Engine Idles fine - Bike Will not Move

[Guest]

Greetings,

I've got a new problem with my '82 GS850..
I just finished a partial rebuild of the engine, put about 130ish miles on it with no trouble up 'til now.

I noticed my first problem after a short ride - the 2-4 pipes were blueish, as I expect them to be after riding, but #1 looked cold. Like the brilliant individual I am, I grabbed #1 to see if it was hot. Fortunately(?) it wasn't. After firing up the bike again and feeling the pipe for about a minute - changing idle, revving the engine, choking and unchoking, I realized #1 wasn't firing.

Once I pushed it to a safe location I checked my compression, spark plug gap, spark plug fire, and drained the carb bowl. No water, no dirt, no rust in the bowl. Rebuilt the carbs with the engine. I decided at that time that the issue might be with the intake boots - I replaced the o-rings but not the boots, and they are most certainly the original 82's. I applied a bandaid of RTV sealant around the diameter of the boot, anywhere I could think air would leak in. #1 began to fire again.

Problem #2 now - after I rtv'd the boot, I hooked up my carbtune just for kicks, and sure enough, they're back out of sync. I proceeded to sync then realized my fuel mixture may be a little off, adjust, resync, adjust and etc. I let it sit for a day and came back with a driver so that I could have them drive my car while I rode home on the bike - I fired it up, let the engine warm up for about 5 minutes, and shifted into first. When I did this, the engine became noticeably bogged down. I checked the clutch cable and it was not overly loose, it was just the way I'd left it. So I went back to first, slowly let off the clutch and rocked the throttle. The engine bogged down, would not rev, and then died - but when it died the gauges went dark, the lights all went off, and the starter wouldn't engage. After this, I had to jump the bike off my car for the next attempt. Same story.

I have an early appointment tomorrow @ the spine hospital, so I don't have time to look @ my charging system tonight. I have the pages open in my browser for the charging system health directions.

What I really need here is some guidance - while I have rebuilt two of these bikes now, this one really doesn't make sense to me. My thoughts right now are to:
A) Check charging system for voltage variations, check battery health
B) Reset Idle Mixture
C) Resync Carbs
-
If this fails,
D) Drain gas tank, carbs and replace with fresh fuel
E) Repeat.

If you folks have anything to add, or maybe point me in a different direction, I'm all ears. I'm not sure if it really matters, but the battery that's in it now is yr2000. It's a sealed dry-cell, and has run the bike up until now.
You all have a great night, I look forward to hearing how I might've screwed this one up

[terrylee]

If the battery is that old, I'd replace it, they usually don't last more than few years if taken care of. Get new battery, make sure it is fully charged and do the tests from the Stator Papers on Basscliff site. If all checks out ok with charging system, check to make sure you're getting 12 volt to each coil (or at least no more than .5 volts lower than that). If not do a relay mod, old wiring can be a problem. terrylee

[koolaid_kid]

Wow, a 13 year old battery. Do yourself a favor and spring for a new AGM battery. I got 7 years out of the AGM in my GS1100E, but 13 years is amazing.

[Call Me Ahab]

Battery Life & Charging System

Okay... So this afternoon I checked compression again, I'm at 98~102 in all cylinders.

I have 11.94-12.0v @ the coils while running. 12.50-12.59 @ battery while running. Hasn't had time for a full charge, so when off it reads 12.55-12.7.

My problem jumped over 1 cylinder. This perplexes me. #1 now fires - runs strong. #2 no longer fires. Plug sparks, shocks me when I grab it, even dropped in a colortune plug to take a look - nada. No ignition.

When I shifted into first on the center stand and let off the clutch, engine knocked a little bit, shifted back and no knock.

I'm growing frustrated. When I pull the plug, it is wet fouled. There is no oil in the cylinder that I can see. This leads me to believe that it is gas... But if there's gas in the cylinder why won't it burn? I rev the engine - #2 no ignite.

I drained the fuel, that wasn't the problem. So far as I can tell, charging system is all right. But the one thing that I have no idea where to start diagnosing - Why did the power shut off completely when my engine stalled? Is this normal? I've stalled before and never had my gauges go dark, what would cause this?

[koolaid_kid]

Have you checked your petcock? #2 cylinder is where the vacuum line attaches. Not at all unusual for it to leak and flood that cylinder.

[Call Me Ahab]

I have it on an alt fuel source - bottle that hangs down. Vacuum line is plugged with a small bolt.

[koolaid_kid]

If the wire shocks you when you grab it then the wire and/or the cap is bad. It should be insulated from leaking electricity. Try swapping the #2 cap with the #3 cap and see if it still shocks you.

[Call Me Ahab]

If the wire shocks you when you grab it then the wire and/or the cap is bad. It should be insulated from leaking electricity. Try swapping the #2 cap with the #3 cap and see if it still shocks you.

.. Seriously? This is cause for concern then, the wires and caps are new: less than 3 months old. Every plug will give a small jolt if I grab it. Swapped #2 and #3 - no change. Changed plugs, no effect. Checked gap - set at 32 and no change.

Every plug I put in that cyl fouls, but will not ignite. If it is igniting, it isn't consistent.

So what I have done so far...

Swapped plugs, drained fuel, checked the carbs for any broken off points from idle screws, checked jets for clogs, synced carbs, reset idle mixtures.

Battery looks like it's still strong as ever - I moved it over to the gs1000 and it started right up.

One more item that puzzles me - I performed the same maintenance on both bikes, but the GS1000 runs compression @ 126; the GS850 is only @ 96.
Could the timing be off on the 850? If it is, how was I able to put nearly a hundred miles on it - and why is it causing problems now. Specifically, why did the problem migrate from #1 to #2?!

[tom203]

Since you have plugged vac line to rule out petcock problem, it seems that the carb feeding the fouling cylinder must have leaky/misadjusted float needle- might have been OK for hundred miles but maybe something got stuck. Why not pull carb rack, orient carbs in their normal position and use your fuel bottle setup to see how well the needle seats hold back the fuel.

[BigD_83]

Not to cause great alarm, but if your R/R is shot, it could easily stall at low rpms. Your running voltage at the battery seems low as well. Have you dug into the stator papers yet?

[Call Me Ahab]

Not to cause great alarm, but if your R/R is shot, it could easily stall at low rpms. Your running voltage at the battery seems low as well. Have you dug into the stator papers yet?

I've started, but there's a lot of information there. I'm looking at a few possibilities, but I won't know for certain what is wrong until I can sit down with a print out and look over it all.

Initial tests do indeed show low voltage in a few areas - but I think my idle speed is lower than what the test called for, I set @ 1000 not 1500.

Since you have plugged vac line to rule out petcock problem, it seems that the carb feeding the fouling cylinder must have leaky/misadjusted float needle- might have been OK for hundred miles but maybe something got stuck. Why not pull carb rack, orient carbs in their normal position and use your fuel bottle setup to see how well the needle seats hold back the fuel.

Correct me if I'm wrong, you mean set up the carbs in the same position as they would sit when mounted, hook up fuel line and feed fuel into the carbs? When I do this, what am I looking for - fuel leaking out the front / back?

[koolaid_kid]

Correct me if I'm wrong, you mean set up the carbs in the same position as they would sit when mounted, hook up fuel line and feed fuel into the carbs? When I do this, what am I looking for - fuel leaking out the front / back?

You are correct. And it will flow to the lowest point, be it front or be it rear.

[Call Me Ahab]

Great, thank you!

I'm seeing some pretty significant differences between the gs1000 and the gs850. The engine revs high and fast and returns to idle very quickly on the gs1000, compression ratings in the high 120's. The gs850's compression is only in the high 90's. Could I have mis-timed the 850 AGAIN? Or would incorrect timing produce a more noticeable drop in compression? Could this compression difference also be due to valve shim wear?

[Call Me Ahab]

Dubya tee eff m8?

Okaay - now for a mildly annoying update.

I checked all my valve shim clearances. Only two were really out of spec - one at .102 and another at .100. I swapped the two 260's for the two 265's from intake / exhaust of the same cylinder and now all four are .38-.5.

The rest of the shims had no measurable clearance. W T F

So, I moved from here to my timing. It was perfect. Growing agitated, I started looking for trouble. I found some steel wool strands stuck to the ignition points and magneto, brushed off as much as I could with a small bore-brush.

I checked compression again after this, with the battery fully charged. Same battery, now all 4 read at 140 - 160ish psi. Again, WTF?! My last readings before charging the battery put me at 11.9-12v at the coils. All my wires and caps are new. Plugs were cleaned and gaps double checked.

I checked the carbs, let fuel flow freely into the assembly for a few minutes, no leaks, no spill-over, nada.

The only thing I know that is certainly a problem is my intake boots, I have new ones on the way. Currently, the boots are patched w/ rtv sealant.

What in God's name could be wrong here? Could my boots really be THAT bad? Regardless, I'm not going to try to fire it up again until new boots come in. If anyone has any suggestions of what else could be wrong, please let me know!

[koolaid_kid]

Okaay - now for a mildly annoying update.

I checked all my valve shim clearances. Only two were really out of spec - one at .102 and another at .100. I swapped the two 260's for the two 265's from intake / exhaust of the same cylinder and now all four are .38-.5.

The rest of the shims had no measurable clearance. W T F

You have to fix that. You must reshim until you can measure clearances within tolerance. There is no other choice.