80 GS850L won't rev to redline, fuel Starvation?

[Guest]

Not my bike. I sold a perfectly good running GS850L to a nice young man and he brought his buddy with him on a "Bobber" 80 GS850L. They asked me to check out his buddies bike because it wouldn't rev past about 1/2 rpm. Now here is the setup.

Carbs look clean and idles really well. Cheap POD filters and mufflers cut off so only running open headers. Bike actually sounds good but loud. I don't judge. First thing I did was to reduce idle rpm to a nominal 1100 RPM by ear. Blipped the throttle and it instantly returns to a smooth idle. It's a bobber so no tach and no speedometer. Fully warmed up and grab a bunch of throttle and it revs to what sounds like about 5k rpm then just a WHAA sound and won't increase.. If you hold the throttle wide open it will eventually die!k It revs off idle like a champ but just won't keep increasing RPM. First thing I told him was that it will never run right with those PODS so he says he's going to buy a stock air box on ebay. I then told him if he needs help putting it on I'd help. Like I said nice couple of guys but have no idea how a motor should run or to make one run.

It is running on all 4 and charging system seems to be working although I did not test idle and 2500 rpm charging voltage. This just acts and feels like fuel starvation.

I know with the air box missing the carbs are easy to pull and check, which I am willing to do. I just didn't want to spend a lot of time and I really don't want to charge them for helping. So I guess what I'm looking for is "Does this sound like I'm on the right tract with carbs lean from the pods or should I check somewhere else"?

[jdvorchak]

After posting this I just realized that I need to pull the carbs and check to make sure all of internal parts are there (pilot jet rubber plugs) inside the carbs and float level as a start. Now I wish he would have left the bike for a day or two so I can do some proper tests. LOL

[Nessism]

You might want to check the Newbie Mistakes link in my signature. The bike won't run for crap with pods and stock jetting, but it sounds like that is just the tip of the iceberg of that bikes problems.

[Cyrano]

These engines run very well with a stock set up. When you start to put pods on and change the Zorst then you may as well lick you finger and hold it in breeze to guess what jets you need. You can't even use somebody elses settings as every bike will be a bit different.

All you can do to help that bloke is clean and balance what's there.

[smilinbrad]

My GS550 wouldn't rev when it was too lean. Those of you with a full set of digits can check by pulling the choke while running near the stumble speed. If things get better it's too lean.

[gustovh]

He will need 122.5s at the bare minimum and probably 125s, for mains. Anything less and it starves. Bet you anything his jets are still stock.

V

[jdvorchak]

Here is the strange part. I forgot to mention that it won't rev with the choke pulled either! Well thanks for the suggestions and kinda what I figured. I think I'll just start checking stuff and what ever is left over is probably the problem. Like stock jets and I'll peruse the newbie post listed. I had forgotten about that post.