Cafe Racer Forum banner

swingarm swap.

11K views 48 replies 7 participants last post by  buckandaquarter 
#1 ·
Howdy, I'm new to the forum so if this was already addressed, please steer me in the right direction. I've just bought a 77 cb5750 SS from Lossa Engineering in Long Beach, CA. I saw the same bike on craigslist but the owner had put on a Nighthawk rear swingarm which added 2" to the length and changed the angle of the shocks. Looks pretty cool. How much work is involved with this kind of mod? Drastic handling changes? Thanks
 
#11 ·
ok the CL ad probably didn't use a nighthawk swingarm since most of the Nighthawk swingarms are shaft drive. From the pics it looks like he used a 1979-1982 cb750 DOHC swingarm which is pretty much a bolt on mod except for a small mod you have to do. Most DOHC swingarms have a lopsided pivot and you need to cut the pivot to be even on both sides so it is the right length to bolt into a cb750 frame. A DOHC arm adds 2 inches to the K frame (the bike you like on CL) but only 1 inch to the SS because the 77 SS swingarm is already 1 inch longer than the K arm.

This post has pics on the different swingarms and where to cut (you have to sign in to view the pics):
http://forums.sohc4.net/index.php?topic=34880.0

as to what it would do to your bike is kill the handling. I would at least try go to to 14" shock if you want to extend the arm like that. I know you think it looks cool and all but really it is a shit move.

Now about your Lossa eng bike. Somewhat clean but lossa doesn't know shit about cb750s so I would venture to say he actually made yours handle worse than a stocker. How you ask? well on a cb750 the front fender is a fork brace, and when you delete it you need to put something there to make up for the loss of rigidity. Otherwise your forks are going to deflect under cornering, worse than that heavy road groves will push your front end around and kill what dampning the forks will give you. you don't have to go to a front fender but you need some kind of brace. The cheapest way to make a brace is to cut the mounting bracket out of the stock fender. It is not as strong as the bracket with fender but it is better than what you have. I am not keen on the cheap ass pod filters but eh - you will learn soon enough all about those. basically what you have is a STYLE RACER - not a real cafe racer, you want a real cafe bike you have some work cut out for you. cafe racers don't just look the part they have to function and your bike as too many consessions to style for the sake of perf.

dare I ask, what is wrong with the stock SS tank that you want to shit can it. they are nice tanks and give extra fuel without the ugly look of the 77-78 K tanks.
 
#10 ·
ok the CL ad probably didn't use a nighthawk swingarm since most of the Nighthawk swingarms are shaft drive. From the pics it looks like he used a 1979-1982 cb750 DOHC swingarm which is pretty much a bolt on mod except for a small mod you have to do. Most DOHC swingarms have a lopsided pivot and you need to cut the pivot to be even on both sides so it is the right length to bolt into a cb750 frame. A DOHC arm adds 2 inches to the K frame (the bike you like on CL) but only 1 inch to the SS because the 77 SS swingarm is already 1 inch longer than the K arm.

This post has pics on the different swingarms and where to cut (you have to sign in to view the pics):
http://forums.sohc4.net/index.php?topic=34880.0

as to what it would do to your bike is kill the handling. I would at least try go to to 14" shock if you want to extend the arm like that. I know you think it looks cool and all but really it is a shit move.

Now about your Lossa eng bike. Somewhat clean but lossa doesn't know shit about cb750s so I would venture to say he actually made yours handle worse than a stocker. How you ask? well on a cb750 the front fender is a fork brace, and when you delete it you need to put something there to make up for the loss of rigidity. Otherwise your forks are going to deflect under cornering, worse than that heavy road groves will push your front end around and kill what dampning the forks will give you. you don't have to go to a front fender but you need some kind of brace. The cheapest way to make a brace is to cut the mounting bracket out of the stock fender. It is not as strong as the bracket with fender but it is better than what you have. I am not keen on the cheap ass pod filters but eh - you will learn soon enough all about those. basically what you have is a STYLE RACER - not a real cafe racer, you want a real cafe bike you have some work cut out for you. cafe racers don't just look the part they have to function and your bike as too many consessions to style for the sake of perf.

dare I ask, what is wrong with the stock SS tank that you want to shit can it. they are nice tanks and give extra fuel without the ugly look of the 77-78 K tanks.
 
#13 ·
as to whether you are an ignorant asshole or not...well you basically paid lossa's premium for a bike that is mostly paint and cosmetics and you want to change the stuff you paid a premium for.

and the bike you want to build yours like is basically a worse "posuer racer" than the one you currently own. It is not a good example of a cafe bike by any streach but rather a cafe styled bike built by chopper mentality.

and just to thorw this out there - not shiny bikes don't make anyone less of a douchebag - in fact paint or how clean it is has nothing to do with it. A cafe bike is a functional bike first and a cool looker second. Every mod you make should improve the performance as much or more as it improves the look.
 
#12 ·
as to whether you are an ignorant asshole or not...well you basically paid lossa's premium for a bike that is mostly paint and cosmetics and you want to change the stuff you paid a premium for.

and the bike you want to build yours like is basically a worse "posuer racer" than the one you currently own. It is not a good example of a cafe bike by any streach but rather a cafe styled bike built by chopper mentality.

and just to thorw this out there - not shiny bikes don't make anyone less of a douchebag - in fact paint or how clean it is has nothing to do with it. A cafe bike is a functional bike first and a cool looker second. Every mod you make should improve the performance as much or more as it improves the look.
 
#16 ·
it is not my intention to light the guy up like a roman candle for the sake of jollies - I am giving a harsh but fair opinin based on the general ethos of the board so he may see where he stands and how he may improve his bike to get the best riding expirence out of it.

A chopper is built as a "look at me" bike, a cafe bike is built around an enhanced riding expirence. The problem is when you approach cafe bikes from the chopper perspective you get a bike that is nice to look at but in the end really doesn't deliver on its looks and isn't as fun to ride. If you care more about who you impress in the parking lot than how impressed you are on the road then hey - maybe a chopper is a better bike for you.
 
#17 ·
it is not my intention to light the guy up like a roman candle for the sake of jollies - I am giving a harsh but fair opinin based on the general ethos of the board so he may see where he stands and how he may improve his bike to get the best riding expirence out of it.

A chopper is built as a "look at me" bike, a cafe bike is built around an enhanced riding expirence. The problem is when you approach cafe bikes from the chopper perspective you get a bike that is nice to look at but in the end really doesn't deliver on its looks and isn't as fun to ride. If you care more about who you impress in the parking lot than how impressed you are on the road then hey - maybe a chopper is a better bike for you.
 
#18 ·
I hear you on the intentions and totally agree.

One point tho (and I'm sure I'll get flamed to death for this one) in regards to choppers being only "look at me" bikes, I mostly agree with ya...although some choppers are really nice cruising bikes. A buddy of mine has a beautiful 1950-something Triumph that most people would call a "chopper" that is f-ing legit.

I guess this raises the age old question of chopper vs. cafe....but to me, this bike is excellent, regardless.



 
#19 ·
I hear you on the intentions and totally agree.

One point tho (and I'm sure I'll get flamed to death for this one) in regards to choppers being only "look at me" bikes, I mostly agree with ya...although some choppers are really nice cruising bikes. A buddy of mine has a beautiful 1950-something Triumph that most people would call a "chopper" that is f-ing legit.

I guess this raises the age old question of chopper vs. cafe....but to me, this bike is excellent, regardless.



 
#21 ·
Anyone who calls that bike a chopper is an oozing fucktard and should be punched in the mouth with a rotting carp....
 
#20 ·
Anyone who calls that bike a chopper is an oozing fucktard and should be punched in the mouth with a rotting carp....
 
#23 ·
Geeto, I dig what you're saying. I want a functional bike more that a styled one. I wish I had read through some of this forum before I bought it but I'm confident that it's a good platform to work from. Yeah, I suppose I have approached it from more of a chopper mentality seeing as that's what all my friends ride.

Here's my background: I'm a stunt performer in the movie business and I have wanted a bike for a while now. I need a performance machine but didn't want a modern sportbike. A bobber was out of the question because it's no good to me in terms of developing riding skills I can use in my work (also harder to justify as a tax write off). Enter the cafe racer. First place I looked was Carpy and Benji but I don't have those kinda funds. I saw Lossa's Bomber Nero bike and liked the look and he had the 77 available.

It was my idea to lose the front fender (again the chopper mentality) and have since learned about the weakness of the front end. We're looking at putting this brace on:
(scroll down)
http://dotheton.com/index.php?topic=4875.0

Do you just not like pods at all or just the ones that are on my bike? Velocity stacks? I can't say I'd be super eager to put the stock airbox back on just because it really does look better with that area cleared out a bit (I know, posuer) so what are the options. As for the swingarm, yeah, bad call.

Tank....well...I like knee pockets. I know they're purely cosmetic but shit, I like 'em.

Believe me, my views on these bikes are constantly evolving and I appreciate your constructive criticism....even if you do seem like a bit of a prick. Haha. Keep it unreal!
 
#22 ·
Geeto, I dig what you're saying. I want a functional bike more that a styled one. I wish I had read through some of this forum before I bought it but I'm confident that it's a good platform to work from. Yeah, I suppose I have approached it from more of a chopper mentality seeing as that's what all my friends ride.

Here's my background: I'm a stunt performer in the movie business and I have wanted a bike for a while now. I need a performance machine but didn't want a modern sportbike. A bobber was out of the question because it's no good to me in terms of developing riding skills I can use in my work (also harder to justify as a tax write off). Enter the cafe racer. First place I looked was Carpy and Benji but I don't have those kinda funds. I saw Lossa's Bomber Nero bike and liked the look and he had the 77 available.

It was my idea to lose the front fender (again the chopper mentality) and have since learned about the weakness of the front end. We're looking at putting this brace on:
(scroll down)
http://dotheton.com/index.php?topic=4875.0

Do you just not like pods at all or just the ones that are on my bike? Velocity stacks? I can't say I'd be super eager to put the stock airbox back on just because it really does look better with that area cleared out a bit (I know, posuer) so what are the options. As for the swingarm, yeah, bad call.

Tank....well...I like knee pockets. I know they're purely cosmetic but shit, I like 'em.

Believe me, my views on these bikes are constantly evolving and I appreciate your constructive criticism....even if you do seem like a bit of a prick. Haha. Keep it unreal!
 
#27 ·
I am a bit of a prick, but hey it is the Nu Yawker in me, you cali types could use a little tough love every now and again.

daytona used to make the fork braces for both the cb750 and the early GL1000 but I don't think they make either of those today.

The 1975-1976 GL1000 swap used to be the cheap way to get dual disc on a spoke wheel bike. The forks are 37mm as opposed to 35 for the cb but are taller. This was a real advantage to the 1969-1976 K bikes since they had crappy brakes and the forks were just ok. In 1977 honda revised the front end of the cb750F to have dual disc, a mag wheel (comstar), and better 35mm forks. The problem with your bike is Lossa swapped out your better brakes and forks for earlier crappier ones just so the bike could have a spoked wheel for looks. If you had the stock setup you could run a modern twin piston caliper dual disc setup found on the 1982 cb750F and 900F which is an awesome brake setup, but at this point you would have to swap the entire front end so the GL1000 is probably a better bet. One nice thing about the GL1000 front end is the rim is a DID alloy job instead of steel - but it needs to be since that front end is hella heavy.

I know I said the 1969-1976 forks were crappy, but remember honda won daytona on a modified ad blueprinted set back in 1970. Still not as good as the 77-78 forks.

There are a lot of positives to your bike being a 1977 and all. The 1977-78 F bikes had big valve heads and a true 72 hp which means they are actually the fastest production cb750 made. You don't need a big bore kit and can keep up with most cb750s that have them.

The best hp setup I have seen is always from a stock airbox with a K&N filter inside. I will explain later why but I have to go to work.

I
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top