04/05 450 carb on a 400ex

[MEOFF]

i just bought a 04/05 450 carb where should i start with jetting on it or should i just buy a jet kit for it

[2001400exrida]

what kind of mods are you running? lid on or off?

[MEOFF]

Air box lid is cracked open stage 1hot hot cam 11-1 piston rev box k&n filter

[CJM]

Stock bore?

Id guess about a 160 main and a 40 pilot. Thats where Id start.

[Stickman400]

I tihink you mean a 50 pilot CJM. A 40 in a 450R carb. is quite small.

[2001400exrida]

i agree. the stock pilot in the 04/05 450r carbs is a 48, so a 40 would not work. Also don't forget when passing along information, the 06+ carbs are different than the 04/05 trx carbs, the jetting specs are not the same, so it's important to pay attention to that.

I have an 05 trx450r carb on my 426. My quad has a full sparks, lid off with k&n, it's an 11:1 compression piston and stage 2 hotcams

I'm running a 48 pilot 180 main and HRC needle on the 3rd clip position.

Keep the stock pilot in and just go up to a 170-180 mainjet and you should be very close.

hope this helps.

[slightlybent47]

Originally posted by MEOFF
i just bought a 04/05 450 carb where should i start with jetting on it or should i just buy a jet kit for it



You’re new so try the search function. There are many threads on this subject.

[CJM]

Yes Stickman your write, typo lol.

[MEOFF]

I can't get my quad to run with the 50 piolet and a 180 main if I pump the hell out of it then it runs and will backfire and throw flames out the exhaust if I choke it it will fire right up idle but will not respond to any throttle then stalls out

[CJM]

Whats done to your engine?

[MEOFF]

Look on post

[CJM]

So its not bored, stock piston but 11:1?

180 is WAY to rich, I run a 168 with my 426.

160, 50 pilot.

[MEOFF]

I got a 55 polit any less and it wont idle and now I have a 185 main but I can't get it to rev out with out stalling unless I have the choke on

[CJM]

Your too rich.

What does your plug look like, black and wet or white and clean?

[JOHNDOE83]

Originally posted by CJM
Your too rich.

What does your plug look like, black and wet or white and clean?

I dunno, if he had the choke on to run right, he would be to lean right?

I wonder how he sealed the hotstart?

[MEOFF]

I got silicone on it it doesn't seem to be leaking or sucking air any place I thought it was lean because it run with choke when I jetted it with the stock carb the plug was white and when I changed jets or moved needle it would foul the plug haven't checked the plug with this carb I haven't had it running that long and it basically idles now and I can't get it throttle up without choke on so checking plug really wouldn't do me much good right now

[MEOFF]

I also live in Michigan and am right on the Saginaw bay that may be y our jetting is so different I want to try a big main jet like a 210 or something to see if that changes anything

[JOHNDOE83]

Originally posted by MEOFF
I also live in Michigan and am right on the Saginaw bay that may be y our jetting is so different I want to try a big main jet like a 210 or something to see if that changes anything

That would be a good start, atleast you can eliminate if its a lean or rich problem by doing that.

If it still doesnt run right, I would refer back to cjm's theory or start looking for other possibilities that might cause the same problem.

[CJM]

I say air leak. Check the carb boots, exhaust, etc. FWIW both my friend and I used the hotstart stuff and RTV'd on top of that with no issues.

But possible its too lean, but then again my jetting will be vastly different than yours b/c of your location.

[2001400exrida]

if no vacuum leak, go drastic with the jets and see how it reacts.

[MEOFF]

think i got screwed on the carb i got i put a 210 main in it and a 155 and it didnt change i sprayed startin fluid around the carb while it was running to see if it would rev up but nothing happened the bowl on the carb is dented thats what makes me beleive that the carb is junk i even tried raising the needle and no change maybe the float is junk i dont really know i asked the guy a couple times why and how the bowl got dented and he don't answer just says its a good carb and they are tricky to dial in i don't know what else to try i did buy it from a guy on this site i would be greatful for anymore ideas on what to do with this carb my next idea is take the main jet right out and see what it does then

[CJM]

Like I said-if the hotstart isnt plugged enough it will leak a bit of air and it will never run right. Did you use an adapter to connect it to the airbox boot or a plumbing part?

The bowl being dented worries me as well. Id get a good bowl off ebay or something and a new float. Id also clean the carb to be sure.

[MEOFF]

guess i will try to reseal the hot start i might try and pound the dent out of the bowl and the adaptor came with it i just didnt expect this to be such a pain since the guy said it was a good working carb whats the best wat to seal the hot start

[CJM]

Using the hotstart parts sands cable then filling with RTV.

[MEOFF]

It was sealed when I got it but when I unscrewed the hotstart I didn't see any cable it looks like the plastic fitting with silicone in the end of it is that the right way or wrong way to seal it could that be the problem why it wont run then

[Baileygunns]

The bowl looks like some one tried to free up a stuck float. That's not effecting anything.

The hot start has the rubber boot on it that would seal the cable. Under that is the hot start nut (plastic) that has had the open end sealed with RTV. If you unscrew the nut you will find the Hot start spring and brass plunger. All are new OEM parts. It was seat the correct way.

Like I told you over txt... I can't jet the carb for you over the phone.

If you're not happy, send the carb back. But I really do thing you either need to clean that carb again buy soaking and blowing air through all the passages and start over on jetting.

Are you sure you're petcock is flowing enough fuel? Is there enough fuel in the tank or should it be on reserve?

You said you already cleaned it, did you put it back together correct? Where is the fuel screw set at? did you take it out to clean?

It's not going to run with a 55 pilot and a 210 main... Sorry.

[JOHNDOE83]

I would blame the hotstart, sealed is all that matters wether you used the hotstart pieces or just filled it with RTV, if the hotstart is empty with just the rubber boot filled with rtv at the end I would blame that.

without the hotstart, you fill the entire hole with rtv then fill the tiny hole inside the carb port.

with the hotstart you have a spring and plunger that plugs it and you fill the top with rtv to ensure a seal.

I would reseal it and try again before you get to frustrated and give up.

the adpater or the rubber pipe fitting do the exact same thing, there is no issue there.

The 50 pilot and 210 main shouldnt matter either, to rich on main jet wont rev out fully and will sound like a rev limiter, to rich on pilot would foul out plugs and flood the motor at start up.

check out the FAQs on www.jetsrus.com it is the only right info on main jetting and carb tunning on the internet.

[MEOFF]

When I cleaned the carb I used carb cleaner and air Ive had it apart several times now tried to set the hot start out but could get it out now you guys are talking about a spring on that is that under the plunger or on top of it under the plastic cap and with the 55 pilot it idles great it wont start with a 50 in it just touch the button and it fires right up im thinking the problem is the hotstart or the accelerator pump because that doesn't squirt like the stock one it doesn't seem like its pulling fuel

[Baileygunns]

Is the fuel line kinked? You might have to trim a very little bit off the petcock side of the fuel line so it keeps a smooth "S" shape...

[riotact]

Since you cleaned the carb and probably took out the jets and what not,I would almost be willing to bet that you lost the needle jet.Look through the back of the carb at the needle and see if it is going into a little round brass piece.When I cleaned my carb before I put it on I also lost mine in the can of cleaner and didnt realize it untill i tried to fire it up and jet it.It wouldn't run right,and backfired like crazy.

[MEOFF]

Didn't lose it its in there I made sure of that im thinking the problem is in the hotstart or the accelerator pump getting tired of working with this carb its acting like its not getting fuel

[CJM]

Take apart the side of the carb where the black cover is. Look at the accelerator pump and ensure its pumping. I would also take it apart and verify the spring sin there and the rubber is good.

[MEOFF]

i trimed the gas line so it didn't kink the first time i put it on the spring is in the pump and it goes up and down when throttle is pushed rubber looks good no cracks but it still doesnt spray like my stoke carb does so right now im not sure on what do next

[CJM]

Theres a passage for the accel pump inside the carb body. Perhaps thats clogged.

Heres an idea that might work.

If you can get it to run long enough, dump about a good 1/4 of a cup of seafoam inside the tank. Make sure to only have 1/4 of a tank or so or just run the carb off a small bottle of gas and seafoam. This stuff will clean out the entire carb, trust me.

[MEOFF]

Still don't have this thing figured out yet I got it to idle with a 50 polit but it still wont run after quarter throttle unless I pump throttle fast tried different main jets and moved the needle up and down so now im at a loss again

[JOHNDOE83]

Try the old carb, if it runs the same you can rule out the carb as the issue.

Possibly try sealling the tiny hotstart hole inside the carb port to rule that out as well.

[MEOFF]

It runs good with the stock carb and I sealed the hotstart on the inside would the wrong needle cause my problem and I was wondering if the stock 400ex needle would work thinking about Tring that

[JOHNDOE83]

Yes the wrong needle will cause problems like your describing, just recently there was another thread where the guy was having a similar problems like yours.

I believe they came to the conclusion byu matching part numbers and it was found that the needle in the carb was a dyno jet needle.

He ordered the right one and the problem was solved.

I believe Zrpilot was the one who helped him match the numbers.

[MEOFF]

right now it will idle 1/4 to 1/2 engine dies out 1/2 to full if i pump the throttle and get past the mid range i can hold the throttle in one spot and it will run any ideas 50 pilot and 178 main needle is in 3rd position i have moved and it doesn't make a difference fuel screw is 2 1/2 turns out any ideas

[MEOFF]

Think I found the problem I put the stock 400ex needle in it and it runs from idle to full throttle now does that make any sence

[JOHNDOE83]

Ya thats a good thing, now your getting on the right track, refer back to jetting and see if you can get it dialed in or if other problems arise.

[CJM]

No sense. Unless the needle you got isnt a 450r needle. Ive compared the two needles before and couldnt see any real differences.