188 replies to this topic

[EunUCh]

I read your post wrong,sorry Bomber,when you said "pick of crank" I read it as "choice of crank" not pic, as in picture,sorry bout that.

Bear with me,thats bare ,not be ar, as in beer,bloody english language.

 

[EunUCh]

The weights are at 180,the middle ones are thinner than the end ones but are spread out around the circumferance a bit more. 

At a glance with just a rough measure and half educated guess i would say they would be close but would need to do a water test to 

confirm it for sure.

I hear you oljohnno.

[Uncle Chop Chop]

As far as a cut down alloy 12 port head goes, I saw one today. So don't count out that option.

[EunUCh]

^{Hadnt thought about cut down alloy head,didnt even know they existed to suit blue motor.}

 

^{Hadnt given too much thought on the flywheel options either so didnt do too much looking into it.}

^{Have tried a 6kg  over the the standard 8.2kg (if my memory serves me correctly) both with a 6 cylinder balancer on snout and the only real difference i could perceive was slightly better pick up,the shakes were still at the same place,no better ,no worse.}

^{Could get off the mark on flat ground in second gear in both cases,didnt do it often,just to see if it would.}

^{I have read a bit about the heavy flywheel,but was not enough to make me think on it,for this reason.}

 

^{My XS1100 has no flywheel worth speaking of and has no where near the shakes as a starfire,although a different animal to some extent i thought the principles would be very close so didnt go looking.}

^{looks like more research,thinking,might even just sit under a gum tree with a couple of cold ones and contemplate for a while}  

 

 

[hanra]

Them gumtrees are good on sunny days like today No Balls.

[EunUCh]

HaHahaha,pretty close to the starfire balance factor that washer.

Just a few grams oljohnno,just a few.

[EunUCh]

On a more serious note,I intend to cut the crankshaft up and weigh the counter balance and crank pin weights.

I will weigh them in water but my question is,do i I allow half the the main bearing journal as being part

of the weight or do i just subtract the journal weight/s from the measurements i get and treat the journal

as a mass that is rotating on it's axis that has no effect on the balance?

[Uncle Chop Chop]

This might be a better crank option.

 

http://www.crankshaf...uilders.com.au/

[EunUCh]

The way I see it so far.

The shits of things have a balance problem.

Make the rods/pistons as light as possible,that can be done.

 

If the cranks on these things is underbalanced as suspected then by how much is the next thing to find out

which as already stated wont be easy.

 

We have a four cylinder crank which is flat,apparantly a four has pretty good primary balance due to 1,4 and 2,3 being 180

out and tend to "cancel" each other out to a point if my info is correct you could get away with no balance weight at all in that

respect.

 

Bar doing the what sounds like complex numbers to find the weight of the counterbalance weight and pin/throw weight what

if we take just one throw and balance weight and treat it as a single,get it close to right and do the same to the others?just a thought.

[EunUCh]

So far I have cut number 1 off and set it on knife edges,the crank pin is the heavy part even without any mock rotating mass attached

to the big end journal.

Its a wonder the thing has not broken more than things bolted to the block.

I can just imagine what 1&4 and 2&3 are doing to each other in certain positions and the main bearings

from the last engine show signs of wear in areas that confirm what appears to me as the crank flexing slightly in

tose positions.

I think it was a vicious plot by the designer to give the starfire a bad name.

[EunUCh]

Looks like I need a few ideas on where to go from here other than swap engines out.

Anyone got any bright ideas they might want to share on how to go about getting a bit of

balance into this thing without having an expert balance it only to have it come back the same?