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Johnson Engineering
100 Blake Road
Denver, IA 50622
(319)984-9299 fax

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updated March 6, 2003

From time to time we'll post questions we've received regarding our line of v-twin performance drivetrain products. If you've got a question concerning the use of our products on your bike, please let us know. To find topics, use the "find" command under your browser's edit menu. Also be sure and check our online library of product literature, for answers concerning application.






XL '89



is there anyway to "add" a fifth gear to the trans to make it a 5-speed?

Not that we know of. Same holds for four speed BTs.




Is TwistGear an overdrive?

No. TwistGear, WideGear, and SportGear are close ratio fifth gear replacements. We manufacture our own one piece countershaft/fifth gear and main gear to maximize acceleration, and use final or primary ratio gear to dial in fifth-gear engine speed characteristics.



6 speeds

Will TwistGear,SportGear, or WideGear work in my aftermarket or converted 6 speed?

You can't mix 5-speed parts with 6-speed parts. We don't know if our trapdoor kits fit aftermarket 6-speed cases, but if you've installed a 6-speed in your stock 5-speed case, then the answer is yes. You'll have to reinstall the 5-speed drum and forks.



axial bearing load

Don't helical gears lose a lot of horsepower because of the side loads generated?

There is a loss of power whenever helical gears are employed, but it's so insignificant that it can't be seen on a dyno.

Keep in mind, straight cut gears also register a power loss, but again it's negligble. Not so with overdrives, which can lose in the neighborhood of five percent.

Both the automotive and the trucking industries are relentless in their pursuit of fuel economy - anything that threatens to rob power is replaced. Both use helical gears consistently in their transmissions for greater strength, more reliability, and a much quieter drivetrain. Loss of power is not a factor.

XL '03 1200C


what's needed

What do I order (part #'s, etc.) to obtain the 13% gear reduction?

How much will it cost?

Our SportGear page and PDF documents both have the part numbers and references you'll need. Make sure you download the file "SportGear Tables.pdf" for P/Ns. Prices are as shown on our price list. When you're ready, print it and fill in the info.

Pulleys and belt are dealer items, and we list the P/Ns. There are also a number of aftermarket sources.

Labor varies, depending on whether or not pulleys are swapped, but generally require a minimum of 3 hours. Reference a fifth gear R&R.

Buell 1998 S1W


backcutting gears

Johnson Eng, I'm interested in your gear for my 1998 Buell S1W.

How much is it?

Where do I have it installed?

I want to have the transmission gears backcut. Do you recommend this and should I have it done at the same time as installation of your new gear.

Where do I purchase the Euro 29/55 pulleys for the bike? I plan to drag race this bike at Stugis.

Would the stock gearing be more of a benefit for racing? I might convert it to chain drive.

1. The price is shown on the website as $570

2. A dealer or good shop. Very simiiar to a fifth gear R&R.

3. SportGear needs no backcutting, it is already done. The remainder of the gears can be backcut, but this process removes the hard case off of the dog teeth. We don't recommend it because of potential wear problems.

4. The pulleys and belt are available at your dealer, or check aftermarket sources found on forums like and American Thunderbike Club, both linked on our news page.

5. The pulley selection depends on your racing application. If you want to go faster than 140mph then you must have SportGear on 29/55 sprockets.

Fatboy 94

Twist Gear

torque and pulleys

My 94 Fatboy has had the tranny sprocket changed to a 30-tooth for the low end grunt. Would I gain anything, torque-wise by going back to a stock 32-tooth sprocket and adding the Twistgear - compared to what I have now?

Secondly, from how I understand the Twistgear, wouldn't it be advisable that I keep the 30-tooth sprocket and still add the Twistgear?

Would I or wouldn't I be running more revs?

I first figured I can keep my 30-tooth sprocket and have a normal 5th gear for my long trips, but now that I've read your brochure, I think that was premature thinking. Please clarify.

Do you have any numbers as far as torque difference between 32T sprocket with Twistgear as opposed to the 30T sprocket without?

Your products are top shelf, but I'd hate to go through the expense of going back to the stock setup with the Twistgear and then find out I've lost torque. Granted, for engine life, comfort, gas economy, your reccommendation is the way to go.

Yes, you gain both torque in 1st and lower engine rpm's in 5th if you go back to 32T with TwistGear - this is our recommendation.

If you put in TwistGear and keep the 30T sprocket, you may get too much reduction, or overgear, with first gear becoming nearly unuseable.

It's your call on how much reduction you want in 1st gear, but again you'll probably be overgeared.

All our helical products run 1:1 final, so overrevving isn't anymore a problem than it was before.

TwistGear (41/20) with 32T/70T pulleys results in 11.12:1 first gear stock gears (32/17) and 30T/70T pulleys results in 10.89:1 first gear. Therefore TwistGear configuration will produce 2.1% more torque than present configuration in first 4 gears.

TwistGear, SportGear, and WideGear are guaranteed for 120 days regardless, and for a full year against defects. That's as good as it gets.

FXST 2001


chassis mods

I have a 2001 FXST/Standard and would like to know exactly what I will have to have to put a wide tire on.

WideGear will take care of the engine and transmission. You need to select your choice of swingarm, fender, wheel/tire, etc. Check with your dealer or with distributors online.

We ship direct, or order through your local dealer.

Fatboy 1996


chassis mods


Yes, WideGear works on your 1996 Fatboy. No - you can run up to 180 tire with your stock swingarm, but you'll need an aftermarket swingarm for 240 tire.

FXRS 1987


aftermarket frame

I own a 1987 FXRS, and am planning on buying a wide tire stock frame from BIGBOAR Question: would your kit work on my o.e.m. motor and trans ?, and how about the BIG BOAR frame?

WideGear will work in your engine/trans if you upgrade the clutch basket to 1991 and upgrade the transmission driver pulley also. Please see the upgrade note on the website.

WideGear is designed for use in frames that don't offset the tranny or engine. If the transmission plate's offset, it would have to be reset to stock alignment.

Road King


starter coupling

I need the extended starter splined coupling. is it avalable seperatly? If so at what cost?

Do the splines go all the way through? I would need to shorten it to only .375" longer than stock.

Do you have a way to offset the primary .375? I have a Road King running a 180 tire with a 1" belt at present. To run a stock belt I need to offset motor and trans .375 or the primary .375

I believe I can move the rear belt pully and clutch over with a spacer and special nuts and still have enough engagement to the splines in the shaft.

Our starter coupling is 30mm (1.18") longer than stock, $55 plus shipping.

No, there is a 1" gap in between the splines. It doesn't look like this will work.

We only offer the 30mm offset parts right now, but since the FLT frame tube is outside the belt, it wouldn't do any good to move the primary out - the outside belt edge cannot move outboard (without serious frame cutting) because of frame interference.

It seems that running the 1" wide belt is the only option you have unless you chop the frame.



rubber mount


How much is it?

Does it work with Dyna rubber mount systems?

Does the starter have to be modified?

What after market wide rubber mount or softtail frames should it work with.

Varies with application. You can download most of this information from the website, including a Dyna running a 240.

The kit has a longer coupler for the starter, so no starter modifications are necessary.

The only frames it won't work with are the ones with offset engine and/or trannys. WideGear provides the spacing via a longer mainshaft, not by moving the tranny.

XL 1200


fat tire conversion

Do you make a wide tire kit for a 2003 sporter 1200?

We get a fair amount of questions concerning a Sportster version of WideGear. To be candid, we don't think there's a big enough market, although that could change. One of the problems we think customers would encounter would be finding other parts required, like struts, fenders, swingarms, axles, etc. In other words, the other items that we don't manufacture ourselves. We may yet make a Sportster kit, but not right now.

ST 01



I have a 2001 softtail Deuce. Whcih kit would you recommend and where could I purchase a swingarm?

Well, IF you want a wide look (per your question about swingarm sources) then you'd need WideGear, which is a perfect match for your project. You also get the unique performance advantages (helical gearing, close ratio gearbox) with WideGear, just like TwistGear.

There are several sources, start by checking with your dealer or online or from the major distributors. You'll also need fenders, struts, axles, etc.

I know this doesn't exactly answer your question, but I hope it's pointed you in the right direction.

Dyna 02



I own a 2002 Dyna Wide glide and want to put a larger rear tire on it without going through nightmares and changing rear swing arms, shock towers, transmissions and fenders.

What does your kit do and what do I need totally for the fat tire conversion. I would like to keep the original final belt drive.

Wide tire conversions are difficult. Simply put, you can't go wide without increasing clearance all the way down the line. This begins with moving the transmission pulley (or sprocket) far enough out so that either the belt or chain will clear whatever size tire you decide on. That's for starters.

The swingarm is fundamental. You simply can't get a "wide" (above 150mm or so) tire into the existing swingarm. Check the clearance for yourself, and you'll see why. It's like trying to get a size 12 foot into a size 6 shoe.

The issue of belt width is also integral. The method of final drive (belt or chain) is related to how much tire clearance is available. For maximum tire width use chain, or run a 1 1/8" belt if horsepower is conservative.

Our kit extends the primary out by 30 mm (1.188") because of our extended mainshaft, the part that your clutch attaches to. This is matched at the front by a 30mm spacer between the engine and the innter primary, and an appropriate spacer between the transmission and the inner primary. Unique to our kit is an exclusive close ratio gearing change, as well as other significant benefits.

To sum up, wide tire conversions are an expensive and time consuming proposition. Doing them correctly is crucial, but when done properly you'll have something you can truly call your own.

SportGear™ and TwistGear® are trademarks of Johnson Engineering, Inc. Buell™, Dyna™, and Sportster™ are trademarks of the Harley-Davidson Motor Company. No affiliation with the Harley-Davidson Motor Company is implied or inferred.