The ambitious GT750 build!

General discussion about Street two-stroke Suzuki motorcycles.

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

So I finally had some time to donate to my GT750 again. I decided as my my jugs and crank are still with the machinist that I would finish stripping the frame down so I could paint it and start polishing\painting things and putting it back together again.

So here's where the day started
Image

Things seemed to be going well, I managed to get the top clamp off the fork, the brakes off, and most of the front end
Image

However then things got a little more frustrating. Naturally I didn't have the correct tool for the steering stem nut, but no problem I thought, I'll just knock it loose with a punch like I've done with other nuts like this I've come across in the past. Well after beating it senseless with a punch it would't budge, the damn thing was so rusted in place it didn't give a millimetre.... So out came the penetrating oil... nothing...then the torch...still nothing... bigger hammer... still nothing.... then out came the air chisel, and that finally broke the damn thing loose... although I may be getting a new nut for reassembly, the air chisel did a bit of number on it,
Image

Finally the last few nuts and bolts surrendered and I was left with this at the end of the day
Image

Not just to extract a few snapped bolts, degrease it, and give it a fresh coat of paint so I can start building it back up....
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

So it's been a while, not much has happened, but I figured I'd post the progress I've made.

First order of business was the frame. It had more tar, hardened tree sap, and god knows what else stuck to the bottom of it than I would have thought possible. So to clean up the areas that I could't get a wire brush into I decided to pick up one of these cheap sand blasters.
Image

My compressor wasn't really up to the task but it was enough to let me use the blaster in 2-3 minute intervals allowing it time to recover and cool. Which worked out. I'd blast a corner, then wire brush another spot while the compressor did its thing. I also wire wheeled the swing arm and cleaned up the battery box.

Then I hung them outside under cover and gave them a few liberal coats of flat black paint. I think it turned out rather well. I did however make a slight mistake and did the swing arm and battery box in gloss black. I actually like it better so I decided to leave the gloss. You won't see much of the frame when its done so I doubt you'll notice the difference.
Image

Once they were clean and painted I decided it was time to do something about the centre stand, which had a great big freaking hole in it and was full of water. So I drilled a couple holes in it and heated it up with a propane torch to boil out all the water. Then wire wheeled and blasted it clean. Then it was time to weld it up

Image
Last edited by dude99 on Wed Aug 03, 2016 12:30 pm, edited 1 time in total.
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

I also decided to touch up a few of the factory welds that I didn't like

Image
Image
Image
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

And as one of my favourite Youtubers is so fond of saying "a grinder and paint, make me the welder I aint"

Image
Image
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

So with the frame done, I decided that it was time to clean up the cases I would be using for the engine rebuild
Here's the bottom one after liberal cleaning and blasting
Image

The top after cleaning and buffing out some casting marks from the factory..... I may have been a little OCD with the masking tape
Image

Somehow I managed to loose the picture of the two halves painted side by side, so you'll just have to make do with three pictures of the top half. Nice and shiny!
Image
Image
Image
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

Knowing that my crank should be done in the next week or so, I decided to start reassembling the transmission and other goodies into the bottom case:
Image

I bought the DVD that some others here suggested in one of my other threads and it was a big help. Lots of little tips. It also led me to the final conclusion that whoever reassembled this engine last had NO CLUE what they were doing. I had my suspicions from the use of orange silicone as a case sealant, but from everything else I'm seeing, I don't know that this ever ran after it was reassembled last time.

In the original set of cases, the ones I'm not using, they didn't line up any of the pins on the crank, so they all got squished flat into the cases. One of the transmission shafts was full of shrapnel (I originally thought one end was supposed to be closed until I blew it out with compressed air and a bunch of chunks blew out), they also forgot to reinstall the spring that I believe is for finding neutral.... Then, after watching the DVD and leaning how to properly assemble the kick start shaft and install it, I found this....

Image
Image

Seriously! How do you not notice the cases aren't fitting together by what I imagine was a pretty big gap... I can see the scene now "The cases won't fit back together! Damn it Cletus, just use a bigger wrench, she'll go"...............idiots.....

Oh, and the waster for the oil pump drive was on the bottom side instead of the top, and the clutch basket had a bolt snapped off of it, that no-one bothered to remove and replace the last time around
Last edited by dude99 on Wed Aug 03, 2016 12:27 pm, edited 2 times in total.
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

Then there was the severely cracked water pump drive gear, no ones fault on this one, but I will be replacing it with a better or new one before the engine goes back together.

Image
Image

Is the plastic gear just pressed onto the end of the shaft? I broke it trying to drive it off.... the metal hub is still on there....
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
User avatar
tz375
Moto GP
Posts: 6213
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: The ambitious GT750 build!

Post by tz375 »

It is not supposed to be a tight fit on that quill shaft. It is located with a short hardened pin through the shaft and retained with a simple E clip.

It should just slide off.
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

Weird, I had to drive mine off of the shaft with a punch....
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
User avatar
tz375
Moto GP
Posts: 6213
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: The ambitious GT750 build!

Post by tz375 »

That's odd. Did the PO lose the drive pin or fit a pin that was too long or did he locate it with loctite red? maybe the bore was damaged in some way and then hammered onto the shaft.
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

The gear and about 1/3 of an inch free play back and forth, but would not come off the end without being driven off. The pin and clip seemed to be the correct ones as far as I could tell, but who knows... Nothing in this engine surprises me any more....
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

After another long gap I figured I'd throw up a few pictures of my progress. This project should start to move along more quickly now as fall the fall rains set in and my times relegated to the garage.


First off, my crank and cylinders are back from my machinist. So off we go with fresh bores and a fresh crank!

But first, we of course have to paint the cylinders
Image


Naturally the head got a coat of paint too, but I didn't snap a picture of that. I'll let you use your imaginations to picture how it turned out. While the paint was drying I decided to put together the bottom end of the engine. Finally all the bits are there!

Image

Nothing left to do but bolt it together
Image


Ahh the sight of a freshly rebuilt bottom end, it makes ya proud

Image

Of course, no restoration project would be complete without a little bit of let down. I discovered that I seem to be missing the cap and plug for the end of the transmission shaft, damn it all....
Image

It also seems from the research I did at this point, that there should be a plug in the end of the kick start shaft as well... Of course I have no memory if it was there or if it wasn't when I put it together..... but I'm not pulling it apart now....

So I'm now hunting down a plug and a cap since the parts are NLA from Suzuki.



Another issue I had was the top two radiator mount bolts had snapped off in the front of the frame. I had somehow forgotten about these when I had painted the frame *sigh* So after drilling them out, managing to get one side serviceable, and then of course snapping the el cheapo tap off in the hole I left it there for the day.

So after much thought it became clear that a new repair would be necessary. I managed to get most of the tap out, but not enough to allow me to go in with a new tap... So I decided I would cut the nubs off and weld on a nut. So I made myself an alignment jig and got to work.

Here's the very technical jig I made. I used the one side that had a few threads left to hold it in place while I fixed the other.

Image

The two sections I cut off and one of the nuts I would be welding on it there place

Image

The finished product, not bad for a beginning welder.

Image


Then there was the last task of the day. I had to make a new cap for the steering head bearings. The original one had melted when I was trying to get the very stuck steering head nut off with a torch.

It turns out that it’s the same diameter as the cap off of one of my aerosol cans. So I cut it down and melted a hole in the middle of it. Looks pretty good, hopefully it’ll do the job.

Image

Here’s the new nut I got off of ebay, much nicer than what was left of the original after I finally got it off. Seems a shame to hide it away since its so nice and shiny.

Image
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
Eddie
To the on ramp
Posts: 280
Joined: Fri Oct 19, 2012 9:57 am
Country: U.S.
Suzuki 2-Strokes: 1974 gt750, 1963 superhawk

Re: The ambitious GT750 build!

Post by Eddie »

glad to see your making progress!,,, giving me inspiration for whenever I have to rebuild mine ,,,hopefully no time soon but at least you know everything is done right and is new! good job!!
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: The ambitious GT750 build!

Post by dude99 »

Thanks!

I was was feeling more ambitious after work today, so I decided to finish putting the top end on.

mmmm, shiny piston
Image


and after much struggle to get all the pistons into their bores (the cylinders are freaking heavy!) here it is, all bolted together. Just the ancillaries to go back on now.

Image
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
Post Reply