Total newbie rebuilding GS850 for first time

[roadflare]

Im Zack,

I have a 1980 GS850 I will be tearing into soon, it ran last summer and died last summer. I'm not sure what's wrong with it, and I'm not about to pay someone to tell me when I have metric wrenches sitting in my tool box. I have never worked on a bike motor in my life, I paid a nice premium to a good metric mechanic for him to straighten out my carbs but it was more money then I want to spend again. I laid this out as factually as I could for ease of use so here goes...

What happened:
Freeway speed, it started feeling challenged to maintain the speed, almost like the pistons grew too large for the cylinder. (I know that is not possible but thats how it felt. "bogging down") I pulled over, shut it down, and let it sit. It wouldn't start again until after it cooled down and then it made horrible metal on metal noises. I limped it home, 25mph tops and parked it. I haven't started it again out of fear of grenading the whole motor.

Whats been done:
Jetted carbs, oil changed, filters etc. intake is the pod filters, (it didn't come with an air box when I bought it.) Carbs rebuilt/syncd'. Straight pipes (off of a harley, no baffles)

The plan:
I intend to pull the motor out of the frame, and do a complete rebuild from its toenails to the top of its head. I want a bullet proof bike that I can just enjoy with regular maintenance. I don't plan on rushing this. I want this motor done right and if it takes all summer for me to get there then it takes all summer.

What I need:
Any pointers on the actual rebuild of the 850. Do's/Dont's, where to start, what to look for, things that are more troublesome areas then others. Indicators that the motor can be saved, Indicators that the motor should be scrapped.

What I have:
I have a good spot to work, the majority of the tools to do so, the shop manual, a big can of elbow grease, and a huge fear of wrecking the motor haha

thanks for taking the time to read through this!

Zack.

 

[eil]

Hi Zack!

Well, clearly some mistakes were made in the past but now you have three gigantic advantages that put you a head above the ordinary motorcycle wrench-monkey:

1) A good factory service manual: http://www.mtsac.edu/~cliff/storage/gs/GS850_Manual_HiRes.pdf
2) Joining this great forum
3) A willingness to dig in and be throrough.

Hard to say exactly what could have happened to the engine. Did you adjust the valves when you got it? If not, maybe you burned an exhaust valve. Or something else, you won't know until you've torn it apart.

I wouldn't bother removing the engine until you've torn into it and have a good idea what went wrong. The only reason to remove the engine from the frame is if you need to split the cases to get at the transmission or crank. Or if you want to paint the frame or engine.

Once you have the engine put back together, it would behoove you to find a stock airbox, reset the carbs to stock (or close to it), and buy fresh new rubber carb boots. That way, you're starting with a known baseline which is essential if you're new to wrenching on bikes. Even an expert is going to have a hard time dialling in decent performance with pod air filters, jetted carbs, and a free-flowing exhaust. (I'd suggest a stock exhaust as well but those tend to be expensive even if decent shape and I don't think those have as much impact on the engine's breathing as much as pods do.)

Do post pics of your ride and put your location in your profile if you wouldn't mind a helping hand from someone close by. (This forum has operatives across the globe.)

Don't miss the mega-welcome, your starting point to everything there is to know about these bikes: http://www.thegsresources.com/_forum/showthread.php?196338-New-Members-CLICK-HERE!!

 

[Jedz123]

I agree with Eli, keep the motor in unless you NEED to pull it. First step, I'd follow Eli's lead and brush up on your GS anatomy. Knowing how to get around in these bikes is key in fixing them.

I would do an oil change to see if any metal shards do come out with the oil. If there is metal I'd then drop the oil pan out and look for more debris. Also swap out the oil filter and see if you can't find anything. I hope nothing majorly went wrong with your bike.

The 850's are tanks so hopefully it was just a fueling issue. These motors will take a trashing before giving out.

Also post pictures as you tear through it! We might see something irregular and can point it out. Steve might chime in with some ideas, He's the 850 master in my book.

You should post your location in your profile so we know where you are at. If your local to some you'll be surprised who will come out and help in person. Great support system here.

Good luck and Welcome to the GSR!

 

[Steve]

Steve might chime in with some ideas, He's the 850 master in my book.

Somebody ringing my chimes? :-k

.

 

[Wingsconsin]

"Calling Steve... "nthego:
"Now Paging Steve...you're needed in GS850 triage. "

 

[Steve]

"Calling Steve... "nthego:
"Now Paging Steve...you're needed in GS850 triage. "

The GS ER is not quite ready to open yet, but it will be soon. :encouragement:

Apparently, "roadflare" is not accustomed to being on a forum that moves as quickly as this one. :-k

Hey, roadflare, where are you? There is a good chance that one of the members here might be close enough to help, if necessary.

Please update your profile to show a basic location and also add a sig that says what you are working on.

.

 

[sinkankan]

If you're going to strip the motor, spend the extra dollars in an original gasket set for the motor, cheap online copies just don't cut it.
And replace all the electronic/electrical units like the coils, igintion, leads, plugs, stator and regulator. Realistically they can still be bought after the engine rebuild but can breath new life into the motor, especially after you done the carbs.
just remember the three basics, air (air box or pods) fuel (carbies) and spark.

 

[roadflare]

I can honestly say I wasnt expecting this much of a reply from the gurus! Thanks for taking the time to get back to me. I have updated my profile as requested. I will not pull the motor from the frame. Although I kind of want to so I can really clean the motor up. It has that "I've sat out in a bunch of nasty weather" griminess to it. Aside from general cleanliness I dont have a real good reason to pull it hehe. might end up creating more work for myself.

Also I have a few pictures of my 850 up on my profile. from where it came from and the directions it went while I was in school. I was finished about 2 weeks ahead of the class in the street rod class, so the instructors were kind enough to let me work on my bike while we were in the shop. I thought the patina would be cool at first, but after seeing it I really didnt like it. I went with the Airplane theme, when i was really young my dad had a goldwing with a side car on it. We would go for rides, my head next to the motor listening to it whine and hum. I always felt like I was flying, I still do. So the Aerospace theme seemed appropriate.

 

[roadflare]

the 850 goes into the lab today. In the immortal words of Mario... "Here we go!"

 

[roadflare]

OK! so the first night in went pretty smooth, I was nervous about the DOHC part but it was relatively easy to get through. I have run into an issue however. The jackhole that last had his mitts in the motor decided that they were going to use an allen key style bolt for the exhaust flanges.

The Problem:
Inner exhaust flange on right side, bottom bolt, absolutely refuses to budge.

Steps Taken:
fire, half a can of penetrating oil, easy out both over the outside of the bolt and also inside, hammers, cursing.

Results:
Stripped the easyouts, got it to budge a little bit.

also im having a hard time getting the pictures to upload. I dislike computers very much and they dont like me either.

here are some pics of the current progress.

 

[eil]

Only one exhaust bolt gave you a problem? That's pretty good, actually!

Allen head bolts aren't all that bad, you just need a set of allen ratchet bits. Harbor Freight has a good set for cheap. Allen keys are handy sometimes but pretty useless on larger bolts. Of course it would have been far better if they had used stainless steel ones with antiseize.

Don't use easy-outs, they will break inside the bolt and you won't be able to drill them out due to their hardness. Use left-handed drill bits to drill the bolt out, starting with the smallest one and working your way up.

 

[roadflare]

OK! I think i have the sizing of the pictures thing figured out so i can at least get some progress updates going. here is where i left off last night due to the exhaust bolt. you can see its cousins in the bottom corner haha

 

[roadflare]

the problem has been found. Oil wasn't getting to the cam shaft and it seized up. The D "craddle" for the exhaust cam on the cylinder head is beyond repair. I havent looked at the cam shaft or the cap yet. But that was the metal on metal sound I heard. I took it to a machine shop that works primarily on metrics and he couldn't do anything for me except give me a "sorry for your loss" card and a hug haha!

Secondary problem:
Why wasn't it getting oil? Where does the oil feed into the cams? These are going to be looked at either tonight or tomorrow.

so I'm in the market for a 1980 gs850 cylinder head if anyone has one just laying around haha.

 

[eil]

Something probably got stuck in an oil gallery somewhere. If you can't locate the blockage, throwing a new head on will only put you further into the hole. You need to find the problem. Unfortunately, that probably means splitting the cases and tearing down the whole engine for a full rebuild. It's a ton of work and usually expensive. If you just want a rider, you may be better of finding a new engine or parts bike and doing a swap. I would only recommend the full rebuild if your mechanical skills are up to par, or if you want the education of rebuilding an engine.

 

[gustovh]

Pull the jugs and then pull the engine and oil pan, check and inspect what you can without cracking the cases first. The oil pump is behind the clutch, the oil pressure switch sits on top of the screened pick up in the pan. You may be able to determine the issue with a good inspection and reduce your work and increase your knowledge in the process. The engine really is pretty easy to work on, and you really want to clean it anyway.

That said, if your engine is shot, there are others to be had. Parts wanted, parts for sale sections and craigslist as well for parts bike.

Good luck

V

 

[Dogma]

If the damage was limited to one side of one cam, then the blockage is in the head itself. If it was both ends of one cam it's harder to say for sure, but does suggest a systemic problem. That might mean restricted flow to the head spacing the intake cam (closer to the feed), or there was enough of whatever floating around to accidentally block passages to both ends of the cam.

I think I'd blow air back through the oil passage in the torched cam journals and see what you can get out of it (after removing the head). Maybe a piece of stiff wire might displace something too. If a PO got crazy with silicone gasket maker, you might have the stuff all over the place, just waiting to clog something else. The only reason for something to be on that side of the oil filter is someone put it there. You need to determine the extent of the mess. Dropping the oil pan may reveal some clues too. Things that made it through the oil passages and back down to the pan.

 

[roadflare]

Thanks for all of the info! I ended up going with a new motor. The hot rod part of my brain landed on an 82 1100GK for $399 on the eBay. It's getting hard tailed anyways so moving some motor mounts won't be that big of a deal during the process.