This thread will start out in the RSD....but after a bit of discussion and working out the bugs I will probably move it into the Tech section.  I did this work a little bit at a time over the past 6 months, and unfortunately the photo documentation could have been better.


FRONT PULLEY

The stock front pulley is a 23 tooth pulley.  The Kawasaki EN454 LTD used a 25 tooth pulley....which will decrease rpm's by 8% if used alone.  According to the speed chart that Serowbot prepared 60 mph with the stock gearing would be 4,008 rpm....with the Kawasaki pulley it would be reduced to 3,688 rpm.  This change will pull the rear wheel forward as a result of the larger pulley diameter - the change does work with the stock sized rear tire....oversize tires may not clear the swing arm. (RYCA bikes with 18" wheels cannot use ths pulley conversion without modifying the swingarm for tire clearance).

The Kawasaki front pulley costs about $ 80 new.


The Kawasaki pulley has a wider center hub and it needs to be machined thinner to work on the Suzuki.  This can be done on a lathe if you have a way to hold the pulley  - mine was done on a milling machine.  The metal is very hard and a carbide tool was used to do the cutting.

Front of Pulleys


Back of Pulleys


The stock Suzuki pulley has the side flanges welded on, the Kawasaki pulley has tabs that are split and they stick out and are very rough - and they hit the engine case and pulley cover.


To provide more clearance I took a flat punch and hammered the tabs a bit flatter.



The rear post on the engine case interferes with the larger pulley, and has to be trimmed.





The bolt for the oil seal retainer has an extended bolt head and it can be replaced with pan head screw for more clearance.




Finally - You need to install the nut with threadlocker and a good lock tab washer, torque it to 94 ft./lbs.  If you have a RYCA you will need to raise the front of the belt guard a little bit for clearance.  On my outer cover I had to trim a small place where the outer flange just rubbed a bit on the outer cover - this support matches up with the one that had to be trimmed on the engine case






REAR PULLEY

The stock rear pulley is 68 tooth, and a Kawasaki KZ750 from around 1983 has a rear pulley that is 65 tooth. The combined change in the ratio is a reduction from 68/23 (2.95) to 65/25 (2.60) - which will reduce the 60 mph stock 4,008 rpm to 3,532 rpm.....a nearly 12% reduction.

You cannot use only the rear pulley in this conversion - as there is not enough travel for the belt adjustment to take up the slack caused by the smaller pulley diameter.


The Kawasaki pulley is cast iron......and weighs 2.4 pounds more than the stock pulley which is made from aluminum.  It increases the rear wheel weight from 34 to 36.4 pounds....and I see no way to trim off any fat.  The center bolt hole is larger than the Suzuki hole - so you have to make a spacer to take up the extra room and center the sprocket on the hub.  The bolt circle is also different - so after I had the hub spacer made I installed the sprocket and marked the new hole locations, and drilled them on a drill press.

Kawasaki Pulley


Cutting out the spacer from an aluminum sheet


Trimming the inside diamter


Installed on hub and trimming the outside diameter


Once the pulley was on the hub......it then became necessary to trim the hub to correct for the difference in the pulley offset.


Trimming the hub to correct the offset


After I trimmed the hub and went to install the new pulley, I discovered the bolt threads did not extend deep enough allow the bolts to be tightened - so I had to install some washer on the outside.  This winter I will make a proper looking plate to fit on the outside in place of the washers.


When I installed the rear wheel I discovered I had some play/wobble that I did not like......so I cut some strips of rubber from a floor mat and installed them.  The wobble is gone.......now we will see how long that solution will last.


I also discovered that the smaller pulley would hit the left shock mounting bolt.  I had to remove the bolt, trim the length of the hex head, and then plate the bolt and put it back on.



And this is what it look like installed.


There is just barely enough belt adjustment to make this work.  On my Cafe' conversion I have about 1/2 turn left on the adjusters before I bottom out the axle in the swinge arm.  This winter I plan on extending the swing arm table 1/4" and will make the slots a bit longer....while filling up some of the front of the slot.  On a stock bike with normal length shocks it might provide a bit more adjustment room.

So far I have only gone on a 5 mile test ride as the weather has been too cold to ride much.  I really think this is going to be a great change.  It now becomes obvious when you shift into 5th gear.  My rpms drop to 3,300 at 60 mph (18" rear wheel), and the engine is loping along and sounds great.  There are hills in this area that most likely will require shifting into 4th to keep from lugging the engine too much.  I am sure this conversion does not provide any higher top speed, and I expect that 4th gear is now the gear to use for speed runs, and 5th is now the overdrive for cruising.  I am not sure how well this conversion will work on a stock engine/stock bike/saddlebags, large rider, riding double, etc.  My bike has a Wiseco, Stage 1 Cam, better muffler, large foam air filter, etc, weighs about 320 pounds and I weigh 160....and the engine pulls this bike strongly with the new gearing.  So far I am very happy with this change......now for the long term testing scheduled for the spring of 2014!

Super Thumper wrote on 11/20/13 at 07:22:15:


I really don't like the mess and maintenance of a chain....the belt is nice and clean.  Also the Cafe' conversions raise the rear end with 3" longer shocks....and that combined with the location of the rear set pegs and smaller diameter sprockets results in the chain hitting the peg mount, as well as the pivot point for the swing arm.

That is really, really cool. If you made a kit for us'ns what don't got a machine shop in our carport, I bet you'd sell a few of these.  

Well......I am not in the business and posted the info so you could do it yourself.  Wth the labor involved, and the cost of new or used parts, this conversion would most likely be in the $ 500 - $ 600 range.

The source of Kawasaki pulleys appears to be somewhat limited.  The same 1-2 used front pulleys have been on eBay for about a year, same for the 1 rear pulley.  These seem to be commercial sellers that have very big prices on their stuff.....and don't care if it doesn't sell quickly.  I ended up buying a new front pullley when I was offered a discount coupon for an online parts seller and it was just a bit more than a used one.  For the rear pulley I just kept watching and eventually got a good deal on one that was in good condition.  If you watch eBay continuously you will most likely find a bargain eventually.


I don't have the ability to machine the front pulley myself - my lathe cannot grip it properly.  A fellow at the gym I go to owns a machine shop and did it for me as a favor....he said it would have been about $ 150 if he had charged me their normal labor rate.  The front pulley can be done alone and it is a worthwhile upgrade.
(UPDATE:  I have made some mandrels to hold the pulley in my lathe, and I when I can find reasonably priced used pulleys and the time needed to machine them....I do have some for sale in the Marketplace).


If you have the tools.....or friends and family that do and will machine the parts for you for free....this is a very worthwhile conversion.  It really makes the bike a freeway flier!  If you have to pay someone to do this.....it would be expensive.

   

strang wrote on 05/18/14 at 06:00:27:



I guess there may be some confusion about what low and high gearing is.....and maybe I got confused as well.  When something is geared low....I suppose the thought is that the machine is like a tractor....and goes slow for high engine speed.  On the other hand....when you shift into a higher gear....you go faster.  

Making the rear wheel bigger allows you to go farther with each wheel revolution.  The wheel size change is done mostly to lose the Cruiser look and make the bike look more like a standard motorcycle where the front and back rims are the same diameter.

Using more teeth on the front pulley makes the pulley a larger diameter, and it drives the rear wheel farther for each revolution of the engine.  When the front pulley is larger - it move the belt farther with each revolution of the pulley.

Using less teeth on the rear pulley makes the pulley a smaller diameter, and the rear wheel moves farther for each revolution of the engine.  When the rear pulley is a smaller diameter - it takes less movement of the belt to make a full revolution of the pulley.

Quote:


Probably a lot of truth to that - cars, bikes, everything.  Everything made in the new millennium hasn't bee the same quality of yesteryear.  I suppose the thread got pulled to thin through the engineering & manufacturing process, supply lines, metal grades, so fourth.

Serowbot:

Thanks for doing that.  It confirms what I thought....after the conversion any high speed attempt I do should be done in 4th gear.

Dave

I didn't keep track of the mileage on the bike when I installed my double pulley conversion - but I would guess I have about 2,500 miles since the change.  My bike pulls the taller gearing just fine.....and I suppose I have lost a bit of acceleration - but it is not noticeable.  My bike has a Wiseco, Stage 1 cam, some porting, a Mikuni round slide carb, and it makes noticeably more power than the stock engine.  I am going to be changing my speedometer to a new GPS one from Speedhut, and it does have a 0-60 and 1/4 mile feature where I can actually make some measurements....so I will do that sometime in the future just for kicks.

If you have the stock engine, I would definitely just start with the front pulley conversion.  This larger sprocket does pull the rear wheel forward until almost all of the belt adjustment is used up - so if you can move your rear axle all the way forward and your tire does not rub the swing arm - you will be able to use the pulley.  An 18" wheel is too big to use this conversion without clearancing the swing arm.  MMRanch had a 140/90-15 Michelin Commander rear tire and was able to do the front pulley change without tire issues.

And doing either the front or rear pulley conversion will not increase the top speed you can go...the stock engine is only good for about 85-90 mph (even though your speedometer may indicate a bit higher).  You may find a strong tail wind or steep downhill to help make a higher number....but on flat ground with little wind the bike just runs out of power and will never make it to 100 mph.  Since I have done the conversion my bike will actually go faster in 4th gear than it will in 5th.  In 4th gear the engine can rev up and get higher in the power curve and get to a higher top speed....in 5th the engine does not rev up high enough to make HP/Torque and the wind resistance just wins the battle somewhere just shy of 90 mph.  With the double pulley conversion....5th has become an overdrive that is used for steady cruising at 60-70 mph.