Cooling my EX Better?

[FoxRacing81]

I have a 400ex thats bored and stroked to a 610. Heres the motor mods.

610 bore/stroke
nickel coated rockers
hotcams stage two
ported and polished
k&n filter w/ no lid
wb r4

I run 20w50 atv oil and octane booster to try to keep this thing cool, and it still runs REALLY hot. Anything I can do to make it run cooler? Big oil cooler? Anything?

thanks
610ex

[Aceman]

Holy Chit!! I didn't even know 400's could be made into 610's, I thought around 500cc was the biggest. Man that thing must haul!! Anyways have you tried running air scoops, a cooler plug, maybe an aftermarket oil cooler like FST has. I don't think it's a very good idea to run octane booster, seems like a lot of guys on here don't like it because it causes deposits in your engine. You should use race gas which I think will help lower your engine temp a little. You could also purchase a Warp Drive Temp Gauge from C&D Racing to monitor your engine temp.:D

[mojoe2878]

DAMN:eek2:
your cylinder wall's gotta be paper thin.
you could probably install scoops and a bigger oil cooler and some race gas, like Aceman said, to help some but i dont think that things ever gonna run a normal temp.

[cals400ex]

who makes a kit that goes that big?? :huh


what compression is your bike?? is it jetted properly??

i have a feeling you need to be running straight race fuel and nothing else. octane boost may harm more than it will help.

[FoxRacing81]

I'm not sure who makes it, I bought it off of a guy who already had it installed. Its brand new and not even broken in so the power isn't really there yet. Need to get her broke in and vavles adjusted and maybe go a little bit down on the front sprocket. Right now, the torque isn't really there. I'm thinking break in and re-gear it.

I'm considering running Race Gas if I can find a local place that sells it. If I have to drive out of my way, I dunno.

What companys sell bigger oil coolers? or anything to make this thing run cool.

[Screamin440]

My only question is this: Do you KNOW it's a 610 or are you just going off of what the guy told you?

[FoxRacing81]

by what he told me. But I don't think he'd lie. He has a quad shop so I could tell everyone not to go to him if it isn't. But I may need to replace the headgasket so I guess I'll find out.

[Aceman]

If I was you I wouldn't run that thing until you put some auxiliary coolers on there. During break-in engines run warmer than usual, you're going to kick yourself if you cook that engine from overheating it. Definitely run race gas, just find a local fuel distributor they usually carry it.

[fmf400ex03]

id run like a 110 octane and no octane boost that crap will make it run a lil hotter thats why we run it in the sleds, if that is a 610 than whats the life on that thing break it in and then rebuild it. unless its a like 600 dirt bike motor cuz i dont think u can go that big because of the timing chain and stuff like that. but who knows dont be serprised if u need mad tranny parts and a new motor soon

[bigbadktm]

im thinking maybe an old air cooled xr500 motor bored and stroked out. if thats a stock 400 bored and stroked...that kinda scares me. might have to have the head coated on the outside. just saw an article in dirt wheels with a 400ex that was coated and all. maybe even ceramic coating on the exhaust to help pull the heat outta the cylinder.

[EPDP99]

scoops, larger oil tank, extra oil coolers and check air/fuel screw on carb. 1 full turn out helped mine a ton. that motor is def. gonna run hot during break in. Mine did.

[Toadz400]

I'd definately look into getting your engine coated with ceramic and your exhaust too, that would definately help with heat problems. Definately run race gas instead of octane booster, that stuff is no good. Make sure your jetting is good, don't be afraid to run it a little rich, it's always better than lean.

[JIMTED79]

610!!!!!!!!!!
WHAT IS THE BORE AND STROKE ON THAT BIKE?
AND IS IT A 400EX OR DID HE SWAP MOTORS?:confused:

[UglyMotha™]

BS :o



there's no such thing if your talking bout the 400ex motor :rolleyes:

[XCR 440ex]

need to retart your timing 4 to 76 degrees with a new wooddruft key, should only be running race gas with octane no less that 110. also try having a 3 angle grind on your valves that allow better air flow. also FST and desert atv make different oil cooler changes. FST has a kit that has a larger cooler and redirects the oil to the top of your rocker arms. desert atv make a larger cooler

[UglyMotha™]

i dunno but i just may be retard here :o but doesn't 76 degrees just seem a little excessive :huh :huh

[sickmojave]

Originally posted by XCR 440ex
also try having a 3 angle grind on your valves that allow better air flow.

the 400ex came stock with that and correct me if I'm wrong but isn't it for a better seal not flow.

[XCR 440ex]

ha was suppose to be 7 degrees my daughter spilled crap on my keyboard and sometimes the 6 and the 7 sticks .....haha

[XCR 440ex]

as for the stock valves coming with a 3 angle grind , yeah i guess they did come with a type of 3 angle grind on it but it isn't flowing and don't seal up that great. and yeah the grind is more designed for a better seal your right but that is what you want since the stockers don't seal up really good you do get some blow by back in the head and down in the case which generates more heat, so in doing the 3 angle grind it makes the flow of the air more constant and less blow-by also port and polish will help the air flow. All the inprovements that you can do for your engines air flow will help with its heating problems. dig?