Thorough cleaning & won't start

[Jman750e]

First, many thanks and much gratitude for everything on this site. This is my first bike and this site has been much help. Anyway...

Bought 1980 GS750E last summer. PO said he cleaned carbs but that it needed a new petcock. Petcock replaced. Bike ran all last summer, not amazing but well enough. Just finished a THOROUGH carb cleaning (boy did it need it). TOTAL strip and dip. Bought a carb rebuilt, not necessary but what the hey. Good thing I did because PO had booggered up a few of the jets. Installed carbs. Needed to use a starting spray to get it started, but when it did... WOW. It was like a totally different bike. Went for a test drive. This bike is a lot faster than I originally thought.

Problem: Go out to start it the next day and I get nothing. Didn't use starting spray because I read somewhere that was a bad habit to get into

Only other thing to note is that it doesn't have its vent hoses. could that be the deal breaker?

[Mith]

When you say you went out and tried starting it and you got 'nothing', what exactly did it do? Did the starter crank? Did you put it on prime for for a bit first? Did you check to make sure you had spark? Have you done a valve adjustment recently? When you had the carbs apart, did you adjust the floats as the rebuild guide instructs? The more detailed info about recent maintenance will help.

One last thing, when you swapped out the jets that came with your rebuild kit, did you verify the sizes were the same as what was in the carbs?

[cowboyup3371]

Yea, what Mith said. Is the battery charged and good? Are your fuses all good? Might want to sit down and go through your entire electrical system since the charging is a known weakness for this thing.

[rustybronco]

Did you make sure the passages in the float bowls were not plugged up?

[spyug]

Welcome aboard. Now not to beat you up but you need to state your problems clearer and in more detail if you want help. the statement is too general as you can see by some of the answers you already got.

I take it from your statement about the use of quickstart that the bike does turn over but doesn't fire. Is this with or without the enricher (choke)? Is the battery in good shape and fully charged?There are many other questions I can put to you but i don't want to complicate things.

Basically, these bikes come jetted lean from the factory and can thus be hard to start. They almost always need choke, even for a minute or two.If the valves are tight they can be very difficult to fireup so you should do a valve adjustement. They are also prone to having issues with wiring and connectors that can cause less than full voltage getting to the coils, ultimately causing weak spark. In combination these things can make it quite a chore to get going.

I'd start with the carbs. Did you make sure to "bench synch" them? The butterflies need to be set so at rest they are slightly open about the width of the thickness of a paper clip. If the butterflies are jammed shut (seen it) the bike won't start. Overflow tubes should also be in place. Are you using the stock airbox or pods? The carbs work best with a stock airbox and if you run pods they may be too lean if the jets are not changed up (to richer versions). It is also important that there are no airleaks at the intake boots or in the carbs themselves so hopefully you replaced all o-rings. Remember over leanness caused by more air than fuel is the big culpret in hard starting.

Have a look at the things mentioned and let us know what you find.

Good luck,
Spyug

[Jman750e]

Sorry about vagueness of "nothing". The motor turns over just fine. I've read the stator papers, did the tests, good to go. Battery - good. The replacement jets matched number for number. Have not yet synched the carbs. Also have not replaced the boots or checked valve clearance . The PO replaced the stock filter box with cone filter, the air box is still there. I guess that might contribute to the failure/difficult to fire. And yes, used full choke during start up.

Just surprised that during my test run it ran so well and then the next day it wouldn't fire. Should I have to prime the carbs for the first few rides after a rebuild to work out any air pockets in the carb? and are those vent hoses between the carbs necessary? Local bike mechanic who looked at it last year said it was missing them but that they didn't matter.

Gonna go put some of the great advice I've just recived to use. Thanks guys.

[1948man]

Did u bench sync after cleaning? Are your sparkplug caps seated firmly on the plugs?

[spyug]

The PO replaced the stock filter box with cone filter,

I'd say this is a lot of your problem as I previously stated. Theses filters are not restrictive enough and your stock jets won't be rich enough. You are running very lean. You might try going up (richer) a couple of sizes in the primary circuit jets.

It really is important to make sure to run more to the rich than the lean as far as starting goes. Going back to the stock airbox would likely be the easier choice as fiddling with jets and pods can become a frustrating balancing act.

As mentioned also, valve clearances are important so please take the time to check them. Weaker spark to can be an issue and you might do a voltage drop test to see how much voltage gets to the coils. As the bike ages the circuits tend to become more resistant as connectors corrode.You may find the coils get as much as 1 to 1.5 volts less than battery voltage resulting in a weaker spark. There is the "coil relay mod." that takes care of this and is a very good and fairly easy modification to make.

Play with the carbs first.

Let us know how you make out.

Cheers,
Spyug

[BassCliff]

Greetings and Salutations!!

Hi Mr. Jman750e,

So you used "carb kits"? The parts in those kits are generally of lesser quality than the OEM jets, seats, O-rings, etc. That could be part of your problem. But I also wanted to bring to your attention the float bowl gaskets. Most of the aftermarket gaskets have punch-outs that need may to be configured to match the stock OEM gaskets. Notice in the pictures:









Make sure the replacement gaskets match the OEM gaskets. All four carbs may not be the same.

Anyway, let me dump a TON if information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Rebuild Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[Jman750e]

BassCliff, you are like the psychic Einstein of the the GS! Now that you mention it I remember that the gaskets weren't an exact match. What a rookie move. Whenever I worked on my car and had to get new parts I never moved foward unless the new part was an exact copy of what I was replacing. Why I didn't do that with this is beyond me. Will be taking the carbs off tomorrow and modifying the gasket. Later this week I'll do a carb synch, valve adjustment, and carb boots. Any other obvious GS specific things I may have missed?

Thanks to all of you for the advice.