AHHHHHHHHHH.... stupid carb....

[NMills]

Well... i need help again... i put my 450r carb in today... and ran into several problems.... first it was a high idle do the choke being partially on... but now i can not get it to run right... i got it close to a idle but it would back fire thru the carb and thru the exhaust... not at the same time... now i'm wondering if i did somethign wrong... if I keep on the throttle it's not too bad... but i don't want to raise the throttle that high.... i have a 165 main.. i think the pilot is stock... i had the a/f screw at 2.. 2.5.. 3.... and 3.5 and did not make a idle difference... still sputtered and everything... can anyone tell me what i need to look at??

thanks...

[JOHNDOE83]

Hotstart?

Maybe need a bigger pilot, I use a 50 at 3 turns out and never need a choke and idles smooth.

[DragonGunner]

Sounds lean....go with bigger slow jet....I would also raise the needle, lower the clip one notch....make sure boots are all tight.

[NMills]

Hot start?? what should i have done with it??? i just tucked the wires up..
Also... next to where the throttle cable goes into the carb there is a threaded hole... maybe a 1/4 inch or bigger... should that have something in it?? is a 50 pillot big enough... it's kinda cold up here... till summer anyways...

But could really be that not getting enough fuel is causing the back/after firing???

sorry for the questions... i'm sure it's been covered before...

[honda400ex2003]

my vote would also go toward a bigger pilot either a 50 or 52 would get you where you need to be imo as both have suggested previously.

steve

[NMills]

other then a 50-52 pilot and 3 turns out on the a/f screw... anything else i should do??? also... can anyone post a pic of the pilots location?? just i'm not too carb savvy... ask me to pull apart a chinese dinner or a pizza... i' can do it... carbs.. not really...

[honda400ex2003]

make sure there are no air leaks around the intake boot and the hot start system too.

it is number 45 on this diagram:
http://www.bikebandit.com/houseofmotorcycles/2005-honda-trx450r-carburator/o/m2689sch305085

ill see if i can find a pic of a carb too

steve

[NMills]

So the main jet screws into the pilot??? i never knew that...

[honda400ex2003]

no the main jet is next to the pilot. the pilot is off on the side of the carb, the main is in the middle of it where the needle comes down.

steve

[honda400ex2003]

44 on that schematic is the main also if that helps you out a bit.

the pilot is the only flat head brass piece in the carb. the main is a hex that is a 1/4".

steve

[honda400ex2003]

finally found one.

arrow points to the pilot jet.

it is a 400ex carb but it is in just about the same location on a 450r carb.

http://www.exriders.com/vbb/attachment.php?s=&postid=2179873

edit: sorry i cant get it to embed, you will have to download it and check it out.

steve

[honda400ex2003]

There we go, saved it to my dt and posted it. steve

[NMills]

Well.... i'll have to try the bigger pilot... hopefully it helps... guess everyone goes thru this.... right??? or am i the only one???

[honda400ex2003]

lol you're not the only one thats for sure. it is trial and error if you dont ask. we would have recommended that you start with a 50 anyway along with a 162 or 165 for your setup with the needle on the 3rd notch and 2.5-3 turns out on the f/a.

steve

[NMills]

ok... lets move on... now the threaded hole on the top of the carb.... next to where the thottle cable goes in... what is that for??? do i just plug it?? or is it meant for something?? also... do i need little rubber hoses for all the vents??? or can i just run it as is???

[NMills]

Originally posted by honda400ex2003
lol you're not the only one thats for sure. it is trial and error if you dont ask. we would have recommended that you start with a 50 anyway along with a 162 or 165 for your setup with the needle on the 3rd notch and 2.5-3 turns out on the f/a.

steve

Well.. i already got the 165 as i was too lazy to pull the 175 out of my 400 carb... the needle i left alone... figured i'd start with one thing and move to the next as needed...

[honda400ex2003]

the hoses can stay and get vented while one of them on top can be plugged.

ill find a pic again of what needs to be blocked or unblocked.

in the meantime look at zrpilots install thread. I will find mine also and show you the pics.

steve

[honda400ex2003]

http://www.exriders.com/vbb/showthread.php?s=&threadid=421133&highlight=install

http://www.exriders.com/vbb/showthread.php?s=&threadid=314423&perpage=13&highlight=carb&pagenumber=1


steve

[JOHNDOE83]

Originally posted by NMills
ok... lets move on... now the threaded hole on the top of the carb.... next to where the thottle cable goes in... what is that for??? do i just plug it?? or is it meant for something?? also... do i need little rubber hoses for all the vents??? or can i just run it as is???

I think hes missing his hotstart.

[tri5ron]

You need to plug the hole with a hotstart plunger from Honda.
Do not attempt to just plug it with rtv, rubber plug, threaded plug cap, etc.,
It needs to be the actual hotstart plunger to do the job correctly, with the least amount of frustration.
(Go ahead,...ask me how I know this)

Experience is one of lifes toughest teachers.
It gives the test first, and the lesson afterwards.

[NMills]

Originally posted by tri5ron
Experience is one of lifes toughest teachers.
It gives the test first, and the lesson afterwards.

How many times do you get a failing grade??? hehe... So a plunger... hmm.. guess i get to go back to the store... :devil:

[tri5ron]

Yep,... Then jet it like Steve suggested. That should get you pretty darn close.

I spent two weeks battleing mine, trying to get it right, because I tried to cheap out and do the rubber plug idea. Put in the factory Hotstart plunger assembly,... (like you are SUPPOSED to do in the first place), and magically, all my troubles went away.

HMMmmmm,... go figure !

Now go apoligize to your carb for calling it stupid, and maybe it will forgive you, and play nicely.

[NMills]

it had played nice in the beginning i would not have called it stupid.... so therefore... i will NOT apolgize to it...

[honda400ex2003]

Originally posted by NMills
How many times do you get a failing grade???

you have no idea how many times... lol freaking michigan tech and mechanical engineering classes.

although after you get a 0 on a test you actually took, everything else is a cake walk. :D

fyi: its not gonna work till you apologize not only to your 400 but your carb too. ;)

steve

[NMills]

I'll apologize to the 400ex for the abuse it took... but i still think the carb should have played a little friendlier...

[tri5ron]

Carbs and females often have alot in common.
Sometimes even when you've "fiddled" with it just the right way,... how everyone says it'll work,... and you've even told them how nice they look,...

...they're just not "in the mood" to do what you want them to...
:D

[honda400ex2003]

HAHA got that right!

steve

[NMills]

AHHHHHHHHH..... Still having problems... backfiring... at a idle... won't stay running... hit the throttle and it's fine.. i put a 52 pilot jet in it... and it did not make a difference... it either races and nothign or it drops to a idle and back fires out the carb.. i went both directions with the a/f screw... moved the needle up and down... hot start was plugged....

What am i missing... how to you "tune" the 450 carb???

AHHHHH...

[honda400ex2003]

i think you have a leak somewhere still.

it is the same as tuning a 400ex carb, everything is the same once you get it sealed up correctly.

check your holes especially the hot start stuff. if it is not sealed properly it is going to act just as you described.

out on f/a =richer

lower needle position= richer i.e. 4th notch

2nd notch leaner than 3rd

same as the 400 one.


lets see some pics of all of the holes you have plugged and how you have them.
steve

[NMills]

All the holes??? there more then one?? i thought it was just the hotstart hole?? is there more??? and when you say notches... it that from the flat end or the point of the needle?? that part confuses me... i've gone in both directions with the needle... and the same with the screw...

[honda400ex2003]

there are others that need to be plugged on the top of the carb.

I was referring to the needle positions as to lean or richness, with the point down.

you have a leak somewhere- look at the threads on how to install it by zrpilot and by myself. he shows what needs to be done, and i have more pics to show it also.

steve

[NMills]

Well... everyone was kinda right... air leak... tho not the ones you were thinkin of... the hot start i believe is blocked... so that's out of the way.. i drilled and pluged the vent on top... but what did not do... Classic rookie move... any guesses??? well.. i can't wait forever for that response...

i forgot...

TO PUT THAT DAMMED AIRBOX ON!!!!!
I kicked myself in the *** soooo hard...
So theres my air leak... awww.... crapppp...

[JOHNDOE83]

I plugged my hotstart with great results, what did you plug and do you have any hotstart pieces?

Just wondering if theres still a issue and what you did to block it?

[NMills]

Was it you that used a 12mm bolt with teflon tape?

[JOHNDOE83]

No, I do not reccomend that either, use RTV on the bolt...lol.

I used RTV silicone with no hot start at all or bolt, but there is more then just the one hotstart hole on top of the carb.

[NMills]

Really??? I droppped a 12mm bolt with teflon tape and it seems to be running fine... now i'm at a loss where these "other" holes are.... Be willing to enlighten me????

[JOHNDOE83]

Inside the carb hole that goes in the intake boot on the motor, inside that part of the carb on the top side of it there is a tiny hole that connects into the hotstart, if there is ANY leak with the plug on top, this tiny hole can make big issues.

I first filled that tiny hole with RTV, then filled in the entire hotstart area with RTV, that way it would be 100% sealed.

I can see how some people have issues, but it can be plugged without anything special.

[NMills]

But if nothing gets past the plug on top.... i should have nothign to worry about... wether it's pluged from the bottom or top should not matter... right??? I know you are saying in case... but what i'm saying is'nt incorrect...

[JOHNDOE83]

I think your right, but like some have the precaution of just buying the hotstart pieces, I have the precaution of filling that other hole also.

Ive seen a diagram of the carb somewhere, and saw that there isnt any other conections to the carb through the hotstart, its just the hotstart housing in there, but in the case I could be wrong I went ahead and made sure to fill the entire area along with the small hole.

I like the bolt idea though, I would use RTV or loctite of some type on it instead of teflon. just a personal preference I guess.

So after the airbox thing your runnin pretty good now?

[JOHNDOE83]

Heres my old 450r carb install thread.

http://www.exriders.com/vbb/showthread.php?s=&threadid=425850&highlight=450r+carb+install

[NMills]

Runnin much better... had a high idle... backed down i A/F screw a bit thought it was runnin better and then found i had snagged the throttle cable... but i was out of time and did not play with it... by the weekend i'll have a much better update as i plan on goin ridin for a while...