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1976 GS750 Clean and Rebuild

  • Thread starter Thread starter shryke300
  • Start date Start date
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shryke300

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In my last project build I got an un-roadworthy GS back on the road. I have ridden it for a few months now and wanted to make it actually look good. :) SO.... I bought some more stuff :black_eyed:and have decided to take it down to rebuild to a more attractive state.

Goals:
1) I think I want to go tracker/streetfighter-ish. I would love cafe, but to do so the right way would take a lot more money and I don't think it would be as pleasurable to ride (would look really nice, though).
2) Increase horsepower (850 swap)
3) Increase braking power (would like to do a dual disc, twin pot setup)
4) Clean
5) Paint. (Satin Black with Polished highlights. Deciding on color of tank)

What I've Learned:
1) Clean your motor while it's still in the frame
2) Take off as much from the frame as you can before you try to remove the motor if you are doing the old tire trick.
3) Take off the front sprocket before you remove the rear tire or chain.
4) I tried all kinds of stuff to clean the motor, including simple green and the spray on engine gunk remover. The gunk remover worked pretty decent. The best thing I found to use, though, was plain WD40 and a pressure washer. There is a video online. It works for oils, greasy grime. Scrape off the majority, soak it down for a day or two with WD40, pressure wash it, then use a tooth brush and bristle brush to clean up the remaining grime that will be left (not a lot of it).
5) Clean the motor to almost spotless condition before you start to take anything apart. Dirt is everywhere and will get in the motor. I had TONS of crud around my supposedly sealed up head bolts. Stuff rags in openings into the case as soon as they appear.
6) Do as many mods as possible before you take it apart. It takes longer than you think to get back together.
7) If you are going to use a sprayer make sure you have plenty of room.
8) Wipe the insides of the jugs with a rag soaked in diesel or such after honing. Wipe until it comes out clean.
9) Be VERY careful dropping the jug on the pistons. Just because they are sliding down OK does not mean they are not doing something harmful. The rings WILL come out of the grooves.
10) When making mods, one thing always leads to another.
11) Get a Cometic Headgasket. The cheap ones in packs are not worth it.
12) You will never take as many pictures as you need or label as well as you should.




More to come...
I am working on uploading pictures now and plan on posting the build as I go.
 
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38 years of road grime. I don't think this has been cleaned by anything other than rain. Simple Green is not touching this. Some of it has to be scraped.

I got the frame...

and the motor...

Getting ready to clean:
 
This is one side of the '79 850 cylinders:

Here is the other:


Does anyone know any good tips for cleaning or to get that baked on gasket off of the 850 jugs?
 
Look at this grime! All up in those bearings...



Some WD40, pressure washing and elbow grease:



MUCH cleaner. Still a little left to get, though.

Now... Planning my cuts:




Anyone have any ideas about that old gasket?
 
Looks like you're being pretty thorough with the tear-down. Good!

I think I see rubber flaking off around the sides of the flange on the intake boots, that's often a good indication that they are junk and need to be replaced.

Are you going to lower or hard-tail it? Hard-tail is great for wrecking one's back and making the bike impossible to control.
 
I wasn't sure about the boots. I was hoping that new o rings would take care of any issue. I guess that isn't true? I wan't to cafe it, but I am also always changing my mind as things pop up. the aluminum bracket lowering it was so I could get an idea of where the wheel would be when the suspension is bottomed out. I see so many great customs that have almost no travel before the wheel hits something and I've always wondered how they get away with it. This is my first motor rebuild, aside from the bottom end of an '84 s-10 in highschool. I'm trying to learn and not mess anything up, so any suggestions are VERY welcome. I will have some more pics up maybe tomorrow form pulling the head and jugs. Right now the jugs are stuck on one head bolt. I'm suprised at how much junk is on the head bolts. Not realizing that junk was in there, I think some may have fallen into the case as I pulled up the jugs. I'm thinking I have to split the case now to make sure that little grime doesn't screw anything up? I would greatly appreciate any help from someone with any knowledge and experience rebuilding these things. Right now I'm kinda winging it with a haynes, the service manual and this forum.
 
An 850 kicker is a fun bike. 0-rings might be all that those manifolds need.
 
Sooo... A little more breakdown. I've been trying for the last couple days to get the jugs off. They got stuck just off the last two pistons. So much gunk was in the head bolt channels it was keeping the jugs from slipping off. I went ahead and slipped the pistons off to give me some room, soaked the passages in WD-40 and worked the jugs up and down until they came free. I cannot believe how dirty it is under the jugs and around the head bolts. I did not realize I needed to stuff rags around the pistons this early and some of the grime made it in the case. I think this means I need to open it up to clean it. Any chance I could just flush it with something? The rods look a funny color. Not sure if this is ok or not...? a few of the clutch cover screws would not come out, even with my impact screwdriver (not sure what the technical name is), and I had to drill the heads off. Easy-peasy after that. Getting closer...

Nastiness:





Stator Side:


Stripped, stuck screws:


Not a problem any more:


Clutch Side:


Keeping track of all the nuts and bolts:


750 piston vs 850 piston (the 750 also has the rings on it still..)
 
FYI, I am doing this rebuild using this forum, the service manual from Basscliff's site and a Haynes manual I purchased. I have never done this before, so those of you that have, and warnings and wisdom will be warmly received, lol. I would like to get it right the first time.
 
The dirt/debris that builds up over the years at the base of the cylinder studs is always something to be careful with.
I try to carefully remove most of it before it tries to jump into the crankcase. You can flush the engine with diesel, kerosene, mineral spirits or solvent. (about a gallon is all that is needed) and drain.
I slosh them around on a rotating engine stand myself. Remove the oil pan after draining, clean the oil pick up screen after removal and replace the JIS screws with Allan's. (sorry, I cannot seem to find a pic currently)
If you are not yet committed to using the early head and carbs, I would suggest using an '80-up 850 head and some 34CV carbs from a 1000 or 1100 model and pods.
 
That sounds interesting... SO:
1. Carefully cleaning hte rest and flushing the case should take care of the dirt issue? (I know you said that, just want to be cautious)
2. The '80-up head will fit on a '79 850 jugs?
3. How much will the 34CV and new heads give me?
4. Are the CV carbs as sensitive as the mikunis to pods?


Thank you!
 
Can anyone tell me what the black bolt in the picture is for?

Got the cases split! I had some sludge and wanted to see why my kick start had stopped working. Still can't figure it out... nothing looks broken! so... I'll take the opportunity to clean them up and paint them. I think I will DEFINITELY have a challenge getting it back together properly again. Nothing ventured, nothing gained....
 
Help!!!!! Valves and cylinders

Help!!!!! Valves and cylinders

Ok... So I have two separate issues: valves and cylinders. First things first.... I contacted a guy about hot tanking and reseating myh valves. He wanted $150. Good price? The real problem though, is if my valves are still good. Can anyone tell from the pictures below if the valves are pitted? any other issues? Or is there too much carbon buildup to tell?






Now.. My second issue are the '79 850 jugs i got off of ebay. It does not fit. I am going to assume this means the posting was not entirely true. It looks like the 1 and 4 cylinder sleeves are contacting a ridge on the inside of the case. Is this what everyone refers to when they talk about grinding the case to clearance the '80 850 jugs?





If anyone can help, please respond... :)
 
Been slowly working on cleaning the cases and acquiring parts. .. I should have some pics to upload later this week. I do have a quick question about the 850 swap. I think I have a 1980? The ad on eBay said it was a79, nut I had to grind the inside of the case to get it to fit. Do I need new carbs? Will my vm26's work? Or will I have to get some cv's? Also, any way to tell what year I have?
 
So I've done a little work since the last time (not much though). So far I Cleaned all the carbs again (boring) and have painted everything with por-15. The first time I just did the covers and they looked amazing until the last coat. I was doing it with a brush and did not get good enough coverage. so.. I sanded it down and shot everything with a spray gun today. Some of the stuff looks really good, some does not. I think with por15 if you know what you are doing, it looks AMAZING. However, I have painted anything with a pray gun before and evidently did not get the settings right or put enough solvent in it. I had a lot of issues with the spraying and will have to do some of the parts over again. I think I will do touch ups with eastwood. Don't get me wrong, por15 on a couple of parts looks like liquid molten gloss black lava (sorry, don't have pics). It was BEAUTIFUL, and their tech support was great. I just don't think my skills were there. Until I get more practice with a spray gun, I think I would use the eastwood products. It is now time to start putting things together.




With respect to the 850, here is what needs to be ground on the crankcase:


This is it ground:
 
I like how you're working on this one. Sorry I can't help out about the 850 cylinder issues. One thing- what was your prep before painting the cylinders and covers with por15? Just thorough cleaning? I would have prepped by either bead blasting, vapor blasting, or soda blasting- this is too big a job not to have super clean surfaces to paint. The cylinders and heads look fantastic, but the clutch cover has too much orange peel in my opinion.

By the way, for cleaning around the countershaft sprocket area, I always go with a gallon of K1 kerosene in a bin, and an automotive parts cleaning brush. Cheaper and more effective than WD40, which is 85% kerosene anyway.
 
Thanks for the help! the kerosine treatment is a good idea. I had a soda blaster and was going to shoot it, but got scared off by all the risk google said it had. To prep, I wire brushed as much as i could with a wire wheel on my drill, scrubbed several times with Dawn and scotchbrite and brushes, then clean with simple green then clean with por15 degreaser with rubber gloves on. I don't think the prep work was the issues, I know I was not spraying it well and now don't have enough to fix everything. I will definately do something with the side covers, though. I think they look terrible, as well.Stay tuned! BTW, i'm open to all help! :)
 
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