Tecate up and running again

[tecat-z]

On april 21stwe made our annual spring trip to silver lake dunes in Michigan expecting to have a great day. Well everything went great for about 15 minutes. Then just cruising in 3rd maybe 1/4 throttle my tecate suddenly siezed. Couldn't believe it So when i got home i took it apart to find it looked really lean on plug, inside exhaust, and even on dome of piston. Mind you i had a 52 pilot, stock needle in middle grove and a 190 main on a brand new 38 keihin A.S. carb. Plating was hurt a bit in the process so i had it re-plated again, and of course all new top end components. Got it running last Saturday after i pressure tested the crankcase, and then reversing things and vacuum testing. All was well in that dept. This engine is fresh from the cases up. So then i went riding slowly for about two hours and still noticed some pinging in the low to middle under very little load, "which is where it siezed". So i went to a 55 pilot, raised the needle, and threw in a 210 main. A bit better but still pinging in the transition from pilot to needle, but pulled the main very very fast and clean. So i then checked cylinder pressure and was shocked to see 189psi. Did it 3 times with two different gauges and dam! This after i had the head squish band altered and more volume added to reduce psi's to roughly 175. So i have ordered a richer needle to clean up the eretic mid throttle due to it being very lean there and now will mix with VP C12 fuel. This bike runs extremely well and will only get better here shortly. It's truly amazing the appetite for fuel this engine has and the power it puts out I am by no means a go fast all the time person, just the kind that loves to roost in the sand with my buddies and occasionally turn the heat up on them. Can't wait till next time.

[BigGreenMachine]

Well it's not over 200lbs so really couldn't you jet it richer to solve the pinging?

Sounds like its a powerhouse. The next time my T3 is torn down it'll be going fourstroke.

[ccdhowell]

Interesting that you're going up on the jetting as much as you are. You would've thought you had an indication of a lean condition before it seized on you. And that it seized at partial throttle is new to me. I think of engines seizing at full throttle when you're pulling real hard for long periods of time. I guess I learned something from your misfortune. Glad to see you made a quick recovery with it. Chris

[scooterroo]

what are you saying james? next time your yanking out the 2 stroke motor and dropping in a 4 stroker? hey tecat-z post up some pics of that baby.

[tecat-z]

No two engines are created equal, even if they are same year and same spec. They all vary to some degree. Just the way engines, and all of the components work together.( timing, crankcase volume, squish band, chamber size, and even manufacturing tolerences): Remember this is a kx cylinder with full kx ignition and flywheel. While it is true some engines may run just fine 190psi, many things determine how resistant to detonation any engine is. I am fattening up the middle with a -5 thou needle in width, with same length and taper. Should provide much more fuel to cure lean condition. But will not all together eliminate detonation. This engine is a 71mm bore which displaces 256cc. Very small in my opinion considering what people run these days. Hopefully by next weekend i will have the needle and fuel and begin some more easy tuning. I have high hopes in having a very reliable powerful bike for this season. And if Sprock brings his Dyno to TF i might even make a pull or two to see what this little guy cranks out.