Engine problem

Ge4orce · Two Stroke Sniffer Joined: 14 Oct 2004 Karma :

Hey my Yamaha xtz 125 is giving me sleepless nights.The problem is something with the engine or the carburetor.I have took the bike to the yamaha dealer and the mechanic has fiddled with the jets and the carb settings but it still won't fix the problem.The bike pulls ok in 1st,2nd and 3rd but wheen you go into 4th and 5th and give it full throtlle or nearly full throttle it justs keeps on missing.It misses espescially on the low to midrange and after it stops to miss its has no top end power.The mechanic suggested that the piston rings may have been damaged.I just wanted to here if any of u guys might know what the problem is
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Honda is the best

ms51ves3 · Super Spammer Joined: 08 Jun 2007 Karma :

When you saying missing do you mean misfiring?

Ge4orce · Two Stroke Sniffer Joined: 14 Oct 2004 Karma :

Yeah sorry I mean misfiring.I don't actually speak English so I don't quite know all the terms in english
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Honda is the best

ms51ves3 · Super Spammer Joined: 08 Jun 2007 Karma :

Ge4orce · Two Stroke Sniffer Joined: 14 Oct 2004 Karma :

Yes the spark plug has been changed.I don't think the plug cap has been replaced
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Honda is the best

cestrian · World Chat Champion Joined: 24 Jul 2006 Karma :

So it's OK in 1st, 2nd and 3rd.....is that at full throttle in those gears?

Higher gear + full throttle = heavy load.

Heavy load + weak spark = possible misfire.

I suggest cleaning all the connections in the ignition system. Can't do any harm can it?

Ge4orce · Two Stroke Sniffer Joined: 14 Oct 2004 Karma :

Yes that is at full throttle in those gears.I will clean the ignition and replace the spark cap
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Honda is the best