starving for fuel or choking on air?

[rain or shine]

I have a 1980 GS850L that will start and run. The things is if you rap the throttle it will rev fine up to about 5,000 rpm but over that it acts like its running out of fuel. The rpm's fall and the only way to save it is by pulling the choke. Also if you hit the throttle and let it fall back down to idle and immediately hit it again it will die. At first I thought this was an air issue because of the poor condition of my breather box boots so I bought velocity stacks for it. Same result so i left everything off the back of the carbs and laid an old T-shirt over the back to block air flow and it ran fine. So how do I know if this is an air or fuel problem?

Any help would be great... Bill

[Steve]

OK, if I understand you correctly, you are running velocity stacks ONLY?

In that case, consider yourself very lucky that you can get it up to 5,000 rpm.

You will need to re-jet your carbs. A DynoJet kit is advised.

.

[BassCliff]

Greetings and Salutations!!

Hi Mr. rain or shine,

These engines need a specific fuel to air ratio (mixture) to run properly. By removing the airbox you are increasing the air input significantly. You must install larger fuel jets in your carbs to compensate. When you draped a t-shirt over the carbs you restricted the air intake and it ran better because the fuel/air mixture was closer to optimum. Now, 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

[chef1366]

Clean the carbs and install new o-rings
Fix the airbox and run stock jetting or get K&N pods and get a Dynojet kit.

[rain or shine]

Thanks for the info. I'm going to let you all know how it turns out.

[rain or shine]

I put the jet kit in and the bike ran great until I went out for a road test. I rolled the trottle pretty hard and when I came out, it started backfiring trough the Cabs and now it will not idle. It still runs and will maintain speed going down the road. I've noticed that it backfires more during acceleration than while holding a steady rpm down the road.

Any ideas......?