any advice? about to swap my flywheel

[Jamoi]

I just have 1 question... who's going to lighten my flywheel for me??

I got one you can have.. It's quite heavy, weighty or massful so rather than post it I may take a ride out as soon as I can and drop it off to you?

You are a ledgend!

[gl_s_r]

Did you want one with the standard machining or the big daddy of reduction?

[Jamoi]

Hmm I'm thinking big daddy reduction (I miss my MX bike!), but hadn't considered the structural integrity of a severely lightened flywheel until someone mentioned it a few posts back...

Is the standard reduction, Rogers spec? Do you think it's enough to be worthwhile?

Although, i don't want to be fussy... a lightened flywheel is a lightened flywheel

[VTRDark]

I may take a ride out as soon as I can and drop it off to you?

Are you popping along to jamies workshop day Mark?

(:-})

[E.Marquez]

Hmm I'm thinking big daddy reduction (I miss my MX bike!), but hadn't considered the structural integrity of a severely lightened flywheel until someone mentioned it a few posts back...

Is the standard reduction, Rogers spec? Do you think it's enough to be worthwhile?

Although, i don't want to be fussy... a lightened flywheel is a lightened flywheel

The Ditchfield spec is far from the lightest version possible (thats not a bad thing, as im sure Roger had a very good reason to do what he did)

I did one much like gl_s_r showed in his pic, but took a bit more out of the weight with a custom ground tool as the finishing cut.

It was a pain to do and I really can not "feel" any difference between it and my normal "lightest" one.

If someone wants to go lossless ignition (ie batter fired, no charging circuit) you could really drop some weight by removing the basket and it's magnets , machining a trigger wheel, using Ti fasteners to attach it to the flywheel..


And then if you really wanted to go nuts on a track toy, you could remove the started gear and clutch bearing

[lloydie]

Jamio how I do them by only taking down the disc to 125mm makes it much happier to rev and you do feel if why don't you wait till the workshop day and have a go on mine to see if you like it or if someone closer who has one will let you have a go on there's ?

[Jamoi]

To be honest, I'd be happy to stick anything on there and see how it feels I would like a go on kermit at the workshop day though

[gl_s_r]

Hmm I'm thinking big daddy reduction (I miss my MX bike!), but hadn't considered the structural integrity of a severely lightened flywheel until someone mentioned it a few posts back...

Is the standard reduction, Rogers spec? Do you think it's enough to be worthwhile?

Although, i don't want to be fussy... a lightened flywheel is a lightened flywheel

The Ditchfield spec is far from the lightest version possible (thats not a bad thing, as im sure Roger had a very good reason to do what he did)

I did one much like gl_s_r showed in his pic, but took a bit more out of the weight with a custom ground tool as the finishing cut.

It was a pain to do and I really can not "feel" any difference between it and my normal "lightest" one.

Agreed, despite the fact it was a lot lighter (around 3lb) there wasn't a massive massive change... but I did it because I was bored one day and done it to Benny spec's to see the difference. I didn't use any custom tooling though to do it Erik.. just the standard stuff we have here.

I reckon Llloydies post has the most relevance in this thread with it all but then Benny run one being held together with araldite if I remember so it does make you question some things doesn't it? I personally wouldn't worry about a diameter being turned down being a weakness or creating loss of integrity or one would have gone bang in the 15 odd years this mod has been done and used including the race track..

[Jamoi]

I'd be really happy with any variety/version you are prepared to part with Mark, plus it means I don't have my bike off the road while I'm waiting for mine to be turned down.

I can give you my one after I've swapped it over.

[E.Marquez]

I didn't use any custom tooling though to do it Erik.. just the standard stuff we have here.

Nothing fancy here either.. I had some old HHS tooling thats not been used in years, I ground a U shape tool to "gouge" out the motor side of the weight, leaving a good ridge at the ID to retain the starter clutch.

This flywheel was junk as it had been removed by the PO with a three jaw puller and he damaged the basket.... We found him a good replacement and I was offered this junk one to experiment on.

3lb... really ?? your getting three pounds off a VTR flywheel? Thats amazing.. I would not have thought that possible based on what I remove now commonly and what the weights come out as.
So your getting a flywheel to the sub 4lb 5 oz or less range? (that would be 3 lb off on average)

[gl_s_r]

Assuming the scales are correct... But I'm sure I read on the hawk forum someone lightened one by 8lb a long time ago??

I think Carl had this one so maybe he can confirm if the scales are right?

[agentpineapple]

I was there when he weighed it, and can confirm that its bloody light compared to the original.....
carl is away for a week and I doubt he'll be able to confirm it until he gets back, I know he's itching to fit it, hence him wanting to buy an electric impact wrench.

[bigtwinthing]

I was there when he weighed it, and can confirm that its bloody light compared to the original.....
carl is away for a week and I doubt he'll be able to confirm it until he gets back, I know he's itching to fit it, hence him wanting to buy an electric impact wrench.

he could just have really tight nuts!!!

[8541Hawk]

And I thought Americans were bad with "If a little is good, a lot must be better"........

That is some serious material removal.

When I did mine I looked at all these options and went with what we called the 'Moriwaki" spec at that time.
This is just a simple 13mm cut off the O.D. of the weight.

I didn't go lighter for a couple of reasons.

First looking at the firing order of 270-450
I would think that a extremely light flywheel could cause issues at low\lower RPMs during that 450 degrees of crank rotation when the engine is basically just coasting and using the energy in the flywheel to keep things spinning.

Another way to look at it is you need flywheel weight to have that big fat torque curve, the lighter it get the more "peaky" the engine gets.

Then there is the "balance" issue.
There were 2 opinions on this concerning the flywheel and 1 other issue I see as someone who spent a couple of years balancing engine rotating assemblies for a living.

On the flywheel the "Mori" set up was passed on by Bob H. (RIP) and he also stated there was no re-balancing needed with this mod.
This makes sense as you are not taking a lot of weight off but the engine does spin up much quicker.
Which makes this the way to go on the street IMHO as you still get a factory like idle.

The there is the Revolution spec, which also came with the information that you need to balance it afterwards.
This also make sense as these engines do spin high rpms and you have removed enough material with this method that you "might" have issues at the top of the rev range.
I also look at this a a "Race" set up not only due to the extra expense of balancing but also I would say that this is light enough to start loosing some bottom end which means the idle will also start to get finicky.

Then there is the last issue of not knowing first if the factory balances the rotating assembly with the flywheel weight attached or if they use it as a harmonic balancer\damper
If they do either one and you change the weight too much you get too the point where you nee to balance the complete rotating assembly or you might be in for a nasty surprise.

So I do find it interesting watching these threads and look forward to hearing the out come but personally I stick to the two methods I listed.

I figure both of those sources had plenty of flywheels and engines to play with and stopped taking weight off when they did for a reason.

Carry on

[gl_s_r]

And I thought Americans were bad with "If a little is good, a lot must be better"........

That is some serious material removal.

When I did mine I looked at all these options and went with what we called the 'Moriwaki" spec at that time.
This is just a simple 13mm cut off the O.D. of the weight.

I didn't go lighter for a couple of reasons.

First looking at the firing order of 270-450
I would think that a extremely light flywheel could cause issues at low\lower RPMs during that 450 degrees of crank rotation when the engine is basically just coasting and using the energy in the flywheel to keep things spinning.

Another way to look at it is you need flywheel weight to have that big fat torque curve, the lighter it get the more "peaky" the engine gets.

Then there is the "balance" issue.
There were 2 opinions on this concerning the flywheel and 1 other issue I see as someone who spent a couple of years balancing engine rotating assemblies for a living.

On the flywheel the "Mori" set up was passed on by Bob H. (RIP) and he also stated there was no re-balancing needed with this mod.
This makes sense as you are not taking a lot of weight off but the engine does spin up much quicker.
Which makes this the way to go on the street IMHO as you still get a factory like idle.

The there is the Revolution spec, which also came with the information that you need to balance it afterwards.
This also make sense as these engines do spin high rpms and you have removed enough material with this method that you "might" have issues at the top of the rev range.
I also look at this a a "Race" set up not only due to the extra expense of balancing but also I would say that this is light enough to start loosing some bottom end which means the idle will also start to get finicky.

Then there is the last issue of not knowing first if the factory balances the rotating assembly with the flywheel weight attached or if they use it as a harmonic balancer\damper
If they do either one and you change the weight too much you get too the point where you nee to balance the complete rotating assembly or you might be in for a nasty surprise.

So I do find it interesting watching these threads and look forward to hearing the out come but personally I stick to the two methods I listed.

I figure both of those sources had plenty of flywheels and engines to play with and stopped taking weight off when they did for a reason.

Carry on

Hence my question on the second page of this thread but think it was a little lost in translation with lots of book talk being thrown about when I wanted an answer like yours and I agree, why stop when they did?

Why do you think there was no need to balance the mori spec but Rogers would need to be? I would assume that the lighter the part the less any imbalance would be a problem?