Hey guys,
Just thought I'd consolidate everything. This isn't as a complete rebuild as some of the others as the engine was pretty recently rebuilt. I blew a head gasket (my fault) which caused me to do a mild top end rebuild.
Here is what's happening:
The previous owner had a 89mm bore (522cc), 10:1 Wiseco piston in the motor, but I'll be putting new rings on it since I broke a compression ring taking it off:
Moving up towards the head. The previous owner had some port work done. A quick measure of everything shows that it's nothing really more than a quick cartridge roll job. It sure does look nice, though. This time around, I had a valve job done on a Serdi by Leggett Engine Research. They do a lot of dirt modified / sprint car work. The intake valve has been back cut as well. They also did a light (.003") head skim.
On the cylinder side, I had Curtis (flattracker94) at Full Circle V-Twin do a 5 stud cylinder reinforcement.
Here it is with the through bolts slipped in to give you an idea:
You can see the countersunk bores where the bolt heads sit. Curtis also added material (at the top of the photo) so the bolt can sit flush.
I don't have a photo yet as they'll be here tomorrow, but I'm replacing the stock Yamaha cylinder head nuts / washers with Raceware products. They're a little pricey, but they're the real deal. Overkill? Probably, but it's worth it imo.
I'm replacing the stock camshaft with a Johnson J2 roller set-up.
(soaking the rollers in Brad Penn oil)
Advertised numbers are:
I: .540" lift, 287* duration @ .040", 105LCA
E: .515" lift, 280* duration @ .040", 105LCA
Like all roller cams, it features very fast ramps, which should help prevent any piston clearance issues.
Rounding out the valve train is R/D springs and Schumann Motorworks chromoly retainers and locks (lighter than stock, and hopefully longer lasting than titanium. I don't trust aluminum retainers).
On the induction side, I am adding a velocity stack that Curtis made (he made a bunch of them) that fits inside a K&N. Also, per flow bench and dyno work Dale Lineawaver did, I'm making a filtered end cap to compliment it. The velocity stack pushed the intake tract length to about 11" from the valve seat. This is still a little short for a street motor, but would be perfect for a race set-up. Regardless, it's longer than stock which should help fill in some holes in the power band. It also dramatically smooths out the inside. There is a step where the carburetor meets the filter and the filter has a big flat area inside which causes turbulence.
The filter material is from Uni. You can buy a larger sheet for <$20 and it is available in several different mesh sizes. Naturally, I picked the largest mesh size.
What it fixes:
Inside the filter and end cap (needs to be siliconed on still):
All this is being paired up with an exhaust I partially fabricated this winter. It features a machined spigot that is port matched to the exhaust port (they're flush with one another) and slightly tapers out to the i.d. of the 1 5/8" o.d. primary pipe. The primary carries this diameter until it steps up to 1.75" o.d" after about 15.5" from the manifold face. Then it enters a megaphone/reverse cone before entering the muffler. Total length from the valve seat is ~60". It could be shorter for more peak power, but this set-up clears the kick start and should be faster in the mid-range. Curtis built the megaphone/muffler and the spigot. He also did the tig welding after I tacked it all together. It's ceramic coated inside and out by H.M. Elliott out of Mooresville N.C. (they do a lot of NASCAR stuff).
Before ceramic coating:
After:
This megaphone/reverse cone set-up actually tunes like a true megaphone set-up. The megaphone mufflers don't since there is muffler packing material disrupting the pressure wave.
I'm hoping for some pretty good power out of this. I don't expect anything earth shattering, but I expect it to be more than the typical performance build. We will see...