'74 400WR Rehab

[jack topper]

Hi Gang,

I'm putting my '74 400WR back to riding condition. I started an ignition thread on the Vintage Restoration section a while back, but Left Kickers is probably the better place to be. I'll post progress pics as I move along.


I found an odd addition to the exhaust manifold. It looks as though the PO welded a curved piece of sheet metal onto the lower section of the manifold. Not sure why he would have done this...maybe to re-direct the pressure wave returning from the convergence cone back up into the exhaust port? Or maybe it's manufactured this way, but if so, it looks pretty gnarly and not up to the typical Husky fit and finish I've come to expect.

Also, the guts of my pipe have disappeared since I took it apart in '78. I need the final cone (convergence cone), spring, exhaust tube and circlip if anyone has spares or knows where I might find them. They're called out as pieces 18 through 21 on page E6 of the Husqvarna Spare Parts manual; otherwise known as parts 15 14 711-01, 15 14 705-01, 15 14 709-01 and 28 22 058-02, respectively, if I read the manual correctly (some of the numbers are not very clear on the page.)


One last item: Looking at the cylinder exhaust port, I see a series of 5 holes along the right side of the port (rider's left). Is there any significance to them?


Joe Chod: Any chance of my becoming a real member someday?
JT

 

[jack topper]

Putting a new chain on today. The axle was adjusted all the way to the rear of the slot with the old chain. Any recommendations out there as to how far forward I should position the axle as a starting point before I cut the chain to length, or anything else I should keep in mind?
JT

 

[justintendo]

Putting a new chain on today. The axle was adjusted all the way to the rear of the slot with the old chain. Any recommendations out there as to how far forward I should position the axle as a starting point before I cut the chain to length, or anything else I should keep in mind?
JT

imho, definitely want to position the wheel closer to the front than the rear, that way you can account for chain break in...

 

[auto]

I found an odd addition to the exhaust manifold. It looks as though the PO welded a curved piece of sheet metal onto the lower section of the manifold. Not sure why he would have done this...maybe to re-direct the pressure wave returning from the convergence cone back up into the exhaust port? Or maybe it's manufactured this way, but if so, it looks pretty gnarly and not up to the typical Husky fit and finish I've come to expect.

This was first done as a hop up mod on the 125 of that time period.Yes,it is there to help the rebounding wave.I've added that plate to both a 125 and 400.If you remove it you will see that the 400 exhaust port is pretty much a flat drop.

 

[Crashaholic]

The exhaust silencer parts are the same as what came inside the 75 250cr and 360cr pipe. Even though its a WR pipe it was prior to the addition of the factory spark arrestor.

Don't know what the holes located to one side of the exhaust were meant to do.

 

[jack topper]

Thanks for the posts...much appreciated!
JT

 

[jack topper]

The exhaust silencer parts are the same as what came inside the 75 250cr and 360cr pipe. Even though its a WR pipe it was prior to the addition of the factory spark arrestor

I've been told that the factory spark arrestor were made by Skyway, but there are no manufacturer's markings on my unit. I've done some surfing but haven't been able to source any exhaust internals. Today I took the pipe to a local muffler shop; turns out there were a couple of old biker dudes working there, one of whom used to have his own bike shop. They were both very helpful and it's looking like we're going to be able to fabricate the internals. The spark arrestor screen is still in place, so i'm going to assume that the convergence cone is still in there upstream of the screen. Please speak up if you think i've got it wrong... I was able to source the circlip from Fastenal. Should know by next weekend whether it works.

Is there a decent rattle-can high temp paint out there that can stand up to exhaust temps?
JT

 

[Crashaholic]

You're correct that the factory spark arrestor was made by Skyway. Sounds like yours is okay since the screen is in place. I've never had one of these silencers apart so I'm not familiar with all of the parts and pieces. Nothing wrong with fabricating the internals. Fortunate you found someone interested and talented enough to do it.

If the circlip doesn't work out I've had luck finding a 3" that worked at McMaster Carr.

I've used satin black VHT engine enamel rattle can paint (550 deg. F) and it failed on the header due to the close proximity to the combustion chamber, but the exhaust chamber performed fine. VHT has an intermittent 1300 to 2000 deg F flat black but if you want a satin finish then it needs to be coated with VHT 1300 to 2000 deg F clear. One thing about the low temp engine enamel is it resists fuel spillage and I don't think the high temp stuff has that benefit.

 

[jack topper]

Thanks for the info Crash; that VHT stuff looks like it'll work on the header.
JT