the bike and removed the bowls to check float heights. The manual states that the heights should be set at 22.4mm +/- 1mm. I found them set at 20.67, 20.78, 20.45 and 20.72. Obviously off. I then wanted to check all my float needle springs so I removed all of the floats. When I did this, I discovered the float post on carb #3 was wiggling around. WTF? When I went to tough it, it fell right off. The previous owner had obviously broken it and tried to repair it with some JB Weld. I don't know how I didn't see this when I rebuilt the carbs the first time. So now I'm screwed. I either need to find someone with a spare #3 carb to sell or buy a whole new set which I'm not even sure where to get. They're Mikuni BS32SS carbs. Shyte.

[Cipher]

Does anyone happen to know how many times the cable drive speed sensor turns per one rotation of the wheel? I need to know this for setting the speedometer up. I could raise the front wheel and count the rotations but I'm just wondering if anyone happens to know offhand.

Interesting I do believe it is standard across all suzukis. Its buried in the archives somewhere.

https://www.thegsresources.com/_forum/showthread.php?189003-Speedo-drive-gear-ratios&highlight=speedo+thread

[JohnnyL]

Does anyone happen to know how many times the cable drive speed sensor turns per one rotation of the wheel? I need to know this for setting the speedometer up. I could raise the front wheel and count the rotations but I'm just wondering if anyone happens to know offhand.

[JohnnyL]

60 degrees in February in Indiana! We just had to pull the bikes out from under their winter covers and go for a family ride.

[Rijko]

Thanks Steve, will be looking for something like that.
BTW the one i posted has a .110” orifice so is unsuitable for
use on the GS.

[Steve]

No experience with that particular device, but my 1979 KZ1300 came with an electronic solenoid to shut off the fuel. One of the common "improvements" was to remove that solenoid. I think it also had a vacuum-operated petcock, so not sure why it also had the solenoid. I never had problems with mine, so never removed it.

.

[Rijko]

I have been thinking about an electronic fuel valve next to the Pingel i have.
Sure forgot to shut it off more than once, but lucky enough not to suffer float failure.

Anyone use something like this ?

https://centuryfuelproducts.com/afc-151-lockoff

[Buffalo Bill]

Yet another vote for OEM.

1. In racing use, where you have wide open throttle for much of the time, there is not enough manifold vacuum to keep the petcock open.

.

I figured this out the hard way only this summer. Kept getting sluggish throttle response right at mid corner transition from trail braking to power on.
You're confirming my theory Steve. I'm gonna select Prime next track day.
Thanks!

[TeamDar]

My opinion on petcocks is this. If you have the 1980 style oem petcock without the lever I would replace it with a Pingel. If you have the lever style oem and don’t really need the high flow of a Pingel then a replacement lever type oem is fine. I have both type on my various bikes and have never left a Pingel in the ON position. Maybe I’m different, I also know how to use an easy out without breaking one and I can use the factory oem valve adjustment tool while adjusting valves on the shim bucket engines instead of sticking zip ties in the spark plug hole.

[bwringer]

Unless you have the sort of brain that can remember to turn off the petcock EVERY SINGLE TIME and turn it back on EVERY SINGLE TIME 110% without fail, then I'd install an OEM-style vacuum petcock. I do not have this sort of brain. I don't know if anyone like Pingel offers a "prettier" vacuum petcock; the stock piece does look a little plain.

FWIW, I replaced my GS's petcock in about 1997, and it's still working fine.

The petcocks sold down at Cycle Recycle downtown are the good stuff, and I'm pretty sure he normally keeps these in stock:

https://newmotorcycleparts.net/fuel_system_parts/petcocks/petcocks_suz.html

My wife used to have an old Honda with a manual petcock, and every single time we went for a ride, one of us would forget to turn it on or off at some point. Quite frankly, I think manual petcocks are dangerous; having a bike crap out in traffic shortly after setting forth is a great way to get run over.



Anyway, a fair amount of breather vapor is pretty normal, especially in air-cooled engines; this is why it's normally routed back into the airbox to be burned (that steel wool stuff in the valve cover helps the vapor condense a bit and drip back into the engine), and why airboxes get so grody inside. With no airbox, you'll need to filter and catch the condensate.

I wouldn't worry too much about the exhaust smoke yet either, although I would not run it more than necessary until you can actually go ride it and put some stress on it to help seat the rings properly. You're also likely idling pretty rich, so that can foul the plugs after a while and be a little more smoky.

[JohnnyL]

I've been letting the bike idle a little bit to burn in the header wrap. It's pretty stinky. I'm noticing a lot of smoke coming out of the exhaust and the crank case breather tube. I assume this is normal until the rings get seated in?