That's a very interesting concept on the "scavenging" through the intake manifold. I did not take a very close look at the seals buried within the springs before installing the heads.
Recap / babble:
It's a rather odd situation as the
smoke started like 300 miles or so after the first build...cam, cam bearing, adjustable pushrods, carb, exhaust, ignition module, coil and a couple other misc parts.
The first thing I did was check the plugs, they were looking rather good....clean with an oil ring around the first thread.
I then suspected excessive oil from the breathers, so I re-routed the breathers away from the air cleaner with some clear silicone tubing to get idea of how much oil was coming out the heads. Nothing significant and I still had smoke. However, I did encounter some
odd debris in the which came out of the breather setup.
Next came a compression and leakdown test. I lost those numbers, but both cylinders were close to 110 or 120 PSI or so (slow to build up) and leaking more than 10%, one was near 15%. (Shortly before I did the cam upgrade, the compression was 155 front / 160 rear on a relatively cold engine.)
I pulled the exhaust and saw oil on the exhaust valves.
Here's the rear valve. Here's the front.
Ah ha! Leaking exhaust valve seals.
Strip the engine. Deliver parts to shop.
The shop said the heads looked good, the guides not far from new...no cracks, the valve stems good, seals dried a bit and could be suspect....
nothing out of the ordinary for a 98 EVO with 30K miles.
OK...
along comes the second build; a
street port with a 5 angle radius
valve job, new (slightly stiffer) springs, new seals, shave .060 off heads, bore cylinders .010, new pistons/rings, and .030" head gaskets.
Once I got all the parts, I spent an afternoon measuring and documenting fits including
piston to valve clearance. To the best of my ability, everything in the top end came out within spec.
Got 'er back together this past Sunday night. Moday after work I washed the bike. After she dried, I went through a heat-cycle process starting with a 1 minute run and cooldown. First minute yielded a loud exhaust leak. Thought it was the head gaskets. I found that I had forgotten to replace the O2 sensor bung plug in the front head pipe. Oops. After viewing the
video of the first start-up, I was shocked to see a puff of smoke at startup. Also note the light stutter or miss which
seemed to disappear on the subsequent 2, 3 and 4 minute cycles when the choke was deactivated.
Tuesday after work I went for the first ride. Warmed up the bike for several minutes, and then rode pretty lightly a couple miles to the edge of town where I started the 30/60/30mph tenfold routine. Then rode between 40 and 50 mph for the next 10 miles to the shop that did the machining work where I was
told to put a few hundred miles on it before worrying about it. First ride I put on 70 miles.
Now at 150 miles,
I've still got smoke. The same smoke that I had after the fi
Smokin' hot?
