2003 Husaberg FE650 FCR41 Deceleration pop

tdetlor · Aug 26, 2014

I recently purchased a 2003 FE650 for a great deal. Didnt want to start when i bought it. Adjusted the valves, changed the oil and coolant. new iridium spark plug and cleaned the dellorto carb. Fired right up, took it for a test ride, great. Deceleration pop noticed.

Threw an fcr41 carb on it. My jetting is probably off but it runs. and runs well. however im getting alot of deceleration pop, quite loud too.

Current jetting.

175MJ
45PJ
OBDVT Needle #5 down from top.
1.5 turn out on the air screw

Any help would be greatly appreciated!

Thank you all

Tim

husabutt · Aug 26, 2014

Generally decal popping is caused by a too lean pilot jet.

If the exhaust system is not sealed well at the joints this could also be a factor.

Mikuni American Corporation

Snecx · Aug 26, 2014

It's good to make sure the exhaust isn't leaking. I've experienced constant popping on deceleration due to exhaust leaks alone.

tdetlor · Aug 27, 2014

Thank you both for your input. I'm going to double check tonight, however im almost positive its sealed quite well, at least at the head connection. The joints may need new seals.

Could it be caused by an exhaust valve not sealing correctly? wait that cant be right, it wouldn't want to start then.

Skjetvingen · Aug 28, 2014

My headers leak how can I fix it?

Ghost · Aug 28, 2014

With a temperature resistant silicone. It's important that it doesn't harden to solid, the seal has to have some movement after hardening due to the vibration otherwise it will just crack.

regards

/Nick

zaga · Aug 28, 2014

Hi
WURTH super RTV (the red one).
Cheers
ZAGA

Goose916 · Aug 28, 2014

zaga said:
Hi
WURTH super RTV (the red one).
Cheers
ZAGA

agreed, still, those header pipes are notorious for leaking. While I kinda like the mild decel pop, I wish I could figure out a permanent solution for the leak without welding. With the RTV, you're going to have to re-apply on occasion. Cest la vie!

tourist · Aug 28, 2014

Goose916 said:
agreed, still, those header pipes are notorious for leaking. While I kinda like the mild decel pop, I wish I could figure out a permanent solution for the leak without welding. With the RTV, you're going to have to re-apply on occasion. Cest la vie!

yeeup ...

Here's something I have found myself spending surprising amounts of time pondering: Do the headers have to be pulled a little apart to reapply, or can the RTV just be squeezed into the joint with them assembled?

Skjetvingen · Aug 30, 2014

Any more tips to get it more quiet, you can hear me 3 kilometers away

Taffy · Aug 30, 2014

I never use any liquid - ever.

it is the pilot screw under the carb. try to get an extended one that you can adjust in seconds just by pulling over. we sell them of course....

the 45PJ isn't too small - if anything it is too big as we run 40s in europe and 42s in the USA.

hope this helps.

Taffy

bushmechanic · Aug 30, 2014

tourist said:
yeeup ...

Here's something I have found myself spending surprising amounts of time pondering: Do the headers have to be pulled a little apart to reapply, or can the RTV just be squeezed into the joint with them assembled?

not really tourist, if leaking/popping is a problem, need to pull them apart clean thoroughly with sandpaper and water based degreaser if you want the rtv to be strongest

have only seen people try to do this on jap mx bikes and the odd late 00 model huskys, the "problem" is usually something else IMHO

WArdogG · Aug 30, 2014

It may also be worth checking the exhaust packing.

Burnt out silencer packing can also cause popping.

New packing will also make the bike a little more quiet.

cheers

Taffy · Aug 31, 2014

it's none of those things. it's simple

GET AN EXTENDED PILOT SCREW ya lazy git! and test, test, test!

or get a smaller PJ and test, test, test!

I've never packed anyone's exhaust, RTV'd, fluffy stuff - nothing......

regards

Taffy

zaga · Sep 2, 2014

It can be a bit of those things.
But I agree with Taffy it's major major the carb. You need to spend some time with it.
Cheers
ZAGA

Idle · Sep 4, 2014

Sorry, just bumping this to push the spam off the first page.

Snecx · Sep 4, 2014

I am the unlucky one to have my exhaust packing being burnt after 80-100 hours. Twice. The glass wool just fell out after the rivets are ground off. And I had to use RTV to seal some leaks to prevent backfiring on my FI FS570. I have Akra header and muffler.

On my other carb'd bike, simple tuning got rid of all the backfiring. The exhaust system was sealed up good, but it was running too lean. 2 turns of a screw fixed it.

So it can be one of these things. Try the simplest stuff first like Taffy said, get it tuned right. Then if that doesn't work, check for leaks.

tdetlor · Sep 5, 2014

Ive managed to nearly eliminate the decel popping by richening the pilot. However I believe Taffy to be correct in the PJ being too large at 45. Im going to jump down to 42 and give that a try.

Seems i have to run the bike on choke for a few minutes until its good and warm before it wants to stay idling without slowly quitting out on me.

Ive also noticed that swapping the carb has given me another problem. Believe its called wheelitis, very difficult to keep the front wheel on the ground. Going to twitch from the 45t to a 42t sprocket :giggle:

Tim

zaga · Sep 5, 2014

Hi
Sorry Tim I can't understand, you've said that you had to enricher the pilot to cure the poping, and now you say you will go from a 45 to a 42 ?

What PJ are you using now and how may turns out do you have on the PS ?

Running the choke is normal, what is not normal is not needing it.

Cheers
ZAGA

tdetlor · Sep 5, 2014

My mistake. Hah. I had to run it at 1.25 turns out. Seems like the best spot. I currently have a 45 in now.

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