changing sprockets

[Dot Heton]

John, I love your expirience and willingness to do things outside of the conventional way but you and I use our bikes in completely different ways. Your blanket statement of a 36 tooth rear being useless is, well, "useless". If I put an 18 in front and a 36 outback I will still have exactly stock gearing and it will give me more clearance over the swingarm. I was asking how much clearance it would give me but I guess nobody knows. I'll just have to do it and not worry about it.

 

[xsjohn]

Dot......Wonder what kind of clearance you will have over the shift shaft..........doubt that the 18 would raise it much over the swingarm......I doubt it would even raise it an 1/8"...but it will lower it the same ...gave away all my 17's or I would measure it for you.......I cut some off my shift shaft 10 years ago just as a precaution and it did jingle a bit on it before when the chain was a little loose.........that shaft is plenty tough for what little bit of work it has to do.....

xsjohn

 

[Dot Heton]

Your right, it will be very little gain but right now the chain tings off the pivot area and a slight increase might be enough. I do most of my cruising on slow boulevards and around the lake that has a 20 MPH speed limit. You don't want to go much faster, you'll miss the sights.

 

[Bandito]

I switched my bike to a 17/31... it's just exactly what I needed.

No longer am I being passed by 50cc scooters with my 36. LOL.

 

[MacMcMacmac]

I went down 3 teeth on the rear sprocket on my 83 Special. Could have gone more, as it still revs out at highway speeds. Stock 104 link chain went straight on and adjusted to about the mid point on the arm.

 

[rikkibobbi]

Yep.. I have 2 650 specials out here in Newfoundland... both have 36t sprockets....Friggin useless... I have a 34t on now and its getting better but I think I might be going with the 32t afterall.

 

[CDNTX650]

I retarded the timing slightly on my 78 and it sure idled alot nicer. Highway always sucked cause it was a hardtail.

 

[Bandito]

Yep.. I have 2 650 specials out here in Newfoundland... both have 36t sprockets....Friggin useless... I have a 34t on now and its getting better but I think I might be going with the 32t afterall.

34t claims to be standard, but it's not the case on the Canadian bikes I have found. I've looked at 5 of them out here, and all have 36t rears. I have two sets of spare
wheels, both had 36t rears, all original. So I am going to say that it was likely this
was the standard gearing in Canada. I can't see that many people swapping to 36t.

I switched to 31 and 102 link chain. Much better, bike seems to run very well.
Cruise along at 110 around 4k.

 

[Sundie]

34t claims to be standard, but it's not the case on the Canadian bikes I have found. I've looked at 5 of them out here, and all have 36t rears. I have two sets of spare
wheels, both had 36t rears, all original. So I am going to say that it was likely this
was the standard gearing in Canada. I can't see that many people swapping to 36t.

I switched to 31 and 102 link chain. Much better, bike seems to run very well.
Cruise along at 110 around 4k.

This might be a "west coast" thing rather than a CDN thing. All the CDN bikes around here are 17/34.

 

[C-Los SD]

I just put on 750 big bore. The revs seem to be a lot higher with 17/32 and more vibration at speeds higher than 65 than it was with 650. Would going to 17/34 help? What combo are you guys with 750's using?

 

[jay760]

To bring the revs down either smaller back sprocket or bigger front, I run 18 front standard back, a friend with an 840 runs 18/31

 

[MacMcMacmac]

34t claims to be standard, but it's not the case on the Canadian bikes I have found. I've looked at 5 of them out here, and all have 36t rears. I have two sets of spare
wheels, both had 36t rears, all original. So I am going to say that it was likely this
was the standard gearing in Canada. I can't see that many people swapping to 36t.

I switched to 31 and 102 link chain. Much better, bike seems to run very well.
Cruise along at 110 around 4k.

Hmm, I went to a 31 tooth, thinking I had a 34 tooth. I'll dig out my old sprocket and recount the teeth. It was amazingly low geared stock, so you might be right. Could still use higher gearing though, maybe up one on the front. I'm in Ottawa, but I got the bike across the river in Quebec.

Glad to hear there are still bikes from my yoof rolling around the rock back home. Where at Rikki, Sinanty?

 

[Hooligan83]

I wonder what the numbers would look like on a rephased motor with cam and 750 or 840 conversion, running 18/32 and a Mike's 5th, with Pamco Ignition and PMA swap with a lightened flywheel, proper exhaust, and a set of Lectron carbs, of course running a 19/16 wheel combo too.

 

[SINKING78]

Fuel to this old fire... I run a 17/32 and want to run a 18/32. Mike's says that the shift shaft guard must be removed. WTF is the shift shaft guard? I know what the shift shaft is. Anyone running an 18T, what are they talking about? I have a 78SE.... It's the shaft, the case, and the shifter linkage... what am I missing here? Is the guard an OEM thing?

 

[osteoderm]

Fuel to this old fire... I run a 17/32 and want to run a 18/32. Mike's says that the shift shaft guard must be removed. WTF is the shift shaft guard? I know what the shift shaft is. Anyone running an 18T, what are they talking about? I have a 78SE.... It's the shaft, the case, and the shifter linkage... what am I missing here? Is the guard an OEM thing?

The shift shaft guard is an obvious metal tube that slips over the shift shaft inside the side cover. It has a rubber-lined plate and a single bolt tab. Yes, it's OEM, and if you're not seeing it, it probably has already been removed.

Scroll down this post for pics...

 

[SINKING78]

Ost, Thank you It was never there, and that's what I was thinking. I've been into this motor enough to know what I'm looking at, but have never seen a "guard" when I replaced the seal so I was confused... thanks again..

 

[jamesgs4]

you don't need to remove the shaft guard to run an 18t. Just trim the lower mounting tab shorter and bend the other tab slightly.

 

[marp68]

I switched my bike to a 17/31... it's just exactly what I needed.

No longer am I being passed by 50cc scooters with my 36. LOL.

How does the bike handle in the city?

I'm running 17/34 stock now, but would like to lower the revs on the roads outside town. Still I also use it sometimes in town. I don't go much on freeways, but like to run both cruising and more active on smaller (curvy) roads outside towns.

I choosing between 31 and 32.

Have a -75 and weight 83 kg, sometimes with my girlfriend.

/M

 

[nj1639]

Marp,
I found that reducing the rear will give you more use of the lower gears while riding in town, Try the 31. I'm running 18/32 on both my bikes but rarely ride with a passenger and if I do they weigh in around 110 lbs, I'm 180.
18/32 is about the same as 17/30.
I love the curvy roads around her but you will be doing a lot of shifting to keep the rpm's where they need to be.
I have a friend with a stock geared '78 xs650. When we ride the country together it's like two different horse gaits, him on a Quarter horse and me on a Standardbred....

 

[marp68]

Hahaha.. okej, a quarter horse, but what would I call the Ducati Monster I had a couple of years ago...

I think I go with 31 then, since it gives me noticible lower revs compared to 34, but still it seems to be okej on the smaller curvy roads outside town when I like to drive more active alone. There are not many big and steep hills to climb around here neither. And my girlfriend only likes to cruise and weights a little bit more, so hopefully the 17/31 will not be much of a problem. And when driving more active, I usually drive on a higher gear. Also to be able to use engine braking more as well.

I was first thinking of going with the 32, since i've read that other people thougt it was a good compromise, but regarding the revs it would not be much of a difference from 34.


/M