78 GS750 Shifting problem After engine rebuild

[chuck hahn]

What he means is the ratcheting thing.. part 10 here and the associated springs.

https://www.partsoutlaw.com/oemparts/a/suz/50d3fff3f8700230d8b4e15d/gear-shifting

[Carter Turk]

What he means is the ratcheting thing.. part 10 here and the associated springs.

https://www.partsoutlaw.com/oemparts.../gear-shifting

I get that, but I don't think the bike will shift 2nd-5th w/o spring #17 attached.

[chuck hahn]

It for sure has to ratchet the drum between each gear. Thing is its been so long since ive been in a trans that I don't remember the specifics.

[ptakattack]

The spring is attached. The GS750 manual wasn’t super clear with the positioning of the spring, but I compared it with a gs1000 manual and I’m fairly certain it’s on correct

[ptakattack]

I believe I found the main issue. One of the gears that a shifting fork attaches to does not move freely back and forth.

I’ve attached a picture with the case split. It is not currently split, the picture is just to show which gear is not moving freely.

https://drive.google.com/open?id=1MAK2Oq7LA1cFLuZTyCL0ryH8CAJV2SHw

[BadBillyB]

That gear will not move freely side to side with the shift fork installed. It is held stationary by the shift drum. In order to see if it moves freely you would have to remove the shift fork. Did you read my last post. Use a better camera

[hannibal]

The drum moves the fork and the fork moves the gear. I think he's saying the gear won't move so therefore the fork won't move and the drum won't turn.

[ptakattack]

So I ended up pulling the fork off to try to get the mentioned gear to move back and forth and it seems to be seized up. I pulled the engine, split the case and removed each gear and the gear mentioned will only move with the help of a hammer.

I was able to find a transmission for $28 on eBay, hopefully once I have it, it will just be a matter of reassembling the bike and moving on.

I will give an update once it comes in on the verdict once it is installed. I was really hoping to avoid pulling the engine and splitting the case again, but I'm more comfortable doing it now that I have an idea of why it isn't working properly.

Thank you to everyone who has chimed in and helped out thus far!

[BadBillyB]

The first time i started it, the bike was getting caught up on something (it wasn't running long). I pulled the oil cover off and noticed one of the shifting forks was out of place.

Sounds like this is where the damage was done. With the shift fork out of place, the trans may have gone into 2 gears at one time binding the motor. At high rpm this could actually blow the engine cases apart. In your case it may have only damaged the counter shaft or the gear itself. Any drag racer who knows how an overriding auto transmission works in a motorcycle can confirm that massive damage can occur when 2 gears are engaged at once......Billy

[Carter Turk]

Since there are 3 shift forks 2 with the same part number, could one of them been swapped to the wrong shaft?
Not sure if the one fork riding by itself, appears the same when turned around and the cog fitting into the drum would line up.
Maybe something to clarify when the ebay tranny shows up.

[hannibal]

Sounds like this is where the damage was done. With the shift fork out of place, the trans may have gone into 2 gears at one time binding the motor. At high rpm this could actually blow the engine cases apart. In your case it may have only damaged the counter shaft or the gear itself. Any drag racer who knows how an overriding auto transmission works in a motorcycle can confirm that massive damage can occur when 2 gears are engaged at once......Billy

But this couldn't happen with the bike in neutral right?

[BadBillyB]

But this couldn't happen with the bike in neutral right?

If the shift fork that controls 1st and 3rd gear is not properly located on the sliding gear, then 1st, neutral and third gear can not be selected with the shift lever.....If the trans is in 1st gear (in error as the fork is installed wrong) and you shift into 2nd gear and let the clutch out, the trans will bind up stalling the motor and binding the transmission shafts. At high rpm's this can bust the engine cases.....Billy

[hannibal]

Gotcha. Thanks for explaining this.

[ptakattack]

While I have the engine split, can anyone offer insight on the kickstart "punch mark". The manual only states to make sure they are aligned, but it does not explain how to align them. Based on my generic google search, I think I have it correct, but not 100% sure. Here is a picture of the kickstart now. The transmission is coming in today, however, I will not be able to get to working on the bike till Sunday afternoon.punchmark.jpg

Thanks,
Mike

[ptakattack]

Just thought I’d give an update, the bike shifts fine with the new transmission. I rode the bike about 10 miles with no major issues. Thanks for all of your input!