Ok cool, what is the "terminal" measurement where it's absolutely done for?

I usually judge it by the amount of play/slop the rod-crankpin fit has in the tdc part of tge stroke with rod and crank out of engine , if you can feel a fair amount of slop thats no bueno , it will just hammer out a new rod , usually compeletely unuseable at 4.88mm imo

Fyi: i will only re-rod at 4.92mm or larger at smallest measurement


Tip: watch for coning of the crankpin and ovaling (out of round)

I figure this engine has probably seen better days then..but I've got two more 21-4C, so we'll survive :D
I was just hoping I could get more mileage out of this, for the hell of it really, no real good reason. It does seem round though it is only measuring too small.

Other question, for your expert judgement: with the flywheel on, if you can move the crank in and out (not up and down, but in and out) does this mean the bearings are shot? Seems to move quite a lot, difficult to tell just by eyeballing it but it's quite a bit.

If you pull the crank out while pushing the collet tight up against the front bearing , then install flywheel and tighten flywheel nut it should get tight no matter , if front bearing races/balls are worn it will most likely leak out the front bearing.

With the flywheel nut securely tightened, it will move in and out. And when I took the flywheel off, I noticed it seemed like the inner metal bit of the front bearing would move in and out with it.

gotta make sure your collet is tight up against the bearing before installing the flywheel Elvind ;)

a bearing that is too loose can do that...... no matter how you tighten th3 flywheel it will walk in and out

so youre saying that when you pull the crank out to push the rear bearing forward then push the collet in so it pushes the front bearing towards the rear bearing and tighten it all down it will still move?

(this is not an argument)

novarossi rocks!!

[QUOTE=houston;11396966]so youre saying that when you pull the crank out to push the rear bearing forward then push the collet in so it pushes the front bearing towards the rear bearing and tighten it all down it will still move?

(this is not an argument)

novarossi

My FMS did that exact thing. It had 6.3 bearing and with collet tight against front bearing it moved in and out.

Well I tried just sliding a new rod on the crank and sort of jiggling it about, it does seem a bit loose in there.. might not serve any purpouse to use that further then?

Yeah, even without the flywheel on if I pull the crankshaft in and out, I can visually see the inner tubular metal part of the bearing moving in and out. Does this mean the bearing is done for?
I have another 21-4C engine which also has this but much less of it, so I was thinking that might be the start of it?

I would say your front bearing needs replaced by what you are saying. The crankshaft barrel (induction window portion ) should but right up to the backside of the front bearing inner race. Provinding case has proper depth in crank bore between bearings, this thrust movement of crank should be minimal. Front bearing is usually the one that dictates endplay due to design. If barrel of crankshaft is longer than the crank bore in case, this endplay will be more pronounced due to one small radial bearing now trying to also control thrust of crankshaft aggravating the wear rate of the front bearing. Also not good on the connecting rod when crank is walking in and out with the varried loads these engines experience at full song.

Hello, for the Nova Plus 4 which is the best pipe, 9901 or 2096? another pipe would you recommend?

Thanks. Best Regards.

U cant go wrong with either

Either.

9901 for a tad bit more fuel mileage with a little less grunt.

Another popular choice is the 9853 for more bottom with a little less mileage.

2096 for a combination of good mileage and bottom.