Paso 750 Rear Tire solution (160/60/16)

[paso750]

the P750 sprocket

[Desmo_Demon]

Silly me.....I just remembered that all the newer Ducs do not use the old retainer system but instead use a flatter sprocket and use a huge nut on the shaft to hold it in place.....now, if I can just get my hands on a 520 to check it out.

[paso750]

as Terry and I are discussing this topic offline here a short summary of our current thoughts:

a sprocket like this would be nice, but according to Antti this could be from an early 750 Sport or similar and is quite rare. In fact I didnt find it listed ie at AFAM or JT sprockets. (if someone has some info about this let us know!)


I personally don`t like the before mentioned option 1 as I don`t trust the center bolt only.
Option 2 has by far too much offset and overhang of the drive shaft. Material could be removed from the sprockets back and the inner sprocket/adapter flanks but this would be approx. 4mm max. (still 7,5+mm offset). Downside this would need to be done with every new sprocket.

As Terry has a 748 sprocket the idea was then to reverse it. Depending on if the inner sprocket/adapter was recessed or flat the gained offset would be around 4,5-6mm which should be fine in most cases. (To compensate the overhang one could have a small prolongation of the drive shaft fabricated)



A recessed sprocket/adapter would be an original Paso sprocket with the teeth removed, a flat one an original Paso sprocket with the sidewalls removed or an 748 sprocket w/o teeth.
The advantage of this solution would be that one would need only one or two parts made by a machine shop once. Then when replacing the sprocket one would only have to have the threads drilled through of the new sprocket.

Currently Terry is leaning towards option 4, I towards option 3 as my setup is different.

Seeing that newer bikes like the 749 have a flat round retainer clip this will be the next thing we`ll check. Thinking that a bigger surface area between the 2 sprockets is better the next step would be to check if this retainer clip is flat and has the identical width as the one of the Paso. If so it would only require 2 holes drilled through it. But it looks like the outer part of this clip is sheet metal and too soft to use it instead of the original one.



Any thoughts on this matter are highly appreciated.

G.

PS: if I would have thought about this when rebuilding the engine I`d had tried to swap the drive shaft with a longer one from another Duc, it might have made things easier.

[Desmo_Demon]

As Gerhard stated, we've been burning up the server with Private Messages while discussing this instead of throwing our half thoughts and partial ideas into the forum that may confuse people....and probably by quite a bit.

I think we are to the point of us having to do one of these conversions and try it out. Gerhard may have his system completed within the next week and it may take me a week or two to get all of mine done by a friend who find time between projects at work. Our two systems will be very similar with the main difference being the recession being left on the OEM Paso sprocket or having it removed. I believe we both will come up with a slight shaft extension to be bolted onto the end of the shaft with a single bolt.....more of a "peace of mind" thing than anything else.

A recessed sprocket/adapter would be an original Paso sprocket with the teeth removed, a flat one an original Paso sprocket with the sidewalls removed or an 748 sprocket w/o teeth.

Looking at the 748 sprocket, it is not as easy as just cutting the teeth off. The sprocket and mounting boss is nearly twice as wide as the OEM Paso. Putting the 748 sprocket onto the shaft has it sticking out far enough that it is almost flush with the end of the shaft. Looking through my old sprockets, using a 748/916/996, ST2, ST4, or M900ie sprocket as the one that goes closest to the engine case would require machining its thickness down by at least 4 mm and probably closer to 5.0mm.

[Brutus]

as Terry and I are discussing this topic offline here a short summary of our current thoughts:

a sprocket like this would be nice, but according to Antti this could be from an early 750 Sport or similar and is quite rare. In fact I didnt find it listed ie at AFAM or JT sprockets. (if someone has some info about this let us know!)

Got one of those lying around. Last week I changed to bridgestones 16" and now fitting the oscams with the new tyres. The santamonica sprocket (as shown above) fits perfectly. I measured by holding a laser thingy at the rear sprocket. Pointing it to the front and I got the offset in mm's I needed. Only problem is the chain is just to short. Think I'll look for a 36 or 37 teeth rear sprocket.
cheers Léon

[21783mike]

As Gerhard stated, we've been burning up the server with Private Messages while discussing this instead of throwing our half thoughts and partial ideas into the forum that may confuse people....and probably by quite a bit.

I think we are to the point of us having to do one of these conversions and try it out. Gerhard may have his system completed within the next week and it may take me a week or two to get all of mine done by a friend who find time between projects at work. Our two systems will be very similar with the main difference being the recession being left on the OEM Paso sprocket or having it removed. I believe we both will come up with a slight shaft extension to be bolted onto the end of the shaft with a single bolt.....more of a "peace of mind" thing than anything else. .

Hope you got a chance to get a close look at my set up without any of this BS..... Very inexpensive tires, no sprocket spacers, sticky enough to drag hard parts. 1,000 miles now with no regrets, very happy with these tires, only unknown is how they will do in the wet and I hope not to find out on the way home...LOL

[paso750]

I love this kind of reply. Now show us where in Germany, Italy etc you can get those south korean/japanese Shinko tires and that sizes ??? In the US it may not be a problem finding some.

G.

[21783mike]

I love this kind of reply. Now show us where in Germany, Italy etc you can get those south korean/japanese Shinko tires and that sizes ??? In the US it may not be a problem finding some.

G.

I'm glad you enjoyed it. Where in Germany, Italy ect you find them is really not much of a concern to me.... If the govt in those countries treat there citizens as though they are children and they allow it... well I feel sorry for them but it is not my job personally to rectify their situation. My response was to someone that the solution I have used would be of help.... I am sorry to have offended you by not solving the issue for the entire world.

[Desmo_Demon]

Hope you got a chance to get a close look at my set up without any of this BS

Yeah, I looked at it well enough to see that it is a no frills, simple solution, but......you may be limited to only one tire brand (not like that may be any issue, especially since the Shinko tire costs are quite nice compared to the others ).

I would have gone your route after you stated what you did, but I have two D205 tires with a few miles left on them that I want to use these tires since they were free (and I'm a cheap bastard), plus I don't like the idea of having to trim down a new tire every few thousand miles. If I don't like the sprocket shimming arrangment, I will go to what you have done, but until then, I'll keep playing around with this sprocket shimming idea. None of this is costing me a thing, but if I go to an arrangement like yours, I'll need to pick up another front sprocket. It's only time and potentially a $30-$40 cost if I have to go back to the OEM sprocket arrangement....It'll be a little while until I get back to it, though. Looks like my stator or regulator on the ST2 fried on my way home from the rally, yesterday.

Edit - I almost forgot.....it was a pleasure getting to meet you at the rally. Sorry we didn't get much time to talk. As you go to more of the rallies, you find out you have LOTS of people to catch up with!

[GT-UK]

I don't know if it's of any help, but the AFAM Japan website (www.afam.co.jp/E/index2.htm) says they can make offset front sprockets: "We welcome any inquiries or orders on "made-to-order" for unlisted items and models. The delivery date is about 2months, The price is from Yen18,000. Please consult your nearest AFAM Dealer or us for quotation and technical information".

GT-UK

[randtcastell]

"
Hope you got a chance to get a close look at my set up without any of this BS..... Very inexpensive tires, no sprocket spacers, sticky enough to drag hard parts. 1,000 miles now with no regrets, very happy with these tires, only unknown is how they will do in the wet and I hope not to find out on the way home...LOL"

Mike, sorry to be dense, but could you remind me which shinkos you've fitted. i asume they are 130/70 and 180/60. is hat correct. and what's the link to a photo. thanks very much. best, randy.

[paso750]

@GT-UK 18.000Y are 125GBP. There`s one company here in Germany which makes offset sprockets which cost €90. That`s quite a bit less but still expensive considering that it`s something that`ll need replacement sooner or later. Guess it depends on how much or how little one rides to make this investment worthwile.

@randtcastell 006 Podium front and 747 rear. Pics are on the first page of this thread.

G.

[GT-UK]

I agree, the cost of a 1 off sprocket is expensive. But if a group of, say, 20 or 30 got together, maybe the price would come down significantly.

GT-UK

[ducinthebay]

Another way is to make a welded up sprocket. Take two sprockets, machine the teeth off of one, and machine the core out of the other and weld them together. If you have a good machinist, put a little lip on the two parts so that they nest and don't get welded out of round.

Cheers,

[21783mike]

"
Hope you got a chance to get a close look at my set up without any of this BS..... Very inexpensive tires, no sprocket spacers, sticky enough to drag hard parts. 1,000 miles now with no regrets, very happy with these tires, only unknown is how they will do in the wet and I hope not to find out on the way home...LOL"

Mike, sorry to be dense, but could you remind me which shinkos you've fitted. i asume they are 130/70 and 180/60. is hat correct. and what's the link to a photo. thanks very much. best, randy.

http://www.shinkotireusa.com/product/product.php?id=72
http://www.shinkotireusa.com/product/product.php?id=5