World War 2 Style Military Motorcycle Project:

[pamcopete]

terribletabo1,

Well, here is a member that used one on his project. I think he calls it a "Jack Shaft". Perhaps you could PM him for the details:

xs650temp.proboards.com/index.cgi?board=project&action=display&thread=5141&page=9#72330

[terribletabo1]

Oct 14, 2009 10:44:04 GMT -5 @pamcopete said:

terribletabo1,

Well, here is a member that used one on his project. I think he calls it a "Jack Shaft". Perhaps you could PM him for the details:

xs650temp.proboards.com/index.cgi?board=project&action=display&thread=5141&page=9#72330

Thanks, interesting project but I guess it probably wouldn't look right with what I'm going for.

[terribletabo1]

I found this:
High Ratio Primary Gear Set
www.xs650.org.au/Racers.htm

Ivan Hoey has decided to start making some of those exclusive parts needed for racing. First item to be produced is the High Ratio Primary Gear Set.

On the XS650 the primary gears are 27 teeth on the crank gear and 72 teeth on the clutch basket. The gears that Ivan is having made are 20% higher than the original ratio, these are exactly the same as those produced by Halco Tuning in England that are now unavailable.

So, why do we need to use the higher ratio primary gears?

The available options for secondary gearing on the XS650 are limited, the largest front sprocket that will fit the XS is 18 teeth and the smallest rear sprocket that will fit is about 30 teeth so if you want to go faster you would have to rev the engine higher and getting more horsepower to the top end might not be best option, you'd like to keep those rev's down a bit and make the engine live a bit longer.

By using the high ratio primary gears you speed up the gearbox allowing more scope for final drive sprocket selection with the added bonus that you also effectively reduce the load on the gearbox and transfer that load onto the engine.

Let's dream here for a minute, you're going down the main straight at Eastern Creek or Phillip Island and the tacho is pinned at maximum rpm's and all the other bikes are passing you like you're standing still and you know you have the maximum gearing that will fit your XS 18t front and 30t rear sprockets and power to spare but no more rev's. What do you do? Instantly the answer comes to you, fit a set of high ratio primary gears

Ivan has now had a second batch made so if you want some get your order in before they are all gone.

The price remains the same for now at $700 per set + postage and packaging for overseas buyers.

If you think that's expensive then consider this, Halco lists these in his 2001 catalogue for £285, on todays exchange rate that's AU$679 so you are effectively buying these at six year old prices. Name something else you can buy today for the same price it was six years ago!

Here's what they look like
Top:- This pic compares the stock on left and high ratio gears on the right

The conversion does require some modifications to the clutch basket and back plate.

Some clearance needs to be gained with the side cover as well (see below pics) but this is only minor work.

I also contacted Heiden Tuning and got a reply:

Hello,



Perhaps you can change to a 18 tooth front sprocket. This gives about 6% lower revs.

There is also an option to change your engine’s internal ratio. We sell gear sets that replace the original primary gear on the crankshaft + secondary gear behind the clutch.



Stock:

27t primary

69t secondary

2.556 ratio



[glow=red,2,300]Our gears:

32t primary

69t secondary

2.156 ratio

So our set gives 18,6% lower revs. We sell these sets as gears only (so you have to mount the clutch house to the sec. gear yourself) or as a bolt-on set, complete with CNC milled clutch house.[/glow]

Does anyone have any experience with either of these? Not sure if it will help and which to go with for my project.

[pamcopete]

terribletabo1,

That would reduce your 60 MPH RPM's to 4531 with a 18 tooth front and a 49 tooth rear with a 18" wheel. Much more livable.

You could then install Mikes 5th gear and reduce the RPM's further to 4342 at 60 MPH. You're getting there!

By comparison, a 17/34 sprocket ratio with a 16" wheel is 4280 RPM. That's stock on an '80 to '83 Special.

Here is a modified Xcel Spreadsheet that includes a 49 tooth rear sprocket and Heidens primary gear ratio to allow you to see the RPM vs MPH for all combinations of primary gear ratios, gears and sprockets.

www.amckayltd.com/xs650revs2.xls

Just click on the numbers in the cells for front sprocket, rear sprocket, rolling distance and primary ratio to reveal pull downs to select whatever numbers you want.

[terribletabo1]

Thanks for all the time & help pamcopete!
Yeah, this looks much better now. Which one do you think is better? The IVAN HOEY version or Heiden Tuning version?

[pamcopete]

terribletabo1,

Well, the Ivan Hoey says that there are a limited number available, and that was written in 2007 (apparently), so if that is correct, it's the Heiden.

This is starting to get expensive, that's why I initially suggested an intermediate shaft. Plus, you will have to split the case to install Mikes 5th gear, which I think you should do if you are going to go this route.

[terribletabo1]

Yeah, I bought the Mikes 5th gear awhile ago & the motor is in pieces now. :-)

I actually sent my Mikes HP camshaft & HP rods to Heiden Tuning for a 270 rephase.
I'm curious if the large sprotor + high ratio gear set + Mikes 5th gear will change the character of the engine? Are there any advantages or disadvantages of having this setup or does the changes balance each other out?

[pamcopete]

terribletabo1,

Well, in your case, everything will balance out because you are trying to overcome the high revs problem of your 49 tooth rear sprocket. Mikes 5th will mean you will still have high revs in the lower gears, but highway riding will be more pleasant.

For others, the high ratio gear set results in a too high a low gear ratio and the benefits are only apparent in 5th gear at highway speeds. Mikes 5th gear is the opposite. It allows you to retain a good gear ratio from 1st to 4th with that added bonus of a lower revving engine at higher speeds in 5th.

[terribletabo1]

I'm wondering if the extra teeth would cause more heat in the engine? I did order the MikesXS High Performance Oil Pump with Double the oil volume pumped by the stock unit. I'm hoping the high ratio gear sets won't cause the engine to overheat.

[pamcopete]

terribletabo1,

Well, I don't see a connection between the extra teeth and overheating.

[terribletabo1]

I was discussing my project with a mechanical engineer friend of mine & he suggested a be careful messing around with the stock sizes because it might cause overheating in the engine. I probably explained it to him wrong.

[pamcopete]

terribletabo1,

Well, your friend was probably thinking that if you reduced the RPM's below what they would normally be for a given MPH, the engine would be 'lugging" as if it was in too high a gear, but in your case, all you are trying to do is to get the RPM's into a normal range to overcome the 49 tooth rear sprocket, so you will be running the engine at or slightly above the normal range of RPM's for the given MPH.

[650skull]

terribletabo1,

i have spoken to Ivan Hoey about his racing primaries and an XS650 club member here in Aus that has a set in his road bike. The gearing for a road bike with Ivans primaries is 17/36 and with these primaries the revs drop again as the gearbox turns faster so does the back wheel. another benefit is the clutch seems to work better as well. With such a large rear sprocket , even if you installed the racing primaries you would not loose any of your torque on start off, in fact you would still be better off than a standard 17/34
With your gearing and Ivans primaries and mikes 5th gear you would be getting close to original gearing but i don't know if you are going to reduce the vibration
Last i heard Ivan had sold out but i am sure he would have some more in his mind and if he got enough inquiries he would consider getting some more made. [e-mail] It would be worth you while getting in contact as he would be more than willing to discuss this with you.
[

[terribletabo1]

Oct 19, 2009 7:28:50 GMT -5 650skull said:

terribletabo1,

i have spoken to Ivan Hoey about his racing primaries and an XS650 club member here in Aus that has a set in his road bike. The gearing for a road bike with Ivans primaries is 17/36 and with these primaries the revs drop again as the gearbox turns faster so does the back wheel. another benefit is the clutch seems to work better as well. With such a large rear sprocket , even if you installed the racing primaries you would not loose any of your torque on start off, in fact you would still be better off than a standard 17/34
With your gearing and Ivans primaries and mikes 5th gear you would be getting close to original gearing but i don't know if you are going to reduce the vibration
Last i heard Ivan had sold out but i am sure he would have some more in his mind and if he got enough inquiries he would consider getting some more made. [e-mail] It would be worth you while getting in contact as he would be more than willing to discuss this with you.
[

Hi,
Yes, he just responded to my request for info:

High ratio gear set will change the final gearing about 20%
I think 49 tooth rear is too many teeth.
I run 17 > 36. But my disc is not part of the sprocket.
Ivan

It seems similiar to the Heiden Tuning version (18,6% lower revs) & they sell these sets as gears only (so you have to mount the clutch house to the sec. gear yourself) or as a bolt-on set, complete with CNC milled clutch house.

[terribletabo1]

New Billet Clutch Basket from Heiden Tuning for the High Ratio Gears:


Cobbler solo seat: