78 GS750 Yoshimura Resto-mod

[Guest]

Hey Folks, little background on this project. Picked up a 78 GS750 about a month ago with plans to install a wiseco big bore kit. Long story short I was unable to obtain the ownership for the bike as I believe it was never registered in Canada. I found a frame with ownership for sale and purchased that, well the same seller also had a stage 2 Yoshimura top end including everything, pistons, cams, cylinders etc. He also had this awesome what looks to be yoshimura exhaust as well, although it might be a wolf header aswell as there are no markings on it.

With the exchange rate and machining costs, the wiseco big bore installation would cost me as much as these parts combined so I figured this was a no brainer and these yoshi parts are extremely rare. The pistons are 69 mm, should be approx 844 cc when all is said and done. Seller said the compression ration is 11:1 but I'm skeptical on that.

- Stage one of this build is going to be pretty simple, but the bike is going to evolve as time and resources become more plentiful.

To do ASAP:

- Add bracing to stock frame and fix minor imperfections
- Sandblast and paint new frame & exhaust
- Strip current bike down and paint/refurbish parts as I go.
- Polish engine cases
- rebuild carbs
- rebuild suspension and install new rear shocks
- 530 chain conversion
- eventually paint the entire bike
- install yoshi topend

Future modifications:

Modern front end and swing arm
Larger carbs
gsxr wheels
trim seat
this list will certainly grow



The bike already has dyna ignition and HEL brake lines.

20170414_153010.jpg

Pics of the yoshi goodies can be found here

https://photos.google.com/share/AF1QipMM1iC7hOWljAtVcjMj59tTORTLxJTjz0H4hKfWuKgKLlCwuC1dX8WN6VlkN8f5fQ?key=WjIwRF8xdkFwQXhYZVJocjRVaXVxZUpJQWZwRzZn

[steve murdoch]

Seems like a fun project to follow along.
I would certainly keep all the stock parts to sell to restorers going for the original look.
Odd about the ownership. Another hour wasted at Service Ontario?
Sure looks like a Yosh pipe and not a Wolf.

[Guest]

Yes I'm definitely keeping the stock parts, the photo makes the bike look alot better than it really is. I'm all for preserving these old GS' but I do like to make them my own as well.

Haha yeah an hour or my life I'll never get back.

And about the pipe, I agree.

[1978GS750E]

I've got another 1978 GS750 to rebuild if you want to get some of your money back out of the stock parts?????

[Guest]

I've got another 1978 GS750 to rebuild if you want to get some of your money back out of the stock parts?????

Yeah more than happy to help! What do you need? I have NOS standard pistons and rings also have 1st oversize pistons and rings although they aren't knew, they are very close to it.

[Guest]

Got the majority of the bike striped down today, all that remains is the front end and electrical.

Next up is prepping the "new" frame for paint, I'm going to bring it work this week to sandblast along with some other parts.
20170611_154314_HDR.jpg

[Guest]

Got the frame primed and painted today, also did some very minor frame bracing while I had the chance.
Yoshi exhaust has also been primed using VHT header paint, I'm going to let it cure before I apply the base coat.
Also stripped the head down to lap the valve and change the valve seals, discovered that the head has also been milled down 20 thou.

Next on the to do list while parts dry: Rebuild front forks and begin assembling the engine.

pics: https://goo.gl/photos/gypURgaoB3CJ4dy16

[Guest]

Picked up some vintage goodies today, morgan racing seat and SW street stroker shocks!
Couldn't help myself.

https://goo.gl/photos/ArM6ozyEsp3FAfEb6

[steve murdoch]

The project has moved from the garage to the rec room? Excellent!
Were you at the swap meet in Paris on the weekend?
I saw a pair of S&W just like that.

[Guest]

The project has moved from the garage to the rec room? Excellent!
Were you at the swap meet in Paris on the weekend?
I saw a pair of S&W just like that.

Haha it's scattered throughout the entire house, I'm lucky to have understanding parents.

I wasn't, but they very well could be the same pair!

[Guest]

Got the engine assembled! Still need to degree the cams but I should have it in the frame very soon, going to begin tackling the front forks tomorrow.
20170702_211451.jpg

[Guest]

Anyone have any advice on valve clearances for this engine with yoshi cams? Intake 0.375" lift and Ex 0.350", I also have stiffer valve spring, heavy duty retainers and keepers. I know stock is 0.03-0.08mm, although that seems awefully tight.

[Guest]

Big things happening today, got the engine in the frame! Also got the new tires mounted up and the forks rebuilt and painted. If all goes as planned I should have a rolling chassis come the end of the weekend!
20170706_201641.jpg

[Guest]

20170706_202009.jpg

Camera doesn't do the paint justice, really happy with how it turned out

[steve murdoch]

Anyone have any advice on valve clearances for this engine with yoshi cams? Intake 0.375" lift and Ex 0.350", I also have stiffer valve spring, heavy duty retainers and keepers. I know stock is 0.03-0.08mm, although that seems awefully tight.

Have a look at page 2 of this thread from Chuck78.
Slightly different cam specs but i think i see .006-.008.
I hope i am reading that correctly.

http://www.thegsresources.com/_forum/showthread.php?239452-Yoshimura-GS750-1000-2V-Cam-specs-catalog