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QuAdEr 317
12-13-2004, 03:24 PM
next season im racing and i wanna kno what bore i should get so that 450s aint smoking me in the straghts n what not....what kind?what size? what all to get? also its for mx

400exrider707
12-13-2004, 03:47 PM
Drop in a CRF 450 motor

QuAdEr 317
12-13-2004, 03:49 PM
Originally posted by 400exrider707
Drop in a CRF 450 motor

thought bout that but thats big bucks
1) buy motor around 2 grand or more
2) jb to do my frame to acept it - around 800
3) radiatior for it - ???????

i was thinking motor work lik a 440 or 460 would be about 1500

JDiablo
12-13-2004, 03:50 PM
go with a 460 like me:devil:

gotahemi2004
12-16-2004, 09:31 AM
i got a 04 with a 440 just installed with port work and cam, carb , pipe , intake , plastics done for bout 2100 bucks.. i just cant tell if it has mor epower than a 40 cuz i havea yfz im use to rideing and going backt he 400 feels weird.. they guy said it should run with a 450 without a doubt... i got another 30 min or so before the rings set so i cant get on yet lol ill let ya know how it does in caparision to a 450

Colby@C&DRacing
12-16-2004, 01:00 PM
I would build a 426 it has alot of torgue and will rev really fast. If you are going to keep up with the new 450's you need torgue and a motor that spinns really fast.

TC426EX
12-16-2004, 02:37 PM
Originally posted by Colby@C&DRacing
I would build a 426 it has alot of torgue and will rev really fast. If you are going to keep up with the new 450's you need torgue and a motor that spinns really fast.

I second that reccomendation...

QuAdEr 317
12-16-2004, 02:45 PM
Originally posted by Colby@C&DRacing
I would build a 426 it has alot of torgue and will rev really fast. If you are going to keep up with the new 450's you need torgue and a motor that spinns really fast.

thanks colby..if u were doing the work what parts would you use?cam,piston,pipe,carb, and what not....also what would be mandatory lik would i need a carb or what thanks a lot

ckasper18
12-16-2004, 02:53 PM
Go with the 426 kit way more reliable and only a couple horsepower difference.

RedRacer44
12-16-2004, 03:01 PM
I have had my hands in on a few EX builds and we had the best luck with the 426 motor. They rev fast and make a lot of torque, very fast and easy to ride on the MX track. We had problems keeping 440s together for long periods of time and 416s are nice but not enough power output.

The 426 power is very smooth and pulls hard outta corners, mind you its not like a 450R but the power is there. The last 426EX we had would run with my 450R when it just had a pipe. Granted I would pull him in 3rd gear, but he was right there with me in most of the holeshots.

That 426 had a 13.5:1 piston (if I remember right), White Bros Race Cam, Sparks exhaust, K&N Filter, and 40MM FCR carb off a CRF bike. We never got it on a dyno but it had some serious power. With some head work, that thing woulda been crazy fast! Only problem we had was the quad would blow a head-gasket every now and then :(

JDiablo
12-16-2004, 03:19 PM
so your saying that the 460 wouldnt be as reliable at the 426?

RedRacer44
12-16-2004, 03:24 PM
I havent had any experience with a 460 personally, so I really couldnt tell ya. We tried a few 440s and just couldnt keep them together for very long, but I have other buddies who built 440s and have had nothing but good things to say. So who knows.....

JRDrider22
12-16-2004, 03:46 PM
the 460 will take you out of the production class. the 460 will put you in the open class. either get he 426 or the 440

QuAdEr 317
12-16-2004, 03:53 PM
why would that take you out production it dunt say a cc range at nationals

JRDrider22
12-16-2004, 04:06 PM
check the listings. its 0-450

RedRacer44
12-16-2004, 04:28 PM
Any of the production classes (A-C), the limit is 450cc. Same as the Pro class rules and ProAm Production class rules. You could run the Open classes at nationals. As far as on a local level, most places dont really enforce the "open" class rule, at least around here they dont.....

markk
12-19-2004, 08:57 PM
I have only been passed by one 450 in a feild at our local track in Casey Illinois, And he was right on my butt entering the feild, and we both hit tires going back into the woods. Now at a GNCC u might have a little bigger problem with the 450's blowing a 416 away. I have been thinking of a stroked 440, that way i can get that extra tourque and still rev pretty quick.
My understanding with a 426 is they run and performe great, but heat becomes a problem with alot of mud.

QuAdEr 317
12-20-2004, 11:57 AM
so does this sounds about right? full pipe,port n polish head,cam,426 piston JL proly unless sumtin esle is better,carb........which carb would be the best for a 426? i heard sum carbs have a lot of problems but i dunno which carbs there are n which are good let me kno please........also bout where to send my head,what kinda cam please help this is for mx racing

QuAdEr 317
12-20-2004, 12:01 PM
also maybe a rev box along with that...i seen TC has a rev box, cam, and ports n polishes i think
ne1 dealt with them? how was their service

QuAdEr 317
12-20-2004, 12:09 PM
also you guys recomend a aftermakret clutch or nething liek hinson? if so whats the reason?

torqen2k1
12-20-2004, 09:02 PM
Well go for the 426 im definately satisfied with my motor. Ive heard that GT Thunder has some good rev boxes. That their buikt for the 400ex not reboxed 250r rev boxs. Also I had a local engine builder do my head porting and a valve job. So look for a good known engine builder.

P.S. get some air scoops, run synthetic (Red Cap Mobil 1) oil and a bigger oil cooler to keep the temp down.

spiderrider04
12-21-2004, 09:15 AM
Originally posted by QuAdEr 317
so does this sounds about right? full pipe,port n polish head,cam,426 piston JL proly unless sumtin esle is better,carb........which carb would be the best for a 426? i heard sum carbs have a lot of problems but i dunno which carbs there are n which are good let me kno please........also bout where to send my head,what kinda cam please help this is for mx racing

C&D did my motor work and i have nothing to say but great things about them. i got a ross 426 kit, port, polish, and hotcams stage 2 cam. i race mx with it and i have beat piped 450rsi and yfz's. i haven't got a carb yet but i have heard good things about the fcr 39 and 41, so i was looking into them. i was also looking into getting a tc rev box and some air scoops.

as for an aftermarket clutch, i'm running the stock clutch right now, and so far so good.

Jersey450R
12-21-2004, 09:50 AM
A Pro Production Yahama 426 motor would be your best bet.

RIDER11X
12-21-2004, 10:46 PM
I know the 8 plate clutch mod is a popular one, but I am a bit leary of it myself. I have read about problems pieces of the basket beaking off and going through the tranny with them. It make me wonder if it makes they hook up so good that it overstresses the basket, instead of allowing a little bit of slip that would cushion the hit.:confused: Anyone have any knowledge of this?

Rico
12-22-2004, 07:24 AM
Originally posted by RIDER11X
I know the 8 plate clutch mod is a popular one, but I am a bit leary of it myself. I have read about problems pieces of the basket beaking off and going through the tranny with them. It make me wonder if it makes they hook up so good that it overstresses the basket, instead of allowing a little bit of slip that would cushion the hit.:confused: Anyone have any knowledge of this?

I wouldn't run a stock basket with an 8 plate setup. The horror stories you've heard were probably not with a Hinson basket. Put a new stock basket in with a 8 plate and replace it once a year and you'll be fine. But if some idiot that had 4 years of use with is stock basket and then threw a 8 plate kit in there kinda got what he deserved if you ask me.. Stupid Hurts

Rico
12-22-2004, 07:32 AM
Originally posted by markk
Now at a GNCC u might have a little bigger problem with the 450's blowing a 416 away.

I"ve not had this problem..:confused: Short shift and stay on the gas hard and they won't blow you away. With good suspension I"ve passed plenty of 450's in the ruff straight aways.

Person that started the thread....
I'd also say go with a 416. Why push your cylinder to the max and cause problems for an extra .5 HP..:confused:

Also people are talkin about max CC in racing and what not. That only goes for GNC Racing in the PRO class, which 98% of this site is not, so don't base your engine on those rules unless your racing against Tim Farr and the boyz..:cool:

RIDER11X
12-22-2004, 10:56 PM
Originally posted by Rico
I wouldn't run a stock basket with an 8 plate setup. The horror stories you've heard were probably not with a Hinson basket. Put a new stock basket in with a 8 plate and replace it once a year and you'll be fine. But if some idiot that had 4 years of use with is stock basket and then threw a 8 plate kit in there kinda got what he deserved if you ask me.. Stupid Hurts

Good point Rico!:cool:

nosliw
12-22-2004, 11:42 PM
how different would the suggestions you gave quader317 for mx differ from, oh let's say, me wanting to make my ex into a torque-monster trail machine? :D

TC426EX
12-23-2004, 05:56 AM
Originally posted by QuAdEr 317
also maybe a rev box along with that...i seen TC has a rev box, cam, and ports n polishes i think
ne1 dealt with them? how was their service


Their service is great if you ask me I couldnt be happier. Its really up to you to make a decision on a motor builder though, and I am not a spokesman or marketing guy for TC. All I can tell you is that I love the work I had done, and can hold my own against 450's with this setup.

GT Thunder also does great work and has an awesome turn around time as well.

Hopefully you have some time on your hands before youd need your motor back since it is the off season after all for most people and most of the good engine builders are backed up this time of year. Your best bet is to call around and talk with the companies personally and see who you like the best. Youre looking to make a significant investment, so do as much research as possible...

RIDER11X
12-24-2004, 11:30 PM
Originally posted by RIDER11X
I know the 8 plate clutch mod is a popular one, but I am a bit leary of it myself. I have read about problems pieces of the basket beaking off and going through the tranny with them. It make me wonder if it makes they hook up so good that it overstresses the basket, instead of allowing a little bit of slip that would cushion the hit.:confused: Anyone have any knowledge of this?

When I posted this^^^^^^^^^^^^^^^^^^^ I was referring to this that I found posted on GT Thunder's website:

Critical Note:
I have seen several clutch
basket backing plates
break sending hardened
steel pieces thru the
engine , doing
considerable damage. I
now replace my clutch
basket with a new one
once per season on the
400EX.

It sounds as though the backing plate is at fault more than the basket itself.........:confused:

rummerd
04-18-2005, 02:28 AM
well, its an old post, but good info in it. I just bought JMR_426ex's quad from this sight. It has a 426, rev box, head port and polish with hardened rockers, bigger valves and stronger springs and a Lectron carb. This is apparantly a pretty good setup according to what I am reading here. Should run with a 450 that has mild bolt ons, maybe hang with cammed and higher comp. pistons W/head work? Answer me this, How would a 440 with the same mods compare? Also, as to head gaskets occasionally leaking, is the higher compression piston to blame mostly due to the higher presser in the combustion chamber, or is the larger bore cause less sealing area the main cause of the failure?
If I understand you guys correctly, A well built 400EX is the bigger bang for the buck against a new 450 machine. Don't really see the extra $ being worth the few HP a mildly modded 450 is going to get ya or am I way off base on that?

NacsMXer
04-18-2005, 07:02 AM
Originally posted by RIDER11X
When I posted this^^^^^^^^^^^^^^^^^^^ I was referring to this that I found posted on GT Thunder's website:

Critical Note:
I have seen several clutch
basket backing plates
break sending hardened
steel pieces thru the
engine , doing
considerable damage. I
now replace my clutch
basket with a new one
once per season on the
400EX.

It sounds as though the backing plate is at fault more than the basket itself.........:confused:

You are correct. GT Thunder says the backing plate is the weak point on the 400EX clutch.

TC426EX
04-18-2005, 08:06 AM
Originally posted by rummerd
Also, as to head gaskets occasionally leaking, is the higher compression piston to blame mostly due to the higher presser in the combustion chamber, or is the larger bore cause less sealing area the main cause of the failure?
If I understand you guys correctly, A well built 400EX is the bigger bang for the buck against a new 450 machine. Don't really see the extra $ being worth the few HP a mildly modded 450 is going to get ya or am I way off base on that?

As far as your head gasket leaking, thats probably because the engine in the quad you bought still uses the stock head studs. If you can check on that I would do so. The stock EX studs are notorious for failing once higher compression/bore has been added. I blew a ton of head gaskets on my 426 before switching as well. With the engine you have in there, HD studs are pretty much not and option, and something you MUST install.... Also, you may want to add an HD rod in there sometime because there are alot of high compression 426 and 440's that snap rods like mine, doing extensive damage. Those 2 reccomendations will increase your reliability ten fold.

As for your second point, yes the modded EX can hold itself against the 450's if you ride it right. The 450's are liquid cooled though, and that is a huge advantage over the EX. After being ridden very hard for an extended period of time, a heavily modded EX can have the tendency to fade off a bit. Thats why some people add an auxillary oil cooler to help keep the temps. on this air cooled engine down. So, while the modded EX can still compete fairly well with the new 450's, the new bikes have a newer generation motor (compared to the EX which hasnt been updated or changed since like '96), and theyre liquid cooled meaning you can pound on them harder and longer....

rummerd
04-18-2005, 09:01 PM
well, that's one of the reasons I decided to buy this quad, it already has the additional reliability mods done to the motor, with the exception of the HD rod. I was already planning on adding that after the first season of riding as this motor is a fresh rebuild. I am going to be looking for a good deal on a similar quad so that my wife can go duning with me again, we sold the R's when we moved to WA state, got sleds again! I would love to find another ex like this one, but I am thinking that I will also be looking for a CRF motor to do a hybrid swap.