Topic: advice on valving for damper rod/ Race Tech valve emulator needed

[78CB750CAFE]

If anyone here has any advice or feedback on where and how big to drill the damper rod, and whether to fill the rebound holes when installing valve emulators, PLEASE let me hear it, I will be doing the machine work in the next week.

Thanks in advance!

[HondaMan]

Are you referring to forks?

I've only done it as an iterative process. I don't think there's any fixed number for hole sizes. It's usually simpler, on the later model forks, to adjust the oil viscosity and type.

For instance, the most smoothness over small bumps comes from teflon-impregnated oils.
Next smoothest, but with less fade, is moly-laced oils.
Most consistent, but after warmup, is straight-weight oil or hydraulic oils (like ATF).
Multi-weight oils are handy on the street, but must be changed every year or so so prevent loss of high-viscosity property.
More damping occurs with heavier oils. These forks were designed around 10w oils when new.

[78CB750CAFE]

HM- I am doing a full fork rebuild with fresh Progressive Suspension springs, RaceTech cartridge valve emulators, and all new Honda seals etc. .  The valve emulators take over the damping duties once done by the drilled holes in the damper rod, I am looking for advice from others who have done this mod on hole sizes and set up.

[MRieck]

If anyone here has any advice or feedback on where and how big to drill the damper rod, and whether to fill the rebound holes when installing valve emulators, PLEASE let me hear it, I will be doing the machine work in the next week.

Thanks in advance!

Drill 3 sets of 2 holes (6 holes in total). Drill diameter is 5/16". I would weld 1 rebound hole

[bwaller]

Do I remember correctly you saying straight rate springs were a better choice with the emulators Mr. Rieck?

[MRieck]

Do I remember correctly you saying straight rate springs were a better choice with the emulators Mr. Rieck?

Yes Brent. I'm not sure if they are available??

[MCRider]

Do I remember correctly you saying straight rate springs were a better choice with the emulators Mr. Rieck?

Yes Brent. I'm not sure if they are available??

Great info on previous post MRieck. I would add to this that 78CB750Cafe should call racetech for their input. Its their stuff after all. I'm surprised that printed instructions from Racetech wasn't supplied with the Emulators.

I had them put in my HawkGT by a HawkGT raceshop, so i can't give install input other than to say what a difference!

As to the springs, racetech probably has them. They suggest straight wind. I'm not sure why but my guess is the emulators give the progressivity we originally tried to get with the springs.

Comments from a amateur, FWIW.

PS: Yes here is the 73-78 CB750 Product Page which includes straight weight springs.
http://www.racetech.com/evalving/english/Srchpr.asp?bikeid=163&manufacture=Honda&model=CB750&year=73%2D78&TABLEINFO=street&langname=english

78CB750Cafe, definitely give them a call. I think.

[78CB750CAFE]

MCrider -I have yet to get straight advice form RaceTech, my emulators came with damping info for a KX 60, and RaceTech has sent me info for every bike in the world besides the CB750.... That page you listed is a lifesaver!

Thank you Mrieck, I am using single rate springs, they were just made by Progressive.

[78CB750CAFE]

actually, that page had NO info for the drilling of the damper.

Barring any arguments I am going to go with Mriecks suggestions, the drilling isn't as critical, I guess it just matters that the damper rod resists flow less then the valve adapter, making the emulator do the work. I will fill the 1 rebound hole as well.

[MCRider]

MCrider -I have yet to get straight advice form RaceTech, my emulators came with damping info for a KX 60, and RaceTech has sent me info for every bike in the world besides the CB750.... That page you listed is a lifesaver!

Thank you Mrieck, I am using single rate springs, they were just made by Progressive.

That's sad to hear. Great products but poor service?  I didn't think the link had info other than they had the springs and a calculator for specific spring weight.

I'm a year away from my cafe project, but I'll call RaceTech Monday and see if I can get an answer.  My current project won't accept emulators, too early.

Yes Mike's info sounds correct. Personally I don't know.  Good luck.

[HondaMan]

Wow, these look like nice, trick parts! 

[MRieck]

Do I remember correctly you saying straight rate springs were a better choice with the emulators Mr. Rieck?

Yes Brent. I'm not sure if they are available??

Great info on previous post MRieck. I would add to this that 78CB750Cafe should call racetech for their input. Its their stuff after all. I'm surprised that printed instructions from Racetech wasn't supplied with the Emulators.

I had them put in my HawkGT by a HawkGT raceshop, so i can't give install input other than to say what a difference!

As to the springs, racetech probably has them. They suggest straight wind. I'm not sure why but my guess is the emulators give the progressivity we originally tried to get with the springs.

Comments from a amateur, FWIW.

PS: Yes here is the 73-78 CB750 Product Page which includes straight weight springs.
http://www.racetech.com/evalving/english/Srchpr.asp?bikeid=163&manufacture=Honda&model=CB750&year=73%2D78&TABLEINFO=street&langname=english

78CB750Cafe, definitely give them a call. I think.

That page is great MC....Thanks. I'd use 15W fork oil. I like the Belray HVI but it is expensive. The last time I bought premium fork oil I almost crapped myself ....the prices were way up.

[78CB750CAFE]

I'd use 15W fork oil. I like the Belray HVI but it is expensive. The last time I bought premium fork oil I almost crapped myself ....the prices were way up.

I have 2 qts of just that sitting in the garage to go in the forks.
 

[Steve_K]

I have put emulators in a SV650 and my 86 GXSR and the instructions were good.  I only drilled the 5/16 holes and for my bikes, the instructions said nothing about changing the rebound hole.  Check that the hole is not plugged with gunk.  I was quite pleased with the change.
Steve_K

[bert96]

 I bought mine on Mikexs and all the informations was with the emulators.

[78CB750CAFE]

the problem with the kit I got is that it is a universal 35mm package, and it came with instructions for valving a KX60's forks. ALL my calls and emails to RaceTech have  yielded me nothing useful, closest thing was instructions for Nighthawks.

 
Again, the drilling needn't be specific, as long as the holes flow more oil then the valve emulator. What I wanted and got from Mrieck was some advice from someone who had actually experimented with installing 1 of these sets. Filling the rebound holes is suggested in RaceTech's literature, and I wondered if anyone had done it. I will do 6 holes and fill 1 of the rebound holes as Mrieck suggested, run 15w Bel Ray HVI to maybe 5.5 inch below the top of the collapsed fork leg, and probably cut my spacer for a little more than 1 inch of preload.

I am still up in the air as far as whether or not to install the "air assist" caps I have (thanks Spikey!), I figure I can always run them with no pressure, and have the option to fine tune with air pressure later if I want.