125sm seized spark plug

[LeeHenry]

My spark plug was seized. I have a coolant leak and it may be leaking into the cylinder. I sheered the threads off the spark plug but everything else came out. So now I get to remove the cylinder head to try to get the remainder of the spark plug out.

Can someone tell me the torque values for all the bolts when I start putting it back together? What gaskets am I likely to need? Is there anyplace in the USA to get the parts or will I need to get them from the UK?

Has anyone done this before and can offer advice? Specifically, how do I make sure the timing is correct when I put it back together? If I mark the cam sprockets and chain will that be sufficient when putting it back together? Can the chain slip on the crank sprocket after I get it off the cam sprockets?

Lee Henry

[keithcross]

Dont want to state the obvious, but have you thought of buying a workshop manual. They arent to expensive.

Keith

[DAVID THOMPSON]

tool to lock crank at tdc needed
tool to set cam timing needed
new head and cylinder base gaskets
good machine shop to repair head
and shop manual
warning when taking off right engine side cover lay bike on side
so you find the oil pressure spring
give me some time and i send you a direct email with info
in it ar dave

[keithcross]

Went to BSA Regal yeserday as I was in the area and met Phil. Nice guy. He took me for a tour of the stores and the amount of MZ spares is pretty impressive.
For your info he had 5 top end gasket sets for the 125 models in stock yesterday.

Keith

[cat]

Went to BSA Regal yeserday as I was in the area and met Phil. Nice guy. He took me for a tour of the stores and the amount of MZ spares is pretty impressive.

Not many places/people would give you a tour.

[LeeHenry]

Thanks to the info I have received so far, I have made good progress. I have ordered parts and a shop manual from Phil. Unfortunately, it looks like I will receive the parts during or just after my next race.

The cylinder head has also been removed and taken to a mechanic. The spark plug threads where rusted in pretty good so it looks like they are going to drill it out and repair the threads. It looks like one of the water jets was leaking into the cylinder.

Does anyone know the head tolerance? I'm not surprised that the cylinder head is slightly warped. I finished my last race with almost no water left. I would like to have the cylinder head ready to be replaced when the manual and parts arrive, just in case I get them before I leave for the races.

Lee

[cat]

Race? ! You race a 125SM ?

Use anti-seize on the spark plug.

[Drew]

Thanks to the info I have received so far, I have made good progress. I have ordered parts and a shop manual from Phil. Unfortunately, it looks like I will receive the parts during or just after my next race.

The cylinder head has also been removed and taken to a mechanic. The spark plug threads where rusted in pretty good so it looks like they are going to drill it out and repair the threads. It looks like one of the water jets was leaking into the cylinder.

Does anyone know the head tolerance? I'm not surprised that the cylinder head is slightly warped. I finished my last race with almost no water left. I would like to have the cylinder head ready to be replaced when the manual and parts arrive, just in case I get them before I leave for the races.

Lee

Lee,

Sorry to hear about the issues you are having with the head.

SFMoto (415-255-3132) is who I usually deal with for parts. They get the parts direct from MZ in Germany, and they will ship to you. I got my service manual from them for ~$45. Best money you can spend, btw! Everytime I've ordered from those guys, the order was usually in my hands in 5-10 business days.

The tools to lock the piston at TDC, along with the tools to set cam timing can be had from Ksport motorcycles.

Don't forget you'll need a Torx E10 femal socket for the head bolts. These are hard to find, so I'd expect it would be better to get via an internet order.

[DAVID THOMPSON]

Torx star E10 female socket for the head bolts

try Auto Zone my local store had it in a set of 4 or 5

but my engine has them on valve cover and an 8mm or 5/16 open end
does the trick my head has regular nuts ?? under the cams

be sure to use white lithium grease when remounting the cams

so they do not run unlubed till engine builds oil pressure

[LeeHenry]

Yes, I race my SM125 in CMRA. It is a blast but I'm still in the learning curve for finding parts.

I received my parts from BSA Regal on Thursday. I spent the morning putting everything back together. The bike seems to be running fine. I was worried with a coolant leak. I didn't know if the bike had overheated. I guess time will tell if the leak is fixed. But I now have a new head gasket and the valves and timing has been checked.

Thanks to everyone who helped with pictures and advice.

Lee

[cat]

Good luck!
You're lucky to have a class you can race the 125 in. Is it stock, no hot-up stuff?