I had a couple of un bored/ported cylinders laying around and decided to have a look at them this morning over some coffee.
There are some interesting differences.
A few things i noticed were:
1. The footprint of the 86 cylinder is a bit more beefy.
2. The transfer port dividers are larger in the 86 model.
3. The intake is beefed up a bit due to being coupled with the coolant bracket.
4. I would like to say the bend or angle in the transfers is a little more round than the 85's. I can't prove this tough.
I am going to take the 1986 cylinder head over to Arlan @ LED on Monday to be fully pimped out for mid range nuclear power. He is also going to modernize the combustion chamber size and shape for race gasoline and fun.
Another thing is that the reed cages are a bit different.
As a matter of fact i just learned about this slight difference. The 85 seems to have a larger area for flow but the 86 style is machined out to accept a plastic insert that smooths the air flow by reducing turbulence and theoretically increases flow. (Thanks to Red Rider for this information)
Another thing i noticed yesterday while changing a stator was the beefing up of the case structures the the following year.
Note how many support ribs are surrounding the timing index mark near the 12 O'clock position. the first pic (Early 1985) vs how many ribs are in the second pic (1986)
I had to change a clutch basket on my daily driver the other day so i thought i would note a few more of the million changes between the two years.
Seems 1986 was a year of simplifying the previous years 250R motor. On of the things i noticed is the 86 has less parts. Check it out.
1985 kick starter shaft
1986 kick starter shaft
1985 clutch basket shaft
1986 clutch basket shaft
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