jst854 Posted April 29, 2010 Report Posted April 29, 2010 I just got a +4 swing arm for my shee as I am building it from the ground up and need help finding a chain as well as a good baseline for the gearing. I know the chain is 520 pitch but how many links will be needed for a + 4 swing arm. I will have around 70 HP and plan on dragging it in the 1/8 mile and was wondering what gear set up would best suit me, I am pretty sure that I have 20 inch tires, I will double check that tonight though. I also have the option of running on alky and my engine builder told me to expect around 95 hp that way, not sure if I want to go that route or not yet as this is not strictly a drag bike, but if I were to do that should I run taller gears than if I ran it on gas? Quote
J-Madd Posted April 29, 2010 Report Posted April 29, 2010 There used to be a pinned topic that showed how to calculate the number of links needed for a particular length swingarm, but I don't see it now. What all is done to your motor? 70 hp on gas will never equal 95 hp on alky. You don't get a 30% increase. More like 6 to 10%, I think. And yes, you can usually run taller gearing with alky vs gas. If it's not strictly a drag bike, you may wanna stay away from alky. You use about twice as much compared to gas. I can't help you on 1/8th mile gearing though. Quote
bansheesandrider Posted April 29, 2010 Report Posted April 29, 2010 I run 13/40 gearing with a +4 swingarm, my chain is either 112 or 116 links, I can't remember. I just buy a 120 link chain, wrap it around the sprockets and cut it to the length I need. I can't give you a recomendation for gearing. But running alky on an all around bike is a pain in the ass- you only get 1/2 the fuel mileage of gas, you have to drain and purge the fuel system if you are going to let it sit very long and your premix oil needs to be compatible with alky. Quote
SAVAGE420 Posted April 29, 2010 Report Posted April 29, 2010 Looks like you will need 117 links. http://metaltechproducts.com/Chain_Calculator.htm Quote
jst854 Posted April 30, 2010 Author Report Posted April 30, 2010 Thanks for the help and the engine is a 4mil stroked long rod bringing the engine up to about a 403. John at Gassrx did all the engine work. It will be running CPI inframes with 35 carbs. Should have it all back together in about a week or so Quote
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