1973 400 CR

[Picklito]

Does anybody want to see the build of an AHRMA racer? For the open class, what other than a 400 CR? Some of these pics are already on this forum, but I decided to bring it all under one roof since the build is now progressing well.

I think it's time for a disclaimer: I have no idea what I'm doing! I'm much more experienced with the 430-era Husky's, so I'm basically making this one up as I go. Should be fun...

Initially, I found this '72 400 CR roach out in the desert, and decided to bring it home since it was so cheap. Just look at those forks. I think it's pretty safe to say that crash is why this bike was parked behind the barn. Ouch. That one left a mark.



Not a bad start for $150.



Definitely has some problems, though. First problem was me...since I'm inexperienced with this era, I didn't realize this one had such a wildly modified frame with the lay-down Fox shocks.



Whoever did this Pro-Fab-ish mod... did a good job, but being that AHRMA racers are limited to 4" travel in the rear, a lay-down like this makes tuning a nightmare: It only takes about 2" of shock travel for the wheel to move 4". It's almost impossible to get correct damping rates like that, so I decided to find a stock MK frame to use with this nicely-gusseted swing arm, sort of like the Mag style.

Second bummer: In order to fit that lay-down mod, the pipe had been hacked up and re-welded. Too bad, as it looked like it was still in pretty good shape. And then there's the Super-Trapp muffler. Maybe that's OK on a yester-year XR500, but not on a Husky CR. Sorry, that's just wrong.

 

[Picklito]

The last major problem was this broken fin, a real shame since it's an original bore in excellent condition, with a beautiful piston to match.



Strangely, I didn't even notice this fin was missing until I had built and disassembled several mock-ups. For now, I'm gonna run it.
I was able to find a nice 73 MK frame, and here's an initial mock-up just to make sure the swingarm would work and to get an idea of shock length.



Those Fox Shox are rebuildable, but that's gonna wait. I've got a special set of Ohlins planned. This should be a more tuneable arrangement for the rear suspension:

 

[Picklito]

It was once a very nicely built racer. Engine mounts, intake, air bell, and the trick air bell mount were all drab plated. Shifter is hanging because the shaft is broken inside. That, and a broken stud in the inner clutch hub are the only internal problems. Still, the engine will be stripped and rebuilt as needed. Original Bing is decent, too. I'll probably run a Mikuni VM.



Tank is aluminum and pretty darned straight.



But it doesn't have the correct rear mount because it appears to be a '75 model. Also, the fuel cap would have been centered on this model.

 

[Picklito]

Here's a detail shot of that funky swing arm. If anybody knows what this is... please let me know, cuz I sure don't! I just wrote it off as having been modified by some custom shop of the day, but then I noticed it has the weird green undercoat that The Factory used. Either this is a more common undercoat than I'm aware, or it was done in the factory?



Here's a mock up with the Ohlins and an X-ring chain. Gonna need to find some room, but I have a solution...



Ignition is in great shape, but those wires are gonna need a little... uh... "protection."



OK, I think that takes care of the pre-build survey. Let's start buildin'...

 

[jimspac]

Cool find, great price, and a fun project to boot. Who could ask for more?

 

[Ron]

I think the green undercoat is self-etching primer. Looks like the same stuff I've used from Dupli-Color.

 

[Picklito]

Good info. I figured it was some sort of primer, but I don't paint much so only familiar with typical black, gray, red versions.

Engine got the usual disassembly and the crank went to Cooksey Crank in Texas where Andrew does an awesome job. It did not need a rod kit, but he did his usually excellent job of truing it up quite a bit. It's been my experience that the straighter the crank, the less vibration you get, and his work has been noticeable on my other motors.

A lot of time was spent inspecting since I really didn't have any history on this motor. Besides one clutch stud and the shift shaft, everything looked to have very little wear. Excellent, really. Cases needed some gasket surface clean up and a few threads chased, then they got blasted, painted, and new bearings. The right side flanges will be bare like OEM.



The flange bolts were pretty ugly, so I replaced them with new stainless allen heads. Countersunk for the trans shaft, button head for the crank flange.



I saw no reason to paint inside the trans.



Trans and shift mechanism (in 3rd gear!) drop in easily. I used the original workshop manual for the details. My main concern was to get all the shims in all the right places. Hope I did! Also swapped to a splined output shaft. Hall's had one in stock!

 

[jimspac]

You will be thanking yourself for the splined shaft everytime you need a countershaft sprocket. I lose track of how many emails I get from those looking for the tapered shaft sprocket

 

[Picklito]

Ya, I was probably one of them. A few shops still had them, so I almost talked myself out of it... Until I tried to remove the old one! NOT going through that each time.

 

[suprize]

What a winner, amazing what bikes come out of the wood work.... How good is the case transfer to barrel ports match up, much overhang or have they been smoothed out?

 

[Picklito]

The port match is pretty good, but I just left it because I'm hoping my broken fin cylinder will only be temporary. Didn't want to bother grinding to match a cylinder I'm planning to put on the shelf. And, I'm gonna ride it like a slow old guy.

 

[Picklito]

I had this custom crank installer made for my 430's, and it fits perfectly onto the 400:



Almost there:



One side done:



Other side:



It looks like there's no gasket in there... but there is!

 

[adam6402]

That is a nifty looking crank puller! Great build so far, keep the pics coming.

 

[Picklito]

Thanks!
The case halves came together nicely, and the crank and trans all spin freely. I let the workbench get a little messy at this stage... was a little bit excited.



I alway like the look of a fresh clean crank bowl. What looks like dirt or overspray on the left case half (right in photo) is actually just some minor porosity in the casting. It really caught the light in this pic and looks worse than it is.



This shot shows off the new splined output shaft. I still need to find or make the C/S sprocket spacer.



About 5 years ago, I bought an NOS clutch arm for my 430, and when it arrived it was the mirror image of what I needed. So I just threw it in a box of a few random NOS pieces I have, and it turns out to be the right arm for the 400.

 

[Picklito]

Time to do the wheels. Yuck. This is gonna be messy. I'm using stainless spokes/nipples from Vintage Husky and rims from Husky Junk. Plan is to keep the funky "Husky Odd" spoke pattern. Hubs are at the blaster now. Stay tuned...

 

[Picklito]

All the 'silver' parts were done by John at Vintage Husky, along with his frame mod. Put her out in the sun today to help the cure.
Husky mug shots. "Face left."


"OK, now face right."



Had some help. I thought we were working on the Husky but, apparently, it's ALL about the ball...

 

[Picklito]

Swing arm came out nicely, too.

 

[suprize]

well underway.... start boltin her up

 

[dartyppyt]

Looks great!

 

[oldbikedude]

That's looking like one sweet piece from a rough start. Amazing what TLC can do. Oh, and a bucket of $$$$ Ha Ha.