Top Speed 60mph on Highway.... Then It Stalls!

[Bikemessenger]

Hey guys! New member here. New motorcycle rider to be exact.

I bought my first ever road bike at an estate sale here in Massachusetts over the winter. I scored a 1982 GS850L in original condition with 9,000 original miles on it for $100. The previous owner passed away and it had been sitting in his shed for 3-4 years. I replaced the tires and bought a brand new battery and it fired right up. Unfortunately, it sat during that time with fuel in the tank so after draining the tank (which was actually very clean inside) I took it to a shop to get the carbs cleaned because the idle was real rough. After the shop finished their work, it now starts up immediately as soon as I push the button with only a little bit of choke.

I got my motorcycle temps and plate and have been tooling around the city on it. It runs fine on the streets but as soon as I get on the highway, the problems begin. It takes a long time to get up to 60mph. So long that I'm holding up traffic behind me. After getting to 60mph (the top speed it will go) is begins to slow down and before stalling out. I then have to roll off the side of the highway and with some choke, it will fire right back up again.

I assume that the engine is just not getting enough fuel at highway speed. My question is why? Around the city it does just fine. It also bogs down at the beginning of first and second gears, but once I hit the mid range RPM's or get to third gear it's OK.

The shop told me to bring it back in on Monday and they'd take a look at it. The mechanic thinks it's the petcock. I know a decent amount about cars, but nothing about the internals of a motorcycle and don't really understand what a petcock does. I'm sure the mechanic will figure it out, but I figured I'd ask here in case there is some stupid little thing that these bikes are known for or it's something obvious other than the petcock. Could there possibly a clogged fuel filter or vacuum issue?

Thanks in advance. I'm looking forward to my first summer riding motorcycles. For as big and heavy as this bike is, it's a very smooth and balanced ride.

 

[tom203]

"It takes a long time to get up to 60mph. So long that I'm holding up traffic behind me"

probably a collection of problems here. Your petcock might be one as your mechanic thinks , but this thing should jump to highway speed before a petcock starves it. Didn't this "mechanic" road test this bike after his work? Sounds like he might not be up to the task here. Go here do some reading about common issues....

http://members.dslextreme.com/users/bikecliff/images/GSR_Greeting.html
Yes, we all are eager to ride, but to do so safely requires that the bike run well, so you can focus on not getting creamed.

 

[Steve]

If the carbs were "rebuilt" by simply installing a bunch of new parts, they were not REBUILT.

They need to be CLEANED by removing all those new parts, soaking them in carb cleaner dip for about 24 hours (each), then put back together with new o-rings. Too bad the original parts are gone, they were probably better than the new parts in the "rebuild" kits. New o-rings are available at cycleorings.com.

The reason for this is that when gas goes through the small holes in all your new parts, it has to go through some small passages to get where it needs to get introduced to the air stream headed into the engine. Those passages are what gets plugged up when the bike sits for 3-4 years.

.

 

[eil]

I'll echo Tom's and Steve's sentiments and also add that it's a whopping good idea to get familiar with the bike and work on it yourself. See the link Tom posted (it's also in my signature) and get a-readin'. If you follow the rabbit-hole, there are links to advice, tutorials, and even electronic copies of the factory service manuals. Once you fix the problems, that bike will have zero problems taking you to 80 mph and beyond in a heartbeat.

The petcock is just a valve that either lets fuel flow or not, depending on the lever position and whether it has vacuum or not. Make sure there's no inline fuel filter and that the gas line is not kinked, these will cause fuel starvation. A new petcock is probably in order, although these tend to fail in the open position rather than closed and will dump fuel into your crankcase when doing so.

 

[JTGS850GL]

I have an 82 GS850GL and I can tell you for a fact that it will do 100 mph if tuned correctly. Zero to sixty should only take a few (4 to 5) seconds. I noticed that you didn't mention doing the valve adjustment as well. That's pretty much a mandatory on these bikes. My guess is it's never been done on yours. There's a bit of maintenance that needs to be done on a 30+ year old bike so, as others have said, you need to learn how to wrench on the bike yourself. It's not hard and is quite rewarding in the end.

I'd be very cautious of a bike shop that didn't verify the bike was in good running order after a major carb rebuild. Ya, your petcock might be bad, but they should have caught that.

 

[gustovh]

One of my rides is an 850L, had a bugger of a time sorting it out. You are not only new to old bikes but new to bikes period, so jump right in and start at the beginning like the others said. Adjust the valves, clean the carbs, new O rings all around, the carb mounts might be toast, surely the O rings are, and last but not least check all the electrics. You did get a great deal, but now you need to invest the time to make it a great ride.

Remember it does no good to adjust and sync the carbs if the valves are not right.

V

 

[Guest]

Sounds like a petcock problem but you do need to do all the maintenance as mentioned.

 

[Bikemessenger]

I appreciate all of the input guys. I don't know if I'm comfortable jumping right into multiple repair tasks myself with no experience. I don't mind learning starting with maintenance, but I'd rather have a shop do any intricate repairs (valve adjustments, carb rebuilds, etc...) at the beginning here.

Symptoms after an afternoon of riding:
- Takes a long time to go 0-60
- Tops out at 60mph in 5th and then slows down until it dies. Starts back up with choke
- Bogs down immediately after shifting into 1st and 2nd gears, probably wouldn't do a burnout if I had the throttle wide open when shifting into 1st
- I filled the tank up the other day with premium (mechanic's advice) and after 38 miles, I'm down to a 1/2 tank already
- It also smells strongly of gas when idling, though it doesn't drip gas onto the ground when shut off

I definitely need to buy a brand new petcock, right? What else should I go ahead and and get brand new for the mechanic?

One other question: Is a VERY slight clunking sound/feeling normal when shifting from neutral to 1st, before letting the clutch out? Does this mean my clutch needs adjusted?

 

[JTGS850GL]

Normal for it to clunk slightly when going from neutral to 1st.

 

[bobgroger]

If it seems like it is starving for fuel after riding a bit, open the gas cap. If you hear a Whoosh! the vent in the gas cap is plugged. We ALL started here like you. You can't afford this $100 bike unless you work on it yourself. You NEED to do everything on the list of the top 10 Newbie mistakes. The brake lines and cylinders are most likely crap, the fork oil is like stinky Jello, the valves are too tight, the electricals are junk. We all came here thinking we could just fix a couple things and go riding. No, if you are lucky it will be dialed in by NEXT season. We will help you.... If there is another member near you they most likely will come over and help you for beer...

As JTGS850L said, http://members.dslextreme.com/users/bikecliff/images/GSR_Greeting.html will get you started

 

[mike_of_bbg]

A little clutch drag is normal; the clutch sits in oil. You might need to tighten up the clutch cable a little bit if your bike is bogging down a lot in gear. They do stretch a little over time.

Good call on the gas cap -> check that. Petcock issue sounds likely too as others have said. Have you looked at your plugs? Post a pic? Check the petcock vacuum hose for any signs of liquid fuel. When the diaphragms in the petcock rot they can send fuel down the vacuum line straight into carb #2 and yeah, that will definitely get the gas smell going. L's have small tanks and yeah, even in my 550 I don't get much more than 100 miles before hitting reserve; since it's only about 2 gallons!

Does your oil smell like gas? Is the level correct? If you leave it idling on the center stand can you see any fuel drops on the bottom of the carb bowls?

Clean air filter?

 

[tom203]

Want a simple approach to start?
Change your petcock :go here order this you'll also need sealing washers under mounting bolts

http://www.georgefixs.com/brand-new...s550-gs650-gs750-gs850-gs1000-gs1100-petcock/

Then change your oil (probably contaminated with gas based on your nose test). Doing this rules out petcock as problem.
Premium gas is unnecessary, it has no advantage-
Is your mechanic familiar with motorcycles?
There was/is a member in Narrangansett,R.I. who fiddled with these critters, maybe "professionally"

As others have stated, it's very unlikely that this thing will be safe to ride without maintenance catchup.

 

[Bikemessenger]

Problem Solved.

Opened up the air box and the previous owner had tried to seal it at some point with some kind of caulking. This had dried out and clogged up the air filter and intake. The air filter was all wet with gas and two of the spark plugs (left side) were ruined and not firing.

Cleaned everything up, replaced the plugs and air filter, re-adjusted the carburetor again and now it's running nicely. Immediately afterwards it was running smoother but it was still bogging down just slightly in the middle rpm's of each gear. I took it out on the interstate and opened it up to about 100mph for approximately 10 seconds and that cleaned the last of it out. It is now running like a brand new bike. It's fires up the split second that I hit the start button and it's purring at both idle and through every gear. I can go 0-60 pretty damn quick and 40-90 even quicker. LOL

The gas mileage improved greatly too (obviously) I put 58 miles on it this afternoon and only used about 1/2 tank and that was with a lot of throttle. Before the fix, 48 miles used up a whole tank. I also changed the oil.

Thanks for your help guys.

 

[steve murdoch]

Good to hear you got it sorted.

 

[Spyder]

Didn't heed a single thing said here... Sounds just like me when I signed up the first time when I bought mine. Scared to death of cracking too deep into it, and just wanted the "magic" answer. Hopefully he won't learn the REALLY hard way...

HAVE to wonder. If his "mechanic" had the carbs out of the bike, how the HELL didn't he notice airbox and filter issues?!?!

Shaking my head....

 

[BigD_83]

I appreciate all of the input guys. I don't know if I'm comfortable jumping right into multiple repair tasks myself with no experience. I don't mind learning starting with maintenance, but I'd rather have a shop do any intricate repairs (valve adjustments, carb rebuilds, etc...) at the beginning here.

Symptoms after an afternoon of riding:
- Takes a long time to go 0-60
- Tops out at 60mph in 5th and then slows down until it dies. Starts back up with choke
- Bogs down immediately after shifting into 1st and 2nd gears, probably wouldn't do a burnout if I had the throttle wide open when shifting into 1st
- I filled the tank up the other day with premium (mechanic's advice) and after 38 miles, I'm down to a 1/2 tank already
- It also smells strongly of gas when idling, though it doesn't drip gas onto the ground when shut off

I definitely need to buy a brand new petcock, right? What else should I go ahead and and get brand new for the mechanic?

One other question: Is a VERY slight clunking sound/feeling normal when shifting from neutral to 1st, before letting the clutch out? Does this mean my clutch needs adjusted?

The nice thing is that you don't have to do all of the repairs at once. You can really only serially monotask. Prioritize, and work your way through the list.

A valve adjustment is actually a very simple task, and shouldn't cost much more than an extra shim or two and a new gasket to do it yourself. This is one task that a "shop" will charge hundreds of dollars that you can spend on fixing other problems.

It does sound like you've made a great start by finding the airbox issue. Now get out there, sort the rest, and ride.