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Discussion Starter #1 (Edited)
Ok so my bikes been down for a couple weeks while I have been prepping for paint in my spare time. Ill post pics after its done... till then its hush hush :cool:

So my painter is sick and i figured why not start taking some mass off the bike.

Ive read so many threads about thorstens race alt but I am cash poor and have acces to a nice rockport lathe and a bridgeport mill.

I want to turn the flywheel and see if i can remove a lb or 2 of rotating mass.... maybe more:rockon

So I took her all apart today have the flywheel out took a couple pics to show the areas i was thinking about cutting.... guys with exp please chime in.

I dont want my motor tame!:rockon

 

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Discussion Starter #4
thanks I actually saw that thread in my search for info along with this one from a tl...

Lighter GSX-R ignition rotor... - Page 2 - TLZone Forums

anyone else done this to their bike? have pics of after? or did everyone cough up nine hun? :wtf

im 78% sure im on the right track just wanted to verify with someone who has done the mod that might be willing to share some wisdom... ive searched the forums here and at rc51forum and still have a lil doubt.... i guess if i mess up it will only cost 50-100 to replace
 

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I personally don't agree with many posters on that VTR site, mainly because in the thread creators case he machined half way through a balance hole, thus now the flywheel will be out of balance. I would not have done that without getting the rotating assembly rebalanced.

But if you do not machine through a balance hole then you are taking off the same amount all the way around the flywheel and thus it will stay in balance.
Pete
 

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Here is a link to an HRC flywheel for sale that you may be able to look at for
reference: HRC VTR1000SP-2¥­¥Ã¥È¥Õ¥é¥¤¥Û¥¤¡¼¥ëVTR1000FSP-1TL1000RSV650 - Yahoo!¥ª¡¼¥¯¥·¥ç¥ó

I have never heard of anyone doing this mod to an RC before other than LDH's
comment on the "used aftermarket wheels" thread thats going on right now.

"Originally Posted by wingnutt
I was thinking in terms of handeling,but I suppose with an engine spooling-up quicker and less gyro it would make a drastic charachteristic change to the handeling

I experienced the same problem with the RC51 with a lightened flywheel in that it would just spin up everywhere, but on the Duc's it's golden and a much more drastically noticeable change to the bike not only in terms of power delivery, but also how you have to ride the bike at pace to make it work."

Stunna
 

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Discussion Starter #7 (Edited)
Here is a link to an HRC flywheel for sale that you may be able to look at for
reference: HRC VTR1000SP-2¥*¥Ã¥È¥Õ¥é¥¤¥Û¥¤¡¼¥ëVTR1000FSP-1TL1000RSV650 - Yahoo!¥ª¡¼¥¯¥·¥ç¥ó
Looks identical to my stocker:wtf

I have never heard of anyone doing this mod to an RC before other than LDH's
comment on the "used aftermarket wheels" thread thats going on right now.
What about all the people running thorstens race alt with such great results? They have greatly reduced not only the mass but centralized it as well... I am thinking mine wouldn't be as great of an end result but surely would add something? I havent found any negative reviews or results with thorstens race alt, but then i havent found anyone who has done it themselves (removed mass from flywheel) save for the quote you offered from wingnut

here is a side by side pic of thorsten vs stock... my desire is somewhere in between....



Thanks for weighing in on the subject stunna

if anyone cares this seems like a q that hasent been answered definitively here...

Ref
http://www.speedzilla.com/forums/rc51-technical-discussion/40276-flywheel-lightening.html

http://www.speedzilla.com/forums/rc51-technical-discussion/52337-lighter-flywheel.html

http://www.speedzilla.com/forums/rc51-technical-discussion/48412-rc51-flywheel-modication.html

http://www.speedzilla.com/forums/rc51-technical-discussion/24864-racing-fly-wheel-clutch-kit.html

http://www.speedzilla.com/forums/rc...306-thorstens-superlite-alternator-rocks.html
 

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The ONLY Neg. thing I have heard\Read is that this mod. is No good for a street machine,:( You know why, cause we
are having to run Headlights, and blinkers and the like.. min. 3500 RPM's just not to go into running off the battery!:banghead That would
kind a suck sitting at a traffic light..
Now IF my RC was a track only MC, I would definitely do this mod.!
 

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Good point about the thorsten mod, but his is a replacement not a modification of the OEM unit right? It sounds like Mikstr is the only person who has ever run a modded OEM unit:
"I picked up a used flywheel for my VTR and had it lightened and balanced by Roger Ditchfield of Revolution Racing in the UK (built some race VTR's in the late 90's and did some R&D on VTR for HRC and Moriwaki) and it really changed the bike. It picks up revs much more quickly now, a noticeable improvement, with no downsides to speak of (have had it on for about 40,000 kms now)."

I think hung had a great question in one of those threads:
"But if i mod the flywheel to lighten it, can I use OEM Rectifier?"

I know that guru-lou would have some good insight in regards to this question as he told me something about not being able to run a lightenened flywheel with certain motor modifications like lightweight con rods.

Maybe the HRC version is made out of a different material?

Stunna
 

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If We could run a "lighten flywheel" and keep our charging system as OEM,> I would love to do this mod., I sure wish I knew
more about electronics and such..

Can someone explain WHY this isn't possible, like with Thorstens set-up... I'm guessing it MUST have something to do with the dia. of the fly wheel
to charging system ratio one way or another..?

Also StunGun... I'm pretty sure Thorsten Lighten flywheel IS a\our OEM flywheel, which he then machines the crap out of:woot: ... However, I could be wrong...? ;)
 

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Discussion Starter #11
The ONLY Neg. thing I have heard\Read is that this mod. is No good for a street machine,:( You know why, cause we
are having to run Headlights, and blinkers and the like.. min. 3500 RPM's just not to go into running off the battery!:banghead That would
kind a suck sitting at a traffic light..
Now IF my RC was a track only MC, I would definitely do this mod.!
My bike is only for meeting up with my friends who like to RIDE, breaking every speed limit i can around every corner of ca hwy49 happily dragging knee when required ;)

I understand the electrical concerns , im only taking off material from the aluminum outer of the flywheel... why would this effect electrical output? I am thinking as long as the magnets are unaltered this should be fine. Am I wrong?


Stunna,

Mine looks the same as that hrc down to the cnc lathe marks... maybe mines a hrc (but i doubt it)

You are correct that thorstens is a complete swap. Another of its advantages is how it centralized the mass to reduce gyro efect. Obviously I can only reduce the weight by modding my stock but after reading budafm's posts I am lead to believe this is the right path.

My point is that I would like to shave a lil and get closer to the weight of the race alt without losing my ability to charge normally. I am hoping that this is an option :banghead

I will be doing my clutch basket as well later on with the primary drive gears leaving my cam silencing gears intact only on the gear drivce and actual cam... but thats another thread for the future for now lets talk flywheels!!!

Who has done this and will chime in... i guess ill be the space monkey if that what it comes down to :rockon

I cant understand why every other big twin benefits from this mod and some people are saying it wont be beneficial to the rc?
 

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My bike is only for meeting up with my friends who like to RIDE, breaking every speed limit i can around every corner of ca hwy49 happily dragging knee when required ;)

I understand the electrical concerns , im only taking off material from the aluminum outer of the flywheel... why would this effect electrical output? I am thinking as long as the magnets are unaltered this should be fine. Am I wrong?


Stunna,

Mine looks the same as that hrc down to the cnc lathe marks... maybe mines a hrc (but i doubt it)

You are correct that thorstens is a complete swap. Another of its advantages is how it centralized the mass to reduce gyro efect. Obviously I can only reduce the weight by modding my stock but after reading budafm's posts I am lead to believe this is the right path.

My point is that I would like to shave a lil and get closer to the weight of the race alt without losing my ability to charge normally. I am hoping that this is an option :banghead

I will be doing my clutch basket as well later on with the primary drive gears leaving my cam silencing gears intact only on the gear drivce and actual cam... but thats another thread for the future for now lets talk flywheels!!!

Who has done this and will chime in... i guess ill be the space monkey if that what it comes down to :rockon

I cant understand why every other big twin benefits from this mod and some people are saying it wont be beneficial to the rc?



Yeah mang., I was talking about Thorsten's Flywheel with reguards to the charging system.;) His is so modded it takes 3500 rpms
just not to run off the battery!

+1 with You, I don't see why it wouldn't work, with how you're talking about doing it.. Other then the amount of weight will be very
small compared to Thorsten's;)

As far as it not working on the RC51... I thnk someone is feeding You some BS because, we've acouple guys here you race RC51s,
who have this
mod. who HIGHLY recommend said mod.!
I just can't remember who:banghead
 

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I bought one of Thorstens race alternator setups about 5 years ago and ran it for 3 while my bike was track mainly with a bit of road work. There is a big weight loss but the most benefit comes from the reduction in diameter and the loss of mass from the perimeter. If you are going to machine the flywheel I would make sure that you don't reduce the magnetic field as I think the whole steel assembly is magnetized.

As far as the benefits of Thorstens alternator go, it does help with turning the bike but the loss of power makes it unuseable for road use. I got just enough charge out of it for the track. One thing also to remember is that these big twins need a decent amount of cranking speed to start. The heavy flywheel smooths out the compression loads and keeps the starting speed constant. If you have one of the small batteries then starting can be a problem. I had lots of issues getting mine to work properly. The steel bolts around the edge ofthe flywheel Thorsten uses to trigger the crank sensor where set to the wrong height so there was no signal when cranking. The rectifier/regulator I got from him also didn't work so I had to build my own. His system is two phase rather than three phase so most dirt bike regs will work if you need one.
 

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Great info, especially the part about the flywheel assisting in a smooth easy start.

If Damon Stewart could read this, I would assume he could shed some more light on the specific details of the electrical side of this question.

I bought one of Thorstens race alternator setups about 5 years ago and ran it for 3 while my bike was track mainly with a bit of road work. There is a big weight loss but the most benefit comes from the reduction in diameter and the loss of mass from the perimeter. If you are going to machine the flywheel I would make sure that you don't reduce the magnetic field as I think the whole steel assembly is magnetized.

As far as the benefits of Thorstens alternator go, it does help with turning the bike but the loss of power makes it unuseable for road use. I got just enough charge out of it for the track. One thing also to remember is that these big twins need a decent amount of cranking speed to start. The heavy flywheel smooths out the compression loads and keeps the starting speed constant. If you have one of the small batteries then starting can be a problem. I had lots of issues getting mine to work properly. The steel bolts around the edge ofthe flywheel Thorsten uses to trigger the crank sensor where set to the wrong height so there was no signal when cranking. The rectifier/regulator I got from him also didn't work so I had to build my own. His system is two phase rather than three phase so most dirt bike regs will work if you need one.
 

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i believe a solid disk has a lower rotational inertia than than of double radius setup, like the picture below to the left. for two flywheel of equal mass, it would be beneficial to centralize mass, but having the "spokes" with the outer radius might defeat the purpose. the moment of inertia for a solid disk would be 1/2mr^2, whereas, the moment of inertia for the outer ring would be 1/2m(r1+r2)^2, where r1 and r2 denotes the inner and out radius of the ring. get a second fly wheel and try it both ways, i'm curious as to which will work better! cheers


Looks identical to my stocker:wtf

What about all the people running thorstens race alt with such great results? They have greatly reduced not only the mass but centralized it as well... I am thinking mine wouldn't be as great of an end result but surely would add something? I havent found any negative reviews or results with thorstens race alt, but then i havent found anyone who has done it themselves (removed mass from flywheel) save for the quote you offered from wingnut

here is a side by side pic of thorsten vs stock... my desire is somewhere in between....



Thanks for weighing in on the subject stunna

if anyone cares this seems like a q that hasent been answered definitively here...

Ref
http://www.speedzilla.com/forums/rc51-technical-discussion/40276-flywheel-lightening.html

http://www.speedzilla.com/forums/rc51-technical-discussion/52337-lighter-flywheel.html

http://www.speedzilla.com/forums/rc51-technical-discussion/48412-rc51-flywheel-modication.html

http://www.speedzilla.com/forums/rc51-technical-discussion/24864-racing-fly-wheel-clutch-kit.html

http://www.speedzilla.com/forums/rc...306-thorstens-superlite-alternator-rocks.html
 

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Hi,

i have a lighterned OEM flyhweel...
Works great since 4 years with a tuned engine... Battery charging is ok!
Handling is great, but i have thorstens clutch basket and hyperplates ( and other parts with less rotating mass ) so i can tell nothing exactly to the flywheel.
I think the wight is about 1550g to 2220g

Regards
 

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Discussion Starter #19
Hi,

i have a lighterned OEM flyhweel...
Works great since 4 years with a tuned engine... Battery charging is ok!
Handling is great, but i have thorstens clutch basket and hyperplates ( and other parts with less rotating mass ) so i can tell nothing exactly to the flywheel.
I think the wight is about 1550g to 2220g

Regards
so you removed about a pound and a half!:rockon
Thanks a ton this was the kind of info i was looking for :rockon if only i was lucky enough that you had pics of your flywheel...

I plan on throwing my clutch basket and primary on the lathe as well to lower that recip mass, prob not as light as yours. I do plan on running the hyper plates as well...

anyone else running an oem lightened flywheel? how far did you go?
 

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so you removed about a pound and a half!:rockon
Thanks a ton this was the kind of info i was looking for :rockon if only i was lucky enough that you had pics of your flywheel...

I plan on throwing my clutch basket and primary on the lathe as well to lower that recip mass, prob not as light as yours. I do plan on running the hyper plates as well...

anyone else running an oem lightened flywheel? how far did you go?
Hi,

sorry, but i can make no pics... I had to know this three month ago... I had opened my ACG cover...
BUT i have found a photo on an other message board,
hope that helps you...
But notice, you have balance the flywheel after lighten.

Regards
 

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