Shock Lengths 86 & 87 VFR

OK, this has been bugging me for a while. I've seen reported numbers all over the place. So I decided to take good examples of each year shock to work and properly measure.

I'll have to say I was a bit surprised. I have also stated incorrect numbers based on a couple mounting bolts thru the eyelets and a metric tape measure.

Well, here we go. This is my set up.



The shock is vertical. Both eyelets are 10mm (confirmed), so I can find the bottom of each with my indicator.



1986:



I think we can probably just say "270mm" in general when talking about an 86. I have 3 other 86 shocks I could measure to see if there is any fluctuation. There might be, but I don't think we need to.

1987:



I also think we can just say "280mm" when referring to an 87.

Well, there ya have it. Like I said, I just wanted to personally know for sure, and I thought I would share. I apologize if any of my statements regarding stock shock length in the past have confused or led anybody astray.

Cheers.

 

The science behind the madness!!

 

I own none of these bikes...but what's the ratio from shock length to bike height? 8mm is nothing to sneeze at. And...are the fronts the same as far as geometry (rake trail)?

 

Thru the linkage, you can realize a pretty decent ride height gain. It is very apparent after making the switch.

Fastdruid might be able to rattle off the exact ratios.

The frames are the same 86 to 87, and with each year's original shock/linkage, the front geometry should be very close.

I don't have a good before / after, but this is my 86 after a 17" wheel swap and a 87 shock. Forks are slid up a bit too.

 

I think I have measurements for the two linkages somewhere, I'll try and dig them out... I've got both if i can't find them, an '86 linkage sat on my desk (to go in my '88), and a spare '89 one "somewhere".

 

All the frames are the same dimensionally and can be interchanged but they're not the same.

Early frames are made from more smaller cast pieces welded together. Later frames are made from fewer larger cast pieces welded together. I'm not sure *when* they changed though. Either 87 or 88.

In theory this makes later frames both lighter and stronger but I doubt there is enough in it for anyone to notice!

 

88. 86 and 87 frames are the same.

 

It's about 3:1 for the early, 4:1 for the later bikes. They're rising rate though so it isn't an exact figure.

86 has an 81mm arm (as measured just now), I have 85mm in my notes for the 87+ but not measured it myself (and I had 80mm noted for the 86).

 

a few adds on aftermarket shock lengths for the 1986-89 RC24

WP has listed a shock for these,and the shocks are height adjstable +- 5mm.
the leght for the 86-87 is 269 to 279mm
for the 88-89 278 to 288mm
YSS offers same shock for a 4 years the RC24 made, its 275mm long. YSS has a 56-180-150 spring, that is 56mm inner diameter, 150mm long and spring rate 180 N/mm that is ~18,35 kg/mm
Wilbers Shocks offers correct lengt for year, 270mm for 86, 280mm for 87-89
Bitubo offer 2 shocks, but one for 86-87, that is for 86 only actually, its 270mm long, 45mm storke and a 16kg/mm spring
the offering for 88-89 is 279,5mm long, same 45mm stroke and a 19,4kg/mm spring
the piston position is also different witch means different damping.

 

Well search for orginal shock numbers give you 3 different shock's used on the RC24/26
ML7-003 as ML7-013 for the 1986 750 as 700.
ML7-691 for 1987 750 as 700
ML7-921 for the 1988 as 1989 750

 

Came across this '87 shock that seems pretty damn nice for a decent price if somebody is looking for some cheap ride height on a '86.

https://www.ebay.com/itm/3651537167...igE=|tkp:Bk9SR6KUs_zXZA&LH_ItemCondition=3000