Determining chain length and sprocket sizes?

[250Renvy]

Is there a general rule when making a hybrid to determine chain length and sprocket sizes?

I'll use 2 examples of my hybrids

250R vs 300ex:
250r chain length = 520x92/ 13/38 sprockets
300ex chain length = 520x86 13/38 sprockets

Will changing my chain length change anything?

250R vs Z400:
250r chain length = 520x92/ 13/38 sprockets
Z400 chain length = 520x96/ 14/40 sprockets

If I shorten the chain should I keep stock sprockets?

Does chain length even matter or do I just go with whatever the requirements of the machine the motor came from?

[400exMO]

Why would you want to shorten your chain? As long as it is in proper adjustment it should be good. I believe the length of your chain with be determined by your swingarm length and motor position. I know my crf front sprocket sits further back in my frame than the 400 did. I had to shorten the chain for that.

[250Renvy]

Anybody have any more input on this? I need to order chain and sprockets and need to know what size I should order.

I can't even buy a 40 tooth rear sprocket for a 250R.

If I go down a tooth in the rear, does that gear it up or down (ie low end or top end)

[k4f5x0r]

less teeth in the back=more lowend more =more topend
more teeth in the front=more topened less teeth=more lowend.

1 front tooth= about 3 back teeth.

[redred55]

40 toother's are available. I may have one I used once if you need it.

[audioworks04]

more teeth in the rear should actually gear you lower
more teeth on the counter shaft=higher

[Glamis400ex]

I run a 13/42 on my CRF450 hybrid. These arn't the cheapest but they are GOOD.

http://www.dirttricks.com/ironman_quad.htm