Backfire xtz 660 '92
 

I've just completed a overhaul of my xtz 660 ' 92. The bike was running fine but using a lot of oil.
I changed the valves, valve guides, timing chain and piston rings.
I put everything back together and she started first time, tick over is ok, accelleration ok, but a slight backfire when I change down gear or ease off the throttle.

I've checked the valve timing and tappets again, but problem persists.

Any ideas?

Davy

Hi

Would start with a carb clean if you havent done yet. Mine has a slight backfire with open airbox and open system. I have installed a larger main jet and dynojet drilled second card, Plug is ok, a bit rich maybe. But I think it sounds rather nice with the popping sound when enginebraking :). Love the bike, Lots of bike for little money :) .

Chris

Popping is lean on overrun, try turning the mixture screw out half a turn. Esp with mods

Hi Gawain,

Yep, that did it. Pilot screw was set at 1 3/4 turns out, so set it at standard 2 1/2. Runs like new !

Hi Chris,

Yes a good bike for the money, engine is a good allrounder- Ive upgraded the suspension back and frount so I use her for touring, light offroad, commuting. Bad point is the plastic fairings which are crap.

Davy

I have a XTZ660 from 1996. The bike is like new and runing very nice. After fitting an open aftermarket exhaust, the bike on low rpm feel's like a new bike. Much stronger and ready to go. The problem is on high revs, where it seems powerless. IN fact, the maksimum speed is 143Km/h. This is about 20Km/h less than with the original exhaust. Nevertheless, I like the open exhaust, because in normal riding conditions the XTZ feell's much better.
So, any idea what to do with the power on high rews?

Is it the needele posittion, mixture screw ar maybe too small main jet? The air filter and everything else on the bike is stock.

Another question about the main Jet. The Tenere's from 91 to 94 have 48HP, then from the twin light models onward they have 46Hp. Does someone know where have gone the 2 HP? The ony difference I noticed between the two models is the main Jet, the first models had a 130, the lattest 123.