125-200cc I seized her again...

Lol. Lucky owner! Cant get much closer than that.

I was running the thick base gasket as usual. Im gonna make sure I have >1mm squish this time.

Do you guys think this was an issue of running lean or would the squish definitly be a factor in this? Ive got some mixed opinions of wether I was running rich or lean. I know for certain the bike would load up after a few mins with good reeds and certainly came down to idle quick. Its a possibility I was lean on top although Motosportz reckons 1.5 turns out on the PJ is reasonably rich! Surely I would have a lifeless top end if I was too lean?

Thanks for all the input so far guys

Squish is a factor but the timing is what causes detonation in my book too far advanced.
But it could be a combination of squish and timing.
Kelly lives lectron so his words gospal on that subject.
Just get the squish to happy level strobe engine to get timing right then sus out jetting change everything at once and you wont know the true cause of the issue.

Squish will certainly be set for upwards of 1mm this time. I always use the thicker of the two base gaskets in the Mitaka rebuild kit and have no problems (with mitaka pistons mind you)... Is it possible that the Wossner piston was of significantly bigger spec and made for a small squish?

People talking here about a cold seizure, yes the piston showed a four corner affair but I was well on my way maybe 25 minutes into riding...

Is it also possible for timing to go out? I dont have access to a strobe so I can't really check...

Bad luck there mate.
Ive had detonation but never had anything look like that .
I like to pull the head off after the bike has been run in and very now and then to have a look at top of piston .
Easy to do . Drain coolant and remove a couple of bolts and its done.
Will show whats happening - especially if there are any strange noises

Yeah ill be doing regular checks in future!

Harley
When I first started useing the Lectrons I was out 3 to 4 turns on the pj, even when useing the ms3 rod I was around the 2 turn mark, The settings you will see others useing on here are to lean for us in the UK, My friend Trigs 125 runs a 36mm Lecron with a ms3 that has been ground slightly richer and the pj is set at 1 1/2 out, runs like a rapped ape, not a dribble of spooge.
My 165 sufferered a fair bit of detonation till Walt the super star came up with a lower compression head and it now runs perfectly but still needs to be richer than all other peoples settings.
And yep I locked this up - Started to detonate slightly pulling up a hill and nipped up instantly,Heres the piston from that episode.

one of the reasons i like to jet the way i do. make it four stroke! then back it off. if you cant make it four stroke with the power jet you need a bigger first number on your rod.

So to get set up on top i wind pj all the way in then progressivly back it out?
Bottom took 1/2 turn leaner from factory and ive not messed with it since.

i guess the point would be "you wont know you are rich enough until you are too rich." then you back it off a bit...its right there on a lectron, tune it! they dont seem very picky tho. the lectron will run ok over a surprisingly broad range, almost to a fault it seems!

This is what I want to do this time, I really can't afford to be running even remotely lean again third time around. I managed to get my idle and snappyness real nice on my last adjustment so I think I may only go a tiny turn richer on the rod, if any. I will however be maxing out the PJ like you say.

When you say "make it fourstroke" though, what do you mean by that, like would that be a sound?

EDIT: I just looked up some youtube videos

yup, a "rich condition". the husqvarna chainsaw manuals like to use that term when jetting. be careful leaving the rod lean too, and driving around part throttle. all you will be driving around on is that " crisp" rod setting..be careful chasing crispness on a 125..
make sure you dont max out the powerjet right away, just go quarter turns and test for awhile..if it runs the same or better then go another. look in the last page of your lectron manual, a quarter turn is 1-2 main jet sizes. 1/8th turns will get it dialed in right!
just a fyi, i do the rod the same way. when its too rich the bottom end gets a rich hesitation (breaks up). i get it there then lean it a quarter turn to get it crisp. altho im tuning a 360, if it isnt hesitating, its crisp! not much in between there...
im by no means an expert, just seem to have good luck jetting..

Those piston pics are ridiculous. They should come with a disclaimer stating "DON'T DO THIS. If your motor sounds like it's full off ball bearings.... STOP".

Ok guys so parts arrived and ive put the thick gasket on to see what squish will be like. I have some solder thats just a hair over 1mm and ive put a line of this on the head to have a look. It seems the solder has JUST been touched - leading me to think squish must be pretty much 1mm.

Im thinking now though when this thing heats up will that shrink any? If I also put the thin gasket on will this create a squish too big?

This is one of the best "why did my bike blow up threads" I've read. All good info and nobody is trying to sell their favorite brand of mix oil. This one looks to me like a combination of things led to the seizure, too cold isn't one of them. I'll ad some general rules of tuning which are somewhat covered in the above info but maybe not obvious.

A lean mixture is more likely to detonate especially if the octane is barely adequate or the timing is too advanced.

Pre-ignition caused by too much advance, too hot of a spark plug or by hot spots on the piston is similar to detonation in the seat of the pants feeling you get while riding and can lead to excessive heat and then detonation can occur.

Too much advance especially in the mid-range when matched with a lean spot in the fuel curve can quickly detonate a piston. One or two degrees timing can be the difference between detonation and peak power especially when the fuel is marginal.

A 110 race fuel is more forgiving then say a 95 octane in instances when the timing is too advanced or mixture is too lean.

The piston skirt is not round when cold but becomes more round as it heats up. When the piston gets too hot for what ever reason it will grow beyond what it was engineered for and that is why an overheated piston will usually scuff the sides of the skirt first. When the piston is at the ideal temperature the center of the skirt is taking the load but when it gets too hot it will over grow and the sides of the skirt will begin to scuff.

As a general rule if the cranking compression is near the 200 psi mark you will need a 100 octane or better fuel.

A lesser octane can be used by "de-tuning" which basically amounts to retarding the timing, going richer on the mixture and increasing the squish. Doing any or all of these will help save your engine if you must run marginal fuel.

All the above are perfectly correct but Im betting my left nut on the lean and to tight squish being the culprit.
Harley if you keep your settings you have been useing - ride along at 1/8 to 1/4 throttle then whack it flat out, my left nut says it will just go WHAAAAA and die, So then you will richen the rod to cure the lean condition and as a trade off your idle will now be awfull as its now far to rich and your left scratching your head on where to go next and untill you fit a MS3 rod you will not get it perfectly right.
Kelly gave me some great advise on grinding my first rod and as luck would have it it came out spot on, So much so that I have ground another couple of MS3s very slightly richer than they come from Kevin at Lectron, Gives a real strong mid range over the MS3 but the MS3 is perfectly all right for most people I just got carried away looking for more and found it.
In my testing with the Lectron I came to the conclusion that the PJ comes on well early in the rev range so it some what affects anything from the mid upwards, You only have to blip the throttle to see fuel start to move up the PJ tube so in one of my moments of madness I made some different tubes to test and have ended up with one that only protudes into the carb bore around 4mm, The benifits are that the PJ comes into play way later and at higher revs only but you need a richer rod for this to work as the mid range will be to lean.
I can go play in the woods for hours playing trials rider and deliberatly do everything possible to make the motor load up and its totaly impossible Leave the woods and go for a flat out blast down the lane and there is no clearing out - next to no smoke even at 32.1 and not a single tiny bit of spooge yet if I pull the plug out it shows if anything a tad to rich.
Where in the UK are you ? If close ish I could have a look at your setup for you if you get stuck.

Hes in Ireland.
Im in gloucester tho

I'm with you johnnyboy on that point. Looking at what everyones saying and my own learning I have obviously been too lean and too much of a newbie to even know what detonation was! As for the squish, i'd like to blame the piston. When I first learned of the squish band/clearance I measured my current setup out of curiosity - pretty sure I was around 0.8mm to 0.9mm. Bearing in mind I'm just comparing solder to a ruler with good eyesight. The solder is a hair over 1mm and looked obviously squished. Same test this time with Mitaka thick gasket and Mitaka piston showed the solder was JUST touched, leading me to believe im at 1mm squish. Again, not accurate testing but definitely bigger clearance than before. And I still don't know what it should be. I'm thinking if I put the slim gasket on too the clearance will be huge.

Looking at the box of the Wossner today I also noticed it was labeled Honda CR125...

Regarding the metering rod, don't even talk. I paid £75 customs on top of the price of the damn Lectron + shipping so I am really hesitant to buy any more nice things from the US. Before even putting anything together today I adjusted the rod a quarter turn richer, set my idle for 1.5 turns out and turned the PJ to 3 full turns out. Started up without choke as normal and idled reasonably close to 2100rpm. Blipping the throttle the engine/power sounds good and comes back down nicely. Obviously as you say though ill probably run into these problems when I get out on it.

Gonna look into my options on getting an MS3 - would I be right in thinking thats also known as the 3-1M? I have the 3-2M currently.