Advice/Help with Yamaha Blaster

[Zephead]

Let me start by saying, it’s a Blaster, not a Banshee.  I’d love to post on the Blaster Forum, but I’ve been unable to get a confirmation email sent for 5 days for some reason.  I figure Banshee folks could give me just as good of advice, so here I am.

 

I bought a 1993 Blaster a couple months ago as a project.  Aftermarket parts include:

 

Full Fmf Exhaust

K&N Air Filter

Boyesen Reeds

Reed Spacer
Tors Delete

Automatic Oiler Delete

Aftermarket Stator

 

240 Main Jet

Needle in Middle position

Air Screw 1.5 turns out

 

It wasn’t running when I purchased it, so I began to tear into it.  The first thing I found was a broken carbon fiber reed, so I ordered up a new set of Boysens.  When I got the cylinder off I didn’t think it looked too bad inside, though I am no expert.  I did find the broken reed piece.  I took the motor off, turned it upside down and gently blew air into it to make sure there were no pieces of the reed valve left.  I then measured the cylinder with telescoping gauges and a digital caliper, and these are the measurements I got:

 

Xt - 65.94mm

Xm - 65.89mm

Xb - 65.81mm

 

Yt - 65.99mm

Ym - 65.99mm

Yb - 65.97mm

 

I also ordered up a Pro X top end kit and gaskets.  I put the engine back together with the new parts and a carb clean.  I torqued all the bolts to the propper specs and even used the Motion Pro torque wrench extension for the hard to reach bottom bolts.  It literally fired right up.  I did a couple heat cycles on it, and then took it for a short ride.  Idle to ⅓ throttle it seemed just fine.  At more than ⅓ throttle it completely fell on its face.  I immediately thought it was a jetting issue, (running a 240 main) but investigated further to find it only had 60psi compression.  I used  2 different compression meters and came up with the same result.  I was running 32:1 Premix.

 

So, I decided to tear back into the engine.  Attached are some pictures of what I found.  This is where I definitely need some help.  I checked the ring gaps and discovered they were 0.63mm and 0.58mm (0.20-0.35 is spec).  I also noticed that the base gasket was wet almost all the way through.

 

The first piston photo is the brand new piston, after being run for about 20 mins, which looks to me like it got too hot.  

https://ibb.co/v3M1KFN

The second is the old piston, which didn’t have any of the black scorched  look to it. 

https://ibb.co/q1TWCpY
 

The next two show the vertical lines in the cylinder.  These weren’t here before the rebuild

https://ibb.co/N7ZzFv1
https://ibb.co/5RSRqHh
 

The last picture is of what looks like a heat spot on the crank, right at TDC.  The crank still seems to be fine, other than the discoloration.   Absolutely no up and down, little side to side, and spins very smoothly

https://ibb.co/pXTCRKP

There also seemed to be quite a bit of unburned fuel in the bottom end.  Any advice or thoughts would be greatly appreciated.  I’m planning to get the cylinder bored and go with Wiseco this time (which I probably should have the first time).

[Zephead]

I should add that I am at 5200ft elevation.

[chee_dee]

It should not even be able to start on 60Psi.

New piston kit always goes with fresh rebore and hone to New Piston specs.

240 Mainjet might only work with Airfilter lid still on. If your ran it without a lid, hard, it will run lean.

 

 

PS: Can't open the pics

PSS: you should do Leak down Tests when ever engine was opened.

 

[locogato11283]

You say there is unused fuel.. And 5200 feet elevation. It sounds like you're way too rich. I agree with the above.. At 60psi it wouldn't start.