[Casadykachow]

Ok need some help here klx 110 2010…got this bike as a project. Was told the crank bearing was bad. Bought the 155 stroker and big bored to 143cc. Completed build with vm 26 carb and yx race head I bought on Craigslist. Tb parts clutch cover and it is a full manual now. Bike rips and runs great until it fouls the spark plug so bad it won’t start again. (See attachment) had a lot of small issues but easy fixes. Can anyone tell what is going on here why the bike dies and fouls the spark plug after about 5 mins. I have a 22.5 pilot and a 190 main in right now. If I go down on the main the bike stays running and bogs out at higher rpms. 150 is the lowest I’ve gone but at higher rpm it bogs and doesn’t deliver the power that I get from the 190 main. I assume I’m running rich by the look of the spark plug. Should I be running a richer spark plug. More gap? I’ve tried quite a few different variations with the jets just can’t seem to get this thing ripping like it should. Can anyone shed some light on why this thing won’t stay running and “fluids” it self out?

 

[Tywrex]

It’s definitely fat somewhere, is it bogging anywhere? When riding the bike, ride around with little to no throttle for a while then 1/4-1/2ish throttle if there is any bogging or hiccups in that range on the throttle it has something to do with either your needle or pilot jet. There’s a few good videos on YouTube that will explain this a lot better than I can but if it’s running fine at wide open throttle leave the main jet alone.The pilot jet controls fuel 0-1/4 throttle I believe, the needle controls fuel 1/2-3/4 throttle, and the main jet controls fuel 3/4- wide open. Hope this helps!

 

[L.Holman]

So you have a YX 160 cylinder head on a 143cc big bore kit? If this is correct, then you may have issues. I did a 55mm stroker on my 2003 DR-z 110 with the YX 160 cylinder sleeve and head with a VM26 Mukuni carburetor. Try using a comp piston with the build. that fixed some issues with mine. Another issue could be the carburetor, if you're using a cheap Chinese VM26 then that is more than likely the problem. I started my build with a cheap VM26mm E-Bay special and had nothing but performance issues till I ordered the Mukuni VM 26mm from TBoltusa.com. I also had to use a comp piston for the higher combustion. The YX160 cylinder head is the same as the V1 rase head.