Hi,
just to explain I have a reasonable mechanical ability but the CRM is the first 2 stroke I have been mechanically involved with.
I suspect that my engine may have seized whilst I was on a trail ride yesterday.
The bike had been standing for approx 10min restarted, stalled, stiff on the kickstart, I checked for neutral incase of drag,kickstart was then locked. This was in the middle of nowhere at the furthest point of the ride from my trailer.
Luckily(it didn't feel it) there was a stretch of muddy down hill.
At the bottom on more solid ground I tried the kickstart again then tried a slow bump and the engine seemed loose. Kickstarted and ran fine.
As I said I was at the furthest point, so decided after a getting onto tarmac to continue the ride as there was nothing to lose.
It then ran faultlessly for over 100 miles of sometimes extreme trails.
I am tempted to bury my head in the sand but I need to have confidence in the bike.
I have taken the exhaust off and the one side of the barrel and the opposite side piston I can see look OK.
Now the questions.
Is it possible to check the little end bearing through the port?
The bike is running well is it likely that it still would be if there was something seriously wrong?
Should I just bite the bullet and take the head and barrel off?

Thanks

It is very likely that you did seize it but not very badly. I've had a couple of 125s seize on me leaving very little trace on the piston except for pinching the rings.

If it runs OK now than you probably caused a minimum of damage but you can't be sure it won't happen again - this time worse .

I would take off the head and barrel for a decent look - maybe you just need some very fine emery paper and put it back together .

The major concern is why did it happen . Take a look at the plug and see if it is running a bit lean. Is this the 'new' engine you were asking about the electrical connections . If so it might need slightly different jetting and going up at least one for pilot and main would be a start . Probably start at two up.

I agree with KNM1 - take the head off and check it out you will most probably find (hopefully just) some minor damage. I had a RD350YPVS that 'heat siezed' and although it ran fine for the rest of the journey home and few additional local trips when I took it apart it did have some scoring. It is better to do now than to have the bike let you down later on and have more severe damage. Take this as a warning that something is not right with your jetting.

Sorry Eddie, could you just clarify for me, was the bike ticking over for 10 mins? or just standing while you had a breather?
Had you been through any seriously deep water, at speed, and possibly, cooled the barrel quicker than piston and internals ect.Is the filter,or was it wringing wet.?
Has the kick start ever given any grief. It may be worth draining the oil down to check for contaminants in the oil.
You could also check the plug, does it show signs of weak running, i.e. whitish colour.
Start the bike and get it warm, then put a new, cheap , BR8ES plug in and allow the bike to idle on that for a while, and then check it's colour.
What plug do you normally run?
Have you access to a compression tester? this would tell you if the bore/ piston / rings had suffered significantly.
Have you had to alter the tick over recently, specifically, to lower it? this might indicate a weakening of the pilot mix.
Of course the advice given by the other guys is belt and braces, and best practise.
Mike

Where would we be without you Mike .

Thanks All
In my heart I know that it did seize and I was extremely fortunate to get out of where I was and even more so to complete the ride.
Yes it is the engine that my previous post was about.
It is a Mk2 bottom end and my original Mk3 top end.
The little end on the original Mk2 top end had disintegrated.
I am already running very big jets in the original Mk3 carb.
160 main and 50 pilot and it is running rich.
The cause is the worrying thing as it had been standing for approx 10 min. Fired up and stalled immediately. Now if it had seized when I was revving it to get moving in a bog as I had been before and after the event then it would make a bit more sense.
I think you might have struck something there Mike as just before stopping the bike I had been through a very deep water filled rut, hence the quick stop to take photos.
I run the BR8EV plug.

Could be right and just a cold seizure. If you know it's running rich then that puts that theory out . Could be a rush of cold water ona cooling barrel and warm piston .

I would still take at least the head off to assure myself of the damage/or lack of.

Oh dear, if she's had a drink out of a puddle, then that's a definite strip down , man that must have been some rut, their normally good for a couple of foot of water .
Mike

So Mike what you're saying is it could be water through the carb

knackeredMk1 wrote:So Mike what you're saying is it could be water through the carb

possibly, via filter, it's not unheard of, but the wet air filter would be the clincher, gritty puddle water
It's only a possible though.

Sorry.
I should have made it clear. The air box was dry, it was one of the first things I checked at the time as I have experienced water causing hydraulic lock before.
I switched the engine off immediately after going through the deep water. It is possible that the barrel with its cast liner would have continued to contract faster than the piston.

That is a possibility, more so if she had been working hard prior to submersion, it was quite common on the old air cooled stuff, less so with, water jacket bikes [ see i didn't cooled there] but it does still happen from time to time, just unlucky if that is the case, as their ain't one of us that ain't put our bikes through deepish water at some time or another.
Mike

My KTM125EXC seized twice after going through water ~1.5 ft. Sorted in the end by increasing the tolerance bore/piston.

Here are a couple of photos to set the scene. The bike had been working hard before it was stopped.
The first shows a bike climbing out of the deep water.

The second shows my bike parked against a tree.

Guys, I've just seen part of the route for the CRM meet up , LT had better get some stock in .
Eddie , do you run a fan on your rad at all?
Cold shock seizure?, it's looking the most obvious culprit.
Mike