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my 421 is running hot! why?


rascal

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hey guys HELP... vitos 421 full drag port ... 4mill vitos stock rod crank, 34mm kehin pj carbs , 172 mains .needles 3rd from bottom.pilots 32, elevation 1100ft... fmf fattys ..kn pods ,timing +4 ...hemi head 2 with 22cc domes . pro flow billet intakes with v force 3 reeds.. i installed a billet high flow impellar too!

plenty of oil ....32 to 1 mix... and high octane fuel....mixed it 50/50 115 and 93 oct..

 

 

dam thing keeps heating up and bubbling into the reserve tank when not MOVING through the wind!! runs great other wise but a little rich in the mid..WHAT WOULD CAUSE THIS..THE BIGGER PISTONS...? .the engine only has 2 hrs total on it.. cant barelly be ridden in the woods!

 

any help or comments would help .... thanks

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I run a 48 pilot @ 5000 feet.

 

first off your running totally different carbs

sec each needle changes variable alot

3rd ones persons jetting is going to be the exact to anothers sure they might be close but always different.

 

 

 

while i do argee 32 is beyond lean there is alot of other variable to be looked into.

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32 pilots is a problem.

my pilots are 57 s ..i wrote it wrong..it idless great..all day long.. its rich too .. mid to top..plug chop was great. brownish..

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First thing is to put a temperature gauge on the return so you exactly how hot it is getting. It could be a o-ring in the cool head. Did you torque the head down in the sequence in three steps? It could be a couple of things.

yes ..i torqed it the way it said.. no leaks either.. plugs look great. ... no collant escaping into the cylinders..

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wrong jetting

na man if anything is perfect on idle..tiny bit fat in the mid...top looks great but a bit rich.. wont pull real hard on a load in 5th and 6th gear..like it a bit rich thow for the higher rpm range!

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make sure the impeller is working ( pop cap, rev bike, look for coolant wooshing around), replace your cap, 13-16psi is available at o,reilley's ( its an import cap) do you have actual coolant in there like 50/50 mix right out of the bottle? or straight water out the tap ( big no no) THEN make sure your radiator is CLEAN that is NO mud or dirt or crap in the rad finn's is your grill stock or one of those aftermarket ones that you cannot even see the rad? wash it out with water and LET it dry before you ride it in the woods. if the finns are bent bad you might try and straighten them. you can't really just put put a bike like this in 1st gear or so. there is no fan and they can get pretty hot due to the lack of flow. the 16psi cap might solve the issue also. IF everything else is ok.

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