cbm4stroke
Member
- Feb 29, 2000
- 24
- 0
Hold onto something sold as the 580 was fired up today for the first time. Started right up and ran like a top. I warmed it up for about 5 minutes shut her down and looked for leaks found none. Let her cool down and then ran it up to the end of the block and back. Smooth and a ton of torque. It will be a fantastic Dual Sport ride, I'm sure it will be geared up a lot taller before its dialed in. First break-in ride this weekend. Want to break-in the new rings and crank for a couple hundred miles before jumping on it. But you can tell there is something special here a smooth and very fast ride.
My 520/540 EXC had approx. 6000mi on it when I disassembled the engine the problems I found were:
Cam had a bad spot through the hard coating---New CAM
Replace the Cam chain it was getting close to the end of the tensioner
Need new Rings compression ring out of tolerance, Oil ring close--Put in new rings for the 97mm KTM piston
That was It as far as new stuff. I think the CAM was bad from the beginning as the spot through the hard coating was just on the edge of the rocker roller identification marks--but it had to go as if it cam came apart it could easily wast the engine.
The Transmission gears, shift forks, shift shafts-looked brand new not even a bad shift dog looked great.
The cylinder was round and true top to bottom it had some minor scuffing on the front to back sides a little more on the exhaust side. I had a very light hone run though it and it cleaned up real nice.
My exhaust valves looked perfect, the intake valves had started to cup not good but it was not too bad. I lapped the valves with a fairly light 320 grit compound cleaned the head up and reassembled with new seals. The valve springs all checked out just fine. I will run this head for approx 2000 more miles and then do a valve job and replace the springs, and guides.
When I went to install the piston pin on the stroker crank there was minor interference with the top of the rod and the pin bore skirts, cleaned up the piston pin bore skirts about 0.002 on each side with a mototool carbide bit--all worked ok. The rod big end is offset 3mm further out on the crank half's which gives it a 6mm stroke increase-3mm up and 3mm down. In order to run with the KTM 540 Kit 97mm piston the small end hole for the pin in the rod is offset approx 2mm closer to the big end making the top of the rod relative to the center of the pin taller causing my interference. This effectively makes the rod shorter. Also you need to run two standard base gaskets to get the cylinder another 0.020 (.5mm) higher. The combo of the shorter rod and raised cylinder makes for proper deck height with the KTM 540 kit piston.
Its basically a dual sport ride and it is going to be a blast
Cheers
Clark
My 520/540 EXC had approx. 6000mi on it when I disassembled the engine the problems I found were:
Cam had a bad spot through the hard coating---New CAM
Replace the Cam chain it was getting close to the end of the tensioner
Need new Rings compression ring out of tolerance, Oil ring close--Put in new rings for the 97mm KTM piston
That was It as far as new stuff. I think the CAM was bad from the beginning as the spot through the hard coating was just on the edge of the rocker roller identification marks--but it had to go as if it cam came apart it could easily wast the engine.
The Transmission gears, shift forks, shift shafts-looked brand new not even a bad shift dog looked great.
The cylinder was round and true top to bottom it had some minor scuffing on the front to back sides a little more on the exhaust side. I had a very light hone run though it and it cleaned up real nice.
My exhaust valves looked perfect, the intake valves had started to cup not good but it was not too bad. I lapped the valves with a fairly light 320 grit compound cleaned the head up and reassembled with new seals. The valve springs all checked out just fine. I will run this head for approx 2000 more miles and then do a valve job and replace the springs, and guides.
When I went to install the piston pin on the stroker crank there was minor interference with the top of the rod and the pin bore skirts, cleaned up the piston pin bore skirts about 0.002 on each side with a mototool carbide bit--all worked ok. The rod big end is offset 3mm further out on the crank half's which gives it a 6mm stroke increase-3mm up and 3mm down. In order to run with the KTM 540 Kit 97mm piston the small end hole for the pin in the rod is offset approx 2mm closer to the big end making the top of the rod relative to the center of the pin taller causing my interference. This effectively makes the rod shorter. Also you need to run two standard base gaskets to get the cylinder another 0.020 (.5mm) higher. The combo of the shorter rod and raised cylinder makes for proper deck height with the KTM 540 kit piston.
Its basically a dual sport ride and it is going to be a blast
Cheers
Clark
