did we ever come to a conclusion about the alloy swingarm for the pre'78 RM125's

[DR]

sorry to dig this shit up but are they legal so long as the rear wheel is a 125B rear wheel and the brake stay mounts to the swingarm?

[motomaniac]

well they were available both aftermarket and as an optional part from suzuki.

[JohnnyO]

Yes i believe they would be legal because they were available through Suzuki in '77.

[caps 999]

to be honest your only saving at the most 1.5 kgs on the arm is it really gunna make that much of a differnce

[oldfart]

Chris , I thought the " B "  model had a small tab on swing arm for brake stay 

[DR]

they do indeed Stew as the torque arm on the B didn't have the floating brakes. Caps I only ask this because my bike is built from pieces and I do prefer the look of the alloy swingarm but want to stay within the rules. There is no performance enhancment in mind and even if it were heavier i'd still be asking the question For arguments sake I'll tell you what my bike consists of and any illegalities I'd like to have pointed out.

Frame - RM125A (no lug or provision for floating rear brakes)
Top Triple - PE250B
Lower clamp RM125C
Forks - RM125C less top extensions (same forks as the B )
Swingarm - RM125C (brake stay mounts to swingarm)
Rear Wheel - RM125B
Front Wheel - RM125C
Engine Assy - RM125C
Tank alloy job  125B

this is the rear end setup I speak of..

[monaro308]

These pics always make me think that these are pre-production RM125C bikes.......

[JohnnyO]

I always wondered why the bikes in the C model brochures had the lug on the swingarm. Maybe they are pre production fitted with the optional B alloy swingarm.

[crs-and-rms]

i have one of the alloy swingarm that has the brake stay on it  im going to put it on my 125b

[LWC82PE]

 

Forks - RM125C less top extensions (same forks as the B )

Double check your part numbers of 77-78 sliders, springs and chrome legs. I know when  there was the nationals protest (i cant remmber if it was a 125 or 250) people said it was only the tall caps that were the difference on the 77-78 forks but when i checked the part numbers of the 77 and 78 sliders, springs and chrome legs there were differernt part numbers. it wasnt simply a matter of swaping the tall caps for the short ones and all was ok. There wer parts that were clearly 77 or 78 only even if the travel was the same, so in theory shouldnt be used. If they were same part number then yes ok to use.

[JohnnyO]

The diameter of the B forks at the top triple clamp is 35mm and the C forks are 36mm at the top clamp. I think you'll find that's the difference.( it is on the 250 anyway)

[LWC82PE]

Ok i thought i would check now anyway

RM 125 B chrome fork legs are different part number the 125 C fork legs
RM 125 B outer fork sliders are different part number to the 125 C sliders
RM 125 B fork springs are different part number to the 125 C springs
RM 125 B damper rods are different part number to the 125 C damper rods.

Now this is based from www.alpha-sports.com if you have 125 B and 125 C paper parts books or microfiche that says the above parts are the same part numbers then, you have proof in hand to show the scrutineer and you will be fine . If not and you decide to use the 78 parts and want to race pre 78 be prepared that you could be protested against. The part numbers are different according to the website so in my opinion you would have no argument as the part numbers are different and its in black and white.

[farmer58za]

Chris , I thought the " B "  model had a small tab on swing arm for brake stay 

In 1978, my RM 370 had the aftermarket Suzuki alloy arm with the tab for the brake stay. When I built a replica last year, I took a later model arm and had a tab welded onto it.

http://s215.photobucket.com/albums/cc198/farmer58za/?action=view&current=RM370.jpg

http://s215.photobucket.com/albums/cc198/farmer58za/?action=view&current=IMG_2802.jpg

Regards
David

[DR]

Not the same on the 125C Johnny, 36mm all the way and identical in appearance to both the RM250C and the RM400C. I have the 125 suspension on my 400 and I had 400 forks on my 125 as I only weigh in at 50ish kgs and rarely rode the 125..matter of fact I've 'never' ridden it in the 5 years I've owned it   

Leith it is not me, but the scruteneer will need to have proof in hand to prove they are not '77 items
Part numbers mean nothing when the parts appear physically identical and offer up no adantages. How is anyone going to dispute them unless they rip them apart to discover the minute change that required the new number

Incidently Farmer58 my 400C has the mount on the swingarm but this is on a new replacement swingarm I purchased over 20 years ago. Mounting the brake stay to the shock mount on the 125 shouldn't cause any woes I'd imagine and it means I don't have to get anything welded

[LWC82PE]

Part numbers mean nothing when the parts appear physically identical and offer up no adantages. How is anyone going to dispute them unless they rip them apart to discover the minute change that required the new number 

The point is there is a enough of a change of to warrant a new part number. Weather the change is cosmeric, physical or performance enchancing is irrellavant. If the parts were identical and had the same part numbers then they would be classed as follow on parts and be allowed. The choice is yours to make if you want to take the risk at not and think no one will know or sport it. If it really mattered to me i wouldnt take the risk after what happend this year, but i do think you could probably get away with it if your realy wanted to but it wouldnt be in the spirit of the rules.