1980 WR390 Silencer Spark Arrestor

Does anyone have a pic of one apart? Hard to tell from the exploded view in the parts manual. I see a spring and I don't have a spring. The spark arrestor cone goes right into the baffle severely restricting the exhaust. I assume that there should be some space between the core end and the cone to allow the exhaust to flow through the entire cone not just the center that is in the core.

Here is what I have and how it is installed. The inlet end just bottoms against the front end of the casing and the core is held in by the SA cone.




As you can see the core being against the cone severely restricts the flow and the only flow is through the small area inside the circle made by the end of the core...

no pics

getting that wierd no pics problem...what format are your pics? jpegs?

I removed and re-uploaded the images... What browser are you guys using?

Firefox

firefox. all pics show fine here except this thread, but yours are showing now.

theyre baack chucky

whats with the long piece of solid pipe in front of the pref core?

I would make the entire length perforated core and maybe drill the cone perforations out a little to improve flow.

That is what I am trying to figure out... What exactly belongs in there? Looks like the core is probably out of something else. The parts manual does not show the core... just the packing.

If you look at a parts manual for 1980 you can see the packing and end caps but not the core.

Thanks. visiteur..
Ill do that mod but I still want to know what is inside of the packing that is shown in the center of that drawing. I know it is a core of some type but are there cenering plates on both ends or is it designed to center itself in the inlet cone which is what mine does now that I have cut 2" off the inlet end to get the core away from the SA cone.

Your 1980 WR/OR silencer/spark arrester has been modified or repaired. The original baffle tube was welded to the inside at the front of the silencer housing. And then supported at the rear with a single centering plate and spring. The spring and plate were removable in order to change the packing. The baffle tube was not removable (unless it broke off inside) Aft of the spring the perforated cone was inserted and then the end cap installed.

Marty

Thank you Marty!
This explains why the baffle tube is not shown on the parts list. I have what I need to repair the botched repair. I cut the tube about 2" and a spring from a GM started solenoid is a good fit in place of the OEM spring. I will drill the solid portion of the tube and use more packing in that area to quiet it down some more and do the mod that visiteur posted.

is center is a phonic fabric !
choice with your dealer parts !

should liven her up. in aus, we don't have the sa issue and I just made a full length pref core for the 400 and set the end cap to take the pref core. I wrapped it in steel wool rather than packing glass. its abit more open than the weave mat packing, bit more low end.

Sounds like that will work. The GM solenoid spring is a good idea, cheap and easy to find.

Marty

Yep! Went to my buddy's shop and asked if he had any and he had 5-6 GM starters under a bench in the back room. Free is even better than cheap! I also thought of a spring out of an old box spring mattress. I have one of them leaning up against the equipment shed that I drag behind the tractor to level the garden after I till it.

I understand in 4 strokes you shouldn't use steel wool because it can catch on fire.
Why better low end? Breathes easier?

absorbs a bit more of the sound wave or something... ive set steel wool in a 4 banger exhaust alight repacked my Pascoe peacemaker pipe on my xl 250 motorsport in 1981( peacemaker was the last thing it was!) went to a mates, indulged in some mild substance abuse (as you do) then rode home the back way....pegged out at 75 mph down a long straight 11.00 at night when the cops light me up...total panic till I realised it was a 6 ft flame out the back of the pipe that was lighting up the nite...slowed down and cruised the rest of the way home making numerous resolutions re don't get stoned and ride home, don't use steel wool .... don't go fast at nite ...you know the sorts of things that go on in your mind after a scare

Alright- I won't get stoned after repacking my silencer. There's a joke somewhere in there about a burning one and a burning silencer...