Bog, only when i go higher elevation

[ae13291]

currently my stock yfz is jetted at 165 main and 45 pilot at 900 elevation with cam mod and open airbox lid and zip tie mod. when i went riding in about 5000 elevation when im in low rpm 2nd gear or 3rd gear and give it some throttle before the whoops, it will bog and then pick up like a raped ape. it doesent have this problem when im in 900 elevation. so is this the main jet or pilot jet? the high rpms are fine, just when i punch it at low rpm it will hesitate and then it will be fine. i was thinking of throwing in a 160 main and a 44 pilot since i think 45 pilot might be a little much for a stock motor. what do u guys think?

*EDIT* so i bought a UNI filter and i cut the restrictive screen inside the stock airbox and i still have the 165 main and 45 pilot (this is still with the stock exhaust) now it seems to be alot better then b4 at high elevation but still a little bog, so then i put in a 162 main and i still felt the same bog, so now im confused, if its not the main? and if the quad ran better with more airflow, i know its running rich but do i adjust the needle? btw now i also have the R&D powerpump, i dident have that last time. i think its adjusted to a 40 leak jet, stock is a 50

should i adjust to a 35 leak jet?

[Ride1Rob]

Anytime u go up that high in elevation with a carb setup the bike is gonna run like crap. No way around it other than to change the jets as you go.

[ae13291]

i changed the main jet to a 162, it was a 165, im pretty sure its running rich, but what other adjustment can it be? and please, just because its a carb doesn't mean it cant run this elevation, my 400ex runs like a champ there.

[miles Machine]

well you accelerator pump is what is affecting your idle/off idle to sudden wot.
Now with that said you opened your exhaust up witch made the bike run leaner...you said it was better...always remember jets the lower the number the leaner the mixture and higher the number the richer it is....except the leak jet which is what controls the amount of fuel the accelerator pump puts out (so smaller the number more fuel larger less fuel) seeing that it ran better at that altitude with the leaner exhaust mod id try the stock setting leak jet....just my opinion...let me know how it turns out

[Ride1Rob]

My best advise for you... Tune the bike at 5000 elevation before you ride it. Once it's dialed in you should be good. That's a dramatic change to try to guesstimate at 900 hoping it'll run right at 5000.

[ae13291]

yea, thats right, my exhaust is still stock tho, i just added a uni and opened up the screen in the intake. but same rule applies, it runs leaner, i will try to adjust it to make it a 50 leak jet again, but if thats not it im going to try the needle.

[ae13291]

bump

there is a 4100 ft difference in elevation...that will affect how you run...if it is spot on for 900 ft, it will not be good for 5000 ft...

these 450r race motors are a little more finnecky than that of a 400ex too...

[ae13291]

Originally posted by speedyquad
there is a 4100 ft difference in elevation...that will affect how you run...if it is spot on for 900 ft, it will not be good for 5000 ft...

these 450r race motors are a little more finnecky than that of a 400ex too...

thanks for the response, but wat do you think it is? should i go down to the stock main? or mess with the leak jet? or the needle? what jet is this affecting? thats the only thing bugging me right now

[yfzrider690]

It's not your main. The main only controls 3/4 to wide open. It is your needle. You are to rich try moving the clip up one. The needle controls 1/4 to 3/4 throttle. It controls most of the power range. The only reason it ran better with the different filter is because you were letting more air in allowing it to have more air to mix with the fuel.

[ae13291]

Originally posted by yfzrider690
It's not your main. The main only controls 3/4 to wide open. It is your needle. You are to rich try moving the clip up one. The needle controls 1/4 to 3/4 throttle. It controls most of the power range. The only reason it ran better with the different filter is because you were letting more air in allowing it to have more air to mix with the fuel.

thanks alot for the response man, it means alot to me. i am going to adjust the needle, the stock setting on mine is 4th clip from the top, im gonna make it the 3rd clip from the top, can i move the carb to access the needle while its still on the quad? or does it have to come out?

[yfzrider690]

I have never taken the carb off to adjust the needle. It's easier if you pull the gas tank off. You don't have to unhook the fuel line, just put the tank sideways on the frame and it will stay. There is a cover on the top of the carb that has two allen head screws that you have to take off and then under that cap is another allen head screw that you take out and the needle is underneath it. If you need pictures I can give you a link to some.

[ae13291]

Originally posted by yfzrider690
I have never taken the carb off to adjust the needle. It's easier if you pull the gas tank off. You don't have to unhook the fuel line, just put the tank sideways on the frame and it will stay. There is a cover on the top of the carb that has two allen head screws that you have to take off and then under that cap is another allen head screw that you take out and the needle is underneath it. If you need pictures I can give you a link to some.

thats cool man, i have removed the needle before, i just wanted to know if you can access it without removing much. thanks again man, hopefully it works