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Hi All,

When I decided putting a 750 Commando engine in place of the 600 cc 99 in my Slimline chassis, I considered different solutions to cope with the vibrations issue.

The sexiest one was to build a Featherlastic but after a few mails with Bob Cox and Mike Harcourt, I gave up because there was no way for me to build or buy the Iso cradle and plates etc...

Finally, I opted for Jim Schmidt's longer rods and lighter pistons (plus a few other parts: camshaft and tappets) without changing the standard balance factor and I'm very pleased with the result. Almost no vibes or very slight ones up to 5000 rpm, a bit more between 5000 and 6000 but quite acceptable (clear image in the mirror & comfortable riding).
You don't feel the vibes in the footrests neither in the handlebar or seat. They are transmitted by the fuel tank only so it's not really annoying.
No crack nor loose nut or other sign of damaging vibrations after about 10 000 miles of use.
Carburation and timing settings are very stable.

And there are other testimonies here or in other forums to illustrate how good Jim's products are.

Hope it helps.

Laurent

<blockquote data-quote="laurentdom" data-source="post: 295883" data-attributes="member: 4663">Hi All,When I decided putting a 750 Commando engine in place of the 600 cc 99 in my Slimline chassis, I considered different solutions to cope with the vibrations issue.The sexiest one was to build a Featherlastic but after a few mails with Bob Cox and Mike Harcourt, I gave up because there was no way for me to build or buy the Iso cradle and plates etc...Finally, I opted for Jim Schmidt&#039;s longer rods and lighter pistons (plus a few other parts: camshaft and tappets) without changing the standard balance factor and I&#039;m very pleased with the result. Almost no vibes or very slight ones up to 5000 rpm, a bit more between 5000 and 6000 but quite acceptable (clear image in the mirror &amp; comfortable riding).You don&#039;t feel the vibes in the footrests neither in the handlebar or seat. They are transmitted by the fuel tank only so it&#039;s not really annoying. No crack nor loose nut or other sign of damaging vibrations after about 10 000 miles of use.Carburation and timing settings are very stable.And there are other testimonies here or in other forums to illustrate how good Jim&#039;s products are.Hope it helps.Laurent</blockquote>

[QUOTE="laurentdom, post: 295883, member: 4663"] Hi All, When I decided putting a 750 Commando engine in place of the 600 cc 99 in my Slimline chassis, I considered different solutions to cope with the vibrations issue. The sexiest one was to build a Featherlastic but after a few mails with Bob Cox and Mike Harcourt, I gave up because there was no way for me to build or buy the Iso cradle and plates etc... Finally, I opted for Jim Schmidt's longer rods and lighter pistons (plus a few other parts: camshaft and tappets) without changing the standard balance factor and I'm very pleased with the result. Almost no vibes or very slight ones up to 5000 rpm, a bit more between 5000 and 6000 but quite acceptable (clear image in the mirror & comfortable riding). You don't feel the vibes in the footrests neither in the handlebar or seat. They are transmitted by the fuel tank only so it's not really annoying. No crack nor loose nut or other sign of damaging vibrations after about 10 000 miles of use. Carburation and timing settings are very stable. And there are other testimonies here or in other forums to illustrate how good Jim's products are. Hope it helps. Laurent [/QUOTE]

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