Best cam profile for me??

[Bill Hilly]

I am considering ordering a cam from MotoCult, and I honestly don't know which of the 3 profiles to get they offer a 292, and a 289, which are pretty close, the claim that they both increase the RPM capabilities to 10,000+, they say the 289 starts making power increases 500 RPM sooner. The 270 says great midrange increase starting at 3500 RPM. I have absolutely no desire, or intentions of running my bike over 8,000 RPM, and even when I do occasionally hit 8,000, I have no intention to actually run at those RPM. It really doesn't explain the complete power curve of any of the cams. I would hate to get a 270 cam, and basically get a stock grind, but if it increases power from midrange to 8,000 or so, then it may be a wise choy for me. Do any of you know which cam is probably best for me ?

[Megadan]

I've had the 292 cam for a few years now and it bumps power across most of the usable rpm range. Their claim of 10k rpm is from the manufacturer, which produces these for 125 to 150cc cg engines. On the 230 to 250cc engines the peak rpm is more like 9,000, but peak power is at basically 7000 to 8000, so there really ain't a point of going beyond 8500

Check out their own dyno on their stage 3 kit that was done with the 292 cam in a cg250 and you can see where the power and torque peak.
https://motocultparts.com/products/s...rmance-package

The only real change with the 292 is that the idle needs bumped up about 100 to 150rpm to keep it stable. Other than that, it's been a great upgrade that I really love. Pair it with their ported head and unlock the best bang for the buck in my opinion.

[Bill Hilly]

Originally Posted by Megadan

I've had the 292 cam for a few years now and it bumps power across most of the usable rpm range. Their claim of 10k rpm is from the manufacturer, which produces these for 125 to 150cc cg engines. On the 230 to 250cc engines the peak rpm is more like 9,000, but peak power is at basically 7000 to 8000, so there really ain't a point of going beyond 8500

Check out their own dyno on their stage 3 kit that was done with the 292 cam in a cg250 and you can see where the power and torque peak.
https://motocultparts.com/products/s...rmance-package

The only real change with the 292 is that the idle needs bumped up about 100 to 150rpm to keep it stable. Other than that, it's been a great upgrade that I really love. Pair it with their ported head and unlock the best bang for the buck in my opinion.

Thanks Dan..
So, I guess the 270 would not be the best choice for me.. Would you still choose the 292, or the 289 if you had to do it again?

[Megadan]

Oh, and yes, below 3500rpm it will make a bit less torque. I have never tried.to run my Hawk below 3000 rpm, stock or with a cam anyway. Small singles like this don't really do well trying to lug around like that anyway.

[Megadan]

Originally Posted by Bill Hilly

Thanks Dan..
So, I guess the 270 would not be the best choice for me.. Would you still choose the 292, or the 289 if you had to do it again?

I would maybe consider the 289 in your case, but I would go with the 292 peraonally pretty much every time.

[chiefmeat68]

So this may be a basic question but what are the trade-offs for the more aggressive cam?

From what I have gathered it may make for a rough idle... and may slightly reduce low end power... but increase mid to top end power?

What other things might it affect? Gas mileage? Emissions? Temps?

[Megadan]

Originally Posted by chiefmeat68

So this may be a basic question but what are the trade-offs for the more aggressive cam?

From what I have gathered it may make for a rough idle... and may slightly reduce low end power... but increase mid to top end power?

What other things might it affect? Gas mileage? Emissions? Temps?

You won't notice a rough idle. An unbalanced single already has that so there is no real change in the idle feel, just a slight unsteady nature of the idle at 1500rpm that will cause it to wander a bit. Bumping it up to around 1600rpm or a bit more steadies it. None of these cams have any additional lift, just duration.

The reduction in lower RPM power will pretty much be unnoticeable. Only a Dyno really shows it, and it's in the lowest part of the RPM range where these engines shouldn't be run under heavy load anyway. Trying to go full throttle below 3000rpm, even on an unmodded CG engine, really doesn't get you anywhere and is pretty hard on the engine.

Fuel economy will take a small hit, but not as bad as you would think. My bike lost maybe 2 or 3 mpg in average fuel economy.

Heat, not really.

Emissions? lol

You have to keep in mind that these engines run a single cam lobe for both valves. Even with a more aggressive cam profile, it has some limitations, chief among which is the fact that the effective lobe separation angle never changes. The only way to change that would be to change the length, position, and angle of the cam followers. This means that many of the running qualities remain the same. Even the big increase in duration from stock to the 292 only adds a small level of overlap to the valves, which is why the idle quality doesn't change very dramatically.

[chiefmeat68]

As always thanks for the info Megadan!