Pro-Link Low Bars - P/N & Availability

[John S. (5594)]

Hi Folks,

I have been fortunate enough to locate a "new" late model forkset - it will soon find a home on my '79 project bike (which already sports '82 Comstars and dual-piston calipers).

The new challange for me here is locating a pair of "Euro" style bars for these forks. I believe that the Honda OEM P/N's are 53120-MA2-610 and 53160-MA2-610 for the right and left bars respectively. If these part numbers are correct - finding NOS components could prove difficult. A quick check shows that David Silver has a few 53120 right bars but no 56150 lefts - and if the prices listed by CMS in the Netherlands are any indication (~350 Euro EACH) - I may have a rough road ahead. Hopefully I just have the P/N's wrong.

As an alternative - I have read about using VFR bars for this application - but also understand that they are not as low as the late model CBX "Euro" bars.

So - could someone tell me if I have the correct P/N's for the late model CBX low bars? And - more importantly - where the heck can I find a pair of these gems?? I won't even ask again about the sports kit throttle/switchgear - another ongoing search (and posting on the ICOA "Parts Wanted" page).

Thanks again in advance for the help - and all the best from sunny San Jose, California

John

[EMS]

John S:

I have a used set of Euro bars for the Prolink, if you are interested. I need to dig it out. Send me a message. I give you my e-mail address.
You may need the following in additon: Shorter throttle cables, shorter clutch cable and a sport kit right side switch which will reroute the throttle cables up and forward, so they do not hit the tank.
As far as putting the Prolink fork into your 79: The Prolink models have a different steering head angle for an increased wheel base. In order to prevent the trail from getting to large and steering becoming too "slow", they also changed the offset in the triple tree. If you put this on a 79 frame, you will end up with significantly altered steering geometry. We tried this out on a project bike and most of us who rode it, did not like it. Straight line stability went to hell and slow speed tight turns became a little jerky. Just so you know what you are getting into. Very much depends on your personal taste and feel.

[John S. (5594)]

Hi EMS,

I would like to pursue obtaining the set of late model "Euro" style bars you have - please check your messages.

And thanks for the heads-up on the steering geometry considerations for my planned fork-set swap. I am aware of the increased rake on the Pro-Link bikes (from 27.25 degrees on the 79/80 to 29.5 degrees on the 81/82) - and also that the trail was kept constant through the model years (120 mm / 2.72 inches).

Without measuring the difference in triple clamp offset - I do believe that I should be able to "tune" the revised front suspension to suit my preferences. The stiffer fork legs should be a big benefit - and I could always machine another triple clamp set from billet if need be (just kidding!).

All the best,

John

[EMS]

John S.: Got your message, will reply through e-mail

The difference in trail is a reduction of about 10mm when you put a Prolink fork into a 79 frame. Doesn't seem to be that much when you look at the numbers and it may not bother you at all. :) When we did the project, we opted against it, because the Ups did not outweigh the Downs. Braking improvement was questionable, so the only real advantage was less flex - a fork brace could do a similar job. Downs were, as I said, less straight line stability at higher speeds - especially annoying on a 79 which is a little squirky to begin with - and extremely quick, sometimes treacherous steering at low speed turns complicated by added unsprung weight on the front end.
As long as you are prepared for that, you should be fine.

[EMS]

Seems like I have to revise myself The result of my quick, office desk trigonometry calculation about the change in trail of 10mm, somehow did not make sense to me. It was just too small of an amount to produce such a difference in handling and feel as we experienced. I went home last night, took some dimensions on both my 79 and the 81 and on a seperate 79 fork assembly. I used the following data: Axle c/l above ground:320mm, trail 120mm, rake 27.5 degrees, offset in triple clamps 35mm, length of fork from lower tt bracket to c/l axle 565mm, distance between tt brackets 185mm. Upper bracket width 25mm, lower bracket width 42mm. I plugged all this into our chassis program, and came up with the following: Rake change to 29.5 degrees and unchanged triple tree would move the front wheel 35mm further forward and result in a trail of 149mm. In order to maintain
120mm, the adjustment in the offset of the lower bracket would be made, changing the fork angle to 34 degrees.
Putting this fork into the original 27.5 degree steering neck, will result in a trail of 45mm. Too low for comfort.
That's more like it. That's why we didn't consider the bike rideable. Now, I would really like to hear from somebody who did the change and likes it.
Maybe I ams till looking at something the wrong way.

[Guest]

I enjoyed reading about putting the late model front end on a early model :) and it makes me wonder how putting a CB1100F front end compares . If anybody has that info, please post.

Thanks, Tom

[EMS]

If you give me the following measurements, I can give you the theory:
CB1100F standard rake. Triple tree bracket offset (both upper and lower if different) distance from edge of lower bracket to front axle c/l. Height of front axle c/l over ground when bike is straight up.
:)

[cbxchris]

I have a 1100F front end on mine now. I used the USA model. I used VFR clip ons. I also used a 1100F swingarm and rear shocks. Mine may be a little low in the front but I do like it. When riding a stocker now it feels so mushy and high sitting in the front. I guess its what you get used to. I`m not saying its the best but just what I tried and ended up with. I also run the 1100F wheels with the rear widened to accept a 170 rear and run radials.

[John S. (5594)]

In light of the work done by EMS - I am reconsidering a simple "bolt-on" of the late model front end. A reduction in trail below 100 mm would be something I could not easily "tune" for stability.

I have read posts and emails from a number of 79/80 owners who have performed this swap and most all are very pleased with the results. But until I receive the late model front end - and take a series of measurements to calculate the geometry impact - I cannot be certain that such a modification would be beneficial and (if EMS is correct on the revised trail figure) suitably stable.

After I get some hard numbers and calculations - I will be sure to post my conclusions. Heck - I may even have a "new" Pro-Link front end for sale - we shall see.

All the best,

John
San Jose, California

[EMS]

Taking a careful approach is the prudent thing to do! CBXChris makes a good point: Whatever you are used to and what you prefer. - Of course there are limits to that. Its called PHYSICS.
CBXChris also changed the rear end which may have a lot to do with the fact that his mods work. Many times, peole who fiddle with stock bikes forget that changes to the rear have an impact on steering behaviour Raising the rear, shortens the trail, making steering quicker. Lowering the rear does the opposite. That's why all these Harley guys on their Arlen Ness sleds need to go around the block to make a 180 degree turn.
Putting a fatter tire on, makes the bike steer harder -whether you like it or not: really fast bikes do not have really fat tires. On tracks with a lot of tight turns, we change the rears on my Ducatis from 6" wheel and 190 rubber to 5-1/2" wheels with 180 rubber. Makes a ton of difference as far as the bikes' "willingness" to start leaning is concerned.