Topic: 1974 CB550. Racetech Monoshock. JMR Head. Built Engine. "BLAC"

[BLAC]

Almost a roller

[riverfever]

Man that seat looks nice.

[redwillis1978]

I would make your lower supports a little longer so the seat had about a 15-degree rake.

Nice garage assistant though.

[BLAC]

I would make your lower supports a little longer so the seat had about a 15-degree rake.

Nice garage assistant though.

The reason I made them how I did was so the line from the bottom of the gas tank would be inline with the seat/subframe bar, I think it might look a little funky if I had it tilt up.  not sure though...

[SOHC4 Cafe Racer Fan]

I would make your lower supports a little longer so the seat had about a 15-degree rake.

Nice garage assistant though.

The reason I made them how I did was so the line from the bottom of the gas tank would be inline with the seat/subframe bar, I think it might look a little funky if I had it tilt up.  not sure though...

I agree.  The only reason you would want to adjust the subframe supports is for rear wheel clearance.  As an alternative, you can keep the line of the tank and seat uniform and use 750-length shocks.

[budman]

Looking good.

[BLAC]

Man that seat looks nice.

Thanks man!  I'm really happy with it!

[BLAC]

I think im going to need 14.5in shocks... fully bottomed out shouldnt be shorter than 10.25 (or else ish will get real..)

What I have done to get these numbers is measure center of eye to eye a little above where I would like the ride height to be and then when down to where the rear wheel starts to get intimate with the seat loop.  That range gives me a spring of 14.25" - 10.25"

Does that sound like im thinking about it correctly?
 

I agree.  The only reason you would want to adjust the subframe supports is for rear wheel clearance.  As an alternative, you can keep the line of the tank and seat uniform and use 750-length shocks.

[SOHC4 Cafe Racer Fan]

That sounds like adequate clearance.  I guess you'll know by road testing.  Keep on keeping on.

[BLAC]

That sounds like adequate clearance.  I guess you'll know by road testing.  Keep on keeping on.

I just dont want to test by buying more sets of rear springs that end up not working lol

Anyone interested in stock length, brand new, Hagon springs? =(

[SOHC4 Cafe Racer Fan]

That sounds like adequate clearance.  I guess you'll know by road testing.  Keep on keeping on.

I just dont want to test by buying more sets of rear springs that end up not working lol

Anyone interested in stock length, brand new, Hagon springs? =(

I'm sure you can sell them quickly in the Classified's section.

[redwillis1978]

Your assumptions includes a zero weight rider or infinitely stiff springs?

You could achieve the same look by adjusting the tank mounts once the geometry was correct.

If your total shock travel is about 4", that's 2 up/down. At ride height your ass end is going to be dragging.

[redwillis1978]

[GV1390]

Looking good homie! Glad you're taking a stab at trying things out on your own, it'll be rewarding in the end.

[Tews19]

Subscribed. I once attempted a frame.mod like yours. Let's just say I have a stock fram now.

[BLAC]

Subscribed. I once attempted a frame.mod like yours. Let's just say I have a stock fram now.

Haha thanks, I hope it turns out.  I'm debating on a monoshock conversion... I love the lines of the subframe and would love to run a monoshock setup that slows the rear to stay open and uncluttered. I just need to do a lot of research on the proper geometry for that...

[Camrector]

Mike le at Kinetic makes a weld on kit for a monoshock cb550 conversion. Might be worth checking out. His exhaust fab skills are sick!  . I sent you a PM with pics showing my same cowl and how it sits with longer (363mm) Fox Podium R shocks. Did that help any?

[BLAC]

Yes and thank you for the pics!  I was looking at the Kinetic kit, and think I can make it for a lot less than $700.  I have a mandrel bender, welder and access to some clevis joints.

I have been looking at theirs and the couple that Cliff has done.  In theory I could bang it out, but I dont know enough about suspension geometry to fee completely comfortable yet

[BLAC]

here is a quick and dirty photochop of my bike with a monoshock..

I think im going to go for it 

[Retro Rocket]

here is a quick and dirty photochop of my bike with a monoshock..

I think im going to go for it 

Yes, retaining the stock swingarm {length} and retaining the correct wheelbase/geometry is a smart move, there are lots of examples of how NOT to do it on the forum with bolted in monoshock swingarms from other more modern bikes, usually stretching the rear out 4/6 inches or more. Member Godfrey has a good example of what you plan, looks damn good too...

Check out Godffrey's bike...

[BLAC]

Thanks for the encouragement and info!

I have seen pretty much every cb550 with a monoshock on the Internet at this point 

My main question is regarding the angle of the shock, should that be in-line with the mounting point of the swing arm brace to the swing arm so it makes basically a straight line or can it angle downward at all from the top mount to the swing arm mount (if that makes any sense).... I will draw up what I mean in the AM

[calj737]

Most of the (good) bikes that I've seen have an angle very similar to the frame tube at the rear of the main section. That allows for the most travel and damping. But, when you buy a shock, a good company will ask you the design criteria of: angle, weight, distance, bike, etc. to provide a unit that functions properly. Don't do this much work on your own then buy an off the shelf unit because its the correct length. It may well not be designed for an application like yours at all.

[BLAC]

Most of the (good) bikes that I've seen have an angle very similar to the frame tube at the rear of the main section. That allows for the most travel and damping. But, when you buy a shock, a good company will ask you the design criteria of: angle, weight, distance, bike, etc. to provide a unit that functions properly. Don't do this much work on your own then buy an off the shelf unit because its the correct length. It may well not be designed for an application like yours at all.

Totally agree.  I am most likely going to have RaceTech custom make a shock for this bike. 

[SOHC4 Cafe Racer Fan]

Most of the (good) bikes that I've seen have an angle very similar to the frame tube at the rear of the main section. That allows for the most travel and damping. But, when you buy a shock, a good company will ask you the design criteria of: angle, weight, distance, bike, etc. to provide a unit that functions properly. Don't do this much work on your own then buy an off the shelf unit because its the correct length. It may well not be designed for an application like yours at all.

Totally agree.  I am most likely going to have RaceTech custom make a shock for this bike.

Matt Wiley or one of his colleagues at RaceTech should be able to hook you up.  They are very competent suspension guys.

[calj737]

I have to commend you. Despite the multitude of folks who chase an aesthetic and don't give much through-thought, you on the other hand have mocked, photoshopped, analyzed, and now are prepared to have professionals perform the critical calculations. Its really great to see someone update these bikes "properly" and get what the want out of it. I doubt this will fall into the "Started, never finished" bin due to lack of commitment.

You will invest far more than the market for this bike will return. BUT, you will have a truly custom bike, that you built, that can be bought, no one else has, and it will still be a blast to own/operate and cheap to repair in 20 years. If I had a hat on, I'd remove it for you-