Topic: CB350F Swing arm options for WERA or AHRMA

[Mille44]

Although I have not really looked into what vintage racing series is available to me in northern California I would like to build my CB350F to where it can be raced if I decide to after the build is finished. Since I am having problems with the restoration of the original swing arm, I was thinking of completely replacing it with a custom made swing arm or the one offered on the 400Four store. What are your opinions? What will be legal in the various racing classes and what wont be?

My swing arm thread http://forums.sohc4.net/index.php?topic=68014.0"

Box swing arm from 400Four http://www.400fourstore.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=4&Product_Code=1954&Category_Code=C

My cafe build thread http://forums.sohc4.net/index.php?topic=66350.0

[J.Webster Designs]

your links are broken.....

[Mille44]

your links are broken.....

Oops. Fixed. Have to do it the old fashioned way then...

[bwaller]

Mille44, you'll need to check out what association you'll join and what class you'll race in before the swingarm answer is clear.

[Mille44]

Well, thats easier said than done. I tried to check with the AHRMA to check what class the bike would fit into and what mods were allowed and never heard back from them. If you have a contact person and number, I would love to get a hold of someone either via email or phone.

In looking at the AHRMA rulebook, the class I think I may fit into is 200 GP plus OR Formula 500? I have no idea... WERA, I'm not sure.

[Triffecpa]

Well, thats easier said than done. I tried to check with the AHRMA to check what class the bike would fit into and what mods were allowed and never heard back from them. If you have a contact person and number, I would love to get a hold of someone either via email or phone.

In looking at the AHRMA rulebook, the class I think I may fit into is 200 GP plus OR Formula 500? I have no idea... WERA, I'm not sure.

In AHRMA, the bike can run in Formula 250 if it has a disc brake up front or 350GP if it has a drum brake up front

If you run stock bodywork, you can race it in LW Vintage Superbike.

The rules in AHRMA are meant to be somewhat period specific.  Can't imagine that a swingarm swap is going to violate any rules though.  Typically they are more concerned about fork tube sizes, wheels widths and brake configurations.

Tracy

[turboguzzi]

The Italian vintage rulebook is VERY strict, but still allows the Bimota style swinger as it was sold already in the early 70's, therefore, its a period piece.

If it fits the 400-4, I guess it'll work on a 350 too.

http://www.motocicliveloci.it/italiano/catalogo/replicabimota.htm

Yeah, do your self a favour, go to the bottom of the page and drool a bit on the bimota kitted 400, it's got that swinger too

TG

[Mille44]

Man that thing is a peice of art! I have a couple of emails out to WERA and AHRMA people, I will post what I hear from them...

[turboguzzi]

just subscribe to wera vintage forum.

All racers, super friendly people and they'll steer you in the right direction.

http://forums.13x.com/forumdisplay.php?f=5

[fastbroshi]

That swingarm has gone up in price by about a third in the past year.   

[turboguzzi]

That swingarm has gone up in price by about a third in the past year.   

Blame the economy!   

[Mille44]

Man that thing is a peice of art! I have a couple of emails out to WERA and AHRMA people, I will post what I hear from them...

Looks like I'm going to be building one of those (with the help of a friend). Any idea why the orbital chain adjuster? To use a custom swing arm similar to the Bimota one and qualify for the vintage races, does it need to have that type of orbital adjuster or can I use one similar to modern sport bikes or dirt bikes with the bolt and block?

[kos]

Man that thing is a piece of art! I have a couple of emails out to WERA and AHRMA people, I will post what I hear from them...

I know for a FACT that you have to run an unbraced stock OEM swingarm on the CB/CR750 F750 bikes for their class. F750 and F Vintage.  However, Superbike classes are open to alloy and braced swingarms for all three classes. Heavyweight SB, Middleweight SB & Lightweight SB

You will need clarification from AHRMA rules committee for any other classes you are trying to enter.

I wrote the rules for those Superbike classes.

KOS

[turboguzzi]

Man that thing is a piece of art! I have a couple of emails out to WERA and AHRMA people, I will post what I hear from them...

I know for a FACT that you have to run an unbraced stock OEM swingarm on the CB/CR750 F750 bikes for their class. F750 and F Vintage.  However, Superbike classes are open to alloy and braced swingarms for all three classes. Heavyweight SB, Middleweight SB & Lightweight SB

You will need clarification from AHRMA rules committee for any other classes you are trying to enter.

I wrote the rules for those Superbike classes.

KOS

Kos, just out of curiosity, why did you allow 17" in SB bikes that where always on 18" ( or maybe a 16" front?)

A racing member of the forum already slashed me in the past for asking, but still...

TG

[kos]

Man that thing is a piece of art! I have a couple of emails out to WERA and AHRMA people, I will post what I hear from them...

I know for a FACT that you have to run an unbraced stock OEM swingarm on the CB/CR750 F750 bikes for their class. F750 and F Vintage.  However, Superbike classes are open to alloy and braced swingarms for all three classes. Heavyweight SB, Middleweight SB & Lightweight SB

You will need clarification from AHRMA rules committee for any other classes you are trying to enter.

I wrote the rules for those Superbike classes.

KOS

OKs, just out of curiosity, why did you allow 17" in SB bikes that where always on 18" ( or maybe a 16" front?)

A racing member of the forum already slashed me in the past for asking, but still...

TG


TG

Actually, AMA Superbikes wore 19" front rims at the start of American Superbike racing...as used on Team Honda's 1979 built 1025 DOHC fours. The reason we went to 17" is that there are no good tyres For 18, 19 or even 16" rims now available, These bikes can make up to 120 RWHP and they are heavy machines. They need more than high performance street type tyres. Note: we also allowed larger widths than AMA Superbikes of the period used... to accommodate the trye selections offered now days.

Another point is that we allowed many different modern style alloy wheels... as AMA Superbikes circa 1978-1982, all used magnesium rims and that is a material, in a old, poorly stored, used condition... you do not want on a 145-150 MPH AHRMA Vintage racer.

KOS

[Kevin]

Another swing arm option would be the aluminum swing arm from MC Again.
I have a brand new one that you can have at a 30% discount of a new one and you wont have to pay the postage from Japan.
$800.00
I also have the offset front sprocket available that you would need if your planning on putting anything larger than a 120 rear tire on the bike.

[kos]

MC Again...is that the name of supplier in Japan? Do they make arms for CB750's?

KOS

[Kevin]

Yes, MC Again of Japan is the manufacturer http://www.mc-again.com , they specialize in CB400F parts.
Unfortunately they do not have a swing arm available for the CB750.

[kos]

Boy...I wish they did make one for Cb750. They are sure "purdy"! (pretty)

KOS

[fastbroshi]

Too bad their prices are turdy, er uh, I mean purdy.  I guess you get what you pay for though.

[Kevin]

That's what happens when the dollar is worthless.......

[kos]

That's what happens when the dollar is worthless.......

"Worthless dollar"...thank goodness, great for my business as it is 90% overseas sales and I don't buy a thing from them!


Keep it that way.. it's been great for last 9 years!

KOS