91 FXR front sprocket change

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Jan 24, 2020 | 11:43 AM

Oldskewl

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From: In my head

91 FXR front sprocket change

Gave my son the FXR and he's running with 6 speeds in a pack all day long, He'd like to lower the RPM's for freeway speeds so just to confirm, running a 32 front sprocket should drop the RPM's by roughly 300? The bike sits at about 3500 RPM's at 80 MPH and the 6 speeds are about 3K. Any disadvantages to changing the sprocket I need to know about?

OS

Jan 26, 2020 | 05:26 PM

grbrown

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From: Bedford UK

32T is the stock front size. Did the 6-speed come with a larger sprocket?

Jan 26, 2020 | 06:00 PM

1997bagger

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From: Ohio

It's a lot of work to put a pulley on the transmission, inner primary has to come off, you have a 32 right now. A 33 will help and don't know if the rear wheel will go far enough forward to get a 34 on it plus it is going to mess your speedometer accuracy up. Another way is the 91 year has the 1.54 (24/37) primary gearing, you can change the front engine drive sprocket and clutch basket to the 1.44 (25/36) off the later Evo bikes giving the more favorable 3.15.
I went the other way from 3.15 to 3.37 by primary gearing, roughly a 300 rpm difference plus your speedometer won't be affected, attaching a calculator to give exact numbers. Negatives is higher gear ratio's will affect pulling power but not going to be that big a deal on a light bike, If he wants pulling power with road gearing then a OD6 is the answer keeping the same gear ratio from HD

https://bakerdrivetrain.com/pages/ca...e-rpm-vs-speed

Last edited by 1997bagger; Jan 26, 2020 at 06:05 PM.

Jan 27, 2020 | 06:20 AM

98hotrodfatboy

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From: Poolville

Best thing I've ever done was going to the Baker OD6... You can get the builders kit for around $2200. Pretty sure your out put shaft is the newer splined shaft so it shouldn't be an issue to do the swap..

Last edited by 98hotrodfatboy; Jan 27, 2020 at 06:22 AM.

Jan 27, 2020 | 08:59 AM

Oldskewl

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From: In my head

Might be having other problems now... The bike is having a hard time finding 4th gear when getting on the freeway, let out the clutch and nothing there, grab another gear still nothing, few times later finally 4th clicks in but by now your rolling at 35MPH.
Speedo cable broke Saturday morning.... Frustrated,

Jan 27, 2020 | 01:44 PM

50pannmore

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From: Rubidoux ca

I have an 86 FXR D with a 34 tooth front pulley and it's it sails down the freeway 95 to 100 no problem obviously not as much bottom end but it sure loves the freeway

Jan 27, 2020 | 01:56 PM

Oldskewl

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Headed home today to drain the fluids in the tranny, check the fluid levels, look for chips then pull the inspection plate to look at the drum for any noticeable problems. I can build a shovelhead (motor) with my eyes closed and I can even do a little wiring on a shovel but transmissions are not my strong suit.