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J&E HC Piston and Web Cam

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That's common practice when increasing an engine's stroke. :smirk: A shorter rod is used so a custom/shorter piston won't be necessary.

:smirk: AFTER going back and reading a few pages, it dawned on me that they were talking about using a different CRANK to increase stroke...should've realised that was what they were talking about earlier..I feel like such a dumba$$ because I have quite a bit of experience building higher performance car engines...:cheers:

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Not really a different crank. The crankpin that the big end of the rod rides on is offset a bit which increases the stroke. A longer stroke means the piston would hit the head unless the rod is shortened.

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HeadTrauma Said

That's common practice when increasing an engine's stroke. A shorter rod is used so a custom/shorter piston won't be necessary.

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ProCycle said

A longer stroke means the piston would hit the head unless the rod is shortened.

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I work mainly in 2 strokes and here we are really concerned with rod/stroke ratio.

Anything less than 2 is bad. (54 stroke-110 rod (2.03:1) good, 62 stroke-115 rod (1.85:1) not so good).

Us 2strokers have short deck to pin pistons available so we can use longer rods, even when not increasing stroke.

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Is it because there are no ports in the cylinder to snag the piston skirt that most 4 stroke builders are not worried about rod/stroke ratio?

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I have always been amazed by how short some high performance 4 stroke pistons are, rings and an inch of skirt.

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I have become aware that many "built" motors are only 1.5:1 rod/stroke ratio.

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There are no concerns with the piston rocking?

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Rocking does effect how well the rings seal.

Just wondering,

Dave

Edited by Shady Dave
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Howdy,

so for those who installed the 223 webcam, was it plug and play? Did you have to get valve pockets done on the JE HC piston? Did everyone boter checking clearances?

I'm tossing up 223 or 190 grinds but I dont want to mess around making valve pockets!

LuKas - if you havent already split your cases... FYI I just split mine and no tool was required (not even a screwdriver). The cases separated easily by hand.

cheers,

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Web Cams recommends checking valve to piston clearance on either cam. It's smart to check even if you don't expect to find interference because the consequences are serious if valves contact the piston. Off the top of my head I'd say that maybe one out of ten 223 cam installs need additional clearance and maybe one out of four 190 cam installs need additional clearance. Good engine builders will always check valve to piston clearance when building a performance motor.

There is a long list of things that can affect cam timing and therefore valve to piston clearance. Here are a few of them:

cam chain wear

tensioner guide wear

head and base gasket thickness

actual distance between crankshaft and base gasket surface

actual cylinder height

actual distance between head gasket surface and camshaft

how accurately the cam sprocket boss is pressed onto the camshaft

how accurately the cam was indexed when it was machined

actual piston compression height

how well the factory machined valve pockets match up to an individual motor's valve timing

accuracy of cam & crank sprockets and flywheel marks

installed height of the valves

I'm sure there's more. All of these things will affect how close the valves will come to the piston.

Howdy,

so for those who installed the 223 webcam, was it plug and play? Did you have to get valve pockets done on the JE HC piston? Did everyone boter checking clearances?

I'm tossing up 223 or 190 grinds but I dont want to mess around making valve pockets!

LuKas - if you havent already split your cases... FYI I just split mine and no tool was required (not even a screwdriver). The cases separated easily by hand.

cheers,

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