HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
TerribleOne

2006 yamaha yz450f

35 posts in this topic

hey guys.. i got myself an 06 yz450 and i cant figure out whats wrong with it

when i get off the gas it back fires i played around with the main jet but that didnt help..

if you have any idea what it could be reply ps.my friends are telling me that i should have got a honda :thumbsup:

Share this post


Link to post
Share on other sites

A simple search would have turned up your answer.

Decel backfires are caused by one or both of two things, usually. Either you have an air leak into the exhaust system (usually at the mid pipe clamp or header), or your idle circuit is lean. The main jet is not in play on deceleration in any significant way.

Since it's a new bike, we'll skip the loose clamps and go right to the idle circuit. It's a pretty widely recognized fact that the '06 YZ450 ships with lean jetting, but try adjusting the idle fuel screw out (richer) by a quarter to one half turn and see what that does. If it doesn't work after you get to a total of 2 1/2 turns out from fully seated, go to a larger pilot. Some in the U.S. have gone as far as a #48.

Share this post


Link to post
Share on other sites

All i did with my 06 450f was go to a 170 main jet and a 48 pilot jet.

That is all you need to do and all that back fireing and poping will go away.

Share this post


Link to post
Share on other sites
A simple search would have turned up your answer.

Decel backfires are caused by one or both of two things, usually. Either you have an air leak into the exhaust system (usually at the mid pipe clamp or header), or your idle circuit is lean. The main jet is not in play on deceleration in any significant way.

Since it's a new bike, we'll skip the loose clamps and go right to the idle circuit. It's a pretty widely recognized fact that the '06 YZ450 ships with lean jetting, but try adjusting the idle fuel screw out (richer) by a quarter to one half turn and see what that does. If it doesn't work after you get to a total of 2 1/2 turns out from fully seated, go to a larger pilot. Some in the U.S. have gone as far as a #48.

I talked to the mechanic for Ty Davis and he said that they use a 45 pilot. He said that 48 is almost too much.

Share this post


Link to post
Share on other sites
I talked to the mechanic for Ty Davis and he said that they use a 45 pilot. He said that 48 is almost too much.

keep in mind his bike is probably not using pump gas and has mods/tweaks/etc most of us dont have.

Share this post


Link to post
Share on other sites

i am in south alabama. all i needed was the 45 pilot too. runs perfect, real crisp throttle response with no popping or backfiring.

Share this post


Link to post
Share on other sites

with the cold air in michigan i haven't had any popping once i adjusted the fuel screw had to back it out! it was running to rich!

i'm also running the stock jetting! too even with the aftermarket pipe!

once the weather warms up (above 50) i will need to go to a bigger pliot, and maybe even a main jet

Share this post


Link to post
Share on other sites

I am going to try the 45 and see how it works. Not that the 48 isn't working but I want to be right on so starting isn't an issue.

Share this post


Link to post
Share on other sites

I also went with the 48 pilot, 170 main combo...it runs great without popping and starting has been a breeze. Temp is at about 50 degrees and elevation is about 500' above sea level.

Share this post


Link to post
Share on other sites

You guys would be helping other 06 owners out if you posted your jetting specs in the sticked thread above here. Use the template.

Share this post


Link to post
Share on other sites
with the cold air in michigan i haven't had any popping once i adjusted the fuel screw had to back it out! it was running to rich!

i'm also running the stock jetting! too even with the aftermarket pipe!

once the weather warms up (above 50) i will need to go to a bigger pliot, and maybe even a main jet

This wouldn't make any sense,, the colder ( denser ) air makes the bike run leaner, meaning you have to richen it up,,, when it warms up the air is less dense and you need to lean it out.

Share this post


Link to post
Share on other sites
with the cold air in michigan i haven't had any popping once i adjusted the fuel screw had to back it out! it was running to rich!

i'm also running the stock jetting! too even with the aftermarket pipe!

once the weather warms up (above 50) i will need to go to a bigger pliot, and maybe even a main jet

Backing the fuel screw out allows more fuel through the carb and richens the A/F mixture. If you backed it out and your popping went away, that means you were too lean innitially.

When the weather warms up you will not need to go to larger pilot or main jets. Warmer weather decreases air density and requires leaner jetting and turning the fuel screw back IN. If your bike runs good now in cold weather, it will require smaller jet #'s in the summer if anything, certainly not richer jets (bigger #'s)

Share this post


Link to post
Share on other sites

ok my bad!!!

i'm just saying what i have done so far!!!

so you guys are saying i'm going to need to get a smaller jet like a 160 when it gets warm out?

Share this post


Link to post
Share on other sites
You guys would be helping other 06 owners out if you posted your jetting specs in the sticked thread above here. Use the template.

i did a while back

:thumbsup:

Share this post


Link to post
Share on other sites
You guys would be helping other 06 owners out if you posted your jetting specs in the sticked thread above here. Use the template.

Considering the fact that the jetting sticky is pretty much already filled to the gills with folks singing praises for the 48/170 jetting combo, stating the same thing anywhere is going to be a bit redundant.

Possibly you could cut us some slack and just write this off as just ANOTHER jetting conversation. After all, it would be a full time job trying to tell people a threads topic is covered elsewhere (ie...engine oil, radiator guards , knee braces, best tires, best chain and sprockets...etc, etc).

Share this post


Link to post
Share on other sites
I talked to the mechanic for Ty Davis and he said that they use a 45 pilot. He said that 48 is almost too much.

Horse poop - the bike is too lean. Has to go to a 48....and I do run race fuel only

Share this post


Link to post
Share on other sites
Horse poop - the bike is too lean. Has to go to a 48....and I do run race fuel only

Just relaying what the mechanic told me.

Share this post


Link to post
Share on other sites

Well i did the 48 pilot and unfortunately POP POP POP. I have a zip ty and have adjusted it from 1 to 3 1/2 turns out a quarter at a time and still pop pop. I ride between 5500 and 7500 and get pop pop at all elevations on decel. I run a 162 main but like someone said I don't think thats the problem. I can get it to pop less at about 2 turns out but it still pops more than I would like and probably should. The bike starts first kick every time with 2 blips of the throttle cold and only with a half a kick warm. It runs strong all the way through. I have no mods except a uni filter. I have also tried the 45 pilot and it was approx. the same result. I think i am just going to have to live with it. It is hard to see guys at the track with bikes that don't pop and sound great though. If anyone has something that I have not thought of it would be great. Thanks.

Share this post


Link to post
Share on other sites
Well i did the 48 pilot and unfortunately POP POP POP. I have a zip ty and have adjusted it from 1 to 3 1/2 turns out a quarter at a time and still pop pop. I ride between 5500 and 7500 and get pop pop at all elevations on decel. I run a 162 main but like someone said I don't think thats the problem. I can get it to pop less at about 2 turns out but it still pops more than I would like and probably should. The bike starts first kick every time with 2 blips of the throttle cold and only with a half a kick warm. It runs strong all the way through. I have no mods except a uni filter. I have also tried the 45 pilot and it was approx. the same result. I think i am just going to have to live with it. It is hard to see guys at the track with bikes that don't pop and sound great though. If anyone has something that I have not thought of it would be great. Thanks.

you need to go to a 48 pilot w/ 168 or "170 mj" - that will clear this up - it did on mine...no popping at all - but I am at 900-2000ft

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0