- Local time
- 6:45 AM
- User ID
- 522
- Joined
- Jan 12, 2016
- Messages
- 4,088
- Reaction score
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- Location
- Iowa City
Maybe I should change the title as this has also turned into a 585 build thread. Since the 585 numbers where odd in my opinion I decided to work with it and learn what I can before getting too far with the 592.
So far I've made a few iterations with the 585, obviously we've already seen the muffler mod which didn't really yield much of an improvement.
585 Stock numbers again for quick ref. I might have messed them up in my post a long ways back, given in duration and opening.
Ex 158, 101
Tr 123, 118.5
In 161, 80.5
St 143, 71.5
Next was a was my tame first step at porting. Since the intake duration was so large I didn't want to go too high on the exhaust or transfers as I was worried about crankcase compression. I wanted more compression so I took 0.050" out of the squish and shot for 0.020" squish, it ended up at 0.021".
Ex 158, 101
Tr 120, 120
In 168, 84
St 150, 75
I wasn't very happy with this and I only had a little time in the day so I just did a quick ignition advance study. Advanced 6deg and it picked up a little, no signs or popping or pulling back on the rope. It's a win.
Now things get spicy... I didn't like the large intake duration, it's got more than enough volume through the carb there is no need for that much and I believed it was a detriment. So I welded up the piston and added 0.065" to the intake skirt.
Ex 158, 101
Tr 120, 120
In 159, 79.5
St 150, 75
So far I've made a few iterations with the 585, obviously we've already seen the muffler mod which didn't really yield much of an improvement.
585 Stock numbers again for quick ref. I might have messed them up in my post a long ways back, given in duration and opening.
Ex 158, 101
Tr 123, 118.5
In 161, 80.5
St 143, 71.5
Next was a was my tame first step at porting. Since the intake duration was so large I didn't want to go too high on the exhaust or transfers as I was worried about crankcase compression. I wanted more compression so I took 0.050" out of the squish and shot for 0.020" squish, it ended up at 0.021".
Ex 158, 101
Tr 120, 120
In 168, 84
St 150, 75
I wasn't very happy with this and I only had a little time in the day so I just did a quick ignition advance study. Advanced 6deg and it picked up a little, no signs or popping or pulling back on the rope. It's a win.
Now things get spicy... I didn't like the large intake duration, it's got more than enough volume through the carb there is no need for that much and I believed it was a detriment. So I welded up the piston and added 0.065" to the intake skirt.
Ex 158, 101
Tr 120, 120
In 159, 79.5
St 150, 75
