Topic: LOWERING STAND-OVER HEIGHT on my "new" 1979 CB650 Christmas present to myself

[EZduzit]

Have searched this forum first, of course, besides decades of m/c experience (82 year old Vietnam vet). Popular options include:

Swapping seat
Removing some seat foam
Rear suspension lowering blocks
Shorter shocks
Sliding forks up in triple-clamps
Swapping forks to a different year/length
Shortening the forks

Have owned many dirt and street motorcycles from Honda, Yamaha, Kawasaki, Suzuki, BMW, Harley. Decades ago I modified the forks and rear suspension to make my Honda CB750 better fit my 26-1/2" inseam. Sold my beloved Kawasaki W650 a couple years ago, following multiple strokes. Thought I was finished. Since then I bought and sold an SV650 project that I abandoned due to a worsening balance issue caused by a small tumor on my inner ear. But I have decided that I want to ride as long as I am able.

I plan to make these modifications mostly myself, and want this to have a finished, professional appearance--not looking for a cheap hack job. And I would like to retain or improve the bike's good handling characteristics, as much as possible. Secondary in importance, it would be desirable to be able to restore the bike's originality, without major expense, when resale time comes, even if purchasing some new or used parts is required.

These modifications need only be suitable for a solo rider--there will never be a passenger--only my 200 lbs (and dropping ). And I would prefer a solo seat anyway.

Would appreciate any helpful comments or links, especially from members who have had success in lowering their bike's stand-over height. But all comments welcome.

Merry Christmas you guys!

[jonda500]

how bout lacing on smaller diameter rims? (I think you've covered every other way!)
If it were me, I would pick modifying the seat.
John

[HondaMan]

I can offer these suggestions from my experience with these bikes:
1. Remember than lowering the axle height(s) with smaller wheels, or shorter upper-chassis heights via shorter shocks and/or forks, will significantly increase the "lifting weight" when putting the bike on its centerstand. If these approaches are taken, consider making corresponding wedge-like platforms for the 2 tires that you can roll the bike up on when needing to get it up on the stand, like for chain maintenance.
2. Lowered seat heights, via custom-modified or aftermarket seats, were the #1 way for riders to shorten the "leg length" needed to ride these, in the days. I even have (2) custom seats I use for my own 750, depending on what I need for a given service. For in-town, lots of stop-n-go traffic work I swap on the shortest seat, which only has about 1.5" foam above the pan. For more comfort on longer trips I use the 2-step seat that has 1" lower-than-stock foam on it, and is sculpted to meet my butt (and hers). While I personally dislike the old "bucket" seats that were common on 1970s touring bikes, they are pretty good off-the-shelf options for the shorter pants inseam. For me, I've found they limit the 'english' I have over the bike for [rapid] cornering in the mountains, and you might need to reduce their thigh-support sections a little bit if you are similarly inclined.

[Kelly E]

One way you forgot to get your feet closer to the ground is boots. I wear White's smoke jumper boots so I can just barely get both feet almost flat on the ground when riding my 94' Kawasaki Concours 1000.

[Don R]

 Be aware as you lower the seat your knees need to bend more to get your feet on the pegs. I have a thin solo dragbike seat that made me feel like a jockey. Great for racing not so much for stop and go traffic.
 I did the opposite of a prudent fix and put rearset pegs and controls on it. lol.

[Sixdog]

Merry Christmas my friend!   This is a pic of your Christmas present ... I will drop it off tomorrow. I did install a lower profile tire on it but these gentlemen here will help you out ... they know what they are doing.

[MauiK3]

I have a Yamiya lowered seat on my 73 CB750, works great, also cuts away a little more where your legs drop over the edge of the seat making it easier. I don't like to do much to the suspension and steering geometry, can be scary stuff.

[WhyNot2]

I've installed shorty shocks on the rear, Swapped the rear swingarm with a CB550, it has the round tubing, rather than the pressed metal appearance. and is longer.

Swapped the front forks with a CB550, shorter, and installed even with the triple tree. (If you want to go shorter, you can lift them in the triple).

Also you can respoke the rear wheel to a 16" harley rim, which has been done by many. I want to have one, but I don't want to respoke my original rear wheel.

I want to buy one when I see it come up for sale somewhere.

I want the seat to remain original, so I can lift it to store tools under it. So I have another seat pan that will get modified narrower but keep the hinges and lock.

Heres what it looks like so far:

[Kelly E]

Here's my 74' CB 550K0 seat that I modified but still uses the stock hinges and lock.

[EZduzit]

Thanks for all the responses fellas. Very happy to have hooked up with Sixdog; he'll always find a welcome place by my campfire. Thrilled to have such a nice bike to work with. I have been truly blessed.

Before even taking delivery of the bike I ordered a (used) factory service manual off eBay. Decades ago I made this a habit with virtually every vehicle I've owned since. Call me old school--I want to see ink on paper in front of me when working on my machinery. Also ordered a lightweight dust cover, which I get for all my bikes. My shop can get very dusty.

Having now had a chance to scope out the seriousness of the stand-over height issue, it seems highly likely that all potential avenues will need to be pursued. Immediately looking for a seat pan which can be modified to produce the biggest gain, as the original seat is very nice and worth keeping that way for the next owner. I plan on completing this mod before committing to further lowering efforts.

The way the stock triple-clamps are designed, the fork tubes can be slid up only ~1/2" before they come into contact with the handlebars. So that's all that can be gained, simply, in front. On my 750-four I shortened and re-ported the forks; that route I'll hold off on for now.

The rear shocks measure roughly 13" eye-to-eye. Likely an easy 1"+ could be picked up here by swapping to lowering shocks, without much trouble. However the net result of fork and shock mods will no doubt require a side-stand modification, besides making the center-stand more difficult to use.

Haven't thrown out the idea of thick boot soles either.

Hope I don't get banned for attaching a photo of my previous Sportster (2006, the last with carburetor) which I converted to a solo bagger by highly modifying a vintage Tour-Pak (set way down over the fender) and fabricating special mounts.

[EZduzit]

Ordered a pair of low-mileage shocks off a '75 CB550F which are reportedly 5/8" shorter than the stock CB650 shocks, eye-to eye. These have an upper shroud which may cause fitment issues. I will attach a photo and description.

My reasons behind this choice are complicated, but include:

I felt OEM shocks would be better quality than the cheap imports now available.
I felt that shortening the shock length by only 5/8" would have less negative affect on handling and ride than the much shorter "bobber" shocks currently available.
Budget (a little over $100 delivered).
The provenance and apparent condition of these are appealing.

[EZduzit]

Scoped out the seat modification parameters this afternoon.

Photos show my use of tempered hardboard to make a rough template of the existing seat profile, referencing off the fuel fill cover and rear grab rail. This shows that there is a space of about 4-1/4" between the existing seat outer surface and the nearest hard parts of the bike (frame, inner fender, etc). Even if I allow a nominal 2" for foam padding, this means that I could potentially lower the seat profile by close to 2"! Surely I can rationalize this as an extremely worthwhile project.

My initial concept is to fabricate a custom solo seat pan using primarily epoxy and biaxial cloth (which I already have). Then mockup a hand-formed foam pad (so I can optimize the fit to myself) and hand that over to a local auto upholsterer I know who has previously done excellent work for me on leather seats. Perhaps I'll sleep on this idea for a couple days to be sure it's the right approach. All comments welcome.

If this forum is deemed inappropriate for showing this customizing, perhaps the mods will notify me or help relocate my thread.

[Don R]

 I've trimmed seat foam with both an electric knife and a loose hacksaw blade. A rotating sander with 80 grit smooths it too.

[HondaMan]

That's a nice CB650!

[MauiK3]

+1 nice bike!!