Rev limit for 750

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What is a rev limit for a rebuilt commando 750 with about 500 miles on it. I don't mind caning the tits off it within reason, jst rather not blow it up. Al
 
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At 7000 RPM you start pulling the wrist pins through the pistons. But I take mine to 6500 RPM all the time with no fear. If pulling down a motor is a several week ordeal for you then you may need a little more moderation. 5500- 6000 should be a good shift point for fast street work. Don't use first gear too hard though it does a lot of work already getting you off a dead stop. norbsa
 
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Norbsa,

In your opinion, where is the weak link in the Commando piston rod assembly? You mentioned that at high revs the wrist pin pulls through the piston, have you seen failures in the rod? And if so, where?

I recently had one of my 850 Commando crankshafts balanced. And in order to balance the rod assembly, the shop removed some material from the ribs on the rod cap. As you know, these ribs provide strength to the cap and removing material will weaken it somewhat.

But if the weak link is the piston, I may be OK with wimpy rod caps.

Thanks,

Jason
 

ILLF8ED

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rev limit

Norbsa,

So you mean my first '72 combat I rode at age 20 in 1973 was getting pushed to far when revving to 9000. The power came alive at 7000 and I thought nothing of these rpms after the previous Honda 305 Superhawk.

This Commando was still running at 5000 miles on the odometer when I sold it. The fact that it had to go back to the shop every other week was the reason I sold it after 6 months. Something about youth and exuberance. It sure was fun when it came back freshly tuned from Bill's Cycle shop in San Bernadino, Ca.
 
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David,
There is a math formula for this having to do with piston speed. But more important the motor just has run out of pony's at 7000 rpm. The power is flat and the vibes get very bad. It can be tunned and balanced to run between 7000-9000 for drags but were talking street bike here.
The weak point on all 750's is the base of the jug. And both 750's and 850's will have their cranks snap off the output side at 100 hp. So I am told buy people who have done it. Quick blips to 8000 shouldn't kill the stock motor. I think that 8200 is were the wrist pin problem kicks in on the Norton bore and it may be some what less on the 850.
 
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