Harley Gearing

Don't know what the difference would be but I run a '96 FLH/Liberty with close to 120,000 on the clock. I had Pete put the Liberty on at about 85,000 if memory serves me right. Stock gearing. I run in 5th all the time. I had the factory rebuild done on the Evo engine at just over 100,000 and Thunder Max EFI installed a short time later. Running a Screaming Eagle cam and true dual exhaust.

Tom
I only have a little over 20,000 miles on the bike with the sidecar just added last fall. The engine is stock 88" Twin-cam (even the exhaust). I'm okay on flat ground with little or no head wind, but going up a good grade forces a downshift or it sounds like I'm lugging the engine down. We were loaded down this week and always running into a 15 MPH head wind then on top of that we were in a hilly county of WI.

go with some performance upgrades. I run a screaming eagle stage one kit and some straight shots on my sportster with no real performance issues. I'm sure you could squeeze some extra power out of that big twin.

Thanks, but I'm trying not to modify the engine. I would rather change the gearing. I'm trying to see if anyone else has used the available sprockets, and which one they used.

Markh00 - 7/8/2013 5:24 AM Thanks, but I'm trying not to modify the engine. I would rather change the gearing. I'm trying to see if anyone else has used the available sprockets, and which one they used.

I know there are guys on the board who have done this with sportsers so I'm sure it can be done on a big twin. Hopefully someone can pipe in with info on the sprocket size you can use.

Markh00, are those Harley transmission pulleys you have listed or are you shopping aftermarket pulleys? I may be interested in doing this with my EVO engine Harley as I find myself in 4th gear a lot of the time as well. I think you would need to use the 29 tooth pulley to make much difference in the engine speed, but I'm not sure if the belt length would need to be changed or if you would run out of belt tension adjustment with the stock belt.

Davet
The only sprocket I see listed in my 2005 HD parts catalog is the 32 tooth. But, J&P Cycle from Anamosa, IA (home of the National Motorcycle museum) has a 34, 33, 32, 31, 30, and a 29 tooth selection from five or six different companies. I know the primary chain ratio, the trans ratios, and the stock rear belt ratio. I have calculated the overall gear ratio and the rear wheel speed @ 3,000 engine rpm for both 4th and 5th gear substituting the alternate sprockets. I don't know the revs per mile on the tires, but If I did the math correctly the overall crankshaft to rear axle ratio for 5th gear goes from a stock 3.15 (32), 3.25 (31), 3.36 (30), to 3.73 for the 29 tooth sprocket. The catalog states the swing arm slots for belt adjustment MIGHT need to be modified to achieve the proper belt adjustment. That modification I do not want to do! So I was hoping someone has changed sprockets and knows the results.

It all depends on the final ratio...if you have a 32 on the front final drive going to a 30 would increase your rpm by 500...rule of thump with Harley's is usually 250 rpm per tooth on five speed trans. myself the final drive ratiois2.267 :1 with a 30 going to a 29 the final ratio is 2.345 :1

Now with belt length , you can drop one tooth keeping the same belt,dropping anymore then that you have no adjustment left. Belts are around the $230 mark if I remember correctly ...with a chain its easy ...just take links out.
hope that helps. 🙂

Thanks for the info. You mention a chain; J&P has chain and the a 5-speed trans-sprocket for a 530 chain, but no rear wheel chain sprocket that I can find. The chain/trans-sprocket is the same price, the chain is about the same and definitely stronger. I wonder about the belt. I see that Harley sells a sidecar belt. Makes we wonder if we aren't over stressing the stock belt.

I have no experience with big twins, but I did lower the gearing by 4% on my 883R by going down 1 tooth with an aftermarket front pulley. That small 4% change made a big difference in ride-ability, especially in 1st & 5th gears. My general observation is that most all bikes benefit from lowering the overall gearing by 4% to 8% when mounting a sidecar.

I understand the better way to change gearing on a big twin is to change sprockets on the primary drive -- rather than switching belt pulleys. Take a look here: http://bakerdrivetrain.com/compensating-sprockets where this "sales" example is set forth: ...stock 1999 carbureted Road King. By going from a stock 25 to a BAKER 23 tooth compensating sprocket, the torque at the rear wheel will increase by 9%.... If you have access to a 1/2” impact air gun, a compensating sprocket change is a 1 hour job....

I have a 1999 Harley Roadking Twin cam with a champion sidecar. I changed the crankshaft sprocket from a 25 tooth to a 24 tooth which was the smallest sprocket Harley had. It is the easiest and cheapest way to go and works fine for me and I carry up to a 300 pound load in the sidecar but I would get the 23 tooth sprocket if I was to travel in the mountians.

sidehack05 - 7/8/2013 11:11 PM

I have a 1999 Harley Roadking Twin cam with a champion sidecar. I changed the crankshaft sprocket from a 25 tooth to a 24 tooth which was the smallest sprocket Harley had. It is the easiest and cheapest way to go and works fine for me and I carry up to a 300 pound load in the sidecar but I would get the 23 tooth sprocket if I was to travel in the mountians.

Yes, much less expansive that way and it doesn't take as long, I did a chain conversion on my final a while back for a diff. reason , I got the kit from Zippers ,that's why I mentioned the chain part. 🙂

Thanks to everyone for responding. I have looked at both Zippers and the Baker site. It does look like the primary sprocket may be the easier way. But I have to ask, why the conversion to the secondary chain if it wasn't to change ratios?

What I would do is S&S 509 cams with a less restricted air filter and some S&S quite slip ons. The 509 is a good torque cam for a 88 and is not a lot more lift then the stock cam as well as a bolt in cam now head work needed.

I put a Baker DD 6 in mine before putting the hack on and went back to stock motor sprocket. First 3 gears are low which I like pulls well on grass and hills when loaded up taking off. 6th is the same ratio as a 5 speed with the stock motor sprocket.

My plains when money is available is to build a torque monster motor that will pull well in high gear. Being mine has over 93,000 on it I want to freshen it up any how. But I have more going for me then many others as I can do all my own work including machine work.