1984 WR400 help

Ok the perforated tube that is stuck in the entrance to the muffler get that out and either re weld onto the rest of the tube or weld on a small piece of pipe to the original outside diameter, the repaired tube then needs wrapping with any 2t packing you will probably require two sheets.wrap and ty wire for easy installation you tube how to.
Put it all back together and give it a run.
The original packing probably got pulled at some stage and never replaced, without the packing helping to support the perforated tube the tube snapped and fell down out of alignment due to vibration etc.
Its important that you keep the repaired tube to the same dimensions as the broken, you will have to clean up the areas to be welded thoroughly and use a mig to spot weld around the joint.

Thanks a lot jo. Which way does the stuck piece come out of the pipe? The direction the rest came out I assume.... I hit it pretty hard and it wouldn't budge. I'll try again tomorrow

Yes should come out in same direction, if the stuck piece has welded itself in their weld a piece tube with a larger id than the perforated od to the end of the long section and test fit it so the new end slips over the stuck section and cut the new section to suit the muffler length.
Hope this makes sense.
Fixing the pipe should solve your top end problem but you may have to look at your jetting afterwards..

yes. I run the fully synthetic motorex oil oil at 80 - 100 to 1 depending on where I ride. I use it in the chainsaw, the whipper snipper and the blower vac. no dramas to date. my 300 kato has run on a similar diet since 010 and has no issues. bikes run smooth and clean / crisp.

I use #2 steel wool in my mufflers and wrap it tight. I like to run close to lean on the needle to give me a real smooth bottom end to needle transition as I do a lot of low speed tight snotty tracks. if I go north to open country, I drop the needle clip for safety.

in aus, we run straight through mufflers and don't need the spark arrestors. I had a Californian muffler on the husky but welded a full length of pref tube to it to get it to the end cap.

you can hear the bikes running on the "riders in the scrub" channel on youtube if you are bored..."really bored"

cheers

Yes any exhaust packing will do, it will hold the perforated tube in place, clean any blocked holes in it and especially clean the screen at the outlet end, that is what was causing your back pressure. That said any silencer for a big bore 2 stroke will work though fitting it might be interesting!

I would not use steel wool, especially in a four stroke! Steel wool will get red hot from the exhaust heat and start a fire even with a spark arrestor. Use proper rock wool muffler packing and do not pack it too tight, too tight and the muffler will be louder and will make less power. Muffler packing burns off and needs to be replaced regularly, it is not permanent, it is a usage item that needs to be replaced once a year or so depending on how many hours you ride.

i have seen 4 strokes packed with steel wool develop severe rust unless stainless is used..
to original poster, make sure to get it packed pretty tight. this makes a pretty big jetting and performance difference, compared to loose packing. let alone missing packing...

Thanks again guys. I'll be cleaning it shortly and will post pics.

I bought 2 stroke packing on ebay for 7 bucks free shipping. Kartwheel, this is a 2 stroke.

Yes, I should clarify, you need to get the packing tight but don't wrap the core with anything or pack the packing extremely tight, too tight can cost power just like too loose. Also, if it is too tight the packing is not able to absorb the sound waves which is the reason you have packing.

Got it thank u kartwheel.

So I tried removing the stuck piece which was in fact ed welded on. I did not get the result I hoped for..... I guess I need a new muffler....

Drill out with hole saw weld in a washer with the tube extension welded onto it as described might even work out easier that way.

Jo, are you saying to cut out that entire cone section, then weld in a washer with the new chunk of pipe?

My first thought was the the cone goes in the direction of flow to increase it but then I realized it was opposite... though it could still help flow that way but I doubt a whole lot since it all hits packing anyways.... so I'll start working on the washer idea

just run a hole saw and cut out the mangled hole weld in a larger diameter piece of tube long enough for the perforated tube to slide into.

Thanks jo, I'll see what u can come up with.

In the mean tine, as a backup, anybody think any of these are worth it?

the first pipe listed above..... the guy lowered the price a bit for me. looking to buy today just looking for somebody to reassure me itll work...

it say this in the description:
All the inside Baffle and Screen appears to be intact. Should fit on several of the Husky Models from the 80's, but due your research just to make sure! This a "Spark Arrestor", approved by the US Forest Service.

bought the first one. 45 bucks. might still try to fix mine if i get a chance. update soon!

the aluminum ones are a good bit lighter...anything with a larger core is going to run much better if you are after better performance. the enduro silencers have tiny cores.

it all depends on your forestry situation. the us spec mufflers are vastly different to aus spec. in aus, they were straight core to the end cap, no springs, no spiral or cone arrestor, no dinger on the end. probably Europe spec as well. they go well like that.

If your careful with the mig you can adapt them easily to suit how you want, i cut off both ends and riveted in an 80mm aluminium tube and made a slip on bracket also cut and welded in a larger tip pointing to the ground this helped with too much back pressure. The original tip had about a 19mm id probably the same as the 250 pipes.mines straight through no spark arrester.