Rear shock travel

[brian kirby]

So I'm working on the bikes I am going to take to the Freestone race in two weeks to make sure eveything is good. Since there was some dispute as to the actual travel of my SoCal Berkshire with the modified lower mount, I decided to take off the spring and measure actual travel at the rear axle. Fully extended was exactly 16'' from the axle to a spot on the frame I marked for that purpose. Fully compressed but not compressing the bumper is 12 3/8''. That works out to 3.625'' of travel to the bumper. The bumper is .75'' and half of that works out exactly to 4'' of travel, exactly how Sandy at Works Performance calculated it.

Now, I suppose you could debate whether the bumper compression is more than half its height, but how much more travel can that be? Another 1/4''? Does anyone REALLY think a possible extra 1/4'' is making a damn bit of difference?? I think not. I suppose to be safe I will put a couple of extra spacers I have in there so I'm not cheating with that extra 1/4'' of travel.

Brian

[Bob Bean]

Brian,
1/4 inch ? Travel.. Naah who cares..
1/4 inch in brain surgery.. Bigger deal.. <G>

Bob

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany

1973 Jackpiner 175
1974 Penton 250 Harescrambler
1976 Husky 250CR
1985 Husky 400WRX
1985 Husky 400WR

[Lloyd Boland]

Brian,
If I remember correctly, at AHRMA tech I was told that bumpers are calculated at 50% compression.  I think your okay without additional spacers.

Lloyd

[OUCWBOY]

My question is how they would rate my 69 Kawasaki 238? It has 4 about a 1/2" of swing arm travel?? AND that is the factory specs. Would I have to put spacers in to be legal, even though the bike is original and made that way??

Donny Smith
Paragould, AR

[brian kirby]

Bob,

You and I know 1/4" is insignificant, the nut twisting the throttle is a lot more important than 1/4" of travel, but it matters to AHRMA.

Lloyd,
 
AHRMA rules say 1/2 the bumper height, but in that other thread is was mentioned that since my lower shock mounts are so far forward of stock (3 1/2" forward) that 3/4" should be used. Sandy set them up for 1/2 the bumper and at 1/2 bumper its dead on 4" of travel.

Donny,

Technically to be AHRMA legal, yes, you would have to install spacers.

Brian

[Bob Bean]

Brian,
1/4 inch ? Travel.. Naah who cares..
1/4 inch in brain surgery.. Bigger deal.. <G>

Bob

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany

1973 Jackpiner 175
1974 Penton 250 Harescrambler
1976 Husky 250CR
1985 Husky 400WRX
1985 Husky 400WR

[Lloyd Boland]

Brian,
If I remember correctly, at AHRMA tech I was told that bumpers are calculated at 50% compression.  I think your okay without additional spacers.

Lloyd

[OUCWBOY]

My question is how they would rate my 69 Kawasaki 238? It has 4 about a 1/2" of swing arm travel?? AND that is the factory specs. Would I have to put spacers in to be legal, even though the bike is original and made that way??

Donny Smith
Paragould, AR

[brian kirby]

Bob,

You and I know 1/4" is insignificant, the nut twisting the throttle is a lot more important than 1/4" of travel, but it matters to AHRMA.

Lloyd,
 
AHRMA rules say 1/2 the bumper height, but in that other thread is was mentioned that since my lower shock mounts are so far forward of stock (3 1/2" forward) that 3/4" should be used. Sandy set them up for 1/2 the bumper and at 1/2 bumper its dead on 4" of travel.

Donny,

Technically to be AHRMA legal, yes, you would have to install spacers.

Brian

[Dwight Rudder]

on modified swingarms, AHRMA measures 3/4 of bumper. Not 1/2. Its in the rule book.

[Dwight Rudder]

Brian, missed u guys this weekend.

[brian kirby]

Unfortunately a bunch of real life things have made it so I wont be able to go to any AHRMA races this year except for the Reunion Ride, Barber or if it happens to be on a holiday weekend. Basically, I am going to miss this entire year of racing.

Brian

[Mick Milakovic]

Hey Brian, I can relate.  Gas prices, septic system overhaul, totaled car and graduation.  I feel lucky to travel 2 hours for a local GP with no district or AMA fees.

Mick

[Dwight Rudder]

damn

quote:Originally posted by brian kirby

Unfortunately a bunch of real life things have made it so I wont be able to go to any AHRMA races this year except for the Reunion Ride, Barber or if it happens to be on a holiday weekend. Basically, I am going to miss this entire year of racing.

Brian