GS-650 - Second Gear

[Guest]

Hi Guys,

Our '81 650 Katana moved under it's own power for the first time in 14 months today.

On the way to the testing station, I noticed that it appeared to jump out of second gear for a split second, then back in again.

It was kind of ker-revs blip-clunk as it got drive back.

Can anyone confirm it's the box? Or should I consider the clutch letting go for a split second? (it's still not right, it's being a bit of a pain to get adjusted correctly).

Thanks,

J

[rapidray]

First, was it a one time thing or did it do it continuously?
Ray.

[G0FHM]

Ray,

It did it twice in the space of a couple of miles......

J

[tom203]

Just out of curiosity, did you manage to get into fifth on way to testing station?

[G0FHM]

Tom,

No I didn't... It was all town work, 3rd gear tops.

I'm aware that 5th is on the same shaft as second!

I hope to god that doesn't play up, else I'm in trouble!

J

[G0FHM]

Incidentally, on the way back I monitored it, and it seemed to be immediately on hitting 3500rpm. It gave a clack from the gearbox, revs rose slightly, then it settled back down again.

I'd suspect the dogs.....

J

[Bribird]

popping out of second gear on my 650 was what started me down the road to totally redoing everything on the bike. I have also had this topic come up before on the 81 650's with other GSR members, Every time it ended up being a believe a loose gear on the lay shaft. I had created a thread of my rebuild covering everything during the rebuild but it got lost when they changed servers a while back....so now I am going off memory.

I ended up swapping the gear from another trans. its a gear with a bronze type bushing where it spins on the shaft...the gear has been discontinued from Suzuki and being I had another complete engine I didnt inquire about whether it would be possible to have the bronze material replaced by some specialty shop. I too suspected the shift fork or the dog for 2nd..but they were both totally fine. Mine started popping in and out like yours...but over the years go to where it would pop into neutral and stay there...I drove it tht way for years until it finally erked me enough to tear the bike down...then started the "while I got it apart" way of thinking...and wahla...I have a new 81 650

[tom203]

Bribird; those undercut teeth on second gear (main shaft) -the ones that slide into output shaft to lock up for fifth, do you remember how worn yours looked. I'm hoping mine will outlast me!

[rapidray]

Time to have the trans undercut! Check the shift forks too while you're in there.
Ray.

[G0FHM]

I'm going to have to live with it for the summer, and have a look over the winter. If 5th happens to be problematic, then I'll obviously have to attend to it a bit quicker!

Next "major" job is the timing chain. PDQ.

Ours has a small slack spot (probably through spending years sitting doing nothing with the tensioner pushing on a part of it). I know they are naturally noisy, but you can hear the slack spot as it comes through the top, and also a slight fluctuation in the engine note as the slack passes between the cam sprockets....

More deep joy!

J

[hjfisk]

If you have to change the timing chain you will have to split the cases anyway . You might as well do it all at the same time. Either undercut the trans mission , or replace it. If that is a shaft bike which I believe it is , and the same as the 650GL I have a complete transmission you can have for $55. shipped within the US. PM me if you are interested

[G0FHM]

Actually, I hadn't planned on splitting the case to do the timing chain.... I'm going to use the "Lazy method" (as instructed by the local bike shop).

I'm certainly intersted in the Tranny for $55... But how much it will cost to ship to the UK is another matter!

If you can get some shipping quotes, Let's see what happens!

J

[G0FHM]

Is this what I'm going to be needing?

http://www.ebay.co.uk/itm/82-Suzuki-GS-650-G-Transmission-Tranny-MM-/400514604466?pt=Motorcycles_Parts_Accessories&hash=item5d4087ddb2

J

[Nessism]

Why does the engine need a new timing chain? Did you measure the stretch per the service manual instruction, and if so, what is the length? Also, how many miles on the engine? Reason I'm asking is because the timing chains typically last the life of the bike.

[G0FHM]

For whatever reason, this one is well and truly goosed!

It doesn't need any measuring (i've got the manual), as when you turn it over by hand, when the given spot passes between the cam sprockets it visibly slackens. Turn it so the slack spot is between the sprockets, either side is tight, and in the middle there is about 1/2" either way of up and down movement.

Also, with the top on, you can hear that section coming through the tunnel.

And at that point at idle the engine revs fluctuate slightly. It's not by much, but it's audible!

I know that they all sound like they are about to burst through the tunnel walls, but i'd rather get this one sorted, as the last thing I want is bent valves and all the associated problems.

It's been sat for years - It hasn't seen the inside of a testing station since at least 2005, when it was first computerised. The spanner guy at the bike shop did say that it was theoretically possible for a section to stretch when sitting idle for years, with the tensioner pushing against it, but I don't know. The tensioner was seized solid and needed strip, clean and relube.

The bike is a 1981, with 69,000 miles indicated. It's first job was as a Heron Suzuki launch/press bike, and had the berries thrashed off it by a string of bike journalists when out on test. One of the magazines I have here featuring it, states that the reviewing journalist stuck 1000 miles on it in 2 weeks... And another has a head to head track test of it versus the GTX.

It's had a hard childhood by the looks of things. Hence why second gear is playing up - I've been told that it's due to being ridden hard in second, and upshifts being done outside the torque band (3000-6000rpm). How true that is, I don't know!

J