I can't junk this bike

[predator]

I just can't, something about this thing I love 81 GS850.
Friend diagnosed the compression low. Completely rebuilt the carbs, new air box completely rewired. Bike sat outside a few years. After a little work I got it running did a little more work runs better. Its freezing outside , I go out in the garage hit the button and this thing fires right now and sits there and idles. Not blowing any black smoke All plugs are firing. I read to be caustious about how much money you put in these things. Anyway I takes off nice but loses power at top end, if you feather the clutch you can get the speed up and it runs ok. I put seafoam in the oil to clean anything cause it sat out for awhile. It definatley improved the idle performance. Just no top end. I'm thinking of draining the oil putting in a full weight (not dilluted with seafoam) oil in and just running it to see if it improves as it runs. Is it possible that sitting caused things to , lets say allow some leakage in the valves and pistons and running it will bring up the performance. What can it be that's causing this top end loss when everything else is running so well? I wrote a post earlier with pretty much the same complaints but the engine has started to actually perform better. I think i'm becoming personally attached to this bike.

[renobruce]

What were the compression numbers? Was the compression checked with the engine hot and the throttle wide open? Have you adjusted the valves? What size main jets are in the carbs? Any mods to the airbox or exhaust?

Need more info...

[predator]

Thanks for the reply, here's what I have. The guy that did the compression test works on a lot of off road racing bikes and in fact has a racing team. He does all the rebuilding. So i'm assuming he knew the best way to get a compression reading. He's at work now and I have a call in to him to get the numbers (if he can remember). No I haven't adjusted the valves and truly don't know how. I started to read the manual and someone here was talking about putting shims in and I just left it at that for the time. I've read on this site how critical valve adjustment is to this engine. Once we got the low compression reading he sort of thought that was it and gave up on it. Does the engine need to come out to do a valve adjustment, I can't remember how much I read in the manual and what it said.
I have nother buddy that rebuilds bike carbs 'alot' he's real good and they were synced and all. Jet size, who knows, like I said I got the bike from someones backyard. My buddy never mentioned anything about the jets but did tell me he was pretty sure the were stock because the bike needed a factory airbox to run. And he said something about aftermarket aircleaners can only be run on a re-jetted bike. I bought a brand new factory airbox and air cleaner. It had 4 individual aircleaners on it when I found it and wouldnt' run at all. Even before the re-build I put on the factory filter and it started up, it did run bad, but did start. Stock exhaust.
Actually when I was riding it it felt like the clutches were slipping and I had to keep on backing off and on the throttle to build up speed. The moto-cross guy said it was more than likely carbs. But the first thing he did was compression and quit there.
I don't know why I got 60 in my mind for compression, but whatever it was he said it was around half of what it should be....don't take this line or those numbers to the bank, it's just something I swear I remember.
Hope that helps and you can get something out of it. If you need more, just ask and i'll do the best I can.

[predator]

Reno, Here's the newest info I got just off the phone. He squirted oil in the plug hole first and it brought up the pressure but it was still real low. he said that told him it was a combo of the rings and valves. Hesid the pressure was around half of what specs were even though he didn't remember the numbers but the two center pistons were the lowest then the left outside better and right outside best....but then again all low. I think my fuel system is good and my concern is this part of the engine, what would you recomend I could do next. Any test to check wheter its either or both valves/rings? If it needed both would the parts be more than the bike itself. i'd do the work myself......I can do it, I just happened to have friends that had garages that were willing to do it.

[BassCliff]

Documentation

Hi Mr. predator,

Please visit my little BikeCliff website. You'll find lots of 850G lovin' there. If you read everything you find there it will really help you get to know your motorcycle, and what it needs to be put back into good running shape. CLICK HERE TO START. Keep us informed.


Thank you for your indulgence,

BassCliff

[Big T]

Since your bike sat outside for years, the first thing I would start with is putting some Seafoam or Marvel Mystery Oil into the cylinders. Pull the spark plugs, use a bit of tubing to get a tablespoon or so into the cylinder. Have the bike on its centerstand

Put the plugs back in and let it sit for a couple of days.

Then try to start it up. It will smoke a lot on start up. Ride it a few times to see if you have any improvement.

At the same time,address the valve adjustment. Check Basscliff's site for the methodology and get a form from Steve. You'll need the valve tool or use the zip tie method.

I'd be surprised if these two bits of maintenance don't give you a big improvement.

[predator]

Basscliff, i'm heading there right now, thanks for the link

Big T, I've done the seafoam thing. I've already run 2 cans through the gas tank. it has made a marked improvement. I use it in all my bikes and I can tell the difference in them all after using it. I can feel the vibrations from the handlebars coursing through my veins already :-)
Al

[salty_monk]

The reason he tells you to put it straight into the pistons & let it sit is he prob thinks the rings may be stuck. Try it, what do you have to lose?

A valve adjust on these bikes can make a HUGE difference to compression numbers so that's also a good thing to do.

As it's sat the rings will probably re-seat & compression will come up as you ride over the first 1000 miles or so... it did on my 78 1000 that sat in a garage for 25 years...

Dan

[SqDancerLynn1]

How many miles on the bike ? DO NOT put seafoam in the oil, only use it as a gas aditive. I use reg Shell Rotella T 15/40 oil in my 850. 850 usually runs 120-150 psi compression. You must check the valve adjustments, you can spend lots of time looking for problems when you don't have a proper baseline to build on. My 850 has 45K head has never been off

[predator]

Ah nothin like a good ass reamin, I thought my old man came back from the dead
Too late, I put some sea foam in the motor oil already, i'll drain it tomorrow and put in the Rotella. I just ran some regular oil when I got it cause I didn't even know if it ran. I don't know how many miles it has on it but I think in my past posts on this subject I had the numbers, i'll look back. I put the seafoam (and not really that much to be honest just to clean the system. The engine hasn't run long with it in it. But I think I've decide I will invest a few hundred more in the bike so i'll go out and get some Rotella. You know something I got people that ream me out and don't believe in full synthetic oils like Rotella, but in this case and this engine, I asked for your advice and i'll follow it.
I'll get a can of seafoam tomorrow and do the plugs as were directed. Now I need it to warm up enough to get at these valves to adjust them. The directions for adjustment were very clear, I can handle that easily. It definatley has enough time that it needs a valve adjustment.
Anything else while i'm out there freezin my balz off I can be lookin for? I'm gettin happier by the hour.
Al

[mighty13d]

where are you located?

[predator]

Mighty 13, i'm stranded in Youngstown, OH. I saw you were from Maine and I feel for you but we freeze down this far too. Wanna ride down and help me?

[mighty13d]

I don't think my bike would like this weather. It also has ice on it from my leaky porch roof! Plus you've been getting some of this really cold stuff that we've been getting up here lately too.

[predator]

Mighty, Cold & snowy. I have the 850 in the neighbors garage (not heated), I go out there, push the starter button to see if the battery is dead and the thing fires up.....no choke, nothing...it started to spit a bit so I gave it half choke for about 15 seconds, it smoothed out and sat there and idled for 15 minutes. WTF, my Gold Wing won't fire like that. And it hasn't run for a month. I got good vibes about this bike. I love Maine in the summer, I used to go to Ogunquit every summer. I don't go there anymore. To many big cities to get thru and the traffic on the east coast sucks.

[duaneage]

get it running and put miles on it. Sounds like the carbs or the o rings on the intake rubber boots are leaking, that would keep the slides from coming up and causing a lean out.

If you did not replace the o rings on the intake boots I would do so. They are not expensive yet go bad after a few years

you probably need a valve adjustment, that would affect the way it runs and the compression figures. It changes the valve timing.