125-200cc Lighten a WR flywheel?

[Idacurt]

Question: I have a WR125,no head light and was wondering if there was a way to lighten the existing flywheel without the expense of going to a CR ignition? Just thinking a slightly lighter fww effect would suit my riding style better.
Thanks for any ideas

 

[Norman Foley]

You can have a machinist put it in a lathe and cut it down, or..... a buddy of mine just drilled a bunch of evenly spaced shallow holes in his Yamaha's flywheel.

 

[CelticDude]

I took my flywheel off tonight and found nothing to turn down, drill or lighten. It is interesting that it doesn't really feel all that heavy.

 

[Idacurt]

What is that big steel washer riveted on the front? is that the weight? I was thinking about turning that down on a lathe a bit?

 

[wallybean]

I took my flywheel off tonight and found nothing to turn down, drill or lighten. It is interesting that it doesn't really feel all that heavy.

Yours is the new Ductati WR ignition. It is quite a bit cleaner and lighter than the old analog unit. I really like the looks of the new ignition compared to the old unit.

 

[Idacurt]

Looking at my flywheel I came to the conclusion my only option to lighten it was to drill holes in the top plate/weight only.I used a micrometer to evenly space location points to drill,Starting with a 1/8" working up to 1/2". All I can say is "Wow" just drilling a few holes made the throttle much crisper and it doesn't seem to load up,lag and then come to life as it did previously.The only terrain I haven't tried it on is the steep gnarly stuff due to the current snow level but on moderate single track terrain I'm all smiles.

By idacurt at 2012-05-11

 

[huskybear]

Looking at my flywheel I came to the conclusion my only option to lighten it was to drill holes in the top plate/weight only.I used a micrometer to evenly space location points to drill,Starting with a 1/8" working up to 1/2". All I can say is "Wow" just drilling a few holes made the throttle much crisper and it doesn't seem to load up,lag and then come to life as it did previously.The only terrain I haven't tried it on is the steep gnarly stuff due to the current snow level but on moderate single track terrain I'm all smiles.

By idacurt at 2012-05-11

What year is your wr? I am thinking of doing the same on my2010 wr144. I think it might help with a jetting issue that I have.!

 

[Idacurt]

It's an 07,I can now stab the throttle and there is no bog/lag like there use to be.

 

[huskybear]

It's an 07,I can now stab the throttle and there is no bog/lag like there use to be.

Sounds good!Thanks!

 

[rockdancer]

It's an 07,I can now stab the throttle and there is no bog/lag like there use to be.

This sounds like a good mod if you dont mind losing some of the luggability
Still no bog issues?

 

[Idacurt]

I have been riding now for over a month like this on tight mountain single tracks and it is perfect for me.I can come out of tight corners now,stab the throttle and I'm off.I found that clutch use is down also.I can see why people switch to the CR ignition but I don't have the $$ to do it and I think this is a good compromise.

 

[Bench Racer 117]

So which holes are the holes you drilled? Its hard to tell what you did. I've not looked at mine so I'm not sure what is stock.

 

[Idacurt]

The bigger circles are the 1/2" holes I drilled,the others are the rivets that hold the weight to the flywheel.

 

[Bench Racer 117]

You did it with the fly wheel off right? They look really clean with a rounded edge. Works well huh? Would you drill more?

 

[Idacurt]

I removed the flywheel and used a drill press.The flywheel is magnetic and the steel filings stick to the drill bit(not good for the bit). Bit needs to be cleaned often and cutting oil was used,Finished cleaning the FW off with compressed air.
I'm happy with the results and decided to stop there.