Questions regarding a CZ125

Hex · Party Boy Joined: 04 Feb 2002 Karma :

Got a friend with a few problems with an old CZ he's picked up.

This things a pre-mix bike and he's been told that it should be a 40:1 mix and it's using a NGK B8HS plug.

Now when running it occasionally stops, the plug though sparking is sparking across to the outside opposed to the electrode.

He's been told his mixture is a bit rich (I've not seen the bike/plug so can't really say, just after a few ideas of things he can look at).

Is the plug the correct one? Is it too hot/cold? Anyone know what it should use and also the gap for the plug?

Also would 50:1 of a modern pre-mix oil work ok on this bike?

Cheers peeps
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

I doubt it is that sensitive to the 2 stroke oil mixture level, but that sounds like a shot spark plug to be, possibly haveing been cleaned up too often with a wire brush (which you should not do as the brush leaves traces of metal on the porcelain and so causes it to short across that).

All the best

Keith
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Hex · Party Boy Joined: 04 Feb 2002 Karma :

New plug, its been through a couple apparently.

Is it the right temp for the plug?

I was thinking its maybe just fowling them up due to oil mix been out, and maybe gap been wrong on it.

Wouldn't happen to know what standard setting for the carb is would you? Don't even know if its adjustable to be honest.
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Skvara · Two Stroke Sniffer Joined: 06 Jul 2004 Karma :

Well if it is CZ there is no need to be precise with mix ratio!!! If you give too much oil, it will be just more smoky. You can give there the cheapest oil!!! Wink

What CZ is it????

Jammy-G · Banned Joined: 17 Mar 2004 Karma :

My friend has a CZ125 bored out to a 160 with high compression and he said he uses a NGK BR6HS.

Not sure if the re-bore would make a difference to the type of plug it needs though.

EDIT- He also gave me this link - might be able to get some good help from there.

https://www.jawa-cz-owners-club.freeserve.co.uk/
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Hex · Party Boy Joined: 04 Feb 2002 Karma :

Skvara · Two Stroke Sniffer Joined: 06 Jul 2004 Karma :

and year??? I've got CZ 175 (1969) and it is good moto, but my NSR 125 R(1999) is much better Smile

JAWA and CZ aren't the same!!! It is quite the same, but JAWA is better in some ways!!!

Hex · Party Boy Joined: 04 Feb 2002 Karma :

1980 think I was told?
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The BCF's very own Party boy! Though he's getting old and feeling it!
Monkey hanger, Born and bred
My little photo portfolio

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Given the comment above about one that was played with using a 6 plug, I would suspect a BR8HS might be a touch too cold.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

Hex · Party Boy Joined: 04 Feb 2002 Karma :

imust bemad · L Plate Warrior Joined: 08 Apr 2006 Karma :

i have a cz125 that i am giving away the frame has been stripped down theres no tank or seat

The engine is in a box stripped down i was going to rebuild it but ran out of time..................oh yeah i have fitted new piston rings and top gasket Laughing

I live in brighton england if anyone wants it

P.S i also have a hayes manual for it as well
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