Topic: megacycle cams for 550 - experiences?

[flatlander]

those of you who have the megacycle 126-00 or 126-20:
where does the powerband come in?
how does it do at mid range?
what pistons do you run it with?

[PeWe]

Start with the specifications

[flatlander]

yes i have those. was looking for some real-life experiences.

[PeWe]

I do not have experience of 550, only CB750
The cam data might encourage others with 500/550 tuning experiences to answer. If they have another cam with similar data.

You can decide which cam depending on your engine and level of tuning.
One aspect here is standard engine with OEM pistons (use 126-00) vs an engine with high CR pistons and ported head (use 126-20).
The overlap differ rather much, 30 vs 50 degrees, the hotter of them give more nervous and higher idle and must have high CR pistons due to the longer overlap when compression is leaking thru the open valves. This cause lower dynamic compression and high CR pistons is therefore a must. 
The much higher lift need pistons with valve pockets to avoid piston/valve collision. 

[flatlander]

thanks! what compression do you reckon the 126-20 needs, up to 10:1 or even higher?

i am going to get some porting done, and new pistons so options are open at this point. indeed, i'm thinking of slightly bumping the compression but not into race category.
the bike will be used on the street, mainly open road for spirited touring - if that's a term. my first gut feeling was for the 126-00 to be on the safe side as it needs to stay usable in traffic, just a bit more peppy but i'd be happy to go for the 126-20 if i can be convinced that i won't kill mid-range power and idle.

[calj737]

I have the 126-20 and 59mm Wisecos for my 500 build. Pistons I believe are rated at 10.5:1 and with that cam I used HD springs mated to a Mike Rieck stage III head with oversized valves.

Thought process was that it should actually improve dramatically the lower end and up to midrange powerband. Can't say as the motor sits by awaiting machine shop.

You might pm Mike and ask his thoughts.

[bwaller]

The 12620 works better with compression (I'd say 1:10.5 minimum) and the power will certainly come on later than stock but it can be "street able". It won't be suited to lugging around town, but it's not a big lumpy cam so the engine will idle. Be prepared to test assemble to measure clearances.

[flatlander]

ok that's all really interesting info. lugging around town - that's not what it's going to be used for. more like leaving town with no hassle, then just keep going all day long. so sounds like i could go the direction of the -20.

cal i will have to look into that and check with mike. if those measures improve low and mid range as well then it sounds like there's not much wrong with them

[bwaller]

I doubt the 20 would actually improve low end, more likely the opposite would be the case. I use it in my race bike but it would be a good "spirited" cam for the street!

[flatlander]

yes that's what i would normally expect. but if mike has some tricks up his sleeve that improve also low and mid range over stock then that's worth exploring. i'll ask him.

[flatlander]

i checked with mike. for low and mid range, the -00 grind produces more torque and will be better.
so no free meal after all, bummer!

[DaveBarbier]

I don't really know much about this stuff so seems like a good place to ask a question. Is this a good upgrade for performance opposed to other upgrades? For the 126-00, I mean. Is see stock springs and pistons but will carb jetting most likely have to be performed? I'm just thinking for the future. My bike is going to be completely stock but with a 4-1 and UNI pod filters with appropriate jetting. I'm just curious if it's worth eventually going down that rabbit hole for a little more power. Will the motor be taxed more and reliability go down the drain?


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1978 Honda CB550K

[Muckinfuss]

Usually, changing just one part with another in the hopes that the engine will pump more air and fuel efficiently is a pipe dream.  Be prepared to tweak and tweak ..... maybe until the day you decide to sell the bike out of frustration.   
My experience........Horsepower is purchased in cubic dollars.  More performance will equal more heat....it's linear in the effect.  10.5+ compression should require 91+ RON at the pump.  12:1 compression.....100 octane race fuel.  Too much cam for the carbs?.....$900+ for ones that breath more air.  How's that for a rabbit hole.  Horsepower is heroin....once you start, you can't stop.

[DaveBarbier]

Completely understood. I'll keep it stock for now, haha. I'm only 5'6" 140 lbs so my 550 won't have trouble moving me. It'll be more hindered from my fear to go faster.


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1978 Honda CB550K

[DaveBarbier]

Oh and thanks!


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1978 Honda CB550K

[PeWe]

One more bike? 
A CB750 to stay with classic bike. 836cc (10.5:1), ported head, cam, lightened alternator make a difference.

It is otherwise cheaper to buy an used 150hp+ bike than repair/ restore/upgrade and old CB750 to less than 100hp.
Honda CBR1100XX Super Blackbird -97 my friend bought for small money, less than my new CB750 4-4 exhaust with all parts.

OEM carbs OK. (I have K6 with OEM carbs, did not run slower than Mikuni VM29 Smoothbore which i have changed back to now giving better throttle response.

[flatlander]

I don't really know much about this stuff so seems like a good place to ask a question. Is this a good upgrade for performance opposed to other upgrades? For the 126-00, I mean. Is see stock springs and pistons but will carb jetting most likely have to be performed? I'm just thinking for the future. My bike is going to be completely stock but with a 4-1 and UNI pod filters with appropriate jetting. I'm just curious if it's worth eventually going down that rabbit hole for a little more power. Will the motor be taxed more and reliability go down the drain?

if your bike is stock now and everything is fine, ask yourself: why do you want to touch it? "a little more power" can mean different things to different people. think about what you want to achieve and also, set yourself a budget.

many people drop a 650 cam into the 550 which would be the cheapest, easiest option. i don't have experience with this myself but a search on the forum should bring up lots of info. here are some specs, for example: http://forums.sohc4.net/index.php?topic=134461.0

if you can and want to spend a bit more, porting is probably the best place to start on these engines. further, you need to look at it holistically. changing only one part will not do much good, you need to consider the combination of all the elements. then it can become quite costly and time-consuming as muckinfuss said.

[DaveBarbier]

I don't really know much about this stuff so seems like a good place to ask a question. Is this a good upgrade for performance opposed to other upgrades? For the 126-00, I mean. Is see stock springs and pistons but will carb jetting most likely have to be performed? I'm just thinking for the future. My bike is going to be completely stock but with a 4-1 and UNI pod filters with appropriate jetting. I'm just curious if it's worth eventually going down that rabbit hole for a little more power. Will the motor be taxed more and reliability go down the drain?

if your bike is stock now and everything is fine, ask yourself: why do you want to touch it? "a little more power" can mean different things to different people. think about what you want to achieve and also, set yourself a budget.

many people drop a 650 cam into the 550 which would be the cheapest, easiest option. i don't have experience with this myself but a search on the forum should bring up lots of info. here are some specs, for example: http://forums.sohc4.net/index.php?topic=134461.0

if you can and want to spend a bit more, porting is probably the best place to start on these engines. further, you need to look at it holistically. changing only one part will not do much good, you need to consider the combination of all the elements. then it can become quite costly and time-consuming as muckinfuss said.

Thanks for the info. I'll stay away from power increases for a while. Stock is good enough for me for now. But eventually maybe I'll look into porting, cams, etc.


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1978 Honda CB550K

[dave500]

they run plenty good stock.