'78 gs750 carb woes

[motorlou]

hey guys, kinda new here but i just wanted to post a question about some carb problems we are having with a '78 gs 750. first was that the carbs leaked like crazy so we bought the kit on ebay that comes with the jets (main and idle) new air mixture screws ect ect. next problem is when we turn the bike on from cold, it takes forever before we can accelerate the engine or it will just bogg and want to die, it takes quite an effort to get past that but then it will be fine after that. i had another gs750 that did the same thing and i never figured it out. anyhow, tonight we changed all the parts that came with the kit and put all the settings like we found them. i would like to know what the baseline setting are for the carbs being that the bike ran like crap after putting everything back. also, i know the air mixture screw is at the bottom of the carb by the bowl, what is the other screw that is on the side of the carbs for? we don't have a manual for the bike. thanks in advance, Lou

 

[Big T]

1st, check your megawelcome and go to Basscliff's site and download a factory manual

Then, do all of the maintenance needed to make the bike run properly

While you're properly cleaning the carbs, remove all the kit parts and put the original stuff back in

Without knowing what maintenance you have/haven't done and what mods the bike has, it's impossible to tell what mistakes you're making again

BTW, the bottom screw is the fuel screw, the side screw is the air screw

 

[Nessism]

1st, check your megawelcome and go to Basscliff's site and download a factory manual

Then, do all of the maintenance needed to make the bike run properly

While you're properly cleaning the carbs, remove all the kit parts and put the original stuff back in

Without knowing what maintenance you have/haven't done and what mods the bike has, it's impossible to tell what mistakes you're making again

BTW, the bottom screw is the fuel screw, the side screw is the air screw

Agree. Your megawelcome was delivered in one of your previous threads so go back, read it, and download a manual.

From your previous threads it looks like you are a big modder. Hope you realize that you can't just slap on pods and chop off the mufflers and expect the bike to run like before. The bike will need drastic jetting adjustments. Good luck with that.

 

[Steve]

... we bought the kit on ebay that comes with the jets (main and idle) new air mixture screws ect ect.

Sorry, but there is a good chance that you wasted money with that move. 99% of the time, there is no problem with the brass pieces in the carb, they just need to be fully cleaned. The only parts that really NEED to be replaced are the rubber o-rings and the float bowl gaskets.

next problem is when we turn the bike on from cold, it takes forever before we can accelerate the engine or it will just bogg and want to die, it takes quite an effort to get past that but then it will be fine after that.

Have you stripped the carbs down and dipped (more like a soak) them overnight? That, followed by a set of new o-rings and proper adjustment will take care of your 'problem'.

tonight we changed all the parts that came with the kit and put all the settings like we found them.

Putting the original brass back in would be a good move, as long as it is CLEAN, but the original settings might not have been proper. After all, there have been 35 years for "previous owners" to lay their hands on them and set them the way they think is 'proper'.

i would like to know what the baseline setting are for the carbs being that the bike ran like crap after putting everything back.

The "baseline settings" will depend on your bike. Do you have the stock airbox and exhaust or do you have replacements for either or both of them? If everything is stock, about 7/8 turn out on the fuel screw (the one on the bottom) and double that (1 3/4 turn) on the air screw on the side. If you have installed a header or pod intake filters, you will need to add a bit more (maybe 1 1/4 turn, total) to the fuel screw, and start with double that (2 1/2 turns) on the air screw. After the bike warms up, do some tuning with the air screw to get the best idle.

i know the air mixture screw is at the bottom of the carb by the bowl, what is the other screw that is on the side of the carbs for?

Somebody has evidently mis-informed you, the screw on the bottom is the FUEL screw, the one on the side is the AIR screw.

we don't have a manual for the bike. thanks in advance, Lou

Did you get your "Official Mega-Welcome" from Basscliff? There, you will find links to his website, which is our GSR library and, more-specifically a manual for your bike.

.

 

[motorlou]

thanks guys, the only mod we did to the "engine" was remove the airbox. we installed pods and kept the original muffler. we disassembled the carbs, dipped them and blew the crap out of them. my next thought would be to put the original brass back and mess with the air and fuel screws see if that changes anything. i can't see how the brass would mess things up if they are original size jets ect.

ps. here is the bike and the "mods" we did to it. stock engine/mufflers

 

[junkmn]

Did you clean out the enrichment circuits in the car bowls?

 

[ron bayless]

Other than the height of the sissybar, that is one beautiful bike.You got some skills.

 

[Nessism]

The bike won't run properly with stock jets and pods.

 

[jsandidge]

exhaust

exhaust

That's not the original exhaust, either. It's a 4 to 1.

 

[jsandidge]

oops

oops

That's not the original exhaust, either. It's a 4 to 1.

Ooops, didn't see the other muffler at first.

 

[tkent02]

my next thought would be to put the original brass back and mess with the air and fuel screws see if that changes anything.

Don't "mess with" anything. Jet and adjust the carburetors properly.

There is a reason Mikuni has procedures for this.

 

[Big T]

See the Pods thread that is currently just below

and the dozens of threads on rejetting

 

[OriginalOwner]

Sorry, but there is a good chance that you wasted money with that move. 99% of the time, there is no problem with the brass pieces in the carb, they just need to be fully cleaned. The only parts that really NEED to be replaced are the rubber o-rings and the float bowl gaskets.

So, it makes more fiscal sense to re-use your brass?

I've been following along as I'm just tonight digging into the very first rebuild of my carbs for my 1981 GS750E.

Can you recommend exactly which kit and a good/inexpensive site online to buy the kit(s).

So far, all the ones I've looked at seem to be priced REALLY high.

Good luck with yours motorlou, that's quite a head-turner you have there!

 

[Nessism]

So, it makes more fiscal sense to re-use your brass?

I've been following along as I'm just tonight digging into the very first rebuild of my carbs for my 1981 GS750E.

Can you recommend exactly which kit and a good/inexpensive site online to buy the kit(s).

So far, all the ones I've looked at seem to be priced REALLY high.

Good luck with yours motorlou, that's quite a head-turner you have there!

Cycleorings.com

You don't need carb kits, just O-rings and maybe float bowl gaskets.

The Top Newbie Mistakes thread linked in my signature mentions such things. You might want to check it out to learn what to avoid.

 

[OriginalOwner]

Cycleorings.com

You don't need carb kits, just O-rings and maybe float bowl gaskets.

The Top Newbie Mistakes thread linked in my signature mentions such things. You might want to check it out to learn what to avoid.

Thanks Nessism for the good advice/links -- and I ain't even mad that you called me a "newbie.":lol:

Cycleorings.com is exactly what I'm looking for, much appreciated - what a great site with fair prices.

Got a site for the bowl gaskets? I'm definitely going to need those as well.

There's a guy on Ebay that sells 4 Genuine Suzuki OEM kits (with brass) for $70.00 -- the kit not only has the bowl gaskets but also the pilot jet plugs that I need too.

If I have to buy the plugs and the gaskets separately at the prices I've seen online, the ebay deal is not only gonna cost less but also have all the brass as an extra added bonus.

What do you think?

:-k

 

[cowboyup3371]

OriginalOwner, you don't need the brass. Any of the vendors in your welcome kit can get the stuff you're looking for. Please post up your own thread asking for the help though instead of hijacking the OPs

 

[OriginalOwner]

OriginalOwner, you don't need the brass. Any of the vendors in your welcome kit can get the stuff you're looking for. Please post up your own thread asking for the help though instead of hijacking the OPs

Thanks for your input.

I didn't see a need to spam the forum with a new thread when I joined the discussion in this one -- I replied to a post and never went off-topic to the discussion. I think your use of the word "hijacking" is inaccurate and quite frankly, a little melodramatic.

Enjoyed your 550 rebuild thread. Good stuff, thanks.

 

[Nessism]

Thanks Nessism for the good advice/links -- and I ain't even mad that you called me a "newbie.":lol:

Cycleorings.com is exactly what I'm looking for, much appreciated - what a great site with fair prices.

Got a site for the bowl gaskets? I'm definitely going to need those as well.

There's a guy on Ebay that sells 4 Genuine Suzuki OEM kits (with brass) for $70.00 -- the kit not only has the bowl gaskets but also the pilot jet plugs that I need too.

If I have to buy the plugs and the gaskets separately at the prices I've seen online, the ebay deal is not only gonna cost less but also have all the brass as an extra added bonus.

What do you think?

:-k

Please post a link to those kits. I'll bet you my 401k they are NOT "Genuine Suzuki OEM kits". For one, Suzuki never offered such a thing, and original Mikuni parts as sold though Suzuki are a LOT of money - about $40 for just ONE float needle and seat alone.

 

[OriginalOwner]

Please post a link to those kits. I'll bet you my 401k they are NOT "Genuine Suzuki OEM kits". For one, Suzuki never offered such a thing, and original Mikuni parts as sold though Suzuki are a LOT of money - about $40 for just ONE float needle and seat alone.

The ad says, "(4) brand new carburetor kits MADE IN JAPAN for suzuki." My first perception was Suzuki OEM and the ad is designed to lead the reader to believe that -- but on second thought, the statement is indeed ambiguous and I suppose it could mean anything.

Here's the link:

http://www.ebay.com/itm/1980-1983-suzuki-gs750-carburetor-4-kits-gs750e-gs750t-gs750l-katana-carb-td-/390661611320?_trksid=p3284.m263&_trkparms=algo%3DSI%26its%3DI%26itu%3DUCI%252BUA%252BFICS%26otn%3D21%26pmod%3D380468709986%26ps%3D54

 

[lemonshindig]

Those are K&L kits, sold by a guy I know, Marcel, out of Auburn, WA.

I made the same mistake. Don't bother with the kits. Just get the o-rings and the bowl gaskets. Really.

Marcel, aka "retro-motorcycles" is a fantastic resource for parts, but his carb kits are K&L. He does indeed lead you to believe that they are Suzuki, though.

I've been to Marcel's shop, it is FULL of shelves that are full to the brim of neatly organized slide-out boxes and all sorts of goodies.

Good luck
-Matt