How many RPM's???

[tony7281]

I have a Honda GX200 (not a clone)
governor removed
18lb valve springs
high flow single stage exhaust header with muffler
UNI high flow air intake
.625" bored carb with #92 main jet
ARC billet connecting rod
8 degree advance timing
indexed spark plug
adjusted spark plug gap to 0.045"

I do have a tach. How many RPM's can I run my engine at?

Are there any more cheap modifications I can make to get more power out of it?

 

[wall gator]

A better cam and head work,is your next place to go...

 

[devino246]

Porting and polishing your head might give you a tad bit. Only polish your exhaust port, you need the intake to be rough.

 

[jareeB]

i have heard that thos rods can handle around 12,000 rpms but most people will never spin them that fast

 

[tony7281]

Yeah, I'm not too worried about the rod. I was just curious what the rest of the engine could handle.

 

[r_chez_08]

i have heard that thos rods can handle around 12,000 rpms but most people will never spin them that fast

Umm- what about the stock flywheel?
I would trust that engine until approx 7k. Depends what balls you have to see how fast that flywheel can spin.
If you really want to rev high, i would reccomend a billet flywheel for safety reasons, and plus a billet wheel is cheaper than having to buy a new engine if the flywheel explodes (sorry) and hurts the block.

 

[tony7281]

I think 7000 rpms is good enough for me. I'm not usually overly cautious. I just don't want to do anything totally stupid. What does everyone else think? Is 7000 relatively doable with my current set-up? Or does something have a really good chance of breaking before 7000?

 

[ipwnr]

well i have revved my engine at around 5000 rpm at all stock except for the governor witch i just un hooked from the carb and still seems to work fine so yeah you can get around 7000-8000 rpm with your current mods and maybe some more

 

[oldbikerarlo]

With a stock cam you will probly top out around 6200, may a little more, but that set up will top out on power at about 4900-5200, from what I have read and the dyno spec's I have seen.

 

[tony7281]

Oldbikerarlo, you were pretty much dead on. I still need to advance the timing 8*, but it's topping out at around 5700 rpms. It gets up to 4200 rpms really fast, but it takes over 20 seconds to get up to 5700 rpms on the road, so the power is in the low to medium range.

It's perfect on the grass. It gets up to 25-30 mph quickly, and has good torque. I'd like to be able to get a little more top speed on the road though even if it does take me some time to get there.

So the question is how can I get more power at the top (cheaply)? I'd like to be able to get it in the 6500 to 7000 rpm range? Is a new cam and some head work the way to go? (I don't want to just change the gear ratio, because I really like having the torque for climbing hills and for pulling a sled in the winter.)

 

[oldbikerarlo]

Well Tony, IMO, you have reached that plato, were the only way to get more, is spend more. You will gain some when you advance the timing. Did you check the piston depth at TDC when you changed the rod? you can gain a little there, with a longer rod, and a thinner head gasket, a cam.

Check ARC's web site in their blog there is some good info and dyno charts, that will help you decide.