Gear change

Not much gain in gear ratios with only the one tooth change (1.5%). 10% with using both 883 gears.
(Did I gigure it right?)

L.

Hey oldtimer, if'n I'm calculating correctly, if you change engine primary from a 34 to the 38, you should get an ~8-1/2% gearing reduction. I'm guessing a Sportster rig pulling a Bunkhouse would be best geared down 6%-10%. Seems I recall 3/4 ton pick-up trucks gear down about 10% when equipped for heavy towing.

Changing the front pulley only results in a ~3-1/2% reduction.

Another advantage of changing the engine primary is the speedometer/odometer still read read accurate. (Mine is off ~4% from changing the front pulley.)

I believe he was talking of going from a 29 to 28 tooth gear. He already has the 38 tooth gear. Power range would be best with 883 gearing, 34 to 28.
Low end pulling would be better with the 1200ci displacement, 883 heads and cam timing.

L.

Hack'n - 7/13/2011 12:30 AM

I believe he was talking of going from a 29 to 28 tooth gear. He already has the 38 tooth gear. Power range would be best with 883 gearing, 34 to 28.
Low end pulling would be better with the 1200ci displacement, 883 heads and cam timing.

L.

Unfortunately after checking, it's a major engine job to change the engine primary from the stock 38 to a 34. Not like the Big Twin. I'll just have to settle for a counter shaft reduction and hope that does the job. That's a 132.00 parts and labor change so not much invested. Cheaper than thinking about a new bike. I have a hitch ordered and an appointment for the gear change on Aug 11th so once it's done, I'll pull the bunkhouse and see how it is before considering adding a Hannigan sidecar to it. Thanks for the responses.

On some bikes, if you go to a smaller primary, it can really make the chain go through a very sharp turn on the small primary sprocket.
Leads to faster wear.
Is the rear sprocket easy/reasonable to change? Would it make more sense?

Jason

Hi Oldtimer,
I have a 1200 sportster outfit that I have recently changed the front pully on, down 2 teeth, it didn't require changing the belt as there was just enough adjustment in the swing arm for the extra length. I have just finished a 600 KM round trip to the west of Sydney where I live, this included some big hills over the Great Dividing Range that separates Sydney from western NSW. I had a mate in the chair and we were able to tackle all the hills resonably well and most importantly I was able to keep top gear on the freeway part of the trip. Before the change I was up and down the gear box at every slight hill.
Apart from LL forks this is the best modification to date.

Sean.

Thanks for the update Sean. My experience is quite similar to yours. By the way, oldtimer should be on the road heading towards/arriving at the National Rally in Ohio USA today, driving camo his Ural rig.