Topic: To crack the cases or not

[Sweep]

Hello all,

I can use some advice.  I'm building a 750 cafe and have the motor dismantled down to the pistons on my bench.  My common sense is telling me that since I've done the hard work to get the motor out I might as well go over the bottom end as well.  The bike has 14k miles and seems to run well but had sort of a low pitched whine/squeak when I started it up.  Splitting them also gives the the ability to put in Carillo rods and possibly lighten the crankshaft.  I'm not looking for a race bike here but I would like the most bang for the buck in terms of my time.

Any reason not to get into the bottom end?

Thanks.

[Bodi]

Well, what do you want to do in there? Replacing the primary chains and putting a high strength endless cam chain are fine plans for example. Carillo or Falicon rods will certainly lighten your wallet but without some serious top end upgrades that's about all you'll accomplish - the stock ones are more than adequate for stock or mildly worked motors. Replacment of the shaft oil seals and the blanking seal is worthwhile. Having a good look at the transmission and fixing any problems is always a good idea and a necessity if you're hotrodding the motor: getting the dogs undercut is nice if you are going for a major power increase. New main and rod bearings might be due but at 14K on a stock motor with no unusual bearing type noises I doubt it.
The noise after startup may be your starter clutch, if the rollers are slow retracting you will get some whirring type sound... or it may just be the starter motor spinning down.
I guess the best reason not to open it up is that you might spend a lot of hours and cash before you get it back together again, but spending time and money is what having these old fours is all about, right?

[Sweep]

Well, what do you want to do in there? Replacing the primary chains and putting a high strength endless cam chain are fine plans for example. Carillo or Falicon rods will certainly lighten your wallet but without some serious top end upgrades that's about all you'll accomplish - the stock ones are more than adequate for stock or mildly worked motors. Replacment of the shaft oil seals and the blanking seal is worthwhile. Having a good look at the transmission and fixing any problems is always a good idea and a necessity if you're hotrodding the motor: getting the dogs undercut is nice if you are going for a major power increase. New main and rod bearings might be due but at 14K on a stock motor with no unusual bearing type noises I doubt it.
The noise after startup may be your starter clutch, if the rollers are slow retracting you will get some whirring type sound... or it may just be the starter motor spinning down.
I guess the best reason not to open it up is that you might spend a lot of hours and cash before you get it back together again, but spending time and money is what having these old fours is all about, right?

Thanks for the reply.  I don't know if I'm making serious power or not but I am going with Wiseco 836 forged pistons, some head porting and polishing, and new valve strings and retainers.  I would like to get this bike built in a reasonable amount of time and since I've never been into the bottom end of a motor I'm a little nervous about opening that can of worms.

[Jerry Rxman Griffin aka MuthaF'er]

Besides losing a chunk of change (~ $1000+) you would lose some weight if you do use Carillos in place of stock rods. Ilbikes (Gordon) has the weights listed under one of his posts. Most CB750 Carillos are special order ie made after you've paid. Buzz at Dynoman might keep a set on his shelf waiting for your call.