PHASE 17: Motor Build Part 2
I have to give a big THANK YOU to Scott at Recreational Motorsports and Big John from Snowest. They were instrumental in giving information on the motorwork and port work done. Scott is a master at machining engines, and a great guy to work with.
The first picture shows how I got the cylinder back from the machine shop. You will see in the later pictures how I fit them to the case so the transitions were smooth and did not disturb airflow.
The remaining pictures show the after shots of about 12-14 hours of measuring, cutting, measuring some more and then finally getting it where I wanted. Micrometers are a must for this type of work. Those and a TON of patience.
You can see how the intake opening was opened up to allow more air into the tranfer area. Once it was all smoothed out and the shape and dimensions I wanted, I had Scott take a look at them. He gave me a couple of more suggestions, I made the changes and then had him sand blast the whole modified area to give it a perfect surface.
Scott then finished bored and honed the cylinders to fit the Swain Tech coated pistons. I had them coated with a Thermal Barrier on the top, and Poly Moly on the side skirts.
Once all the machine work was done, I sent the case, a cylinder, piston, rings and wrist pin to The Crank Shop. (That is the only service Scott does not do - yet) They machined the stock head to 14.5:1 compression. This will make me run 105 octane fuel at sea level, but still be able to run 87 octane at 6,000 ft or higher. (I will be having a lower compression made for sea level as it will be riden in the U.P.)
All I will say about the carb system is that it has 46.5mm carbs bored by Scott. I also had him mill the tops of the slides so they would clear the top. I have set them up to my liking. This fall, after Hay Days, it will also have a Holtzman ATACC system on it. I run one on my MXZ, and it works perfectly at any altitude and any temp.
Once the motor was together, I had to fit the RAVE valves to the new pistons. Since they were larger than the 670 pistons by 4mm, I had to sand them back. I have a 2" coarse sanding wheel for my drill press.
I put the RAVE in the sleeve, and then rough marked the part that stuck out with a Sharpie. I sanded the RAVE guilotine down to the edge of the line. I then put the RAVE back, and checked the fit. I only ground it down until it was perfectly flush. I then ground it down to 0.010" clearance. Which was a little tight, but functional.
I then put new bearings in the rotary shaft and all new seals. I also put new seals in the waterpump.
Scott checked and trued the crank to a 0.001" end play. The inner seals were fine. Scott felt the crank had been rebuilt prior to it being put in the box with the sled. He said the bearings looked new, and the seals were new. FINALLY some good luck.
I scored a Fluidampr from EBay for $51 to help keep everything in harmony. Although it may be a waste, as I am not going to go beyond the rev limits of the crank. Maybe overkill, maybe not.
I also picked up a Carbon Tech 169degree rotary valve from Scott for $51
Everything is ready to go together.
CLICK PHASE 18 TO CONTINUE.
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