Ok i'm usually pretty good at this stuff....but this one has got me now.

After putting the bike back together, it seems it only started once in a blue moon, and I haven't been able to keep it running since. Now it just won't start at all. It has fuel, it has spark, and it has compression...sorta.
At TDC a leakdown test was performed. Cam lobes opposing each other, pressure added to cylinder, everything checks out good.
When cranking with a plug out, good compression.
When cranking with plugs in, get compression out intake, and vaccuum in through exhaust at the beginning of the excaust cam turning onto the valves.
Naturally one would think somehow, the strokes were reversed...so I checked again...nope, lobes opposing one another at TDC.
also somehow the automatic decompression deal on the intake cam shattered.....not once but twice...don't ask me how, it checked out the first time, and I made damn sure the second time, but still snapped. Cam bridges are tight, timing chain is in spec, valve clearances are .005 inches, i don't know what caused that, nor why it is sucking through the exhaust and blowing through the intake...

someone have this happen before? the only time I ever has vaccuum on the exhaust was when a piston was blown apart, but I have compression, and leak down test was good.

I'm lost!

 

Ok, it appears that it can start with the help of a small amount of compressed air being blown into the air box, to help get things along. The choke also has to be on full way, and if turned off it stalls out. It can run without the compressed air, but only with the choke on.
Adjusting the air/fuel mixture screw doesn't do anything, the main is 190 mikuni, needle has been in top and down to bottom clip with little difference. Pilot is a 45.

Here's the biggest catch

the head was ported.

How much of a difference in jetting does a ported head usually amount to? Perhaps I lost velocity of the incoming air? It won't rev up, and just seems to spew gas everywhere. It's hard to explain, and jetting with this is like shooting in the dark.

Oh and it gets pretty hot pretty quick, fan turns on and headers glow. Could be lean, but could be rich with unburned fuel in the head pipes.

I'll keep playin around, maybe try a smaller main i don't know what that would do being that main only deals with approx. 3/4-full throttle, where as the needle is 1/4-3/4 and the pilot is 1/8-1/4ish.
numbers may be a tad off, but the general idea i think is there.

So am I righ, or lean?Adjust which first?

I'll keep dinkin around

 

come on guys this sounds serious...

chosenone hang on someone will have your answer

 

I know you said the cams were opposing each other, but have you checked you cam timing with the motor at TDC with the bolt in the TDC hole? Are the cam timing maks where they should be? it SOUNDS like your cams are out of time.
I know this is redundant, BUT, are the plugs new? NGK plugs can be VERY fickle! I woud verify these and try it again.

 

Devin,

First things first. Talk to the one who did your head work and see if they have any Ideas. Second talk to Eric, Randall or Marky by phone and see what they have to say. E-mailing just takes too long and you can't be as specific as you can verbally. Then I would see what some of the other builders here have to say and where you have duplicate hypotheses go whith that.....

Good Luck.

 

TheChosenOne,

How fast is it cranking? If its cranking slow, then there wont be enough spark energy to start it. If thats the case, hook it up to an ATV battery charger.

 

yea check the battery and start with simple. sounds like their are possibly multiple things cuasing the problem. i dont know about the glowing pipes??? i have heard people say that they have had this happen and its normal but my bike runs great and ahas a few internal mods and i can tell you the pipes dont glow EVER. i did have this happen when my timing was off but you said you checked that. you said you checked the valves. that is where i would have went to in the motor first but if they are good move on. i had a starting problem a year ago that totally puzzled me. i had fuel, compression, air, and most importantly spark. i tore that bike apart and checked everything. you know what it was???? fouled plugs. new plugs and a battery and it fired up and ran like a champ. even though the plugs were fouled thay sparked outside the jug but under compression they were dead. like i said start small. dont go buy a battery if you dont need one. borrow a friends good battery if you think its turning over weak and try that. get some new plugs too. keep us informed and good luck

 

My first thought aswell, Make sure you have the CRANK in the right position. make sure you can see the notch in the crank. this is possible witha flash light. I did this exact thing once ,and my motor started aswell, would run long,and abviously ran like crap. I was 110% sure I had the cams right. LOL[img]i/expressions/face-icon-small-blush.gif[/img]





Bigger.

 

No other comments and I agree with Bigger, I can't imagine what else besides timing this could be.

Any Answers yet?

 

I have to agree with Bombsaint. I had that type of problem with my Z400. It was driving me nut's. Turn's out when I replaced the plug it fired right up and never had A problem again. May be that your looking for A big problem, when it's only A small one. Good luck keep us posted.