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Post by billy on Aug 28, 2010 11:25:10 GMT 1
I guess this has been asked to death already but I couldn't find a thread/post about it, so here we go. ;D
- If one would run premix, what kind of main jet size would be good to start experimenting with? FYI I'm running a K&N type of filter as the airbox is missing.
Might aswell ask - what is the original main jet size on the Mk1 model?
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Post by looey on Aug 28, 2010 13:27:09 GMT 1
12A or 10W carb ?.
And the jet increase in size when running premix will depend partly on what premix ration you're running but it won't be much either way ?.
i.e. if you're running 33:1 then you'd increase you main jet by 1/33rd. So if you were running say a 185 main jet with 33:1 premix then you'd increase a 185 to a 190.
Let us know what carb type you're running and someone will give you an idea what jet size to start with and how much to increase it by with premix.
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Post by billy on Aug 28, 2010 18:28:22 GMT 1
12A or 10W carb ?. And the jet increase in size when running premix will depend partly on what premix ration you're running but it won't be much either way ?. i.e. if you're running 33:1 then you'd increase you main jet by 1/33rd. So if you were running say a 185 main jet with 33:1 premix then you'd increase a 185 to a 190. Let us know what carb type you're running and someone will give you an idea what jet size to start with and how much to increase it by with premix. Oh sorry lol, it's a 10W carbie.  Hey any idea how much 33:1 is in procent? We don't use the same way of measuring the oil ratio so 33:1 and 40:1 etc doesn't say squat to me lol! ;D  I always have about 3% in a cast iron bore. |
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Post by looey on Aug 28, 2010 18:48:35 GMT 1
Yeah, the easy way to work out what a percentage is (there are others way to do it) is divide the small number by the large number, then times by 100. So for 33:1 (33/1) it would be (1 divided by 33 = 0.303030303) x100 = 3.03 So your 3% is actually 33:1  I'm not the best person to advise on main jet size on your setup cos I run a 10w carb with a Micron Pipe but std airbox (pipercross element & inlet nozzle removed) and I'm running a 170 main. I would've thought a 190+ but I'm sure someone will be along soon to advise who's run a similar setup. |
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Post by billy on Aug 28, 2010 23:18:53 GMT 1
I'm not the best person to advise on main jet size on your setup cos I run a 10w carb with a Micron Pipe but std airbox (pipercross element & inlet nozzle removed) and I'm running a 170 main. I would've thought a 190+ but I'm sure someone will be along soon to advise who's run a similar setup. Well you rock on mathmatics anyway, that's always something lol..  I'll wait and see if someone else has an opinion too then.  I know I have to experiment with jets anyway though as nobody can tell me exactly what jet would be spot on, but it would be ace to get an answer on where-ish to start. Btw I forgot to mention the bike has a stock exhaust, so it's just a stock engine with k&n filter and premix. Hey I just checked the jet (as I'm typing this message actually) and it is a 210 jet in it. Previous owner also ran premix but who knows if he did it properly? Never ridden the thing so I have no idea how rich it is, maybe it's spot on as it is lol? ;D |
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Post by looey on Aug 29, 2010 8:59:21 GMT 1
A 210 is a fairly big size in 10w carb, so I'd say you'll be fine to run it with that one fitted. Just don't thrash the lungs off it straight away and check the plug regularly to see how it's burning. Mine's deffo on the safer side of things with a 170, so can't see you're gonna blow a hole straight in your piston  ;D |
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Post by billy on Aug 29, 2010 11:35:37 GMT 1
A 210 is a fairly big size in 10w carb, so I'd say you'll be fine to run it with that one fitted. Just don't thrash the lungs off it straight away and check the plug regularly to see how it's burning. Mine's deffo on the safer side of things with a 170, so can't see you're gonna blow a hole straight in your piston ;D Haha okey thanks, guess I'll be looking for a bunch of jets then and work my way down. |
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I always have about 3% in a cast iron bore.
I'll wait and see if someone else has an opinion too then. 
I know I have to experiment with jets anyway though as nobody can tell me exactly what jet would be spot on, but it would be ace to get an answer on where-ish to start. 
;D