Topic: would you put in a big bore kit and a hot cam if you had the chance?

[SOHC4 Cafe Racer Fan]

You may want to look around and price a running 650 motor.  It swaps directly into the 550 frame and give you an instantaneous power increase, is reliable and fairly fuel efficient.  This solution will likely be less expensive than an engine rebuild and port work.

If you have your heart set on a 550, then either look into the Wiseco kit or the cruzinimage kit, a 650 or hotter than stock cam, and some porting by a professional.

[Retro Rocket]

You may want to look around and price a running 650 motor.  It swaps directly into the 550 frame and give you an instantaneous power increase, is reliable and fairly fuel efficient.  This solution will likely be less expensive than an engine rebuild and port work.

Actually, if I were ever to own a 500-550 this is exactly what i'd do....... then work it 

[b5rider]

You may want to look around and price a running 650 motor.  It swaps directly into the 550 frame and give you an instantaneous power increase, is reliable and fairly fuel efficient.  This solution will likely be less expensive than an engine rebuild and port work.

If you have your heart set on a 550, then either look into the Wiseco kit or the cruzinimage kit, a 650 or hotter than stock cam, and some porting by a professional.

I have my heart set on getting my 550 running  , not really building the ultimate racer.  I do, however, crave more bottom-end power for pulling the sidecar.
 I have to change out these items because they are not in good working order,  so I wanted people's take on what it would do to my bike to put in bigger pistons and a 650 cam.
 
This whole question is driven by the fact that NEW pistons can't be bought anymore for less than $118 EACH. I have to hone the cylinder anyway, so the extra $200 to bore them is offset by the lower price of $250 for the big bore kit.  The cam is not that much more expensive, and if it'll give me a boost in power with the big bore kit, then why not, if the engine is already open.

[lrutt]

I have to say, you can sink a lot of time and money in trying to add a few ponies to an old bike, just to end up with an old bike that has marginal brakes and is almost as fast as a new 300. Or you can just leave it as it is and enjoy it for what it is, faults and all.

[DaveBarbier]

I have to say, you can sink a lot of time and money in trying to add a few ponies to an old bike, just to end up with an old bike that has marginal brakes and is almost as fast as a new 300. Or you can just leave it as it is and enjoy it for what it is, faults and all.

Or you can sink a lot of time and money in it because it's fun and an incredibly rewarding hobby with good people on forums to help along the way.
If you eventually find out it's not enough, you have the 650 drop in as an option. I may be in the minority because I like wrenching as much as riding, haha.
After reading through this thread maybe a 650 motor is in my future...having a spare isn't at all bad, right?


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1978 Honda CB550K

[b5rider]

Go for it. But, I would find it unlikely that some head work is not required if the bottom end is that poor. And if you are doing the bottom end and a new cam, then some amount of work up top is also warranted and appropriate, especially to pull the sidecar.

Springs, valves, guides and seats recut with porting. Then you have a strong, reliable motor.

it has new valve guides and the valves were lapped.

[Rgconner]

This whole question is driven by the fact that NEW pistons can't be bought anymore for less than $118 EACH. I have to hone the cylinder anyway, so the extra $200 to bore them is offset by the lower price of $250 for the big bore kit.  The cam is not that much more expensive, and if it'll give me a boost in power with the big bore kit, then why not, if the engine is already open.

Not to mention a good bore should take care of any out of parallel piston issues, per "Thoughts of Hondaman":

1. All inline fours have this in common: crummy metal holding the cylinders together. As a result, after about 5,000 miles of running, the bores are no longer parallel, nor are they round. Power is lost, almost 10% by our 1970 rear-wheel dyno tests. To fix this, have the cylinders bored one oversize from where you are now, and tell the machine shop to make sure they are in parallel. They "wander" as much as .010", in my experience. Simply boring one oversize and refitting recovers all that power again, and it STAYS for a very, very long time after that.

[SOHC4 Cafe Racer Fan]

Based on your parameters, I'd get the cruzinimage kit and cam and see what extra power you obtain. If it's not enough, find a cheap running 650 motor for a future swap.

[b5rider]

Bought the 600cc kit.  Should be here Friday. Still looking for a 650 cam that isn't stupid money

[Trad]

In my 74 550,  I have JE 60mm pistons from Dynoman, paired with a Ported head from Mreick, hotter cam (I have a 650 cam and having the webcam 358a fixed (dropped it  ), I haven't decided which to run yet. All this with Moto GP Werks pipe, Harisuluv rebuilt carbs, and working on getting the bottom end rebuilt. All in all, I cannot friggin wait to get this bike running. This setup has been carefully chosen from input from all those who have had experience running multiple setups with 550's. I think if you're going to overbore you might as well make it count.

Just to help push you on the hotter cam; I dropped a 650 cam into my 78 550 and found and instant midrange power increase. A noticeable, gain in less than 2 hrs work. It doesn't get much easier than that. 

[b5rider]

In my 74 550,  I have JE 60mm pistons from Dynoman, paired with a Ported head from Mreick, hotter cam (I have a 650 cam and having the webcam 358a fixed (dropped it  ), I haven't decided which to run yet. All this with Moto GP Werks pipe, Harisuluv rebuilt carbs, and working on getting the bottom end rebuilt. All in all, I cannot friggin wait to get this bike running. This setup has been carefully chosen from input from all those who have had experience running multiple setups with 550's. I think if you're going to overbore you might as well make it count.

Just to help push you on the hotter cam; I dropped a 650 cam into my 78 550 and found and instant midrange power increase. A noticeable, gain in less than 2 hrs work. It doesn't get much easier than that.

Thanks for your input.  How did you fix the tach issues when running the 650 cam?

[mrfish2]

Thanks for your input.  How did you fix the tach issues when running the 650 cam?

I dropped a 650 cam in mine and I can agree it gives the bike more mid-range grunt. As far as a tach, my 76 550 has green gauge faces stock, and I lucked up and found a 750 tach with the same color face to match my 550, so you can barely tell it isn't stock. Any CB650 or CB750 tach will work because they have the correct drive gear ratio as the 650 cam.

[b5rider]

Ok.  So I won't have to change the cable or gearing,  just the tach.  Thanks

[Tews19]

and the tach gear that should come with the cam itself.

[b5rider]

and the tach gear that should come with the cam itself.

Thanks.  If you figure out in the next 2 weeks which cam you won't need,  I might take it off your hands

[DaveBarbier]

If only a 650 cam was dropped in, do you generally need to rejet? Obviously it's best to drop it in and test it out with plug chops or a dyno, but I'm curious of other experience.


---
1978 Honda CB550K

[mrfish2]

If only a 650 cam was dropped in, do you generally need to rejet? Obviously it's best to drop it in and test it out with plug chops or a dyno, but I'm curious of other experience.


---
1978 Honda CB550K

Nope, no rejet required. It really is the simplest mod one can do to a 550 motor.

[HondaMan]

If you are sidecar-ing, keep this in mind: this is a small-bore engine. This means it can make plenty of HP above 6000 RPM, but torque will not be its long suit. To make torque in it, you need larger inlet ports (not too much larger, or other troubles will appear) like the 650 head has, polished valves, a PROPER air filter intake tract (i.e, NOT PODS!), slower spark advance curve, higher compression, and higher base-weight oils (like 15w-something or 20w-something) to keep the bearings slick under low RPM loads. Adding a longer spark duration will also help: this means using either OEM coils or something like the 5-ohm Dynas, plus either 10,000 ohm plug caps or the typical 5,000 ohm caps AND resistor plugs, to make the most duration possible.

Look into using the ND sparkplugs X22ES-U, too, for their longer-reach tip. While you have the head off, look through the fins to find (and remove) flash metals that are blocking air flow, and cut it away. Mill the head and cylinder decks about .010" each, maybe a bit more if your new pistons don't have high domes on them.

Finally, look "out" the exhaust ports (with valves removed and head shiny clean) and remove the tiny step blockages that abound in the 500/550 heads. When you make an exhaust, get something with backpressure, don't run it open or with real low restriction: you will need the crossover buildup in the chamber during overlap time.

Cams like the 650 make their HP at much higher RPM. Instead, consider slotting the cam sprocket and advance your stock cam about 3-5 degrees. This will move the torque curve downward in RPM and make it feel more "on tap" than having it all start up above 5500 RPM like the stock 500/550 usually does.

[Tews19]

If you are sidecar-ing, keep this in mind: this is a small-bore engine. This means it can make plenty of HP above 6000 RPM, but torque will not be its long suit. To make torque in it, you need larger inlet ports (not too much larger, or other troubles will appear) like the 650 head has, polished valves, a PROPER air filter intake tract (i.e, NOT PODS!), slower spark advance curve, higher compression, and higher base-weight oils (like 15w-something or 20w-something) to keep the bearings slick under low RPM loads. Adding a longer spark duration will also help: this means using either OEM coils or something like the 5-ohm Dynas, plus either 10,000 ohm plug caps or the typical 5,000 ohm caps AND resistor plugs, to make the most duration possible.

Look into using the ND sparkplugs X22ES-U, too, for their longer-reach tip. While you have the head off, look through the fins to find (and remove) flash metals that are blocking air flow, and cut it away. Mill the head and cylinder decks about .010" each, maybe a bit more if your new pistons don't have high domes on them.

Finally, look "out" the exhaust ports (with valves removed and head shiny clean) and remove the tiny step blockages that abound in the 500/550 heads. When you make an exhaust, get something with backpressure, don't run it open or with real low restriction: you will need the crossover buildup in the chamber during overlap time.

Cams like the 650 make their HP at much higher RPM. Instead, consider slotting the cam sprocket and advance your stock cam about 3-5 degrees. This will move the torque curve downward in RPM and make it feel more "on tap" than having it all start up above 5500 RPM like the stock 500/550 usually does.

Great write up

[b5rider]

If you are sidecar-ing, keep this in mind: this is a small-bore engine. This means it can make plenty of HP above 6000 RPM, but torque will not be its long suit. To make torque in it, you need larger inlet ports (not too much larger, or other troubles will appear) like the 650 head has, polished valves, a PROPER air filter intake tract (i.e, NOT PODS!), slower spark advance curve, higher compression, and higher base-weight oils (like 15w-something or 20w-something) to keep the bearings slick under low RPM loads. Adding a longer spark duration will also help: this means using either OEM coils or something like the 5-ohm Dynas, plus either 10,000 ohm plug caps or the typical 5,000 ohm caps AND resistor plugs, to make the most duration possible.

Look into using the ND sparkplugs X22ES-U, too, for their longer-reach tip. While you have the head off, look through the fins to find (and remove) flash metals that are blocking air flow, and cut it away. Mill the head and cylinder decks about .010" each, maybe a bit more if your new pistons don't have high domes on them.

Finally, look "out" the exhaust ports (with valves removed and head shiny clean) and remove the tiny step blockages that abound in the 500/550 heads. When you make an exhaust, get something with backpressure, don't run it open or with real low restriction: you will need the crossover buildup in the chamber during overlap time.

Cams like the 650 make their HP at much higher RPM. Instead, consider slotting the cam sprocket and advance your stock cam about 3-5 degrees. This will move the torque curve downward in RPM and make it feel more "on tap" than having it all start up above 5500 RPM like the stock 500/550 usually does.

Um,  why can't I just send you my bike.
Seriously, this post is why I view this forum on a daily basis. HondaMan is a wealth of knowledge (even when reading his posts is like reading Edgar Allan Poe sometimes)
650cam is off the books again

[Retro Rocket]

Hmmm, the general consensus around here is that it gives an improved mid range boost, i have no doubt it also improves top end...!!!

[b5rider]

Hmmm, the general consensus around here is that it gives an improved mid range boost, i have no doubt it also improves top end...!!!

650 cam back in the running

[Retro Rocket]

Hmmm, the general consensus around here is that it gives an improved mid range boost, i have no doubt it also improves top end...!!!

650 cam back in the running

hahahaha , this is starting to become fun...

[Tews19]

With my 650 cam I can feel the difference. It may be aubtle.but you also get it in your head that it adds performance. Kind of like changing a stock exhaust to a loud zoom zoom one.

[b5rider]

With my 650 cam I can feel the difference. It may be aubtle.but you also get it in your head that it adds performance. Kind of like changing a stock exhaust to a loud zoom zoom one.

That's what I was thinking. 
I figure,  from the posts,  the 650 cam won't hurt performance,  only enhance it. Whether this enhancement comes at the mid range or the top end is probably subjective without a real dyno test. I'm not discounting anyone's opinion that the 650 makes a positive enhancement to the bike's performance