Hi all. I have a bit of a head scratcher here and I hope you all can help - or bounce some ideas around. Stock cylinders, sent them out to a reputable machine shop with new pistons to have cylinders bored. Everything came back, I put rings into bore about an inch down, measured and filed and measured and filed my rings until I got to the required .018" end gap. Pistons are flat top 10.5:1, cams are Fueling 594's, Fueling race oil pump, heads ported and flowed with O/S valves and high lift springs. I am running a Thundermax on this bike so am able to monitor. Here is what happens: I flashed the Tmax with a close map, initialized the Tmax. While Linked, I started my bike...runs amazing!...for about 45 seconds, then it sounds like it starts to labor for about 3 seconds then dies. While running, the target and the actual AFR are almost bang on to each other, then when it starts to labor, the rear cylinder goes slightly lean and then bike dies. Anyone have any ideas/insight/thoughts?
Thanks.

 

What year and model of bike? Check your fuel tank quick disconnect . perhaps its not seated and starving for fuel. Also check battery voltage ins't dropping below master relay voltage or it might not have enough juice to open injectors. Could also be the fuel pump. Do you hear it running at key on and ign switch turned on?

 

Thanks for the reply, I had some doubts about voltage etc and went out and bought a battery tender, fully charged the battery, I can hear the fuel pump running. Good point about the fuel disconnect, I did notice it was not correctly hooked up when I first turned bike over...i should check that again. What I am worried about(and I really hope this isn't the case) is that the cylider/piston clearance is not adequate and the piston is expanding and lodging in the bore and stalling the bike. I did not check the clearance measurement when I got the cylinders back as I said...they were bored by a reputable shop. I am well aware that I should have measured them, I just didnt and I am fully prepared for the lashing I may receive on here...haha. I am just trying to get other ideas and possibilities to check before I go that route and pull the cylinders back off...

 

If you are doing heat cycle break in then 30-45 seconds is all you should run it the first start. After it cools, then the next start should be for 60 seconds. Do this until you reach 3 minutes and then go ride.
You may have a clearance problem, but hope you don't!

 

I can see where you'd go there, for sure, but... how does that explain leaning out?

 

I wondered that myself...and I found myself on here so maybe one of you fine gents can talk some sense into me....

 

You might get more info in the engine and mechanical section if you don't here. That's all i have to conttibute. Good guys in that sectoon. Good luck.

 

Maybe check your intake runner gasket; you may have a kink in the gasket that opens up when warmed up.

 

Another good idea. I will give the intake area a little sniff of brakeclean or wd40 to check for that. Thanks man.

 

If you piston was ceasing up in the cylinder bore and stalling the bike it seems to me you would know it. Your motor is turning at around 1000 RPM and that would make an awful noise.

I usually start by checking the fuel pressure in instances like this. Eliminates any fuel delivery issues up to your injectors. I use the Fuel Tool MC500.