1957 2 stroke timing - any pointers?

[bhh1989]

Pun intended.

I have a '57 Parilla 125 2T and I cannot find the timing degree in any manual I have (I have the originals in Italian, still not there!).  Does anyone have an idea what ball park degree I should shoot for?

Frustrating part is that the flywheel is marked for TDC and for firing, but the markings are on this outer shell on the flywheel which has broken loose over time and will now move freely once the engine is heated up.  The magnets don't move, just this outer ring.. I have to come up with some other temporary way to mark it for a timing light. To add to that, you have to take the shifter, kicker, engine panel AND flywheel off to change the timing. 

It runs, always has, even after I moved the stator plate around and test rode different setups.  I had it running pretty well and was really getting it on it in top gear then it immediately cut out at high speed - I think I may have almost detonated or something.  Instinct had me pull the clutch immediately when it started cutting out and the engine just totally cut out. Checked everything out and it didn't see any any damage anywhere, retarded the timing a smidge and it runs ok but bogs and is slow rev now.  Could be the old plug it has in it, or could be because it got too hot..

[m in sc]

you're over thinking it.

put a dial gauge in it, find tdc. make a pointer to point to tdc mark on the flywheel. then you have your pointer to time at the firing mark. yes, its really that simple. 

btw.. sweet bike. 

[bhh1989]

you're over thinking it.

put a dial gauge in it, find tdc. make a pointer to point to tdc mark on the flywheel. then you have your pointer to time at the firing mark. yes, its really that simple. 

btw.. sweet bike. 

Duh.  You are right.  I really overthink things sometimes...  It's already marked on the flywheel so I need to get TDC, then adjust this flywheel shell back to where it needs to be and then use the existing markers to create a new marker on something else. That will work.

Thanks! I love it, I want it to look just like this but run like a top.  All the way up to 50mph lol.

[John Ritter]

Message me the stroke and your email and I will send you a picture of a printout of the degrees starting at 1* BTDC and up to 25 or 30* BTDC. It is possible to make an educated guess from that point, I may even have an engine file close to give you a starting point. Also if you know the compression ratio, that helps too.  No I can't post a %#!$ picture here, lol, being old sucks.

[bhh1989]

Message me the stroke and your email and I will send you a picture of a printout of the degrees starting at 1* BTDC and up to 25 or 30* BTDC. It is possible to make an educated guess from that point, I may even have an engine file close to give you a starting point. Also if you know the compression ratio, that helps too.  No I can't post a %#!$ picture here, lol, being old sucks.

Hm.. I'll have to do some measurements to figure that out.  I do have a spare cylinder and piston that may help.

[Dvsrd]

FWIW, I have a Villiers 12D, 125cc, early 50s vintage. It is most likely in a much softer state of tune than a Parilla, maybe 5 hp or so, and a 3 speed gearbox. It is also undersquare and a low revver.
The specs for that engine is around 4 mm BTDC, which indeed seems excessive to most of us.

[teazer]

I thought the Villiers D series were all 50bore x 62 stroke.  Whereas the 1H in my first two stroke was 63x72.

According to Miss Google, the Parilla were 54 x 54. Measure the piston and see if that's correct.  If it is, you could do worse than to start with any other soft 54mm square motor.  I would expect it to light the fire somewhat earlier than say an RD250, but it's a place to start measuring from.

[Dvsrd]

I thought the Villiers D series were all 50bore x 62 stroke.  Whereas the 1H in my first two stroke was 63x72.

According to Miss Google, the Parilla were 54 x 54. Measure the piston and see if that's correct.  If it is, you could do worse than to start with any other soft 54mm square motor.  I would expect it to light the fire somewhat earlier than say an RD250, but it's a place to start measuring from.

Yes, both you and I are correct. Undersquare means smaller bore than stroke.

[bhh1989]

You guys have all been helpful, I had a suspicion tuning this thing would not be like a '70's Japanese stroker.  It likely never was much of a screamer.  It actually has a lot of torque for what it is, kindof like the rotary valve Kawasaki's I've had in the past.  High RPM's though, when I have gotten them out of this motor, aren't really "worth it".

If you haven't seen my previous post about this thing, check out the piston.  It's a wacky design.  I'm not sure why they tried this piston pattern (it is correct and OEM).  To my knowledge the '57 was the only year they messed with this idea, toward the very end of their 2T street bikes.  Afterward they largely moved away from 2T's and focused on their 4T's.

[teazer]

Deflector top to direct transfer gas flows.  Makes for a heavy piston and there are better ways to direct gas flow, but back then people were still trying to work things out.

Makes it impossible to get a squish head though..