FE 550 decelaration popping

Make sure your intake boot isn't ripped! I've ripped at least 6 of them and they pop like heck. thats how I can tell.

x2

surfdude said:

Checked the intake boot, but couldn't find any damage. Also sprayed some brake cleaner over it with the engine running, but it didn't respond to that, so the intake boot seems to be ok. Dropped the needle to the 7th clip, but still had idling problems. After putting back in the 185 MJ it idled ok again, but it hesitates when i open the throttle slightly from fully closed to ride the tight stuff. From what i read here this looks like "rich stutter", so i guess i have 3 options to cure this:

1. Drop the PJ from 45 to 42 or 40 (do i did read here that a 45 PJ combined with a 100 PAJ should work best)
2. Drop the needle a clip
3. Delay the APJ

Which of above options would be the best to solve this "Rich stutter", or are there other options i missed?

Also when i have a little more time on hand i would like to explore the lean setting a little further as it did power up the bike. But with the DVR needle on the 7th clip and a 170 main in there it just didn't work. So for future reference would i be better of to drop the PAJ, or to put in an other needle to get the idling mixture right?

Click to expand...

Hi Surfdude,

Your idle is governed by four factors, PJ, PAJ, FS, and the needle straight diameter.
But they have all got to be set correctly so the transition from one to another operates smoothly.
I am running a 38PJ adjustable PAJ set at around a 65 fixed, fuel screw 1 1/2 turns out and the straight of my needle is an S (CVS) clip 2.
The idle is as steady as you like, and the pick up is good with no hesitations, I also have the AP disconnected.
It has to said that there are a lot of people with different set ups and some work very well, so you have to ask your self is there differences in the carburator casting.
Back in the late nineties I used to fit jet kits for road bikes, the worst were the 600 Kawasakis very few jetted the same, and the differences on some were miles apart.

Regards

Sparks.

FE650E decelaration popping

Tons of good input on this one fellas. I am experiencing the same senario with my FE650E 08'. It has been doing it from new and only at four hours. Although, the main jet in mine is a 160 vs. 182 (550FE), the needle position is 2nd from the top as opposed to the 5th and the mixture screw is .5 as opposed to 1.5.

Any thoughts... ?

RE: FE650E decelaration popping

Leaks in the exhaust system will create popping during deceleration, especially if a more free flowing after market system is mounted.

FE 650 decelaration popping

All factory exhaust and the elevation above sea level is approx. 2200ft/1375m. Does that mean I need to take apart all the exhaust and use gasket maker on all the connections and stay away from adjusting the carburetor?

Re: FE650E decelaration popping

Boozer said:

Tons of good input on this one fellas. I am experiencing the same senario with my FE650E 08'. It has been doing it from new and only at four hours. Although, the main jet in mine is a 160 vs. 182 (550FE), the needle position is 2nd from the top as opposed to the 5th and the mixture screw is .5 as opposed to 1.5.

Any thoughts... ?

Click to expand...

Hi Boozer,

Two things here what size PJ are you using and what is the needle code.
With a FS setting at .5 either means your PJ is to big or you are running very lean.
This goes for the clip position as well.

I am running very similar settings to DaleEO and like him I don't have any popping on the over run.

Regards

Sparks.

RE: Re: FE650E decelaration popping

Just wondering what octane fuel are you runing? To lower octane fuel can make them ping and backfire also.

Re: RE: Re: FE650E decelaration popping

Diesel said:

Just wondering what octane fuel are you runing? To lower octane fuel can make them ping and backfire also.

Click to expand...

Hi Diesel,

Out here in Europe we can get 95 or 98, but I think most parts of the states it's 91. I run on 95.

Regards

Sparks.

RE: Re: RE: Re: FE650E decelaration popping

I know this is an older thread but my 02 650 pops all over the place on decel, but I like it. Whenever I fit the db killer into the end of the exhaust can it doesn't pop. Why would that be?

As I like the popping is it ok the leave the bike like that?

RE: Re: RE: Re: FE650E decelaration popping

Popping on deceleration is an indication of running lean. decreasing your exhaust flow will have the effect of making your mixture slightly richer. You could potentially gain some power with rejetting the carb. You ought to at least look at your spark plug to make sure it's not running overly lean. (In lieu of an exhaust gas analyzer that is)

what was the end result with the deceleration popping. Was it a jetting problem that was fixed, or was it valve or electrical problem? I have started to have this problem with my 08 450 FE! valves are spot on.

Re: FE650E decelaration popping

sparks said:

Boozer said:

Tons of good input on this one fellas. I am experiencing the same senario with my FE650E 08'. It has been doing it from new and only at four hours. Although, the main jet in mine is a 160 vs. 182 (550FE), the needle position is 2nd from the top as opposed to the 5th and the mixture screw is .5 as opposed to 1.5.

Any thoughts... ?

Click to expand...

Hi Boozer,

Two things here what size PJ are you using and what is the needle code.
With a FS setting at .5 either means your PJ is to big or you are running very lean.
This goes for the clip position as well.

I am running very similar settings to DaleEO and like him I don't have any popping on the over run.

Regards

Sparks.

Click to expand...

Thanks Sparks...

This thread has be beaten fairly well, but tons of help. For the most part all, went from the FE set-up to the FS set-up (45PJ / 2(1.5)turns out/ OBDVR 2nd from top / MJ stock. No more Poppy...It was just too lean when one backed of the throttle. Kinda neat if one likes the flame thower effect at night...NOT!

Later...Boozer

RE: Re: FE650E decelaration popping

popping on decel IMHO is neither proof of lean or rich. it's another dimension that we laymen cxan't understand or hasn't been made clear. simple explanations are easy to follow while difficult ones are dismissed with a nah! don't finkso!

i can get a bike to backfire with a 180MJ and do nothing with a 145MJ. weird. PS makes a lot difference. but you need that to be set for best running and not to kill a poppong noise.

my view is that yes there is a popping for unburnt fuel but there is also one for hot points still firing off unburnt gases which is easier coz it's warmer!

tappet clearances are another....

an old trick i was taught was to go absolutely flat out and then close the throttle, you then slow and slow and slow and slow and depending on which part of your jetting is the culprit = well that's where the backfire/popping will be.

having tried this a few times when i first started jetting i quickly realised that this could change with everymod i made. the rule-of-thumb is that it'll pop straight away for MJ, at mid revs for needle, low revs for PJ and needle straight.

then you have to remember that you have overlapping circuits whch may combine to be rich but individually wouldn't be.

i could go on....and on....

regards

Taffy

I fixed the problem with a 45 pilot and needle clip second from the bottom where it was meant to be per manual, but it was second from the top as it came. It was a big jump from 40 pilot standard to 45, but I have the fuel mixture screw out 1 1/4. That jetting was suggested by USA Dirt Bike Magazine in its 450 2007 test although they had the needle clip 3rd from the bottom. With Dellortos you could pull on the enricher circuit and see how it went with different throttle settings, however, with the Keihin I will try Taffy's approach of going wfo and then back off to different settings.