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Sports valves on a Marzocchi fork
http://ducatittandf1.com/viewtopic.php?f=24&t=11337		 Page 2 of 2
Author:  marcotoys [ Sun Jul 10, 2016 1:01 pm ]
Post subject:  Re: Sports valves on a Marzocchi fork
Sauro Collini speaks English very well. He has stayed at my home in Quebec City between June 29 and July 4th. We went together to Calabogie race track (DOCC event) where Sauro rode my 900SS. He also tried my F1 and found my Marzocchi 38mm fork to work very well with the Sports Valves.

Sauro have installed an Elektronic Sachse ignition system on his own F1. There was a short video on his Super Pantah Blogspot (now removed unfortunately, but we could ask him to put it back) showing clearly that his engine revs up very fast with the outer part of the flywheel removed and the Sachse ignition installed.

Gilles
Author:  nick gill [ Fri Jul 15, 2016 6:51 pm ]
Post subject:  Re: Sports valves on a Marzocchi fork
Eldert wrote:
modify the sliders and stancions to accept Kayaba sliding bushings . i found a guy that can hone the sliders to 39 mm for the bushings .
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machine the top of the sliders for the top bushing .
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Eldert


Hi Eldert.
Some technical questions about this modification you will have encountered....
Legs/sliders are honed to 39.00mm or sized for the final kayaba bush diameter ? A modern digital Sunnen Honing machine would gaurentee perfect diameter all the way down I'm sure.
I thought honing aluminium would leave abrasive particulates in the surface that even ultrasonic cleaning wouldn't remove? Glyn, you'd know?
How is the bottom bushing sized for the final bore?

The top bushing is an interference fit in the leg. This too needs to be honed for the stanchion? Stanchions need to be supplied to the machinist for final sizing?

Some part number I quickly found:
Honda XR250/CR125R '81-84 teflon inner: i.d. 37.01mm o.d. 38.75mm height 19.70mm, Racetech #FMBI 38201 P Click here for catalogue list
Honda XR250/CR125R '81-84 teflon outer: i.d. 38.00mm o.d. 42.00mm height 11.91mm, Racetech #FMBO 38122 P
The Kawasaki part numbers are: i.d. 38 x 50 x 10 440651091 bushing, and 920281126 bushing

Many thanks in advance. This seems like a most beneficial modification and will renew worn legs/sliders.
Author:  sports [ Sat Jul 16, 2016 1:20 am ]
Post subject:  Re: Sports valves on a Marzocchi fork
Regarding the honing. If the correct grade of abrasive hone is used, together with copious amounts of cutting oil to help flush out the material removed, It should be OK. Then finish the operation to size with a fine grade hone and polish furiously afterwards.

When I machine the mag fork legs I use a specially made and sized gun drill into the solid mag casting. I don't have the castings cored as this can encourage the gun drill to wander. One pass and the hole amazingly has a beautiful finish ready for a light polish.
Author:  nick gill [ Sat Jul 16, 2016 6:57 am ]
Post subject:  Re: Sports valves on a Marzocchi fork
Great info Glyn. Hate to think what that custom ground gun drill cost. Cheers.
Author:  Eldert [ Thu Jul 21, 2016 3:05 am ]
Post subject:  Re: Sports valves on a Marzocchi fork
for bushings i use Kawasaki parts . easy to get and pretty cheap . part nrs 92028-1126 and 44065-1091 .

for sizing i give the guy that does the honing a Kayaba slider and tell him to make the same size .

another guy does the machining for the upper bushing . lower part of the slider in the 4 chuck and the upper part in a steady rest . make sure the upper part of the slider is 100% round .
sizing is taken again from the Kayaba slider .

the honing machine is a Delapena vertical one . he made tooling for the slider to mount them quick and easy to the bed . as the machine goes up and down by itself he only has to give the mandrel a few turns once in a while .
the oil drain screw is removed from the slider so the honing oil can get out .
the Delapena filters the honing oil so not to many abrasives are floating around .

i had this machining done here in the Netherlands for a couple Scandinavian Bevel racer and charged them 120 euro for a pair of sliders .

Eldert
Author:  nick gill [ Thu Jul 21, 2016 10:08 pm ]
Post subject:  Re: Sports valves on a Marzocchi fork
Eldert wrote:
i had this machining done here in the Netherlands for a couple Scandinavian Bevel racer and charged them 120 euro for a pair of sliders .
Eldert

What is the name of this company please Eldert?
Also those part numbers are for KYB 41mm forks.
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