Topic: Patina Hyena - 550/650 674cc Hybrid Cafe Build

[b5rider]

My mechanic stated the 603cc kit with the 650 cam in my 550 pulls as hard as the 650 in his shop.  I rode it and confirmed the throttle response was amazing.  I didn't get a chance to really open it up,  but it's a very noticeable difference

[SOHC4 Cafe Racer Fan]

My mechanic stated the 603cc kit with the 650 cam in my 550 pulls as hard as the 650 in his shop.  I rode it and confirmed the throttle response was amazing.  I didn't get a chance to really open it up,  but it's a very noticeable difference

603cc with a ported head or not versus a stock 650??

I'd say 550 big bore kit, cam and ported head versus big bore 650 (674) with ported head -- which pulls harder then?

[Tews19]

Hmm interesting. It's an upgrade but not sure if it's that strong. I rode Hellraiserxl 's 650 stock and it has more torque. But I could be wrong. He and I plan to ride.aide by side once he gets his redone.

[DaveBarbier]

My mechanic stated the 603cc kit with the 650 cam in my 550 pulls as hard as the 650 in his shop.  I rode it and confirmed the throttle response was amazing.  I didn't get a chance to really open it up,  but it's a very noticeable difference

603cc with a ported head or not versus a stock 650??

I'd say 550 big bore kit, cam and ported head versus big bore 650 (674) with ported head -- which pulls harder then?

674 with ported head is my plan. I'm going to be asking a sh1t load of questions during this rebuild. You've all been warned! One thing I'm curious about is using stacks or pods with the CV carbs. Trying to see if it would be better to use some non-CV carbs for this. I hear the early 750 carbs people usually use on these don't have the same spacing.

Buying the bike this week. Got the guy down to $300 so it's pretty much a steel in my opinion. We'll see what happens though, it's never in stone until I have the bike in my shop.


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1978 Honda CB550K

[b5rider]

If you're going through all the trouble,  I would definitely put a big bore 650 if I had the chance.  All I could do is get my bike to  stock(ish) 650 power.

[SOHC4 Cafe Racer Fan]

I have a decent ported head (not a Mike Rieck one) and cruzinimage piston kit for a 550 and a stock 650 motor begging for a 674 kit.  This is for my back-burner project.

[DaveBarbier]

Just because of my plan to do a motor swap I still want to try and diagnose these plugs. I finally pulled them after checking fuel level in bowls. You can see the level above. All are exactly the same.

Plugs are arranged 4:3:2:1


I know I should do plug chops, but I haven't gotten around to that. This is from a ride about 45 minutes, mostly highway at around 6500rpm varied throttle positions. Then surface roads to my house, casually putting up my driveway and shutting it off. What do you guys think? Are the inner too lean, like dangerously lean? I don't feel any weirdness while riding, pulls really nicely through all throttle positions and no pops on decel, albeit I don't have anything to compare it to really. I think it's obvious that #4 is rich, it still sparks well and the #4 header is as hot as the others. (Same cost in hospital bill if I grab a hold of it compared to the others) Now if you remember, probably not because there's a lot happening in this forum, but the carb mouth for #4 is bent. Could this be causing my richness? Slightly blocking my air jets?

EDIT: Looking at a plug color chart it seems like the inner two are pretty good, #1 a little rich? #4 pretty rich.


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1978 Honda CB550K

[Tews19]

Looks like both are bent... I have no clue if this will impede proper fuel. I think the 3rd plug looks good.

[DaveBarbier]

Looks like both are bent... I have no clue if this will impede proper fuel. I think the 3rd plug looks good.

Yeah they both are, but it doesn't seem like the left carb mouth is an issue. I don't really think the right one is THAT much of a problem, but it makes sense since this plug is more rich. I don't even know if blocking these air jets would cause a rich condition, though. Just speculating.


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1978 Honda CB550K

[Tews19]

Can you heat up and bend back?

[calj737]

Can you heat up and bend back?

Oh God! Be careful with that! And have a spare set of carbs standing by...

[SOHC4 Cafe Racer Fan]

My mechanic stated the 603cc kit with the 650 cam in my 550 pulls as hard as the 650 in his shop.  I rode it and confirmed the throttle response was amazing.  I didn't get a chance to really open it up,  but it's a very noticeable difference

603cc with a ported head or not versus a stock 650??

I'd say 550 big bore kit, cam and ported head versus big bore 650 (674) with ported head -- which pulls harder then?

674 with ported head is my plan. I'm going to be asking a sh1t load of questions during this rebuild. You've all been warned! One thing I'm curious about is using stacks or pods with the CV carbs. Trying to see if it would be better to use some non-CV carbs for this. I hear the early 750 carbs people usually use on these don't have the same spacing.

Buying the bike this week. Got the guy down to $300 so it's pretty much a steel in my opinion. We'll see what happens though, it's never in stone until I have the bike in my shop.


---
1978 Honda CB550K

$300 for the BIKE is a steal!! I assume you will continue riding the 550 as is (fixing the carbs, of course) while you rebuild, port, overbore the 650 motor.  I WILL BE WATCHING THIS WITH GREAT INTEREST!  I've heard (but have no data) that a ported 674 in the lightweight 550 frame will pull like a ported 750 with an 836 kit BUT be much more agile.  Maybe I will crack upon my spare 650 and trail your engine build!

[DaveBarbier]

Can you heat up and bend back?

Oh God! Be careful with that! And have a spare set of carbs standing by...

I had that idea too but I don't think I plan on attempting that. I think I'd rather live with the rich #4, haha. I do have a spare rack but there's so much pitting and cracks in all emulsion tube holders I wouldn't want to use them again. Maybe I could cut the mouth off and TIG another mouth on from my spare set. Don't think it's worth it, though. I don't even know if it's the issue!


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1978 Honda CB550K

[DaveBarbier]

My mechanic stated the 603cc kit with the 650 cam in my 550 pulls as hard as the 650 in his shop.  I rode it and confirmed the throttle response was amazing.  I didn't get a chance to really open it up,  but it's a very noticeable difference

603cc with a ported head or not versus a stock 650??

I'd say 550 big bore kit, cam and ported head versus big bore 650 (674) with ported head -- which pulls harder then?

674 with ported head is my plan. I'm going to be asking a sh1t load of questions during this rebuild. You've all been warned! One thing I'm curious about is using stacks or pods with the CV carbs. Trying to see if it would be better to use some non-CV carbs for this. I hear the early 750 carbs people usually use on these don't have the same spacing.

Buying the bike this week. Got the guy down to $300 so it's pretty much a steel in my opinion. We'll see what happens though, it's never in stone until I have the bike in my shop.


---
1978 Honda CB550K

$300 for the BIKE is a steal!! I assume you will continue riding the 550 as is (fixing the carbs, of course) while you rebuild, port, overbore the 650 motor.  I WILL BE WATCHING THIS WITH GREAT INTEREST!  I've heard (but have no data) that a ported 674 in the lightweight 550 frame will pull like a ported 750 with an 836 kit BUT be much more agile.  Maybe I will crack upon my spare 650 and trail your engine build!

Yeah that's my plan, ride as is while building the 650. Plus I weigh about 145lbs so it should scream, haha. I have a little "bike fund" and will be slowly completing this over the summer, fall and maybe put it in over the winter. Or maybe I'll just get too excited and get it done as quick as I can and just be broke for a while. I can't wait to hit up the dyno for some HP and torque numbers.


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1978 Honda CB550K

[calj737]

Maybe I could cut the mouth off and TIG another mouth on from my spare set. Don't think it's worth it, though. I don't even know if it's the issue!

Laser welding is about the only way I'd attempt it. Cast body, very hard to weld.

IF you did ever attempt, I'd completely tear it down, preheat the body with a torch, then use a mandrel to "reshape" the softened alloy little at a time. I'd avoid welding it due to extreme heat. It would be badly annealed afterwards from welding.

[SOHC4 Cafe Racer Fan]

Yeah that's my plan, ride as is while building the 650. Plus I weigh about 145lbs so it should scream, haha. I have a little "bike fund" and will be slowly completing this over the summer, fall and maybe put it in over the winter. Or maybe I'll just get too excited and get it done as quick as I can and just be broke for a while. I can't wait to hit up the dyno for some HP and torque numbers.
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1978 Honda CB550K

145 lbs!? Skinny little ba$tard! 

[DaveBarbier]

Maybe I could cut the mouth off and TIG another mouth on from my spare set. Don't think it's worth it, though. I don't even know if it's the issue!

Laser welding is about the only way I'd attempt it. Cast body, very hard to weld.

IF you did ever attempt, I'd completely tear it down, preheat the body with a torch, then use a mandrel to "reshape" the softened alloy little at a time. I'd avoid welding it due to extreme heat. It would be badly annealed afterwards from welding.

Yeah I see what you're saying. I don't know, I'd rather exhaust other possibilities before attempting this. If the fuel level is the same in this carb and all jets are identical, anything you can think of that would cause this?


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1978 Honda CB550K

[DaveBarbier]

Yeah that's my plan, ride as is while building the 650. Plus I weigh about 145lbs so it should scream, haha. I have a little "bike fund" and will be slowly completing this over the summer, fall and maybe put it in over the winter. Or maybe I'll just get too excited and get it done as quick as I can and just be broke for a while. I can't wait to hit up the dyno for some HP and torque numbers.
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1978 Honda CB550K

145 lbs!? Skinny little ba$tard! 

And I'm Swedish, what gives!? Only time in my life I'm glad the Viking blood isn't dominant.


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1978 Honda CB550K

[SOHC4 Cafe Racer Fan]

Be happy with that, Dani Pedrosa, especially on a lighter weight middle-weight 550-framed bike.  Every 7 or so lbs lost is the equivalent of a horsepower gained!! 

[DaveBarbier]

Be happy with that, Dani Pedrosa, especially on a lighter weight middle-weight 550-framed bike.  Every 7 or so lbs lost is the equivalent of a horsepower gained!! 

Haha, Pedrosa, I wish. I'll be done with my dual disc conversion in a week or so...that'll add some weight unfortunately...but add some stopping power. Just hope the 14mm MC will be enough.


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1978 Honda CB550K

[SOHC4 Cafe Racer Fan]

Be happy with that, Dani Pedrosa, especially on a lighter weight middle-weight 550-framed bike.  Every 7 or so lbs lost is the equivalent of a horsepower gained!! 

Haha, Pedrosa, I wish. I'll be done with my dual disc conversion in a week or so...that'll add some weight unfortunately...but add some stopping power. Just hope the 14mm MC will be enough.


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1978 Honda CB550K

You'll have to be the judge as to the adequacy of your MC.  You may end up going with a 16mm or larger. 

How's the dual disc set up coming along? Are you using stock bolts and countersinking/machining the rotor carriers or getting longer rotor bolts?  Did you already modify the carrier for the speedo drive? 

[calj737]

Yeah I see what you're saying. I don't know, I'd rather exhaust other possibilities before attempting this. If the fuel level is the same in this carb and all jets are identical, anything you can think of that would cause this

Are the screws equal too? Is the fouling truly fuel-related and not oil at all? Weak spark, bad cap, bad luck?

[DaveBarbier]

Be happy with that, Dani Pedrosa, especially on a lighter weight middle-weight 550-framed bike.  Every 7 or so lbs lost is the equivalent of a horsepower gained!! 

Haha, Pedrosa, I wish. I'll be done with my dual disc conversion in a week or so...that'll add some weight unfortunately...but add some stopping power. Just hope the 14mm MC will be enough.


---
1978 Honda CB550K

You'll have to be the judge as to the adequacy of your MC.  You may end up going with a 16mm or larger. 

How's the dual disc set up coming along? Are you using stock bolts and countersinking/machining the rotor carriers or getting longer rotor bolts?  Did you already modify the carrier for the speedo drive?

Right now I'm just gathering parts. I was planning on just getting longer bolts, I didn't know machining carriers was an option. I haven't yet modified the speedo drive. Plan on doing all that when I have all the parts since I'm still riding. Maybe stupid question, but I was planning on just getting some grade 10.9 bolts from McMaster Carr. Or is there some bolts off a SOHC4 I should be using instead?


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1978 Honda CB550K

[DaveBarbier]

Yeah I see what you're saying. I don't know, I'd rather exhaust other possibilities before attempting this. If the fuel level is the same in this carb and all jets are identical, anything you can think of that would cause this

Are the screws equal too? Is the fouling truly fuel-related and not oil at all? Weak spark, bad cap, bad luck?

IMS are all the same at 1 turn out. It is not oil, plug is very dry and there's never any smoke out the tail pipe. I hope it's not bad luck, that seems a little unfixable, ha. I could swap wires and test or just cut 1/4" off for better connection...but I remember doing that last year. I'll do a few spark related tests and report back.


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1978 Honda CB550K

[SOHC4 Cafe Racer Fan]

Be happy with that, Dani Pedrosa, especially on a lighter weight middle-weight 550-framed bike.  Every 7 or so lbs lost is the equivalent of a horsepower gained!! 

Haha, Pedrosa, I wish. I'll be done with my dual disc conversion in a week or so...that'll add some weight unfortunately...but add some stopping power. Just hope the 14mm MC will be enough.


---
1978 Honda CB550K

You'll have to be the judge as to the adequacy of your MC.  You may end up going with a 16mm or larger. 

How's the dual disc set up coming along? Are you using stock bolts and countersinking/machining the rotor carriers or getting longer rotor bolts?  Did you already modify the carrier for the speedo drive?

Right now I'm just gathering parts. I was planning on just getting longer bolts, I didn't know machining carriers was an option. I haven't yet modified the speedo drive. Plan on doing all that when I have all the parts since I'm still riding. Maybe stupid question, but I was planning on just getting some grade 10.9 bolts from McMaster Carr. Or is there some bolts off a SOHC4 I should be using instead?


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1978 Honda CB550K

I don't think there are any magic bolts. The MC ones should work fine with locktite.

I got my rotors thinned and drilled from Goddfrey and he countersank/milled the carriers so I could use the stock bolts.