Sign in to follow this  
Followers 0
soulsedg3

Silencer packing

12 posts in this topic

So i just bought 2003 yz450...it pops really bad on decel and a tiny bit in neutral. I got it home and went down road quickly at night and my buddy said it was popping flames outta the(i think) stock titanium exhaust. The guy that sold it to me says the pcking needs to be redone and gave me the packing(fmf) that he had bought.

I browsed quickly and read bad packing robs a lil power...but no mention of bad packing causing bad decel popping.

Could this be cause? I did read that jetting etc also can do it and cause popping. Im checkin plug etc tomorrow.

Edited by soulsedg3

Share this post


Link to post
Share on other sites

So i just bought 2003 yz450...it pops really bad on decel and a tiny bit in neutral. I got it home and went down road quickly at night and my buddy said it was popping flames outta the(i think) stock titanium exhaust. The guy that sold it to me says the pcking needs to be redone and gave me the packing(fmf) that he had bought.

I browsed quickly and read bad packing robs a lil power...but no mention of bad packing causing bad decel popping.

Could this be cause? I did read that jetting etc also can do it and cause popping. Im checkin plug etc tomorrow.

 

You shouldn't be too concerned with decel popping as it's pretty normal. If the packing is blown out it is louder and so is the popping. The bike will run better with good packing.

Share this post


Link to post
Share on other sites

Thats good to know guys! Im attwmpting repacking in a few mins. the seller gave me fmf packing with the bike. Will let ya all know how it goes and if it tones it down

Share this post


Link to post
Share on other sites

Well. I had noticed someone had pulled the stock exhaust apart from the backside. Which i though was weird. Consider the inner baffle usually attaches from the front. Well....i was right. Baffle wont remove.

So i was thinking why the hell did they pull the back off. Got looking a bit closer and realized they chopped the rear of the silencer off....i saw some writing that was cut halfway lol. thereby shortening it!

The packing towards back of silencer looked descent...i cant tell what middle of it looks like. So im just putting it back together....cause i wanna do one ride on monday. I think im gonna order a fmf slipon right off.
I do have a question though. If they shortened the stock silencer.....what does that do to my fuel mixture, will it become a bit leaner or anything?  Will this generally hurt the 03?   Most every thread i see on this, says it can, but very unlikely.   

 

I'm wondering if i should drill out the rivets on the front of the silencer,  pull it apart properly, wrap the baffle inside, then put it back together and re-rivet it.   

Edited by soulsedg3

Share this post


Link to post
Share on other sites

Alrighty.   So i drilled out the rivets with 3/16'th bit.   Going to get some rivets tomorrow to put it back together.   I removed the packing and yup was definitely bad.  I'm guessing this would make the backfires more pronounced.

 

pic:

 

oldpacking_zps7c3f5f77.jpg

 

 

 

So i got looking at the midpipe, looking for the gasket condition etc. and i saw this.   And it completely baffled my mind.   Best way to describe it, it's metal, and it's spiraled, almost like the shavings from a drill bit but obviously a lot thicker.  I tried lightly pulling on it, but it didn't come out.   Absolutely no idea what it is.  Anyone know?  It's really got me freaked out.

 

pic here:

 

twistthing_zps75720ce9.jpg

 

 

So then looking at midpipe, i noticed a drop of fuel coming out a little port at the bottom of my carb.  Gas was shut off since last night.   Seems to accumulate enough to have a single drop of fuel drip once every two minutes or so.  I dont know what that little port or whatever is at bottom of carb, but i'm assuming this is the result of a stuck float? 

 

pic here: 

 

fueldrip_zps77818e7e.jpg

Share this post


Link to post
Share on other sites

I think your model took a muffler packing between the header and back pipe. It appears someone stuffed a piece of wire in there instead. Just buy a new packing and remove the whatever it was they attempted to use in there.

 

Your float bowl leak is likely a piece of dirt or crud stuck between the float needle and seat. You may need a new one. Also check the float height for your model.

 

http://www.pbase.com/jdjetting1/image/52684097

Edited by stevethe

Share this post


Link to post
Share on other sites

Muffler packing between header and backpipe. Never heard of that before. Weird

Everything here in canada is closed for holiday weekend now. Think i could get away with stuffin it back together for one ride?

Edited by soulsedg3

Share this post


Link to post
Share on other sites

I downloaded manual. It shows nothing at midpipe but a gasket. Guess i will attempt pulling header off. :(

Was hoping grayracer would chime in here

Share this post


Link to post
Share on other sites

FOUND IT! LOL.    Evidentally the gasket between the header and cylinder is metal?  (and it appears spiraled?).   the guy i bought bike from, rebuilt kickstarter gears and put new rings in while it was apart.    I'm just guessing maybe he used the old one (manual says to replace).    So i pulled header off, and low and behind this gasket type thing, is the culprit.  

 

Which. kinda sucks, because i wanted to go try and straighten out the carb today following some posts i saw on here......and set the suspension from being to soft....so it was ready for a ride on monday. =(       it's holiday weekend, and monday is holiday here in canada.   So everything is closed.     And i'm not bright enough to think of some makeshift gasket til tuesday, if they even have one in stock. =(

 

spiral_gasket_zps616a40c9.jpg

 

header_gasket_zps01e75e2f.jpg

Edited by soulsedg3

Share this post


Link to post
Share on other sites

Cut a piece of 8 gauge bare solid copper ground wire so that it can be coiled snugly into the exhaust gasket seat with the ends butted.  Makes a perfect header gasket.

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