Engine Trouble Minarelli Progress/Friends BMW

The scratches do not need to be very deep to cause issues. If you can manage to hone that cylinder it may be re-useable. Definitely signs of a soft seizure though. The one Achilles heel of the minarelli has always been thermal control, especially when pushed hard.
 
The scratches do not need to be very deep to cause issues. If you can manage to hone that cylinder it may be re-useable. Definitely signs of a soft seizure though. The one Achilles heel of the minarelli has always been thermal control, especially when pushed hard.
Thats why I want to use my athena, but it has no low end power AT ALL. a transmission would be perfect for that engine
 
The Sport has adequate low end, is tractable at low speeds, but is not snappy like the cast cylinder.
Nicks build with the newest version I think will be more high end than the sport, but may lack on the bottom
a bit more.
 
Not sure why folks just don't get a temperature gauge..

If you monitor temps, you can prevent this kind of crap by simply... slowing down/stopping for a while.

$35.00 of prevention ...

Same with the genius who took LA Hoverbikes Phantom 85 and decided to run WOT for extended periods... on a 20" wheel... 44T sprocket.

That motor didn't die... it was killed.
 
If you’re running a 36 try a 38 or 40T sprocket. The sport Athena will still get you close to 50 mph on a 40T. I don’t think any of these engines are gonna hold up running them WOT for long periods lots of times. My temps run a consistent 180-190 the way I ride.
Anything over 35-40 mph is way too fast for a motorized bicycle unless you’re competing in competition sports with all the protective gear to support you anyway.

My cast iron top end did have a good bit more low end torque over the sport Athena on a 38T but not so much that I felt the Athena was no good. I prefer the Athena but I cruise up to 25-30 mph gently and do not rip up fast a lot. It does run superb though for my style.
My Athena sport really doesn’t come to life for abrupt torque until around 7,500 rpm’s. It’ll jump from 40 to 50+ in a blink.
 
If you’re running a 36 try a 38 or 40T sprocket. The sport Athena will still get you close to 50 mph on a 40T. I don’t think any of these engines are gonna hold up running them WOT for long periods lots of times. My temps run a consistent 180-190 the way I ride.
Anything over 35-40 mph is way too fast for a motorized bicycle unless you’re competing in competition sports with all the protective gear to support you anyway.

My cast iron top end did have a good bit more low end torque over the sport Athena on a 38T but not so much that I felt the Athena was no good. I prefer the Athena but I cruise up to 25-30 mph gently and do not rip up fast a lot. It does run superb though for my style.
My Athena sport really doesn’t come to life for abrupt torque until around 7,500 rpm’s. It’ll jump from 40 to 50+ in a blink.
the relli got me to 50mph with the 36t, I will switch to a 38t if I were to try the athena. I just wish I had a transmission
 
Not sure why folks just don't get a temperature gauge..

If you monitor temps, you can prevent this kind of crap by simply... slowing down/stopping for a while.

$35.00 of prevention ...

Same with the genius who took LA Hoverbikes Phantom 85 and decided to run WOT for extended periods... on a 20" wheel... 44T sprocket.

That motor didn't die... it was killed.
Ill make an investment
 
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