Topic: The Hot Mess - 1975 CB550F1 Frame/1981 CB650 Engine

[Retro Rocket]

That's good to hear! How is that Thruxton treating you? They are some sweet bikes. I see a bunch of them down here.

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The Thruxton is very smooth. It handles MUCH better than the RC51, but obviously lacks the grunt of that beast. The trade made sense because the RC was becoming less comfortable to ride. Superbikes are for youngsters like you!!

Hi Don, I think if you rode the RC51 at the speeds it is capable off, you find out just how good the RC51 actually handle and at those speeds, the limitations of the Thruxton . Not saying the Thruxton is bad, quite the contrary, they are a really nice road bike as intended. Most Hipo, race style bikes are ordinary to ride on the street at "normal" speeds, the handling really doesn't come to the fore until you are riding them at 9-10/10ths at stupid speeds..   I'm sure thats what you meant...

[SOHC4 Cafe Racer Fan]

That's good to hear! How is that Thruxton treating you? They are some sweet bikes. I see a bunch of them down here.

Sent from my Nexus 5X using Tapatalk

The Thruxton is very smooth. It handles MUCH better than the RC51, but obviously lacks the grunt of that beast. The trade made sense because the RC was becoming less comfortable to ride. Superbikes are for youngsters like you!!

Hi Don, I think if you rode the RC51 at the speeds it is capable off, you find out just how good the RC51 actually handle and at those speeds, the limitations of the Thruxton . Not saying the Thruxton is bad, quite the contrary, they are a really nice road bike as intended. Most Hipo, race style bikes are ordinary to ride on the street at "normal" speeds, the handling really doesn't come to the fore until you are riding them at 9-10/10ths at stupid speeds..   I'm sure thats what you meant...

Mick,

That assessment is spot on.  The RC51 has the nickname "pig" for a reason.  It is an unwieldy tool at road speeds.  It shines at track speeds.  It is EXTREMELY stable at high speeds and its brakes are simply better than the Thruxton's. I hate to admit it, but it's a young man's game.  It requires a bit more "work" to toss it around.  But OH, the reward!!

The Thruxton R, in comparison, is mild mannered and comfy.  It has a fair amount of usable torque and is easy to turn.  It is woefully slow in comparison to the RC51. It's much more street-able than the RC51.

Something akin to a FZ-09/XSR900 (especially the new FZ-10) has a higher amount of performance than the Thruxton with the comfort and ride-ability of the Thruxton R.

[Retro Rocket]

That's good to hear! How is that Thruxton treating you? They are some sweet bikes. I see a bunch of them down here.

Sent from my Nexus 5X using Tapatalk

The Thruxton is very smooth. It handles MUCH better than the RC51, but obviously lacks the grunt of that beast. The trade made sense because the RC was becoming less comfortable to ride. Superbikes are for youngsters like you!!

Hi Don, I think if you rode the RC51 at the speeds it is capable off, you find out just how good the RC51 actually handle and at those speeds, the limitations of the Thruxton . Not saying the Thruxton is bad, quite the contrary, they are a really nice road bike as intended. Most Hipo, race style bikes are ordinary to ride on the street at "normal" speeds, the handling really doesn't come to the fore until you are riding them at 9-10/10ths at stupid speeds..   I'm sure thats what you meant...

Mick,

That assessment is spot on.  The RC51 has the nickname "pig" for a reason.  It is an unwieldy tool at road speeds.  It shines at track speeds.  It is EXTREMELY stable at high speeds and its brakes are simply better than the Thruxton's. I hate to admit it, but it's a young man's game.  It requires a bit more "work" to toss it around.  But OH, the reward!!

The Thruxton R, in comparison, is mild mannered and comfy.  It has a fair amount of usable torque and is easy to turn.  It is woefully slow in comparison to the RC51. It's much more street-able than the RC51.

Something akin to a FZ-09/XSR900 (especially the new FZ-10) has a higher amount of performance than the Thruxton with the comfort and ride-ability of the Thruxton R.

Yep, My brother had an RC51 and its the only bike he regrets selling, he has a really nice 2014 CBR1000RR that he loves but for the same reasons you bought the Thruxton he's just bought a GSX1400 Suzuki, a comfortable mile eater that handles rather neutral for a big bike...

[SOHC4 Cafe Racer Fan]

My next modern purchase will likely be a Yamaha FZ-09. Lightweight (414 lbs wet), punchy 115 hp and 67 ft/lbs.

[Retro Rocket]

My next modern purchase will likely be a Yamaha FZ-09. Lightweight (414 lbs wet), punchy 115 hp and 67 ft/lbs.

Fun bike, I love the sound of those triples...

[joeyvans]

My next modern purchase will likely be a Yamaha FZ-09. Lightweight (414 lbs wet), punchy 115 hp and 67 ft/lbs.

414? Wow!

I hear it's difficult to keep the front end on the road.


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[SOHC4 Cafe Racer Fan]

My next modern purchase will likely be a Yamaha FZ-09. Lightweight (414 lbs wet), punchy 115 hp and 67 ft/lbs.

414? Wow!

I hear it's difficult to keep the front end on the road.


Sent from my iPhone using Tapatalk

I've ridden a couple (with different suspension set ups).  It almost feels like a supermoto bike.

[Retro Rocket]

My next modern purchase will likely be a Yamaha FZ-09. Lightweight (414 lbs wet), punchy 115 hp and 67 ft/lbs.

414? Wow!

I hear it's difficult to keep the front end on the road.


Sent from my iPhone using Tapatalk

I've ridden a couple (with different suspension set ups).  It almost feels like a supermoto bike.

Yep, they are a wheelie machine...

[RAFster122s]

Don,  How's Jay doing these days?  Still doing well?  You guys wrapping up the last of the summer riding and bit of fall on the Thruxton Rs and the RC51...is there time coming the Hot Mess gets resumed?

Looking forward to seeing the pieces come together.  Jay has some mad fabrication skills as shown here...

David

[SOHC4 Cafe Racer Fan]

Don,  How's Jay doing these days?  Still doing well?  You guys wrapping up the last of the summer riding and bit of fall on the Thruxton Rs and the RC51...is there time coming the Hot Mess gets resumed?

Looking forward to seeing the pieces come together.  Jay has some mad fabrication skills as shown here...

David

Hi David,

Jay is doing great.  I hung out at his booth at the VVMC Rally (Venice Vintage Motorcycle Club) and we rode together on the Distinguished Gentleman's Ride.  He did a few more shows, tracked his supercharged Camaro SS and his Thruxton R.  I've been getting out as much as possible on my Thruxton, too.  The Summer is pretty endless here.  It was 90 over the weekend. 

I've been distracted modding the Thruxton R and upgrading the brakes on my CB550 stocker (to Beringer rotors, calipers, MC and clutch perch); Beringer is going to show the bike at IMS here in Long Beach. 

I'm hoping to switch back to the Hot Mess soon.  The rebuilt 674cc engine is ready.  Frame is detabbed.  It just needs some minor fabrication work (mods) on mock-up but Jay's been busy with other projects, and I have bikes to ride, so it's waiting still for the moment.  I am hoping we will have it mocked and ready this Winter.

[RAFster122s]

I saw that but didn't recall the thread...thought I would give this one a nudge...never can remember the thread titles.  Those Beringer units looked very very nice...  Totally cool upgrade and it will be great seeing your bike get some press...they wouldn't do that to just any beater out there...so, if they are taking it to IMS in Long Beach then you have something that is respectable...  Their prices are way up there and too expensive for my pockets.   But, it is nice they are showing some love to the SOHC/4 bikes.  A great brake setup can really enhance the experience.

David

[SOHC4 Cafe Racer Fan]

I saw that but didn't recall the thread...thought I would give this one a nudge...never can remember the thread titles.  Those Beringer units looked very very nice...  Totally cool upgrade and it will be great seeing your bike get some press...they wouldn't do that to just any beater out there...so, if they are taking it to IMS in Long Beach then you have something that is respectable...  Their prices are way up there and too expensive for my pockets.   But, it is nice they are showing some love to the SOHC/4 bikes.  A great brake setup can really enhance the experience.

David

It helps when Beringer is trying to promote its Classic line, and when you know the local US representatives, too!  I think my CB550 is respectable enough to look the part, since it is largely stock with a few mods.  I am contemplating putting a Hindle 4-2-1 to spiff it up a little and lose a little weight (current exhaust is ceramic coated mild steel).

[Restoration Fan]

What you gonna do with that ceramic coated one if you buy the Hindle, Don? 
I might be interested in it for my 550 build.  I finally got my side work finished up this weekend and I'm going to be working on the final items on the 500 over the next few weeks to finish it up.  Once I do that, I'm going to start working on the 550 (but I think I'm going to film it and put the build on YouTube when I do it). 

[TjTalan]

I am definitely learning a lot from this thread!


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[SOHC4 Cafe Racer Fan]

What you gonna do with that ceramic coated one if you buy the Hindle, Don? 
I might be interested in it for my 550 build.  I finally got my side work finished up this weekend and I'm going to be working on the final items on the 500 over the next few weeks to finish it up.  Once I do that, I'm going to start working on the 550 (but I think I'm going to film it and put the build on YouTube when I do it).

Ron,

If I go that way, I'll let you know.

[GV1390]

"I am contemplating putting a Hindle 4-2-1 to spiff it up a little and lose a little weight (current exhaust is ceramic coated mild steel)"

I approve of this message.

[DaveBarbier]

What ignition system are you running, stock? I looked through this thread and couldn't find any time when you talked about it.

Mine pretty much dissolved on disassembly. I'm looking into a Pamco route, sending Pete a PM.

[SOHC4 Cafe Racer Fan]

Hmm.  I already have a set of Dyna mini-coils and I have a pair of new Rick's CDI boxes.  I wish I could go with the 550 harness and perhaps a Pamco or other system.  Pete has not developed an 550 system to work with the 650 motor.

[DaveBarbier]

Ok, that makes sense. Yeah, there's no bolt on for the 650 and as far as I can tell, he doesn't intend on making one. But in talking with him it seems easy to adapt the 750 system to the 650. All is the same except the plate because the 650 uses a different size. Just takes some drilling and tapping and swapping over bits and you're good to go. This is the way I'll be going. Hopefully I won't screw it up.

[calj737]

Don I think you can use the C5 with the 650. It needs a different shaft than the 550/750 takes, but apparently they are compatible.

[GV1390]

Don I think you can use the C5 with the 650. It needs a different shaft than the 550/750 takes, but apparently they are compatible.

Yup, right from C5's website (as I sent you the other day):

"HONDA 4 CYLINDER
SOHC ENGINES
THIS KIT FITS THE FOLLOWING:
CB350, 400, 500, 550,
'79-81 CB650, and the CB750 SOHC engines.

JH-3504 FOUR CYLINDER

FITS ALL FOUR CYLINDER HONDA SOHC CB MODELS
** The CB650 1979-1982 kit includes special shaft needed for conversion.
​
$449-469

INCLUDES:
Ignition kit, MC-2 high voltage coils, and sparkplug leads.

This uses our newest CD-2 ignition and MC-2 coils that fit CB750 frames with no additional mounts."

[SOHC4 Cafe Racer Fan]

Don I think you can use the C5 with the 650. It needs a different shaft than the 550/750 takes, but apparently they are compatible.

Yup, right from C5's website (as I sent you the other day):

"HONDA 4 CYLINDER
SOHC ENGINES
THIS KIT FITS THE FOLLOWING:
CB350, 400, 500, 550,
'79-81 CB650, and the CB750 SOHC engines.

JH-3504 FOUR CYLINDER

FITS ALL FOUR CYLINDER HONDA SOHC CB MODELS
** The CB650 1979-1982 kit includes special shaft needed for conversion.
​
$449-469

INCLUDES:
Ignition kit, MC-2 high voltage coils, and sparkplug leads.

This uses our newest CD-2 ignition and MC-2 coils that fit CB750 frames with no additional mounts."

What advantage is there between the C5 system and Honda's CDI box electronic ignition, especially with new CDI boxes and coils??

[sethmcalister]

Glad you asked that question, I've been curious what the benefits are with the C5 ignition setup...

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[SOHC4 Cafe Racer Fan]

Here's the response from Paul at C5:

There are many advantages over the stock ignition. 

First, we eliminate the mechanical timing parts and old magnets which at this age are not accurate or reliable. 

There are no CDI boxes to fail and our ignition sparks 3 times per revolution to improve starting and increase efficiency. 

We provide coils of modern section bobbin design and 140,000 capacity.

There are 4 timing maps inside so you can now retard timing if riding double or in hilly terrain.

The ignition wiring is self contained but you can use a Motogadget to power the coils and ignition if you wish.

[Bankerdanny]

I will take time to go through the whole thread tonight, but right now I am thinking of this very swap. I have a roller '75 chassis all painted up with (I think) a good '77 550F motor installed. I had planned to build a cafe tourer using a Hondaline CBX/V65 style fairing. Then this summer I picked up a clean, ready to ride 550F, so now I have the flexibility to build whatever I want, and I think I want more power in the compact 550 frame without spending a couple grand on major engine work.

I can swap on the Lesters from my 550F and upgrade to dual discs, drop in the more powerful 650 engine then use one of my 2 spare 55 tanks (a '77 F and a '75 K) and install a cafe seat and some vintage hardbags. Voila, Cafe Tourer.

Once winter hits the midwest I will see if I can pickup a complete runner cheap and swap the engine and wiring. Time to set up a MC parts acquisition funds account and start setting some funds aside.