Newbie with carb problems

[Fraggle]

Hey everyone! I am new to the site, My dad just got a 85 GS450L and I am trying to get it going for him. I have some mechanical experience and some experience working on motorcycle and carbs. I own a 81 CB750 myself that I restored myself. When we the GS, I pulled off the gas tank and hooked up my test tank. Then put the bike on the charger and tried starting it. The bike will turn over but wouldn't start. I pulled off the carbs cleaned them replace some of the gaskets but not all and reinstalled them. The bike is doing the same thing though. If I spray starting fluid through the carbs the bike will start but will not continue to run. I am thinking the carbs are not putting out fuel but do not know why. I don't have the gas tank on the bike I am using a test tank. So I know the petcock is not the issue. I would have used the search function but didn't know what to search. Thanks for any help you can give. I have checked for compression and for spark, both seemed good.

[old_skool]

Probably don't have to worry about compression or spark if you got it to run on ether, you need to go back and focus on tearing down and rebuilding/cleaning those carbs properly, somewhere fuel not going where it's supposed to. You alread eliminated the fuel delivery when you substituted the tank, not sure what your using for a test tank, if it's a regular fuel tank, make sure the line from the petcock doesn't have a vacuum hook up you forgot.

[chuck hahn]

Do you have fuel in the bowls? Did you plug the vacuum hose that would normally be attatched to the petcock vacuum port? Did you loosen the bowl drains to see if all 4 carbs are getting fuel? Back off the idle adjustment knob and turn it in till it just touches the throtle linkage and then add about 1 1/2 turns. If the knob is too far in then the bike will not want to start easily. Did you set the float heights when you rebuilt them? Did you check to see that the floats moved freely on all the carbs when you had them off the bike? Lots of things to be considered here.

[chuck hahn]

Oh..and you can throw a tshirt over the throats of the carbs..that always helps too.

[old_skool]

Do you have fuel in the bowls? Did you plug the vacuum hose that would normally be attatched to the petcock vacuum port? Did you loosen the bowl drains to see if all 4 carbs are getting fuel? Back off the idle adjustment knob and turn it in till it just touches the throtle linkage and then add about 1 1/2 turns. If the knob is too far in then the bike will not want to start easily. Did you set the float heights when you rebuilt them? Did you check to see that the floats moved freely on all the carbs when you had them off the bike? Lots of things to be considered here.

Agree, but at this point he might as well give himself a good starting point by going back into the carbs, do a complete disassembly, a proper sync and tune. Should start then, after all, you said it fired on ether too, you just used a shortcut to get it in the engine, use a manual and search here for rebuild threads, save yourself a lot of headaches, instead of guessing. You might find thats all you need.

[chuck hahn]

Yes i agree. Full valve adjustment, full tear down and rebuild, set float heights..double and triple check everything. Get the orings from Cycleorings.com.

[Octain]

Also be sure the airbox is in good shape. Leaky airboxes can cause lean conditions that can harm the engine.
Trash the starting fluid!!

[chuck hahn]

Ether actually rinses the oil off cylinder walls..use a spray bottle with gas in it if you need to prime them. And for god sakes dont do anything unless a fire extinguisher is within arms reach. Back fires lead to burned down houses!!! and toasted bikes!!!

[Fraggle]

I am using a riding lawnmower tank I converted to a test tank. I have the airbox hooked and the vacum port for the petcock plugged off for now. I was just using the ether to make sure the motor would actually fire up. I took the carbs apart cleaned everything i could see to clean. Making sure to blow out every port hole and jet I could find. replaced floatbowl gasket and needle seat o rings. I have a factory GS service manual that I am using. The problem is that there is no gas coming out of the carbs into the cylinders. I am sure there is gas in the bowls, when I take took the carbs back off gas poured out of the bowls. Is there some secret passage way on the carbs I am not seeing? I made sure the choke passage ways were clean. Is it possible for something inside the carbs to go bad and keep fuel from being pumped through them. I need to recheck float height but I did check to make sure the float and they do. I have took the carbs back off and recleaned everything. I did not pull the choke assembly apart though. Any help will be greatly appreciated.

[tom203]

.....Is there some secret passage way on the carbs I am not seeing? I made sure the choke passage ways were clean. Is it possible for something inside the carbs to go bad and keep fuel from being pumped through them. I need to recheck float height but I did check to make sure the float and they do. I have took the carbs back off and recleaned everything. I did not pull the choke assembly apart though. Any help will be greatly appreciated.

There's lots of tiny passages that can get clogged- that's why others were calling for serious dip operation. Once these passages get plugged, they don't respond to gumout and blowing air- they need solvent soaking! Be thankful that you only got two carbs!

[BassCliff]

Greetings and Salutations!!

Hi Mr. Fraggle,

You'll want to thoroughly investigate the links below, go through the maintenance lists, find the proper procedures on my little website, and TAKE NO SHORTCUTS when it comes to checking, cleaning, repairing, replacing, and adjusting everything that needs to be taken care of. You have a 30 year old machine that needs 20 years worth of maintenance.

Now, let me dump a TON of 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 Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. 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

[Octain]

Take em apart and dip em. It's the only way.

[chuck hahn]

As Todd and others said..full tear down in order.Soak the bodies and every jet and poke the holes out with a wire such as a bread tie. Rinse everything well with carbs spray and compressed air..over do everything and youll probably be just right.

[Fraggle]

Alright I have been away for awhile. I started back on the bike. Done a complete tear down and rebuild on the carbs. I got them back on and it still will not start. The only way I can get it to run is by holding my hands over the carbs. When I do this it runs at about 5000 rpm. As soon as I remove my hands the motor dies. Any ideas on where I am going wrong? I checked to make sure both carbs are getting fuel in the bowls and checked make sure floats more freely.

[cowboyup3371]

Airbox needs to be back on for one thing. Secondly, set your mixture screws out to 3 turns and go from there. Did you do a bench synch as well?