PX221 - Snap chat
Post Reply    Forum -> Not-So-Modern Previous12
Author Message
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6500
Location: Victoria, Australia
Fri Nov 09, 2018 7:50 pm quote
From time to time I'd have a lot of difficulty starting, and that's why I used the drill. Sometimes there would be a mismatch between speeds when the motor fired it felt for a second like it was going backwards. That's where I think the extra stress came in... basically using the drill to try to stop the flywheel (intermittently for a very short time), so that stress would presumably be felt at the junction of flywheel and crank. That's my theory anyway, doesn't explain yours!

The only info I have on flywheel weight is not to use anything much more than 1.6kg with a Mazzuchelli bell crank, but I think you were staying with rotary?
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Sat Nov 10, 2018 7:37 pm quote
I would imagine misfiring had a lot to do with your break. Not so sure why mine broke though. I ride quite hard but all smooth. I can only think there was a micro vibration issue. It broke while cruising along. It does rev quite violently and had a 1.9kg flywheel, which may have been a bit heavy in hindsight. Sure this is it.

I don't think the general 200 flywheel guidelines have changed for decades, 2kg flywheel for touring, 1.6kg flywheel for road and 1kg flywheel for track.

As the flywheel weight doesn't affect the max power very much, it would seem the decision is made. 1.6kg it is.
Hooked
Honda elite
Joined: 19 Jun 2007
Posts: 307
Location: California
Sun Nov 11, 2018 12:10 am quote
Jack221 wrote:
I would imagine misfiring had a lot to do with your break. Not so sure why mine broke though. I ride quite hard but all smooth. I can only think there was a micro vibration issue. It broke while cruising along. It does rev quite violently and had a 1.9kg flywheel, which may have been a bit heavy in hindsight. Sure this is it.

I don't think the general 200 flywheel guidelines have changed for decades, 2kg flywheel for touring, 1.6kg flywheel for road and 1kg flywheel for track.

As the flywheel weight doesn't affect the max power very much, it would seem the decision is made. 1.6kg it is.
taking note of flywheel guidelines;

How much do PK flywheels weigh?
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Sun Nov 11, 2018 7:08 pm quote
What has been said here only applies to PX200s. The PX has the clutch on the other end of the crankshaft and a PK has just a tiny cog. The PX needs more weight to stop it shaking itself to pieces.
PKs (smallframes) can get away with much less flywheel weight. Others know way more than me about those.
Hooked
GS160, V50R
Joined: 11 Jun 2014
Posts: 251
Location: Åland
Sun Nov 11, 2018 11:57 pm quote
I believe PK flywheels fit, actually think I use one. 1,8 kg?

Might be wrong, it has haoppened.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6500
Location: Victoria, Australia
Tue Nov 13, 2018 6:02 pm quote
Vespoholic wrote:
I believe PK flywheels fit, actually think I use one. 1,8 kg?

Might be wrong, it has haoppened.
They do fit and people do put them on, but the keyway is in a different position than the P stators require.
Enthusiast
1984 PX(177)EFL
Joined: 14 Apr 2017
Posts: 96
Location: Cornwall UK
Tue Nov 13, 2018 11:50 pm quote
There's the 1.8kg dual key PK/PX flywheel:

https://scooterlab.uk/dual-keyway-vespa-pkpx-lightweight-flywheel-news/

https://www.sip-scootershop.com/en/products/flywheel+sip+touren+for+vespa+_51003000

Jack, I wonder if your image shows corrosion around the keyway, which prevented the two tapers from meeting fully, and concentrating the torsion forces around there, where they would bind, rather than along the full length. Any high spots and you'll still torque up, but not be completely pulled on to the taper. Just a thought from taking my flywheel off outside in the rain so many times this year.
Hooked
GS160, V50R
Joined: 11 Jun 2014
Posts: 251
Location: Åland
Wed Nov 14, 2018 12:00 am quote
Ginch wrote:
Vespoholic wrote:
I believe PK flywheels fit, actually think I use one. 1,8 kg?

Might be wrong, it has haoppened.
They do fit and people do put them on, but the keyway is in a different position than the P stators require.
Yes, I've got the dual keyway type.
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3562
Location: San Diego, CA
Wed Nov 14, 2018 7:32 am quote
Vespoholic wrote:
Ginch wrote:
Vespoholic wrote:
I believe PK flywheels fit, actually think I use one. 1,8 kg?

Might be wrong, it has haoppened.
They do fit and people do put them on, but the keyway is in a different position than the P stators require.
Yes, I've got the dual keyway type.
Yes, this is what I just put on my P as well. The slot timing was a tiny bit off, I did have to retime my stator a smidge. And no, I didn't use the wrong keyway, that would have been a much bigger change .
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Wed Nov 14, 2018 6:58 pm quote
sime66 wrote:
There's the 1.8kg dual key PK/PX flywheel:

https://scooterlab.uk/dual-keyway-vespa-pkpx-lightweight-flywheel-news/

https://www.sip-scootershop.com/en/products/flywheel+sip+touren+for+vespa+_51003000

Jack, I wonder if your image shows corrosion around the keyway, which prevented the two tapers from meeting fully, and concentrating the torsion forces around there, where they would bind, rather than along the full length. Any high spots and you'll still torque up, but not be completely pulled on to the taper. Just a thought from taking my flywheel off outside in the rain so many times this year.
I see what you are getting at and was certainly not helping any. They always seem to go a bit rusty. Something to do with the metals and magnets I guess. Insulating grease either puts them on too tight or too loose. Will need to decide what to do with the new shiny crank when it comes.

The broken off part was still very tight in the flywheel. I think it had been breaking for a while, quite a lot of rub marks on one side of the flywheel, which for this build means its no good. New one will be 1.6kg, so looking forward to that.

How's your set up going? Nice and well behaved trouble free Summer?
Ossessionato
1980 P200E, 1974 Primavera, 04 Ninja 250
Joined: 04 Apr 2013
Posts: 3562
Location: San Diego, CA
Wed Nov 14, 2018 8:22 pm quote
You can always lap it with valve grinding paste if you want a good taper match.
Enthusiast
1984 PX(177)EFL
Joined: 14 Apr 2017
Posts: 96
Location: Cornwall UK
Thu Nov 15, 2018 2:08 pm quote
Ahhh, shiny new bits to play with; what'll be the next weakest point to crack though?
No problems for mine over a great Summer (the beach isn't far though), and safe for the frosty morning runs for a few months now; I'll update in New Year.
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Wed Dec 05, 2018 12:01 am quote
Home soon. Parts ordered
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Tue Dec 11, 2018 5:05 am quote
We have progress.
All stripped down and washed. Good news is the casings are no more battle damaged than they were. Less good is the Crucifom is prematurely worn out. Didn’t order a new one as I was expecting it to be fine. What a mistake that was. I don’t think this double hard one has lasted any better than the Piaggio one. Won’t be wasting money on another hard one.

Nice shiny crank to put in and a 1.6kg plastic flywheel. Going to do some slight dremel work on the cylinder and change the packer to raise the transfers a tad. Just wan't a few more rpm in the porting to match with the lighter parts. Hopefully no more than 9000 rpm in gear but we will see.

mj9.jpg

Enthusiast
1984 PX(177)EFL
Joined: 14 Apr 2017
Posts: 96
Location: Cornwall UK
Tue Dec 11, 2018 5:51 am quote
That's disappointing; how many miles did you get out of the hard crux? You can buy three Piaggio ones for your £60, and it's less damaging on the loose gears – are they all still OK for this build?
I note you say these casings are battle damaged, so another build will be on the cards soon anyway I imagine – a standard crux will probably last between rebuilds!
Molto Verboso
1979 P150X, 1983 P200E, 1996 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1183
Location: Veria, Greece
Tue Dec 11, 2018 10:17 am quote
So, as it turns out, both SIP's and BGM's cruciforms are crap. I wonder if the one by Crimaz is better than these two...
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Wed Dec 12, 2018 2:01 am quote
Gear cogs are fine. All look good enough to go back in. Wasn't jumping gear or anything suspicious. This seriePro one actually didn't last so bad. It did 4500 miles.
The way it failed seems like it was only case hardened. Once worn was as soft as any other.
The Crimaz one is worth a try. And cheaper too.
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 924
Location: London UK
Thu Dec 13, 2018 9:47 am quote
Engine is back in. Not running yet as still waiting for some parts. Busy weekend with real life so should burst onto life again about Tuesday new porting looks good. Dropped compression to 11.2 :1
Pressure test was good even though I had to seal it twice after forgetting to put in the kick-start cog. Yes, I do dumb stuff too.
Just hope she doesn't rev to high.
Land of 10,000 Scoots Rally   Vespa Wasp Pin Badges   Scooter Parts Company
Post Reply    Forum -> Not-So-Modern Previous12
[ Time: 0.2930s ][ Queries: 27 (0.0701s) ][ Debug on ]