450R carb on 500EX??

[44oEX]

I have a carb of a 450R and wanted to put it on my 400ex ( 500ex ). I know it won't just drop in but is there any way to make it fit. and if so would it do anything if I don't use the trottle position sensor.

The reason for this is that I fell the 500 motor is very limited by the stock carb. I don't really want to spend any money on a FCR or anything like that. Since I have this carb anyway might as well try to make it work.

And if I can get it to work would there be any noticible loss in the bottom end cause the carb is bigger

thanks

[440exnacsracer]

how large is the 450r carb..(in mm's)? im sure this would work with a little effort and probably a new throttle cable, probably a trx cable, and you can take the tps off

[44oEX]

well if you measure the inside right at the end it's 43mm but the is a little flange inside so the onside is really like 40 or 41mm

But the problem is that the outside is like 5mm bigger then the stock one. So I would need to modify the intake on the engine and that is the thing I don't really know what I sould do. I do have the 450 intake but there is no way to make it fit ( or is there?)

can I really just not use the TPS it won't change anything??

[chad502ex]

you need at least a 41mm for that fire-breathing dragon. I'd recommend a Lectron for $200 or FCR. Lectron is close to FCR without the accelerator pump. you don't need accelerator pump with all that displacement available in your 500.

hope this helps.

good luck.

chad502ex.com

[Blown 331]

42mm comes on a 450R

[EPDP99]

Chad502ex, Im running a 465 what size carb do you recomend for mine. Since, you have a knowledge with thig big bore strokers(502, 508,s). Thanks, Eric

[chad502ex]

Eric, it depends how much velocity (not volume) your able to pull into your motor. My 502 can run on a stock 400ex 155 main carb, but performance would suck if compared to my 41mm lectron. See my point? Im able to use 41mm cause of heavy displacement (vaccumm) and heavy port/flow/valve/intake work. My point is it depends on the cfm throughput of your motor. Velocity stacks ($10) cut into airbox lids are excellent ways to increase velocity and "ram" more air/fuel into the motor using the same carb. Hint, Hint!

chad502ex.com

[44oEX]

I figured out a way to make the 450 carb fit the 400 intake.
You know how the intake is a piece of aluminum with a piece of rubber on it. Well if you take out the rubber, the 450's intake will slide right on and I'll be able to clamp it and everything. I will have to counter sink the bottom bolt so it clears the clamp but thats no big deal. I'll do a little porting so that everything is smooth and that should be good. I think I'll just get the piece that hooks on the back of the carb and make it fit my custom air box. Sorry no more details on the bullet proof air box it for the build off:devil:

Where should I start with jetting this thing. the mods are... well everything:D

[EPDP99]

well I have no airbox lid and full port and polish with chamber mod and valve job. would you recomend the 39 or 41 lectron?

[cals400ex]

what intake boot you using that attaches the carb to the air box?? just wondering because i bought one of those damn $65 noss adaptors to fit fcr 40mm carbs on the 450. well the adaptor is the same size as the fcr 40mm carbs. the airboot on a 400ex won't fit on.

[cals400ex]

chad, would the air box lid adaptor that GT Thunder sells work as a velocity stack good or would they need to be thinner? i think it is 2 inches in diameter. i am been thinking about adding one of these.

[chad502ex]

If I had to get FCR for my 502 I'd get a 41mm fcr

GT Thunder velocity stacks would work perfect.

chad502ex.com

[44oEX]

Originally posted by cals400ex
what intake boot you using that attaches the carb to the air box?? just wondering because i bought one of those damn $65 noss adaptors to fit fcr 40mm carbs on the 450. well the adaptor is the same size as the fcr 40mm carbs. the airboot on a 400ex won't fit on.

I am going to use the piece that hook the carb to the air box from a 450R. But I am making a custom air box so I'll be able to hookit up to the box. if you have a stock air box I don't know if you could make that part fit or not. I didn't see it yet. Ones I get it I can let you know if there is any way to make it work on stock box.


yo chad where sould I start with jetting this thing?I know how to jet but I would like a starting point. and will I be able to use the hot strat or sould I just take it off?

[chad502ex]

if you can get the 450r carb to adapt, then by all means use the hot start. the hot start is a valve in the carb which leans out the air/fuel mixture for starting. i would start rich and run it wide open on open highway to see if it bobbles, then start backing down in main jets. my website has good info to assit on dialing in your thumper. as far as starting you off, I'd start in the 160's but I'd but your near 155 to 158 main. any bets? jk.

good luck

chad502ex.com

[44oEX]

ok thanks I try that as soon as the rebuild is done. If I get it to work good i'll get some pics and post them so if anybody else wants to do it it will be easer.

[440exnacsracer]

If I get it to work good i'll get some pics and post them so if anybody else wants to do it it will be easer.

good deal