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79 400 xs..


mcmunzell
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Hey everyone...

I just got done with douching my tank in acid...cleaning out the carbs...new plugs...etc.

Here is the problem. I am getting good throttle response, but the RPMS are slow to drop.

I did read that you probably need to re-jet the carb, however I have searched the internet high and low

to find out what Mikuni carb I actually have on the bike. I tried to order stuff for the 400 from MikesXS,

however they are acting like pieces of shit and send sarcastic emails back because they only deal with 650's.

Does anybody know which stock carb came with the 79? and

Does anybody know if the 650xs indicator switch will work with the 400xs? and

Does anyone know if I need to lean it out or fatten it up with the jets and which ones to get?

these were the questions I had to MikesXS to order stuff from them, however they are acting like dumbshits.

I appreciate the help.

Thank you

Mcmunzell

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Hey everyone...

I just got done with douching my tank in acid...cleaning out the carbs...new plugs...etc.

Here is the problem. I am getting good throttle response, but the RPMS are slow to drop.

I did read that you probably need to re-jet the carb, however I have searched the internet high and low

to find out what Mikuni carb I actually have on the bike. I tried to order stuff for the 400 from MikesXS,

however they are acting like pieces of shit and send sarcastic emails back because they only deal with 650's.

Does anybody know which stock carb came with the 79? and

Does anybody know if the 650xs indicator switch will work with the 400xs? and

Does anyone know if I need to lean it out or fatten it up with the jets and which ones to get?

these were the questions I had to MikesXS to order stuff from them, however they are acting like dumbshits.

I appreciate the help.

Thank you

Mcmunzell

have a play with your idle adjustment, its on top at the front of the carb. you need to enrichen the mixture as the revs are "hanging" being too weak a mix.

Mikuni BS34 is the 400 carbs

can't see why the indicator switch cant work, double check its got all the correct buttons on and you may need to rewire the multi plug.

drewps

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have a play with your idle adjustment, its on top at the front of the carb. you need to enrichen the mixture as the revs are "hanging" being too weak a mix.

Mikuni BS34 is the 400 carbs

can't see why the indicator switch cant work, double check its got all the correct buttons on and you may need to rewire the multi plug.

drewps

so theres a chance it doesnt need re-jetting? I will try 2.5 turns. The factory decided back in the day to cover the idle mixture screws for some reason...STUPID. I ripped the cover off of them out and only have one turn to seated. I guess I should turn em out to 2.5 to 3. I will try for revs sake....

That re wiring is WAY out of my understanding. Im gonna risk getting a new one.

thanks

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rewiring is a matter of patience, wiring diagram and not being colour blind.

If you can get a yamaha original service book, they even show where the loom goes!!

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rewiring is a matter of patience, wiring diagram and not being colour blind.

If you can get a yamaha original service book, they even show where the loom goes!!

I dont have either....

I just turned em to 2.5 out....and fired it. Seems to have helped. They were at .5 turns!

Oh and one other thing....I want to take all of the air box gayness off and put two "cone style" air filters on the back.

Do you know if they make them for this carb, and would it affect performance of carb.....meaning having to re-jet.

And one other thing...I have the stock exhaust on it and was looking all over for a performance exhaust for it. This one

is so quiet....I need something a bit louder to at least give people the oppertunity to hear me! just wondering.

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I dont have either....

Oh and one other thing....I want to take all of the air box gayness off and put two "cone style" air filters on the back.

Do you know if they make them for this carb, and would it affect performance of carb.....meaning having to re-jet.

I would suggest you keep the airbox, as these are the best for the bikes ( and rare)

And one other thing...I have the stock exhaust on it and was looking all over for a performance exhaust for it. This one

is so quiet....I need something a bit louder to at least give people the oppertunity to hear me! just wondering.

you could always try bolting on an aftermarket megaphone, then everyone will hear you!!

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I would suggest you keep the airbox, as these are the best for the bikes ( and rare)

you could always try bolting on an aftermarket megaphone, then everyone will hear you!!

I was just going to run straight pipes....but that would sound like a 747 landing in the front yard....

Too loud ya think?

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  • 2 weeks later...

SWEET! Thanks J!

I will lookem up in the parts catalog.....

McMunzell

If you go to a low backpressure exhaust and cone filters you WILL have to rejet. And while someone might be able to give you a starting point the only real way to do it is to do plug chops and adjust the jetting.

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