FE 550 decelaration popping

Funny I had the same thing, thought it might be to lean. The head had to come of and I found one exhaust valve leaking, both had carbon on the seats. Not sure why but the bike always backfired on decel since I owned it. I had suspected compression was down as did not sound like a high compression motor. Just over 100 hours on it.

surfdude said:

When riding and closing the throttle i get a lot op popping from the exhaust. Motor is running fine on the throttle. Could this be a jetting problem? My jetsetting is:

Main jet 185
Needle clip 5 (not sure what needle, guess standard)
Idling jet 40
Starting jet 85
Idle air jet 100
Main air jet 200

As i read in numerous jetting subject over here, i think my FE 550 2004 might be a little rich on the main, but to low on the idling jet. I read suggestions to go for a 170 main jet and 45 idling jet.

Would the larger idling jet help against the decel popping? And what will the effect of the larger main jet be?

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Surfdude,

Just so were on the same page here, I have the exact same bike as you.

We need some more info from you, since it's not in your info. Where do yo live? Elevation where you are riding your bike, and Temperature. All of these things make a big difference in your jetting.

From what you have said so far, you are essentially correct. And the in absence of the above requested information I will make these comments.

First you need to set the pilot screw correctly. Set it at 1 & 3/4 turns out to begin with. Ride the bike around for at least 15 minutes to warm it up thoroughly. Place it on a center stand, and with it idling at 1500-1600 rpm, a nice idle, turn the pilot screw in until you hear the motor just start to slow down. Then, back it out one full turn. Keep in mind that the range of the pilot screw is between 1 & 1/8 turns out, to 2 & 1/2 turns out. If it wants more than 2 & 1/2 turns out, you either need a larger pilot, or a thinner needle straight, and visa versa.

The 185 is too big, a 168 or down to a 162 will be more appropriate. Again depending on altitude and temperature.

The stock needle straight, if it is a DVT is too fat, and thus makes it too lean. This needle straight section is responsible for 70% of the idling mix, and starting characteristics. Increasing the pilot jet will help on closed throttle on decel, but, make it too rich from closed throttle to 1/4. You need to go thinner on the needle straight, and possibly up one on the pilot. My suggestion here would be to go to a DVR needle on pos#5 first and see what that does. And keep in mind also that a change of 10 on the main jet will require a change on the needle position. IE if you drop from the 185 to a 175, you will need to RAISE the needle one clip position by lowering the clip position on the needle, capcie?

Just remember to make ONE change at a time and keep good notes, other wise you'll end up chasing your tail.

Re: RE: Re: FE 550 decelaration popping

surfdude said:

@Spanner
Just had to put in new valves due to a broken valve spring.

@Daleo
I live in the Netherlands and ride on the beach from time to time, so you could say i ride at sea level. Temperature is anywhere from 0 to 25 degrees celcius.

Which main jets do you reccon i should get first, or is it better to get a set like 170 / 168 / 165 to test which set up is best. After i tried the DVR needle off course, but just so that i just have to visit the mx shop once.

By the way, what set up do you use in your bike?

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If your Berg did not pop like that prior to the valve spring breaking, then maybe you forgot to reseal the exhaust head pipes to the head or mid pipe with silicone after reinstalling the head!

Regards,

Joe

Re: RE: Re: FE 550 decelaration popping

surfdude said:

@Spanner
Just had to put in new valves due to a broken valve spring.

@Daleo
I live in the Netherlands and ride on the beach from time to time, so you could say i ride at sea level. Temperature is anywhere from 0 to 25 degrees celcius.

Which main jets do you reccon i should get first, or is it better to get a set like 170 / 168 / 165 to test which set up is best. After i tried the DVR needle off course, but just so that i just have to visit the mx shop once.

By the way, what set up do you use in your bike?

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Surfdude,

I ride at 4400'msl or roughly 1500 meters.

This the set up that is currently in my bike for temps ranging from 40-80F.

Honda NCVR @#3.
HDJ emulsion tube.
40 pilot jet @ 1 & 1/4 to 1 & 3/4 turns out to suit conditions.
162 main jet.
acclerator pump timing gap @ .130" ( to eliminate rich stutter at high alititude/hot engine)
R and D racing accelerator pump spirng. (to compensate for lean bog because of increased ap timing gap when opening the throttle very quickly)
R and D racing accelerator pump cover adjustable leak jet @ 3/4 turn out.
Honda acclerator pump diaphragm (to lessen the amount of fuel delivered when throttle is opened quickly, this cut's down on the squirt time).

See my thread about the R and D adjustable leak jet ap cover.

http://www.husaberg.org/index.php?name= ... pic&t=7887

Contained in that thread is a link to Buzzard's $40 FCR spruce up. I think you will find Buzzard's thread enlightening.

The reason I had went to the set up I have was two fold, performance increase, and to eliminate a rich stutter that I have been fighting since the bike was new. This set up was the result of some great advice by several members here, and a lot of testing.

Like I said before, just be sure to make one change at a time.

If you want, try the Honda needle that I mentioned, and at your altitude you may have to start out @ #4. Be cautious about making too big of an adjustment at once on your main jet. You could maybe start out at a 175, then drop to a 170 or a 168 and then work your way down.

Have a look in my gallery for the Honda altitude compensation chart for the CRF 450, as my setting is basically what a CRF 450 is running with the exception of going about two jet sizes smaller than what is listed for temp/alt that is listed due to the increased intake impulse of your 550 through the same size carb. And you will see that if you apply my altitude and temp that I listed to the chart you will see that's really close to what I'm running.

I know it's seems like you should go bigger on the jets since the motor is bigger, but, the opposite is actually true due to the increased velocity of air flowing through your carb due to the larger motor and the same size carb. You'll just have to play around a bit with jets a little to find what is exactly right for you.

Let me know if you have any other questions.

Dale

had the same situation on my 2004 fe 550 on a ride in tassie, mate suggested re-setting valve clearances did that and problem all but dissappeared had 100 hours on bike when it was purchased it, so it was likely overdue for some attention hope this helps before you get too techo with jetting changes.........colin

surfdude said:

Went to the shop today and bought the 180, 175 and 170 main jets, and a 45 idle jet just in case. Think i'll work my way down from the 185 jet in small steps as many of you advice. The shop also told me that before i was going to make any changes i should first replace the "clothing" in the exhaust silencer, as this could also make the bike run lean.

As i didn't have the tools to open the exhaust silencer, i just cleaned the carborator, moved the clip on the needle from 5 to 6 and fitted the exhaust again with some loctite. Reajusted valve clearance and turned open the fuel mixture screw a bit on a test run. The bike felt like it had more power than before and it even did a wheely on me which i didn't expected. Only when i open the gas from 0 to 100% realy fast it stalls.

Anyway, i'll still have to do some adjustments to get it right. Are there any dangers i need to be aware of that could really damage the bike while adjusting the carborator?

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\. Only when i open the gas from 0 to 100% realy fast it stalls.

In reference to the above statement, does this happen when you're riding it, or when it's on the stand?

Went to the shop today and bought the 180, 175 and 170 main jets, and a 45 idle jet just in case. Think i'll work my way down from the 185 jet in small steps as many of you advice.

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Hi Surftude,

I´m running my FE550 more or less on the same specs as DalEO (thanks again for sending me some parts and infos Dale )
My advice to you: save lots of your time and try a smaller mj than the 170 , everything else is a waste of time.(as you´ll find out)
165 should be fine for your 550 (guess you´ll do lots of WOT in the deep sand?)
If not so , decrease the mj-size even smaller.
As you´re riding in the sand and lots of WOT: Change the needle to DMS - it makes by far the most fun and "screams" for WOT :evil:
You´ll think you have another/new bike with the DMS.
NCVR/S is better to control , a bit more accurate.

So, do your self (and your Berg) a favor; get a DMS.
And pretty soon, you´ll end up with the same settings as DalEO (except for the NCVR)

Peter

Hi Surfdude,

WOT means "Wide Open Throttle" or lots of gas :signyeah:
So, with every change in jetting (smaller mj, "better" needles) your berg will start to become alive as they love it lean (I think Taffy is now down on a 145?)
this means there will be more power, way better throttle control ans response (you can feel every milimeter of using the throttle)
The Downside is, that the more accurate the engine responds, the more rider the mistakes are noticeable (eg getting tired and then using to much gas :yikes: )
But believe me: Once you´ve changed the setting you never want the OEM-settings back.

I really think the DMS will fit perfect.
I´m just a bit suprised about the your gearing , as 14/48 is good for more than 160km/h?


Forget about "paddock -jetting":
please read in the doc the carburation part, there´s so much information packed in there
we should say a big thanks to all of those who helped to built this infosource.
http://www.husaberg.org/wiki/index.php/Carburation
then yo´ll know why "paddock -jetting" is useless.

All the best and keep us updated about the changes

peter

pasted straight from the doc:

Paddock stand jetting
There are a few that have tested their jetting and snap on the paddock stand. These sheytheads have tested the bikes for "snap" and when the bike has bogged; have declared the jetting to be wrong. We trust you all know better!


i don't put personal type stuff in there too often but i still feel justified in leaving it there!

regards

Taffy

you're ok mate keep up the good work!

regards

Taffy

This off throttle popping in the exhaust is an annoyance with most bikes equipped with the FCR carb. As far as I've been able to determine, it has to do with a lean slow speed, or idle jet. This lean jetting is a direct consequence of having an accelerator pump to cover this lean condition, and it makes it possible to pass exhaust sniffer tests, making the bikes compliant with air quality standards. For my own purposes, I have reduced the accelerator pump volume, and richened the pilot jet, which has reduced the backfiring and popping. This has also gotten rid of many gremlins in the bikes performance. As a side note, I also have a late model KTM LC4, and this applies to this bike as well.

sorry but the dell orto back fires like hell!!!!!

this story is as old as adam and eve?

i run 145MJ and i have no backfiring whatsoever. none at all. i have no APJ. sparks has my jetting. he doesn't whinge either!!!!

as i came down from 178 on my WR i had a backfire, i didn't, then i did, then i didn't. it wasn't the MJ and it wasn't the needle, and it wasn't the pilot jet and it wasn't the APJ so don't know what the phuq it was!!!

but you haven't found a cure for it and so we keep looking! i started this a s a subject a fortnight ago and couldn't get posts now we're on the back of someone else's thread opening the debate.

regards

Taffy

I like the poppingon over run .......a lot

I forgot to mention, I have no popping on decel.