Hey i u had some time and money could u build a 400ex to be competative with new quads? If u put on a 440 kit with a cam bigger carb and full exhaust filter no lid air box. Would it be as fast as or faster than a stock raptor ds 450r yfz banshee? I think that it would be able to take a z400. People say that they suck so much but if u had all of this done how would it compare? I know that handling would be a different story... Just wondering. thanks

 

I've heard of some EX's that were pulling away from 450's on a MX track but I don't know who built the motors. If you want a FAST 400EX talk to "AZsand" in the Bombardier forum. He has a 465EX that's set up for drag racing that beats modded Raptors and DS's...... I know it's a drag quad but I bet he knows how to make a 400EX fast.[img]i/expressions/face-icon-small-smile.gif[/img]

 

My quad is only 416cc and I can take stock and piped Raptor's, Predator's and Z400/KFX400's all day. I have never beaten a Banshee that was running good. Never got a chance to race a YFZ or DS650 yet. I don't think I could keep up. Yes, if you put enough money into a 400EX you would be very competitive against the newer machines. Put that money into a different machine and you won't have a chance.

Still, on a slightly modded 400EX if you are a better rider than someone on a newer quad you can still give them a beat down.

I love my 400 but it's time for me to move on to something newer.

 

mxer250-My wife has a 440 that can take stock raptors,450rs.yfzs and banshees so yes it is possible with enough time and money.We dont claim to have the fastest 440 but it is fast enough to hang with the newer quads of larger displacement and it is an excellent overall dune machine so we are happy with it.Just last weekend my wife was racing a hrc kit equipped 450 r and they were pretty even in 300 feet on the sand so the 440 can do very well if tuned and set up properly.

 

That's the key - you can't just go buy the parts and throw it all together and expect it to run like a raped ape - you'll need to do some homework on it or work with a good builder to get things matched up. I've seen a few 440's that didn't impress me in the least - but I think they just slapped it together without educating themselves on the best match of compression ratio, head work, cam and pipe choices.

 

there right set up is the key.

 

My 440 can keep up with just about any stock machine out there, if I could get and afford race gas, I could put in a higher compression pisten and be that much faster.

 

I am having problems with my 440ex. Does the head have to be ported? The manifold gets red hot which tells me it is a timming/breathing problem. The cam placement is correct and the firing/ timing is also correct. I have white bros 440 kit/ je piston 10.5 compression with the suggested mid range cam. fmh power bomb header and exhaust. k&n filter with 165 main jet in carb. no advanced flywheel key, stock cdi box. I have ruled out the possibility of the decompression cam being the problem. Piston placement is correct and I have run 110 oct gas incase the compression was too high after machining down the head. The only thing I can think of is that I need the head ported & polished with larger valves.

Thanks for any good info.

Is anyone running a 440 kit without the head work done?Text

 

you just need to change the jetting. i have a feeling you mainly need to lower your needle clip to the 4th position if your using the stock carb. also, you should put in a 42-45 pilot jet. the mainjet has a lot to do with what mods you all have on the bike.

 

I would guess that if your intake is getting hot, either your out of time or your intake valves are not seating.