tomek Posted December 3, 2020 Share Posted December 3, 2020 (edited) I got my pig 5-6 years ago. Pig-86 Honda xr600r. Bike was in OK shape, had freshly rebuilt crankshaft, couple new gears and new 0.5 mm over Wiseco piston. Bike was difficult to start and had too much for my taste piston slap. I disassembled the engine and inspected everything. Igniter part of stator was pretty much toast and some genius gave too much cylinder to piston clearance. Practically new piston. Sad. I sent the cylinder to APE for 1mm overbore and ordered from them appropriate 11.0 CR piston. On voltage side I went with Rick's 2x100w stator because I wanna have 12v battery. Painted plastics, frame and put engine back together. Most of it anyway. And ,,,,,,,project went idle for number of years. Lol. Quick forward to fall of 2020. Started working on the engine couple days ago. There were some conflicting statements about actual compression ratio of Wiseco piston. They claim 11.0 but real one is supposedly lower. Well, if you want everything right you gotta do it yourself. Quick combustion chamber measurement revealed 54 ccm of volume, and CR of 9.6. Too low, and some people on the internet were actually right about fake CR. Dropped cylinder at my fav machine shop operated by older gentleman. He is gonna remove 0.5 mm from the top. It will give me CR around 10.4, or about what you can run with stock cam on pump gas without octane boosters on this particular engine. Edited December 3, 2020 by tomek Quote Link to comment Share on other sites More sharing options...
tomek Posted December 3, 2020 Author Share Posted December 3, 2020 Trying to figure out kick starter. Back to 1980. Quote Link to comment Share on other sites More sharing options...
tomek Posted December 3, 2020 Author Share Posted December 3, 2020 Brand new beautiful piston. Too bad CR is fake. 1 Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted December 3, 2020 Share Posted December 3, 2020 56 minutes ago, tomek said: Brand new beautiful piston. Too bad CR is fake. Did you contact Wiseco about it? Even though it was years ago, if it were me, I would still contact them, just because. Quote Link to comment Share on other sites More sharing options...
tomek Posted December 3, 2020 Author Share Posted December 3, 2020 9 hours ago, blackhawkxx said: Did you contact Wiseco about it? Even though it was years ago, if it were me, I would still contact them, just because. I got no time for nonsense like that. I use Wiseco only if there is no other option. Their pistons are forged- strong and good quality but typically need minor rework for optimum performance. This is not too bad actually, last project required more modifications in regard to the height of cylinder block and piston itself. Once I set squish height where I wanted I had to machine down piston's dome. Lol. 4 of them. In this particular case it seems someone calculated CR without taking thickness of cylinder head into equation. Standard for Honda 3 steel layers, about 0.7 mm. 1 Quote Link to comment Share on other sites More sharing options...
TOXXIC Posted December 4, 2020 Share Posted December 4, 2020 Nice build. When we bought my son's XX, there was a 1989 XR600 in the backyard. Guy offered it to us for $200, and said he had the title. I shrugged. No magic button (starter) and it looked pretty hammered. My soon was all over it taking pictures. Yours should be a beast when done. Quote Link to comment Share on other sites More sharing options...
The Krypt Keeper Posted December 4, 2020 Share Posted December 4, 2020 Looks fun, Friend asked if I could give his dirtbike a look over. Dropped it off last week, 1987 XR200R, still had original tires on it. 1 Quote Link to comment Share on other sites More sharing options...
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