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Message started by bobber_prjct_2010 on 10/04/16 at 06:28:33

Title: 4-speed to 5-speed
Post by bobber_prjct_2010 on 10/04/16 at 06:28:33

I'm considering converting my '86 LS650 4-speed into a 5-speed for the "overdrive" at higher speeds. I often travel long distances and would love the extra gear. I've read a lot about the chain conversion, but haven't been able to find information on going from 4-Speed to 5-Speed. Can you point me in the right direction? :)

Title: Re: 4-speed to 5-speed
Post by Dave on 10/04/16 at 06:53:57

Splitting the cases and changing over the parts is not anything that folks look forward to doing. Most folks find it easier to just get a 5 speed bottom end and start with that - rather than try and find all the 5 speed parts and move them over to a 4 speed case. You would need both transmission shafts, the shifting drum, and possibly some parts from the linkage in the left side of the case. And.....you have that potentially troublesome starter gear that doesn't have the torque limiter.

If you have a good running 4 speed and are willing to change the final drive ratio....and go with a 140/90-15 rear tire - you can get a very good highway bike. (The jump from 4th to 5th is a very small change.....it only makes a few hundred rpm difference).

Title: Re: 4-speed to 5-speed
Post by ohiomoto on 10/04/16 at 06:58:45

Also, fifth gear isn't that much taller than 4th. I man it helps, but you might be better off going to a larger rear wheel/tire or taller gearing.

Title: Re: 4-speed to 5-speed
Post by Dave on 10/04/16 at 07:08:56

With the stock 140/80 rear tire at 60 mph, the 4 speed bike will be turning 4,135 rpm - while the 5 speed bike will be turning 4,008 rpm. That is only a 127 rpm difference.

If you were to change to a 140/90 rear tire at the same 60 mph the 4 speed bike will be turning 3,952 rpm, the 5 speed bike will be turning 3,831 rpm.

Adding a Kawasaki front pulley (25 tooth instead of 23 tooth) will drop the rpm 8%. In combination with the larger tire you could get the rpm down to 3,636 for the 4 speed and 3,524 for the 5 speed bike.

So.....if lower rpm is your goal - the cheapest and easiest thing to do is to install a 140/90-15 rear tire and do the Kawasaki front pulley. If you have a tired 4 speed bike and need to do the engine work anyhow......find a good 5 speed bottom end.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1384949185

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1448021014

Title: Re: 4-speed to 5-speed
Post by verslagen1 on 10/04/16 at 07:13:10

for the most part top end is the same for both.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1341280735

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1341162964

And I don't think you can put the gears for a 5 speed in a 4 speed case.

Title: Re: 4-speed to 5-speed
Post by Dave on 10/04/16 at 07:33:22

I found the thread where you show your bike....you already have the 140/90 rear tire on your Blue Collar Bobber version of the bike.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1302365063/0#0

You best bet would be the Kawasaki front pulley conversion. If you can't find someone to machine one for you.....I most likely will have one or two for sale once winter sets and I have more time to spend at the lathe.

Title: Re: 4-speed to 5-speed
Post by bobber_prjct_2010 on 10/04/16 at 09:28:05

Thanks for the great info! I like the idea of trying the Kawasaki pulley. This seems to make the most sense. I do have some engine work I'm doing this winter, but not enough to warrant trying to get the 5 speed into the 4 speed case. Thanks again!

Title: Re: 4-speed to 5-speed
Post by bobber_prjct_2010 on 10/04/16 at 10:26:32

43787562737F646279717C63100 wrote:

I would purchase a machined front pulley from you should you decide to build some in the coming months. Thanks.

Title: Re: 4-speed to 5-speed
Post by Kris01 on 10/04/16 at 17:27:37

I wasn't expecting much of a change when I went to a 140/90-15 rear tire but after it was on, it was a pretty big improvement. Of course, I'm used to it now and it feels "normal".

Title: Re: 4-speed to 5-speed
Post by Reeves on 10/05/16 at 06:54:36

63706766797472707B24150 wrote:

Yep Verslagen is right. If i my memory is correct 4 speed tranny have 2 shift forks and 5speed have 3shift forks. 1 fork moves is on its own shaft. It means different engine case.

Title: Re: 4-speed to 5-speed
Post by bobber_prjct_2010 on 10/06/16 at 09:19:36

615656455640330 wrote:

[quote author=63706766797472707B24150 link=1475587713/0#4 date=1475590390]for the most part top end is the same for both.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1341280735

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1341162964

And I don't think you can put the gears for a 5 speed in a 4 speed case.

Yep Verslagen is right. If i my memory is correct 4 speed tranny have 2 shift forks and 5speed have 3shift forks. 1 fork moves is on its own shaft. It means different engine case.[/quote]

Makes sense. Thank you.