lineaway

That analogy is flat out silly, I have seen brand new out of the crate bikes vibrate on the side stand!!!!!

The weight really does not matter. What actually started the engine rebuild in the first place?

No, the center cases have to be opened. Top ends do not vibrate. Since you had a loose needle bearing, I would do rod and mains. The bike is 44 years old. The only reason I would take the time to do it is it could go another 40.

maybe 12 point 7mm socket.

Yes you have to take the clutch apart to get to the center bolt that holds it on. After the bolt is removed it just comes straight out, sometimes not easily.

First give the bike a good clean, chances are you are going to split the cases. The video of adjusting the cam on the spring is exactly where to go next. If you are lucky the top hat just sheared the little tab in the end of the shift shaft. Usually it ends up being a new shift shaft. Lucky you.

To clean a carb takes no parts. The carb needs help not parts. Have you ever cleaned a carb?

So have you changed the main bearings? Pistons do not make any vibration. Rods and mains cause vibration.

You should stay off topics that have nothing to do with your old engine. Everything about a ty 250 mono is different from your old bike. We are talking about an engine that came out in 1984, not 1974. And by the way Dannyboi the TY250R had a standard bore of 68. So you would want at least a 68.25.

mid atlantic trials

You should have the piston before it is bored. This seems the easiest solution unless you can find a mono 250 piston 1st or second over. I have seen pistons, but no rings.

I plan on cutting mine out. I ordered a new spring just in case. I have ridden 2 events since I discovered this problem.

I had the same problem the last time I did my seals about 45 days ago. Try about 340cc and call it good till you have time to fix it. I might get around to it myself this coming weekend

You might consider a new OKO carb.

That is the one. Just turn off your gas and lean it over to fill.

I would pull off the exhaust header and take a quick look to see if the rings are now stuck. You will know by how the piston looks.

std bore on the ytz250 is 68. 68.25 would be much better than going to 70mm. Leaving it at 68mm is probably not the best for performance or longevity.

Sure you don`t need a 67.25 or a 67.5. Chances are a thirty year old bike could need a bore. By the way a YTZ250 piston will work.

A hot saw blade vs the plastic insert. The question is will the inserts come off without damaging them? Update, I forgot the insert is actually held in place by screws.

With all the Beta's in the UK you would think someone might have one. I tried a stiffer one and it was just too harsh.

My little boy is 6` 5`` and 230. But, you are above average! I take it you are not in the states?

You got to be pretty big to need stiffer front. So did you already get a heavier rear?

Go to the owners manual for the correct level, not capacity.

Nicked the piston. The rings are now stuck. Pull the exhaust and look at the piston.

I am sure he removed the bolt, which is the detent for the kick start sleeve. Now it has to come apart and be reassembled properly. Which means removing the clutch. People do this all the time. Not reading the service manual before they start removing bolts. Beta keeps this well hidden under the mid pipe. It is not hard to fix, just time consuming. In fact it sometimes can be done just pushing the KS pedal halfway down and ibstalling the detent. But since he opened the case, the whole thing is better off coming apart. Great way to get to know your new bike.