Several ?'s from 1st time owner

[Mr_Shake]

I just came into an '80 GS850G the other day, and have a few issues that need ironed out. First, it had pods and a 4-1 installed, and I don't believe it was rejetted. I honestly don't even know how what rejetting is exactly. It backfires in the exhaust whenever i decelerate, which may or may not be normal, and the choke bogs it down and kills it. It runs strong after it is warmed up, just feels rough around the edges.
When it is warming up, it pops a little in the carbs, which stops after a few menutes of running. I'm sure it needs a carb synch, I just have very little experience with motorcycles. I am excited about doing my own work on the bike and learning, I just have difficulty doing diagnosis.
Also, shifting is difficult until it has been ridden for awhile. It lurches when you shift from neutral into first, I don't know if that is a telltale sign or not. It is difficult to get back into neutral too.

I tend to write more than is necessary, so thank you for taking the time to read!

[Steve]

Re-jetting is the process of changing the jets in the carburetor that controll the amount of fuel that is mixed with the air that goes through. Since your bike has pods and a pipe, it is capable of flowing more air than the stock jets can handle, so newer, larger jets are required.

Here are the stock numbers from the carb "stickies" at the top of this forum:

1982 GS850GZ Carb. Specs.
mm (in.)
Carb. type: Mikuni BS32SS
Bore size: 32 (1.26)
I.D. no. 45160*
Idle rpm/min 1050 +- 100 rpm
Fuel Level 5.0 +- 0.5 (0.2 +- 0.02)
Float height 22.4 +- 1.0 (0.88 +- 0.04)
Main Jet #115
Main air jet 1.7
Jet needle 5D50
Needle jet X-5
Pilot jet #40
By pass 1.0, 0.8, 0.8
Pilot outlet 0.7
Valve seat 2.0
Starter jet #32.5
Pilot screw pre-set (well.....maybe)
Pilot air jet #180*
Throttle cable play 0.5-1.0 (0.02-0.04)
Choke cable play 0.5-1.0 (0.02-0.04)

With pods and a pipe, your mains should be closer to 130, and the pilot jet about 45. Not sure about the rest. You will probably also have to shim the needles a bit to raise them.


Have you checked the valves? Make sure they are in spec before tuning the carbs, as they will affect the outcome.

Hard shifting? First check cable adjustment. If that is all in spec, how old is the oil? If the oil will need to be changed soon, drain a bit, refill with a pint or so of Marvel Mystery Oil or SeaFoam. Ride for about 100 miles or so, making sure you use the clutch to allow oil to get between all the plates. Drain the oil, replace the filter, refill with the proper amount of a decent oil. If that does not help the clutch action, let us know, we have a bunch more stuff to try. 8-[


.

[twr1776]

First thing to do would be to find a service manual. Clymers, Haynes, or OEM. For the carb jetting check your sparkplug color to see what you have. A white color is too lean which is typical if it has not been re-jetted. Use the search function and you will find a ton of information on your particular issues and any other thing you could think of regarding the bike. Have fun.

[Mr_Shake]

Thanks for the great info! I have a Clymers, I just am lacking most of the tools I need to do some of these checks. I am about to make an order for some bars, what would be some basic tools I will need to get her running smooth?

I just replaced the oil when I got the bike, I used the Castrol motorcycle specific 10W-40. I forgot to mention that it started shifting poorly AFTER I changed the oil. I changed the secondary and final drive oils too. Thanks again!

[BassCliff]

hey howdy hey!

Mr. Mr_Shake (Is that redundant?),

Let it be known that on this day you are cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Please note that "good standing" implies pictures! :-D

Yet another 850G joins the herd! Woot! If you don't have a manual, there's a lot of information to keep you learned in the meantime. The Stator Papers, The Carb Rebuild Series, the valve adjustment pictorial, the tires and oil thread. And if you can't find what you're looking for in the search function, just post a question (hopefully to the proper section).

Thanks for joining us. These good people are teaching me to be a better motorcycle mechanic and a better motorcycle rider.

Thank you for your indulgence,

BassCliff

[Mr_Shake]

I put pictures in the GS owners area. She won't win any beauty pagaents!

[chef1366]

Try a Dynojet.
Part #3306.

[BassCliff]

Mr. Mr_Shake,

Did you get my PM?

Thank you for your indulgence,

BassCliff

[Mr_Shake]

Man, those jets are expensive! I guess I need them though. is there any way to know what jets are in there before I get new ones? Are they marked?

I swung out to the cycle salvage yard in missouri today and picked up a rear cowl and taillight from a 750, we'll see if we can get them to mount up. I like the way they look better than mine.

[chef1366]

Before you do anything you need to adjust your valves and do a compression check. Then take your carbs off and see what was done if anything and see what size jets are installed.
Get a manual.

[Mr_Shake]

Ya I have a manual, I just don't have the tools needed to do a valve check, other than a feeler gauge.

[BassCliff]

Only finger tight?

If you're going to fix it yourself, you gotta have tools. Get metrics, not SAE. The SAE sizes are close but you stand a chance of boogering up the bolts and such. A 3/8" socket set, open end and box end wrenches, from 8mm up to about 19mm should do it for most maintenance tasks, plus a spark plug socket. Oh yeah, you'll need something bigger to take off the axle bolts when changing tires. I just got a huge crescent wrench. Plus assorted flat and phillips screwdrivers. You'll need the valve shim adjustment tool (tappet depressor tool). Your feeler gauge set should also be metric as the clearances are measured in millimeters (.03mm - .08mm) rather than inches (.001" - .003").

You don't have to get them all at once. Just get what you need when you need it. But you will need tools to work on your bike. Happy wrenching! \\/

Thank you for your indulgence,

BassCliff