440 kit, how long will it last?

[CT400exRIDER]

hey i was just talking to a local atv shop and i wanted to put a 440 kit in my 400 but the guy told me that they are very unreliable and wont last long, he suggested a 416 but i want more power than a 416 would give me. so is the 440 a good choice for long term or no?

[Pipeless416]

Originally posted by CT400exRIDER
hey i was just talking to a local atv shop and i wanted to put a 440 kit in my 400 but the guy told me that they are very unreliable and wont last long, he suggested a 416 but i want more power than a 416 would give me. so is the 440 a good choice for long term or no?

every engine modification that you make to your quad will make it "less reliable." this is only because the extra power puts more stress on parts like the gears, clutch, and other internals. i'll stick with this saying..440s are as reliable as the builder. however, when you need to rebuild you'll need to resleeve, so maybe think about a 416 with a stroker crank?

[mod440ex]

iv had my 440 kit for 4yrs. the only thing i have had to do is change my rings, which should be done anyway so its cool. I am even running a 12.5 :1 piston.

[CT400exRIDER]

Yeah it seems that theres a lot of people running 440 kits and i havent read about a lot of people with problems. I know that ofcourse there will have to be more rebuilds than stock with any size you go up but im willing to do that for more power, i just dont want it to turn into a yearly rebuild for me, considering i dont race and dont put too many hours on in a year.


Pipeless416, how do you like your 416, and are you running a stroker crank?

[Barrymaxx]

How well you build it, and most importantly how well you maintain it will be key to making a 440 last. Change the oil often, clean the air filter, and just keep up with the maintenence and you should be good.

Us good gaskets. Also, keep the compresion a little lower.

[mod440ex]

im telling you that i have not been the best at doing the routine maintenance, and i still have not had any major problems with mine. I have had to replace the piston once, and I went from a JE to a wiseco. It still ran but just smoked really bad. The torque pickup that you get from it is amazing, well worth the money.

[flauge]

Ya know, the only thing that keeps me from wanting a 440 is the stock con rod. I heard that there kinda weak and could possibly break with a 440 over time. How long have some of yall been running your 440's and has anybody had any bottom end probs??

[CT400exRIDER]

i definately want the 440 but does anyone know a shop in CT or new england that could do it for me because the guy i was going to go to obviously isnt very confident in himself

[STEVENJANNA]

I built a 440 for mx 2 1/2 seasons ago. This will be the 3rd season and the motor has never been apart. It dominates the C class locally and it makes these 450's look silly. For the $ you'll spend on motor work I wouldn't go any other.

[Pipeless416]

Originally posted by CT400exRIDER

Pipeless416, how do you like your 416, and are you running a stroker crank?

my 416 isnt what it should be since i dont have an aftermarket pipe on it. the crank is stock, so i dont gain anything there either. overall, there is a big more low end torque because of the high comp piston, but its not what it should be since my engine is choking. :(

[Ruby Soho]

Originally posted by CT400exRIDER
i definately want the 440 but does anyone know a shop in CT or new england that could do it for me because the guy i was going to go to obviously isnt very confident in himself

hey, i have a 440ex. bought it like that though. im having HD studs put in within the next 2 weeks. Im going to a guy named Ray, works at Xtreme Motorsports in Danbury. He was recommended to my by New Milford cycles and hes doing it for a decent price.

PM me if you need any more help

[CT400exRIDER]

hey thanks for the info i think i will give them a call

[mod440ex]

i have the stock crank in mine and it still in great working shape, just have someone bore it out and do it yourself. its not hard at all just get a manual and take your time. the key is your break in period.

[PismoLocal]

My quad was bored out to a 440 in 2003 I bought it in 2004 and rebuilt it with HD Studs and a crf cam chain. I also bumped up the compression. It has been raced 2 seasons locally and has made 100+ dunes trips. I have never had any problems with mine until recently third gear is acting up. During my last ride the oil drain bolt fell out of the case, while I was hammering around a track in third gear. I think the lack of oil and stress I was putting on the gear wore it out though not the fact that my quad was bored out.