lightened flywheel.

[rob...]

just testing the water, but would anyone be interested in a lightened flywheel on a service/exchange deal?

i'm doing mine at the mo, i bought a spare on ebay to turn down so the bike wouldn't be off the road while i did it.

when i swap 'em over i'll have an std. one to turn down....

i'm thinking £60 + £15 P&P (they're heavy!!).

there has to be some kind of trust here, so for forum members, just let me know how much you want off the diameter, (1/2" seems popular, i'm going for nearer 3/4"), and i'll sent a lightened one to you, and trust you to send yours back to me once you've swapped....

non members i'll want £100 refundable deposit subject to a usable one being returned.

hope this doesn't breach any rules, just trying to be helpful.

[mik_str]

If I may.... I suggest you contact Roger Ditchfield and get the specs he developed/uses for lightening them. While many have proceeded in the "arbitrary" manner of remaving say 0.5", Roger worked out a spec for doign it and, given his expertise and experience with the VTR, why not benefit from it?

Again, just a friendly suggestion......

[benny hedges]

let me know how much you want off the diameter, (1/2" seems popular, i'm going for nearer 3/4"),

righty ho... i posted roger's spec for lightening the rotor / flywheel and the problem is, it cuts into the magnets substantially.
it's also posted over on superchicken if you care to trawl roger's posts with #flywheel
in fact no need - here yer go.


when you actually measure that up against a standard flywheel, those dimensions will confuse you.
i'll let you work that one out yourself ;)

while cutting into the magnets might not be a problem for a track or race bike, for the road its a bit impractical for a number of reasons....
ive personally wrecked 2 trying to go for the minimum dimensions without exposing the magnets, & that was using alan Richard engineering, the same guys who do roger's machining work in heysham, lancs.

also bear in mind that following roger's spec you will lose the timing marks, so will need to keep your original flywheel for when you do any head work, valve clearances, cct etc...

with this in mind, have a look at the dimensions posted here.

http://www.vtr1000.org/phpBB3/viewtopic ... el#p139088

these are the bare butt minimum you can remove from the top, sides bottom and flywheel plate without cutting into the magnets, losing the timing marks, or cutting into the screws of the starter clutch assy.
this is what i have on my bike atm... the results are very noticeable, the engine picks up rpm very fast, but also when you clutch in, the rpm drops very fast too which takes a bit of getting used to.
i didnt bother balancing mine after machining as there is almost zero extra vibration with the lighter flywheel.

you do lose a bit of the character of the bike as it no longer feels like a big lazy lump, but wants to rev all the time, especially with cam mods and timing advancer.

standard flywheel with starter gear removed


finished item, keeping timing marks

that weighs 1.25 kg or 2.76lb less than a standard one.
you need to leave a 2mm lip at the top with the timing marks and work down from there, easiest done on a cnc tbh unless you have an old crankshaft you can use as a centre,
if you decide to take the lip off, there will be nothing to seal the inside, as it is hollow and filled with magnetite permanent magnets, it is not a solid lump of magnetic steel so there is a limit as to how much metal you can remove without destroying it!
you need to leave at least .5mm on the outside so trust me you cant go less than the dimensions shown lol.

in practice the only way to take more metal off would be to cut holes in the flywheel disc that the starter gear mounts to, or reduce its thickness of the plate a bit (to 10mm from 15 as shown in roger's sketch) and shorten the starter gear boltsaccordingly so they dont bottom out.

you will also need to get / make yourself an m22x1.5 bolt, appro4 40mm long to get the old flywheel off.

good luck!

[lloydie]

there is a cheep standard one on ebay at the minute
http://www.ebay.co.uk/itm/270855589628? ... _808wt_928

[rob...]

good post, thanks.
i'm only offering to take metal from the flywheel, not the rotor.
as said, for road use, perhaps not the best idea.

[mik_str]

I bought a used flywheel and had it sent to Roger directly for machining so I can't comment on any issues related to the actual machining. However, my bike is used exclusively on the street and has now racked up close to 50,000 miles with the said lightened flywheel and I haven't had any problems or issues to speak of.

That being said, many (a few on the Superhawk forum anyhow) have gone to machining some off the diameter with success. I guess, in the end, it may be simpler and almost as effective, with much less hassle.....

[benny hedges]

good post, thanks.
i'm only offering to take metal from the flywheel, not the rotor.
as said, for road use, perhaps not the best idea.

sorry if i mislead you, you can take metal off the side of the rotor, just not a lot,
if you stick to the dimensions shown it will be fine.
i use mine on the road and its great, feels more like a mille engine than a vtr tho, very revvy!

mik it mustve cost u a fortune getting one shipped over from here lol!!!

[benny hedges]

there is a cheep standard one on ebay at the minute
http://www.ebay.co.uk/itm/270855589628? ... _808wt_928

ive also got another spare std one in the garage.

[gl_s_r]

Decided I would try the lightened flywheel route and set up to do it one day when I was bored at work. Made the bolt to remove it and then using an impact gun it took only a few minutes to remove it and have it ready to machine up.

I turned it down to the dimensions in the drawing/pictures Benny had created in the earlier post when he reduced it down and under advice left the timing marks on the smallest amount of material I could. That took all of 10 mins and then another 5 mins to fit it all back up and it was done.

I didn't re-balance it either as i don't think it needs it for what it is.The bike was no different for it and didn't have any new vibration issues after. I just clocked it till it run true and machined it. As it is a simple peice of machining I done this on a manual lathe rather than a CNC as this entailed virtually no set up time or programming etc.

For a mod that only took about half hour it made a nice change to the bike, done the quick action throttle at the same time and it made a bit the ride home a new experience.

Anyway no offence intended in this but the only comment is that £60 for the machining seems a bit steep for 15 minutes of simple machine work.

[rob...]

to be fair i said "i'm thinking" £60....
i haven't actually done mine yet, i'll be doing it over the weekend. obviously if it turns out to be as quick a job as you say it will be cheaper...

how much do you charge for 15 mins work?? £10??
£40 p/h is fair for machining work, perhaps i'd be better off sending it to you, if you're interested??

[gl_s_r]

If it was just a couple to do and 15 minutes work in each I would probably just do it as a favour as half hour out of my life is pretty much nothing in the grand scheme of things. If I was setting it up as a part time income and expected a continual flow of work then fair enough my attitude may be different and I would charge but it would be relative to the amount of time it takes to do the job.

As a machine shop we charge roughly £45 an hour so fully agree with you about it being a sensible hourly price but I think you'll see it's really not a hard or long job when you come to do yours.

As I said before, no offence intended.

[mik_str]

mik it mustve cost u a fortune getting one shipped over from here lol!!!

Indeed it did!!!!! However, considering all the free advice Roger has given me over the years, I felt it only right to give him some business. Also, I knew by having him do it that it would be done corrrectly.

[rob...]

done mine. a bit more involved initially truing up, took longer than 15 mins....

so £40 exchange, if anyone wants one. if not, no worries.

i'll bung a pic up when i get a mo.

[lloydie]

i should have mine of by the week end . anyone up for the task must be cheep ?

[agentpineapple]

just bare in mind it will change the feel of your bike, it will rev faster and the engine braking is harder, it's not everyones cup of tea, strangely my bike has become trickier to launch because of the lightened flywheel.