Post by kopcicle on Feb 6, 2014 20:36:07 GMT -5
I need the 130 18" . Peter and I have been poking around our contacts attempting to find one or two of the Dunlop k180's for a few months now . So far the best price we found is 79 quid for the tire and $65 USD to ship .
Some years back I grafted a KZ 750B (twin) disc rear hub to a 2.15 x 18" drop center Boranni , shouldered rim (circa '78 H-D Sportster). with only minor alterations it fits like OEM .
When I did this we had a spec class over here for the 883 Sportster via the AMA for flat track . The Dunlop K180 130/80 -18 66P was not only in the H-D Screaming Eagle accessories catalog for $66 but could occasionally be had cheaper in store . When the spec class went away so did the tire never to be seen again in North America .
My Canadian Neighbors are in no better shape and the Mexican Republic never did have access to them . I'm left with the UK and Central Europe along with Japan , Thailand , Cambodia , Viet Nam . Even if I do find a reasonable date of manufacture the shipping is going to be awful in any case .
Simply put d**n me for a lack of forethought . I'll just hit on the high points . The swing arm is lightly widened by way of press and fixture near the pivot anticipating a wider tire . The Boranni was acquired for little money but laborious polishing . The lace and true was done with new , oversize , custom made , stainless steel spokes . The disc although a simple CB200C front rotor was turned down .200" on the OD to fit inside the stock caliper . The center boss on the drive hub was turned down near .200" to use a more common sprocket . The bearings were changed to adapt to the XS650 axle . I'm easily $600 in the assembly top to bottom plus my own labor . Smart fix is a slightly longer , wider swing arm and the bill for the powder coat as well as taking apart the 18" and lacing a 19" hoop to it . Easy fix is buy a tire .
Let's examine the replace the rim , swing arm option . Bin the $600 hard money I have in the wheel alone and buy a 19" 40 hole hoop and have it laced . About $1200 before selling the 18" rim and hub or fabricating the new swing arm . I just can't see taking apart a perfect rim and hub . I'd have to find another KZ hub and 2.15 alloy hoop .
Or find the tire ...
Okay , why the tire , this tire specifically . Not so much for your Speedway but more for American flat track the critical factor in a tire is as always limit of adhesion . In this case not so much the limit but how it is approached . Best I can explain is with this one tire tread and various compounds the limit is approached with no small amount conversation between the contact patch and the rider . This is critical when you are braking by sliding the bike near backwards from 120 mph into a corner then immediately back on the gas and into a balancing act between available traction , steering lock , horse power and grit to corner exit .
I'm placing this tire in a 75 HP , 75 Ft/Lb , Alcohol fueled , 38mm carb , lightweight that simply for my piece of mind needs a tire that departs predictably . I expect the tire to be other than on the rails often . Even as I feel the decades of youth disappear the caution of experience appears to replace it . I'll not resort to unknowns in such a critical and fundamental area .
So until I come to my senses I'll buy the tire . Sometime thereafter the light of reason will cause me to assemble a 19" rear . Just not any time soon.
~kop
Some years back I grafted a KZ 750B (twin) disc rear hub to a 2.15 x 18" drop center Boranni , shouldered rim (circa '78 H-D Sportster). with only minor alterations it fits like OEM .
When I did this we had a spec class over here for the 883 Sportster via the AMA for flat track . The Dunlop K180 130/80 -18 66P was not only in the H-D Screaming Eagle accessories catalog for $66 but could occasionally be had cheaper in store . When the spec class went away so did the tire never to be seen again in North America .
My Canadian Neighbors are in no better shape and the Mexican Republic never did have access to them . I'm left with the UK and Central Europe along with Japan , Thailand , Cambodia , Viet Nam . Even if I do find a reasonable date of manufacture the shipping is going to be awful in any case .
Simply put d**n me for a lack of forethought . I'll just hit on the high points . The swing arm is lightly widened by way of press and fixture near the pivot anticipating a wider tire . The Boranni was acquired for little money but laborious polishing . The lace and true was done with new , oversize , custom made , stainless steel spokes . The disc although a simple CB200C front rotor was turned down .200" on the OD to fit inside the stock caliper . The center boss on the drive hub was turned down near .200" to use a more common sprocket . The bearings were changed to adapt to the XS650 axle . I'm easily $600 in the assembly top to bottom plus my own labor . Smart fix is a slightly longer , wider swing arm and the bill for the powder coat as well as taking apart the 18" and lacing a 19" hoop to it . Easy fix is buy a tire .
Let's examine the replace the rim , swing arm option . Bin the $600 hard money I have in the wheel alone and buy a 19" 40 hole hoop and have it laced . About $1200 before selling the 18" rim and hub or fabricating the new swing arm . I just can't see taking apart a perfect rim and hub . I'd have to find another KZ hub and 2.15 alloy hoop .
Or find the tire ...
Okay , why the tire , this tire specifically . Not so much for your Speedway but more for American flat track the critical factor in a tire is as always limit of adhesion . In this case not so much the limit but how it is approached . Best I can explain is with this one tire tread and various compounds the limit is approached with no small amount conversation between the contact patch and the rider . This is critical when you are braking by sliding the bike near backwards from 120 mph into a corner then immediately back on the gas and into a balancing act between available traction , steering lock , horse power and grit to corner exit .
I'm placing this tire in a 75 HP , 75 Ft/Lb , Alcohol fueled , 38mm carb , lightweight that simply for my piece of mind needs a tire that departs predictably . I expect the tire to be other than on the rails often . Even as I feel the decades of youth disappear the caution of experience appears to replace it . I'll not resort to unknowns in such a critical and fundamental area .
So until I come to my senses I'll buy the tire . Sometime thereafter the light of reason will cause me to assemble a 19" rear . Just not any time soon.
~kop