Final gearing option for custom rigid

[ricochet]

Hello,

Got most of the gearing worked out except rear sprocket for my rigid custom.  Motor is a reasonably built 120 inch pan type with headwork on STD heads, G carb and Supertrapp 2 into 1 pipes.  Cam is Andrews S82 and motor is set for 10.7:1 cr.  6 speed with the .86 od tranny.  Rigid frame is a DNA and seems pretty stout/heavy.  This is a custom that will be riden moderatly both in town and highway. Not being raced.

Gearing is all chain drive with 24 motor sprocket, 37 clutch basket sprocket, 23 tooth tranny sprocket and ?? rear sprocket.  51 tooth rear is most readily available but is that correct for this build?  I'm locked in on the primary gearing but can change secondary depending.

Opinion and any thoughts appreciated,

ricochet

[hrdtail78]

With 1.54:1 on primary, and with the 2.22 (51T)  Giving an overall of 3.42.  Might be a little short for a 120.  This is 5th gear.  so your 6th would be an overall of 2.94.  This isn't a bad combo.  Bike could scream up to 100mph.  click into 6th and cruise.

50T= 3.35 5th and 2.88 6th.  This might be a condition where you have to be doing 85 to shift to 6th.

[ricochet]

By Baker's recomendation including the 50t sprocket to get to as close to 3.37 with my setup.  Problem I see is that the sprockets I'm looking at are either 51t or 48t.  No 50 tooth in my desired pattern.  What do you mean by too short?.... that it'll rev higher than desired?

Thanks,

ricochet

[hrdtail78]

Short = low gearing.  Yes, rev higher than you want.

http://www.sprocketspecialists.com/

Look at these guys.  They will make you a 50T if wanted.  Dont know the design you want.

[76shuvlinoff]

For what it's worth  I run 24t  - 23t/ 37t - and then 48t at the wheel with a 93" shovel and a five speed... and at 75 - 80 mph I'm still wishing I had a 6th gear. These days this is on an FLH semi bagger pushing a windshield. For giggles I am going to try a 47 or 46t rear sprocket .... one of these days.

Bottom line  I think your 120"er will have zero trouble with 48t at the wheel.

[ThumperDeuce]

These guys make sprockets also.  I went from 49t to 48t rear sprocked this year and wish I had the 49t back.
http://www.sidewindersprockets.com/titaniumII-sprockets.html