Bike will not idle

[Octain]

Octain - The carbs were cleaned and synched in November, could they go bad this quickly?

From sitting untreated. Yup, sure can.

[tom203]

So it ran fine for 2 to 3 months after the maintenance and then something happenned. Maybe a load of bad gas.Do something simple - Drain all gas from tank and fuel bowls ( dispose of it in your car), put fresh stuff in.

[bmlbytes]

chuck hahn - I went to Auto Zone and rented the compression gauge. From the far left side of the bike to the far right side, here are the compressions: 120, 115, 100, 120

[chuck hahn]

Go to BASSCLIFF WEBSITE and theres a free download service manual fo rht ebike..It should have all the factory engine specs. I was thinking that the valves need as second look at.

[bmlbytes]

Well its technically still within the range of the manual, but on the low end. The manual says:

Standard: 128psi - 171psi.
Limit: 92 psi
Max difference among each cylinder: 28psi

Again (for quick comparison) my pressures were 120, 115, 100, 120

So technically, all pressures are above 92psi and no cylinder is more than 28psi different from another one.

This might not be an ideal result, but is it the problem I am having? I will check the petcock valve and the electrical tomorrow. I NEED it to not be the valves. I can't afford to have someone rebuild the engine, and I don't have the time or knowledge to do it myself.

[chuck hahn]

Not a rebuild of the engine..We mean to check the valves at the shims and camshafts. It really a very easy procedure.. I think in Bsscliffs welcome package theres a tutorial Maybe a experienced member close by would make a home school stop ..never hurts to ask.

[bmlbytes]

http://members.dslextreme.com/users/bikecliff/images/gs850valve_adjust.pdf

If that is the tutorial you are speaking of, it looks pretty simple. I'm not sure what shims I would need, or exactly what tool he is using.

By the way this conversation is going, I have a feeling you are going to tell me to go look at Basscliffs site for something

[damoj19]

now im not 100% about anything but i was having a problem starting and stalling when my hand came off the throttle on my 1982 gs850g for the last week or so but I adjusted the idle adjustment screw/nut directly under the center of the carbs and it stopped stalling on me and it also started idling beautifully.

I also started the bike by jumping it (even though it has a new battery in it) and bike the bike turned a lot faster and started right up b.c it wouldnt on the battery alone. After riding it for about 30 mins or so(with no stalling either) i let the bike cool down and it started right up and the engine was cold. So idk if that helps or not, idk if you have an idle adjustment knob under your carbs or not but it couldnt hurt to take a look to see and turn it if its there. (I think turning to the left is lowering the idle but you should be able to tell by the sound of the engine...if its running)

It is very simple and quick but its easy to look over the simple stuff.

[bmlbytes]

If it is that gold knob under the gas tank, then yeah, I turned that clockwise. I got it to run by itself, but it was at about 3000 RPM. Not exactly the idle speed I'm looking for.

[cowboyup3371]

Idle should be around 1100 or so +/- 100 rpm

[bmlbytes]

GS1100GK - I'm not familiar with the max RPM method. Could you fill me in or link me to where I can find that information?

[niclpnut]

From Bassclif's website:

Highest RPM and Plug Chop Methods

I've been collecting some words of wisdom from the GSR forum and I thought they were just too good to let fade off into the digital demise suffered by those of us who "always meant to back up our files". Here are a few informative bits about tuning your carbs that I thought I might be able to use later. Hopefully, you will find them handy, too.
Back to BikeCliff's Website


Adjusting Idle Mixture, Using the Highest RPM Method


(by Mr. psyguy)

1. Take off the tank, set up some form of remote fuel supply. Set the idle mixture screws at 2 turns out. Warm up the engine and let it run. Adjust the idle to approx. 900 rpm. SLOWLY turn the screw at carb #1 in - at some point, the rpm are going to start dropping and the engine won't run as smoothly. Start turning the screw back out until you get the highest rpm and a smoother sound from the engine. At some point, turning the screw out further won't make any difference (and even further out may again take away the smoothness and the rpm). You want your screw turned IN as much as possible without affecting the rpm/smoothness. Re-adjust the idle to 900 rpm. Stop the engine to let it cool down a bit or place a big fan in front of the engine and do this while the outside air is cooler (morning/winter). Proceed with carb #2. Repeat steps 4 through 10, as necessary, for all carburetors.
2. When complete, re-adjust the idle knob for the correct rpm as per your factory manual (usually 1050 rpm +/-100 rpm). In any case, do not idle below 900 rpm as this may result in insufficient oil flow.

NOTE: (by Mr. Steve)

If you get no change when adjusting the mixture screws, I would suspect a tip broken off in the carb body.

Remove the carbs from the engine, run your finger into the throat, just under the mixture screws. If you can feel a point sticking through, it's likely stuck and broken off the screw. I have used the side of a Phillips screwdriver to roll it over the tip and pop it back up. You can then turn the carbs over and let the tip fall out. You can also verify by removing a screw from #1 or #3 for comparison. There should be a very fine tip on the end of each screw. (Replace screws as necessary.)
Plug Chop Primer for VM carbs
(by Mr. tkent02)

(Editor's note from BassCliff: For CV carbs, reverse the order - see the Factory Pro link below.)

Learn how to do this, it's nothing dangerous. Three separate tests for three separate carburetor circuits. Before you start, put a little anti-seize on each plug, don't install the plugs very tight. No need to wear out the plug threads in the head, you will be pulling them out hot. Bring a pencil and paper; keep track of each plug at each test.

(For Fuel Screw Setting/Float Bowl Height) The low throttle chop: Just putt around a few minutes at about 20 or 30mph or so, keeping the throttle open, but just barely, in the correct gear for this speed. It takes a while to color the plug because there's not much going on inside the combustion chamber. This tells you about the mixture from the pilot circuit, the low-power stuff. Pay attention to how it runs and feels, you can tell rich from lean. If it runs well and the plug isn't black, it's probably doing OK. This one is probably the most important to get right, it sucks to have your engine screw up momentarily at the apex of a slippery corner.

(For Best Needle Clip Position) Mid range: Go out on a highway and run it at about 1/4 to 1/3 throttle for a while, up a long grade is wonderful, but not required, as it doesn't take that long to get a good plug read. The plugs will color faster than the low power check. This tells you about your mixture from the position of the needle. If it spits and pops, that would be rich, if it surges, wanders or loses power for a while and comes back on, that would indicate lean. If it runs smooth and nice, it is close, looking at the plugs will tell you exactly. You need to see a little color here, a mixture resulting in lean, white insulators will run fine, but will eventually burn things up.

(For Best Main Jet size) Full power is done in one hard blast, full-throttle through the gears like a drag race. Does not take very long at all to get the plugs colored, you don't need to do insane speeds. You do need to find a place safe to go faster, where you can see any cops, and yet still be able to safely pull over to remove the plugs. The mixture at full throttle is controlled by the size of the main jet. You definitely need to see a color other than white; too lean here will burn things up in a hurry.

For each of these reads, you need to actually chop the engine. A few seconds under closed throttle as you slow down will taint your readings. Simultaneously hit the kill switch, pull in the clutch and close the throttle. This leaves the plug looking exactly as it was during the run at the power setting you are testing.

To get the mixture right at idle, you adjust for highest rpm, you are looking for the peak combustion temperature here. It won't hurt anything to be lean at idle, because there's not enough heat in the combustion to damage anything.

If the main circuit or even the needle circuit is too lean, you can burn up valves and even pistons from the excess heat.

If you are having problems with your low power running, I would start there. But still check the full-power read, a mixture a little too lean is very powerful, indeed, until something expensive burns up.

Here is an article on reading spark plugs from Dragstuff.com:

Spark Plug Reading 101




Here is a PowerPoint slide show explaining carburetor theory by Prof. Paul Crovella at Morrisville State College.


Also see the very informative CV carb jetting article at Factory Pro.


Thank you for your indulgence,

BassCliff



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[bwringer]

Octain - The carbs were cleaned and synched in November, could they go bad this quickly?

^^^^^ YES. THIS. ^^^^^

Your carbs are clogged. All it takes is four weeks or more of sitting to clog up some of the tiny passages inside.

Ignore all the other crap until you clean your carbs properly. Do it yourself this time. Ain't hard, and we've got simple step by step instructions posted here.

[bmlbytes]

Oh it hasn't sat for 4 weeks. I use it at my primary vehicle. I rode it all through the winter, and have been putting the best gas I can buy in it. I always buy 91 octane, and add Sta-bil. No if it is clogged, it is from dirt or something, not from bad gas, or old gas.

[BassCliff]

Oh it hasn't sat for 4 weeks. I use it at my primary vehicle. I rode it all through the winter, and have been putting the best gas I can buy in it. I always buy 91 octane, and add Sta-bil. No if it is clogged, it is from dirt or something, not from bad gas, or old gas.

Hi,

As a reminder, these low compression engines do not require high octane fuel. In fact, they probably will run worse on the higher octane. High octane fuel contains inhibitors to slow combustion on high compression engines to alleviate knocking and pinging. We don't have to worry about that in most of our GS engines.


Thank you for your indulgence,

BassCliff