1986/87 cr 250 cylinder differences

ZOOK250
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9/17/2010
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Oakbank,Mb CA
ZOOK250
Edited Date/Time 3/1/2015 9:35am
hey guys,

im in the process of rebuilding the engine for my 87 cr 250 that i bought in parts. i have a question regarding cylinders. i have 2 complete, cylinder 1 is marked HF-1 and the other is E-1. i think the HF is from an 86? (i have another 86 cr 250 and it has an HF cylinder). the HF cylinder has additional lower ports 6 transfers, whereas the E only has 4. all the power valve components look the same as far as i can tell.

these cylinders are interchangable as far as i can tell, but which cylinder is a better choice to use for the final rebuild. i cant find a lot of info online, part numbers for 86 and 87 cylinders do not include these numbers.

thanks
curt
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DynoDan22
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9/7/2011
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Victorville, CA US
DynoDan22 2/28/2015 9:26pm
2/28/2015 9:26pm
The '87 cylinder has the rear boost port directly opposite the exhaust port. The '87 case also has the lead port for this boost port and the difference can be seen in the main case gasket. All of my '87 cylinders had the "E" letter on the intake manifold, but this only denotes the mold # for that given year. The power valves are slightly different between the two years. I personally liked the '87 motor over the '86 so I would stick with the '87 cylinder if you have the matching '87 bottom end.
ZOOK250
Profile picture for user ZOOK250
Posts
221
Joined
9/17/2010
Location
Oakbank,Mb CA
ZOOK250 3/1/2015 9:35am
3/1/2015 9:35am
Great thanks Dan. The bottom end has the boost port like you described. The guy I bought the bike from included an 86 cylinder, he probably thought it was an 87. Good thing I bought another 87 cylinder from another Vital member. I thought it would be good to have a spare. Anyone looking for a good 86 cr 250 cylinder?

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