Wow, this is a mess. 1994 Evolution just rebuilt with Wisego 10.1 pistons .010 over and matched to rebored cylinder by a great machinist with a good record. Rings installed exactly as spec'd, along with arrows in RIGHT direction. New Harley valvels. New Andrew EV27 cam. New cylinder studs installed with two drops of red loctite and flange down on the base of crankcase, even though my earlier owners manual shows them installed flange up. Torqued down with an air ratchet to avoid stress and twists. New cylinder stud bolts installed and double checked with two torque wrenches, then marked and turned 90 degrees. I have Vance and Hines 2 inch Longshots with a reducer cone installed at the exhaust exit into the pipe ( done since there were no baffles.. to provide some back pressure. Stock pushrods reinstalled... same position and same color codes. Stock rockers.

Ran the bike 60 miles. Ran good, slight noise in the forward lifters on the initial start up. Finally pumped up, and quieted down. BUT, the bike was too loud now. Just installed stock baffles, not the quiet ones. Fired up, warmed up, and ten minutes later shifting up through third on the on ramp going uphill under load the rear gasket blew. Tried to run the back back down the ramp on the other cylinder and IT blew!

Tearing down tomorrow. Any ideas?

Forgot to mention, new seals, bearings, gaskets. Head gasket is a stock Harley.

 

What head gasket

 

Harley, DJL

 

We use NOTHING but Cometic gaskets here.
MLS EST's.
Last H-D head gasket we used here, leaked around the oil returns.
Torque those Cometic's at 10/20/30/42 lbs.
You WILL NOT have a problem with those, unless something else is buggered.
Scott

 

100% agree`d,

 

Thanks. I'll order them today.

 

ya might have pulled a couple of studs, would have the same sound as a blown head gasket.

 

OK... here is the problem. I put in a SIFTON base cylinder gasket kit. Great gaskets, and they have the brass connector between crankcase and the cylinder drain hole to help prevent pooling of the oil between cylinder and case, which leads to leaks in that area, as most EVO owners are aware of. I can not remember if the set I grabbed in the shop off a shelf had any instructions or if I just didn't read them properly. Others are probably aware of this, but I did not realize that the bottom of the cylinder from Harley is often not fully machined, and that there is a lip present (see photo). The cylinder set down good on the base, but obviously not ALL the way down. I never looked at the bottom of the cylinder and noticed this. The hole in the cylinder needs to be reamed for proper seating of the brass plug. The bolts were indeed torqued down properly, but not for long, as there must have been a small clearance that only got worse as the engine ran. To tear the engine down, I only removed the wrist pin, leaving pistons still in cylinder. It took me about two, maybe three hours to have the engine stripped down. I have Cometic seals/gaskets coming, and will reinstall. Good lesson learned, and fortunately, no damage done.

http://i11.photobucket.com/albums/a1...3-08140543.jpg

http://i11.photobucket.com/albums/a1...3-08140531.jpg

 

Maybe I'm just reading this wrong, but I never "torque down" with an air ratchet, sometimes take it close, and then snug by hand, then use the torque wrench - to avoid stress and twists. Even my little 1/4" ratchet can pull some things off kilter if I put one bolt down hard before any others are snugged a little. I don't use an impact wrench on anything on my Harley, not even coming off (not saying you did, you only mentioned air ratchet). Found out about helicoils on bikes a long time ago, try to avoid needing them now. Or drilling and tapping out to the next size. Had to do that several times on used bikes some gorilla had gotten to first. Or maybe it was a 65 lb monkey; doesn't take much for aluminum.

 

I understand your concern, but actually in the factory manual they instruct you to do this to avoid twisting or "stressing" the cylinder rods. There is NOT a torque setting for these rods. You put two drops of red loctite... I believe it is 262, but don't quote me. since I'm at home. Then you use an air driven impact wrench from above, directly over the studs. YET... what you say rings a bell, because it did bother me not knowing for SURE the studs were seated. They did cinch down to the flange, which you can see visually, and I also used a caliper to verify they were extended the proper height, and all of them matched very closely. But, I did double nut it and then very, very gently just made sure they were snugged up.