CB 360 cam choices
- Thread starter mtrace535
- Start date
frogman
'74 CB360, '71 CB450, '75 CB550SS
I'm sure the gods of 360 will chime in but the main issues with the top ends on 360s is the lack of GOOD oiling. Adding anything into the mix that will let it rev more without fixing the main problem will be just the same as running it stock except it just might grenade faster. I have yet to tear into mine but I have thoughts on improving that issue. I just need a spare head to try it out.
Then again, I have been known to be wrong, if there is something out there would be nice to know about at least.
Then again, I have been known to be wrong, if there is something out there would be nice to know about at least.
Swapmeet Louie
Put some metal in yer eye....
There are only a couple choices for the 360. And last I recall they were in the neighborhood of $400
Pj willknow for sure...
Pj willknow for sure...
http://www.megacyclecams.com/catalog/pages/page%2028.pdf
Megacycle cams. But to make it rev you need better valve springs and light valve caps etc.
Megacycle cams. But to make it rev you need better valve springs and light valve caps etc.
teazer said:
That's who I'm going with for my cam work. Price is less than $300, but requires new valve springs (another $300 from the supplier I found) and you'll need new pistons as well. The cam increases the lift by .040" which will cause contact between the valves and stock pistons. Cost for pistons is another $400.
So all in, you're looking at at least a grand if you want to make use of that cam.
I don't see one listed at http://www.rdvalvespring.com/honda.html so ask them if they have one available.
Pistons don't need to be replaced unless they need to be replaced if you follow me. If teh bores are worn or the pistons are stuffed, go ahead and replace them and that gives you more choices. And while the pistons are on the bench they can be modified slightly to improve valve clearance. If they are OK, go with a glaze busting hone and new rings.
More valve lift is not necessarily an issue, because at full lift the piston is way downstairs. The issue is lift just before TDC to just after TDC where there may be a "negative clearance" issue. That's teh overlap period you hear about when both valves are open.
The fix for that is to deepen the pockets or pocket the valves slightly but first you have to measure the clearance and determine if it's enough. .040" is probably enough but .060' is safer. That's between the underside of the valve and the piston crown.
A mild cam is usually OK for clearance but race cams need a lot of checking and machining and checking and machining etc until they are right.
Pistons don't need to be replaced unless they need to be replaced if you follow me. If teh bores are worn or the pistons are stuffed, go ahead and replace them and that gives you more choices. And while the pistons are on the bench they can be modified slightly to improve valve clearance. If they are OK, go with a glaze busting hone and new rings.
More valve lift is not necessarily an issue, because at full lift the piston is way downstairs. The issue is lift just before TDC to just after TDC where there may be a "negative clearance" issue. That's teh overlap period you hear about when both valves are open.
The fix for that is to deepen the pockets or pocket the valves slightly but first you have to measure the clearance and determine if it's enough. .040" is probably enough but .060' is safer. That's between the underside of the valve and the piston crown.
A mild cam is usually OK for clearance but race cams need a lot of checking and machining and checking and machining etc until they are right.
@teazer - RDValves does have a kit for that Megacycle cam. The kit # is 251-H. I spoke to a guy on the phone there and he said that the 350 spring kit will fit the 360, in this case. Also, the decision for new pistons is also due to a recommendation from Megacyclecams to up my compression from 9.3:1 to 10-10.5:1 when using their cam. At this point, I figured I might as well have custom pistons and go for a bigger bore, too, if I'm going to be modifying that many items.
@66replica - I'm looking to see around 6 or 7 hp (all at the top end). That's about a 15% increase. Most of that increase will come from the cam (duration from 221° to 251° and lift from .341" to .381"), but the compression and bigger displacement should help, too. It's important to note that I'll see a significant decrease in power below the 3K RPM mark. I'm expecting between 20% and 30% loss at those engine speeds, but my bike only sees < 3K RPM in first gear anyway.
@66replica - I'm looking to see around 6 or 7 hp (all at the top end). That's about a 15% increase. Most of that increase will come from the cam (duration from 221° to 251° and lift from .341" to .381"), but the compression and bigger displacement should help, too. It's important to note that I'll see a significant decrease in power below the 3K RPM mark. I'm expecting between 20% and 30% loss at those engine speeds, but my bike only sees < 3K RPM in first gear anyway.
crazypj
Split personality, I fake being smart
Unless your racing, stock cam is fine and will produce power to about 11~11.500 rpm.
Big cam, etc allows around 13,000rpm+, but, unless you've done major oiling mods, the top end will destroy itself pretty quick
A good ignition system would be a better use of resources, stock system in good condition is designed to misfire around 10,500~11,000rpm (points 'bounce')
Biggest problem is exhaust system and getting jetting spot on
Mikuni's are not a complete 'cure' until you change a LOT of parts inside them, race set up isn't even close to ideal for street use
Cheapest way to go would be skim about 0.030" off head, re-profile combustion camber or clearance pistons to change squish, mild porting (intake ports are already too big until you get over 200cc /cyl), re-time cam, decent exhaust then finally ignition
Big cam, etc allows around 13,000rpm+, but, unless you've done major oiling mods, the top end will destroy itself pretty quick
A good ignition system would be a better use of resources, stock system in good condition is designed to misfire around 10,500~11,000rpm (points 'bounce')
Biggest problem is exhaust system and getting jetting spot on
Mikuni's are not a complete 'cure' until you change a LOT of parts inside them, race set up isn't even close to ideal for street use
Cheapest way to go would be skim about 0.030" off head, re-profile combustion camber or clearance pistons to change squish, mild porting (intake ports are already too big until you get over 200cc /cyl), re-time cam, decent exhaust then finally ignition
Swapmeet Louie
Put some metal in yer eye....
That's a $166.00 per horse power. Not including Machine work, gaskets etc. I'm sure I'm not telling you anything you dont already know. I had @ one time thought about doing the same to my cb350 a few yrs back. I'm glad I changed my mind.
Swapmeet Louie
Put some metal in yer eye....
Sonreir said:
I hear ya man., haha... This is why it cracks me up when people put pods on there carbs and after market coils. And claim that when it's all said and done they have X amount more HP . It just doesn't work like that. If it were that easy we would all have hi-performance machines. ya know...
crazypj
Split personality, I fake being smart
mtrace535 said:
"my modern 250f"........................................................which doesn't start MAKING power until 7,000rpm
If it feels 'flat' it probably has original air filters
They will be well past their 'sell by' date and restricting airflow at higher rpm (even if they look clean. the fibers swell up from water vapour in the air over 30+yrs)
