Tuesday, October 25, 2011

10/23/11 Ugh, just when I though I was done all the mechanicals and was ready for final cosmetics... The mounting bracket on the new pipe broke. The white specs you see is not metal, its road dirt

9-26-11 12hr Re-assembled bike, painted and installed pipes, new carbs, K&N filters, new front and left blinkers. Took bike for a ride. With the Spec II Racing stage I kit, the bike is very drivable but still has a great powerband from  5500 to 7500 RPMs. Its like the best of both worlds. glad I made the investment!


Sunday, October 23, 2011

9-25-11 2 Hrs Installed new high out put coils from Spec II racing

9-25-11 10hrs Rebuild Clutch and reassembled bike. Installed new clutch plates and springs from Spec II. Also replaced the front sprocket to 16 tooth per recommendation of Spec II. While I was here I also replaced the seal on the shaft for the main sprocket. I lesson learned here is the placement of the main locking nut is critical or you will have an oil leak.

Sunday, October 16, 2011

9-25-11 Rebuild Engine #2. 8hrs. Honed 64MM cylinders. Checked tolerances on piston clearances to .0015 and set timing with dial indicator to 2 degrees below TDC using the method described in the Yamaha manual. This timing setting was recommended by Spec II. Note the ported racing reeds




9-25 Modify ProX Pistons: 1hr: I used ProX RZ pistons. There is a tab on the piston that needs to be trimmed off so you run them on RD's  Got to HVCcylce to read the procedure. I cut my tab off using a dremmel tool and a cut off wheel


Saturday, October 15, 2011

9-16 Try again and $1500 bucks later

9-16 Overall I did not like the carb/pipe set up it the 32MM flat side and the Bassani pipes. I had bought both used for $500 thinking I would save a few bucks. After the seizure I figured I would go with cast pistons and a matched setup of pipes, filters, carbs and hi output coils from Spec II. While I had the engine apart I also figured I would replace the clutch so I bought new pads and springs from Spec II. $1500 later this is what I have.

Stage I Kit:
K&N 2 into 1 filter
30 MM Mikuni's
Spec II pipes
16 tooth front sprocket
New manifold and cross over pipe

Plus
Hi output coils
New clutch plate and springs


8-25 Bike Seized Up

8-25 Bike Seized up. 15hrs  I was riding the bike on the highway at 60 MPH and it seized the left cylinder. After much investigation both at the shop that bored the cylinders and dialoging with the guys on USA 2strokers forum, I was able to properly diagnose the issue.
  1. Wrong piston clearances: The cylinders were bored to fit stock cast aluminum pistons. The pistons installed were Wiseco FORGED aluminum pistons. Forged pistons expand more so a few thousands off on the clearances and you can have a seizure. in my opinion the bike shop should have known this when I brought the jugs and the over sized pistons to them, but ultimately it was problem because I did not check the clearances after I got the pistons and jugs back. Lesson learned: don't trust even a reputable bike/machine shop; check all factory/mfg recommended clearances.
  2. Slightly Lean Carburetor jetting: I drove the bike for 300 miles without issue, but I was only driving stop sign to stop sign, not highway driving. When I took the bike on the highway at 60MPH the carb was operating in the main jet / jet needle range, and was slightly lean. Being slightly lean did not cause the bike to seize but it added HEAT to the equation. Heat + tight piston clearances = seizure