670X RPM question

[Bogger]

As most of you know I rebuilt the 670X last weekend...

Tonight I took it out for it's maiden voyage....... STUPID power, thing will catwalk now. My question is..... I was told the max RPM on this motor should be 7800...... Since the rebuild I can push 9000 RPM and hold the fugg on.

Is this right????? What may I have done???? How long will the motor hold up if I brap it out to 9000RPM while climbing?????

Used the existing head (cleaned up) installed new pistons rings and gaskets and have it running with the oil injection and tank mixed at about 100 to 1 (300ml to 30 L of fuel)

 

[reaper020]

As most of you know I rebuilt the 670X last weekend...

Tonight I took it out for it's maiden voyage....... STUPID power, thing will catwalk now. My question is..... I was told the max RPM on this motor should be 7800...... Since the rebuild I can push 9000 RPM and hold the fugg on.

Is this right????? What may I have done???? How long will the motor hold up if I brap it out to 9000RPM while climbing?????

Used the existing head (cleaned up) installed new pistons rings and gaskets and have it running with the oil injection and tank mixed at about 100 to 1 (300ml to 30 L of fuel)

I look forward to seeing what everyone else has to say I have a 670x to:d

 

[arcdoo]

that motor in stock form with a single pipe will be making less h/p at 9000 rpm you need to get the rpms back down , i would think clutching its hard on that motor running at 9000 rpm.

 

[Deano670]

Seeing as to how you have freshened the engine up its most likely making more power now that its new and if you you are running the original clutch springs they are probably fatigued. You can try adjusting your clickers up to bring your rpm down 1 click= 200rpm(in theory) but yes at 9000rpm that engine in stock form will be making less hp than it will be at 7800-7900rpm. It wont last long at 9000rpm

 

[Modman]

Seeing as to how you have freshened the engine up its most likely making more power now that its new and if you you are running the original clutch springs they are probably fatigued. You can try adjusting your clickers up to bring your rpm down 1 click= 200rpm(in theory) but yes at 9000rpm that engine in stock form will be making less hp than it will be at 7800-7900rpm. It wont last long at 9000rpm

What Deano said.

New motor = more power to old clutching components = overrev

RPM is perfect @ 7800, don't want too much higher. Keep in mind that stock tack can be out by 200 rpm as well. Anywhere between 7700 and 8000 is good IMO. Anything more than 8000 for long sustained periods ain't good for the motor. Crank the raves in a few turns to help keep the ports lower and it will make more power down low, keepin the powerband lower as well.

Glad to hear its running good. Looking forward to pics from Cooke.

 

[Bogger]

Thanks guys I'll try adjusting the raves and cranking up the clutch

 

[DRD]

Peak power on the 670X is 8000, 7700 on the older non-x motors.

 

[99summitx]

I adjust my clickers to try and keep in the 8000-8200 range with the twin pipes on, at 6500ft my clickers are set at 4 and run right at 8000/digatron.

 

[meierjn]

I think mine tops out at the 8000-8100 range. I'm usually too afraid to look though!

 

[mxz sledhead]

Anything pass 8000rpm is just a waste i never go 6000 on a new motor for
first tank and add alittle oil to the tank

 

[Bogger]

I'm on my second tank of fuel now, still have a light mix in the tank...RPM's seem to have settled down last night I tried a few hard pulls and she is topping out right at 8000....I was relatively easy on it for the first tank, not babied but not beat either.... I'm confident in it again, last night was a good ride...

 

[0neoldfart]

You may want to check your tach - doo tachometers are known for being out by as much as 200 RPM. My 98 670X pulled best @ 8100 RPM on the tach, was actually spinning @ 7950 RPM on the Digitron. These motors like case porting and work ok with SLP twins, but @ 8300 RPM (with twins), the top end won't last long...