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Discussion Starter #21
I've always used Lucas Oil in all my bikes. Specifically 4 stroke motorcycle oil...not additives. Anything better I should maybe use?
 

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thats a good oil, factory gn4 is valvoline atv oil repackaged, castrol atv oil works great too as well as amsoil. as long as its an atv oil or is listed as service grade SJ you should be fine. whatever you do DONT use honda HP4M (silver bottle) this has molybdenum (slickest friction reducer known to man) in it and will make your clutches slip like crazy. its designed for split bottom end race bikes (CRF/TRX450R) and scooters.
 

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Discussion Starter #23
Hey guys...so the bike runs great but there's a bog in the throttle at around two thirds. My question is whether it may be a bit rich with a 185 main jet. Going to do a plug chop when I have the time but am hoping you have some insight. Basically at sea level, slip on pipe, 440 kit w/10:1 comp. piston, uni filter with modified airbox,dynojet needle and jets, hotcams stage 2. Stock valves and springs with valves set to hotcams specs. Fuel screw at 3 turns out. Any input as to the dead spot in the throttle? Plug color seems good at a light brown.
 

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Discussion Starter #24
And does anybody make a fuel screw extension or a flex shaft knob for the stock 400ex carb? This one has the stupid D shaped screw and I hate having to mess with the tool to try to tune the carb when my hands don't fit.
 

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the trick is going to be with your dynojet jets. they are great for stock machines with a pipe and an air filter but after that they make tuning "interesting." the bog you are experiencing in midrange is most likely in the needle. try raising it the needle a click and see if it improves.
 

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ive heard of a company that makes them for a lot of other machines but for the life of me cant think of it. if you can get your hands on the motionpro 90 degree driver it will serve you well for just about any machine you work on. its expensive but well worth it.
 

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Yep i have looked many times for one that will fit a 400ex. They all look like they will but dont say they will so i havent gambled the money yet. I picked up my motion pro 90° driver for around 50 bucks a few years ago and it has helped me tune countless carbs. Good quality product for sure!
 

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ive heard of a company that makes them for a lot of other machines but for the life of me cant think of it. if you can get your hands on the motionpro 90 degree driver it will serve you well for just about any machine you work on. its expensive but well worth it.
Probably R&D Flex Jet. They will not fit a stock 400ex carb. I have one in my Sudco

sent from MOOSE mobile
 

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I have a 05 426 with a 45cr carb on it with doul pips keeps blowing head gasket's
Welcome to the forums! I suggest you start your own thread to get the most answers. As for your head gasket issue. Did they bore the stock sleeve out to a 426 or re-sleeve the cylinder? Do you have gt thunder hd head studs? And are you using a high quality mls (multi layer steel) headgasket? If yu answered no to either of the last 2 questions there is your problem right there.
 

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Discussion Starter #34
Yep....you need gt thunder head studs and cometic multi layer head gasket. Now you'll need to make sure all of your mating surfaces are dead flat as well.
 

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How has the 440 been treating you? Any issues yet? I can grab one locally for cheap, was planning on a similar build to yours....
 

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He should be able to keep with Dad's 450 in the woods and maybe in the open sections depending on tire selection and rider ability. P.S. I live in Fl. and never had an overheating issue. Did blow some head gaskets but went to solid copper and have had no problems. I also run Rotella T oil with no issues in seven years.
 

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on my ex I used a moose racing carb kit that supplies a slotted mixture screw. I have a motion pro angle driver but will not clear the starter. I stuck a slotted bit in a piece of 1/4" fuel line about 8"long and can adjust it from underneath. Redneck engineering on an Amish budget
 
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