Dropped a cylinder!

[k14]

Racing my bike at the burt munro on Saturday. Go out for qualifying, bike running great, take pole by 1.6s and pretty confident about the days racing. Go to start the bike to form up for race 1 and it is a little hard to start and sounds a bit rough. On dummy grid I notice a bit of smoke so call it quits and go back to pit. Strip bike down and find a plug is fouled. Give it a bit of a clean, start back up but still smoking. Call it a day and come home.

Borrow a compression tester from a mate, cyl 1 90psi, other two are 145 or so, pretty consistent. Not sure what has caused the drop of compression on #1 so only thing to do is drop engine out and take head off. Major signs of scuffing on the bore, not sure what has caused that (ring failure?) but also sign that the piston has been touching the head (left side at around 9 o'clock) and also a small mark where the left side inlet valve has just touched piston lightly. This could indicate something worse, maybe big end?

So next step is strip the bottom end. Oh joy, what fun. Looking at whole new engines or bottom ends. They are fairly common on ebay and in the states. Just a matter of finding some money (hello mr visa), getting one here and fitting it up within the next 6 weeks!!!! Should go back to a 2 stroke, at least ACC pays for the damage they cause when they go bang

[Yow Ling]

Them 3 stroke 12 valves are the devils work !! You need a RD350 .

[kwaka_crasher]

Most likely a broken piston ring although with any head contact perhaps a cracked piston (before or after the broken ring is anyone's guess). Not likely to be big end as that would be making one hell of a knock to give that much float on the piston.

[Kickaha]

Them 3 stroke 12 valves are the devils work !! You need a RD350 .

He's ridden one, he didn't like it, he returned it to the pits a lap later

[CookMySock]

How do you get an engine here from the US? I'm having all sorts of hassles getting mine sorted.

Steve

[sharky]

Call Mr Osbourne and ask for a refund

[marsheng]

Took a while before I realized it wasn't the CB150 !!

Shout if you need a hand.

Are you coming to the BOB ?

If you need goods from the US, let me know. I have a few connections.

Cheers Wallace

[k14]

Took a while before I realized it wasn't the CB150 !!

Shout if you need a hand.

Are you coming to the BOB ?

If you need goods from the US, let me know. I have a few connections.

Cheers Wallace

No I won't be racing again till nationals now, got to buy a new engine so have to save every $$ i can! I am looking at my engine options at the moment but will give you a bell if I need any help!

Stripping the bottom end today/tomorrow so may get an idea what the real damage is soon.

[Toast]

Mate, gutted!!!!! Hope that you get it sorted before Nat's!

[imdying]

So will you need to have the new motor converted, or are the changes something you can transfer from the old one? (i.e. what the heck do they change to make it a 450??)

[k14]

So will you need to have the new motor converted, or are the changes something you can transfer from the old one? (i.e. what the heck do they change to make it a 450??)

Yeah but it is not too hard. Remove all valves, one ring and put a plug in the manifold. Only other thing is rtv the valve guides and you are good to go.

I have bought a set of cases with crank and pistons from the states with 1000 miles on them. Hopefully it arrives before christmas. I can use my old head and should be good to go!

If you want a little more background read this. They are a little more developed now than in the article, mine makes 78hp on a dynojet.

[imdying]

Sick. Typically Kiwi