1979 Suzuki RM-400N

 

"Wanted: RM 370 or 400 1977, 1978, 1979, 1980..."

 

That's how the Craigslist ad read. I couldn't believe how many responses I got. I had been searching Craigslist for an RM-400 for over a year without anything showing up, now I had five to pick from: An RM-370B, an RM-400C, two RM-400N's and one unidentified bike that was on the wrong side of the state.

The fellow with the 370 wanted more than I was willing to spend. I almost went for a trade for my spare YZ465G for the '78 "C", one of the 400N's was a literal basket case, and then there was this one. A fine fellow named Josh contacted me and told me he had a 95% complete '79, but it was "ugly". He sent pictures. I fell in love. Ugly is only skin deep, and in the case of a dirtbike, the skin can easily be repaired or replaced. We struck a deal, met half way between he and I, and I got this beauty for $250!

 

It is ugly. For now. But Josh was right, it is largely complete, and actually under the dirt and oxidation, in surprisingly good shape.

I initially felt a little guilty getting it for this price, but as I calculated the li$t of things it was going to need, I didn't feel guilty for long. It will easily end up costing several multiples of that initial price by the time I have it finished. Josh, and in particular Josh's wife were happy to be rid of it.

 

(Notice the uber-cool innertube reservoir buffer!)

The first thing I did after getting it home was find out I had forgotten to get the exhaust pipe from Josh. Doh! The second thing was to hose it down with WD-40 and scrub off years of accumulated grime and grease. These pictures were taken just after that initial wipe down. Somewhere along the line some enterprising soul had fabricated some zoot home made fork protectors from nicely measured PVC pipe. They looked like they really worked great, but I chucked them anyway as they contributed quite a bit to Josh's "ugly". They must have worked well, for as soon as I de-grimed the caked on fork oil from the lower forks, I was surprised to see they were both in quite nice shape, and shined up pretty good for the initial inspection. Here's to Mother Necessity!

The motor has all sorts of compression, and turns over nicely. I am half tempted to irrigate it with some fuel or kerosine, and just try to fire it up. It's a good thing I'm pipe and airbox-less. Perhaps this will force me to tear it apart first. At least the top end. Prudence.

I need to find out what oversize the piston is, and what shape it's in. Pistons, rings, and gaskets for the RM-400's are long out of stock everywhere, so I need to verify what I have in order to make plans for what I need to stockpile.

The rear wheel and swingarm bearings are all shot. In fact, the rear axle is about three inches too long, and came from God knows where. Time to search for a new one.

My initial plans are to get the plastic replaced. No clue if I'm going OEM or repro...let's see how the current auctions turn out! :)

Next I'm pulling the mill and sending the frame off to be powder-coated. Whether I rebuild it or not, there's also going to be some new paint splattered on the motor before it re-mates up with the frame. I am afraid of what I am going to find when I start digging around the swing arm pivot...We'll see. The bike came with a spare swing arm that looks like it may be from a period PE (has a big, dorky black chain guard), so between the two of them, hopefully I'll find one that is tight. The seals are blown on the forks, and the shocks are totally shot, so big $$$ is going to be needed there. Hopefully the motor won't need much, and that will offset this outlay.

Tires are adequate for testing, but we'll need a chain, and new rubber soon after. Surprisingly the sprockets aren't that bad.

The footpegs looked like they may have been from a mid-70's Husqvarna, and really, really sucked, so Mr. Ebay, and $19 helped out there. New surplus RM units are on the way!

I'm not too keen on the ONE gold anodized rim. I will likely look for another stocker for back there.

Ol' Josh came through getting me the pipe and airbox, and thery're both in fair shape. I am still debating getting either a DG or ProFormRacing pipe and silencer...if I can get them. I'd like to keep the bike stock, but the need for new shocks pretty much eliminates that, so that leaves performance. The PFR's look major trick, and generally leave little to be desired, but they have a ridiculous lead time (not surprising as they are hand built on a per order basis), but there's a DG pipe on Ebay right now...Hmmm. Still need to find a silencer either way. And what am I going to do about the shocks? How fast do you want to go??? = $$$!!! Right.

Here's the motor, pulled, degreased, with a little paint stripping and pressure washing.

Since then I've taken the paint down a bit more, and am waiting for a sunny day to dress it in new low-gloss paint.

Examining the piston and cylinder through the intake and exhaust has me optimistic. No signs of gouging or scoring at all. Looks nice, and with that massive compression we may not need do much to the top end.

I found the shift shaft bent, and have been searching for a new one. This one works, but isn't going to stay longer than it has to.

I'm still pondering how I'm going to get it out...Hacksaw this end? Or the other? That's some pretty stout steel, and likely to be a bitch either way.

Another problem area is the magneto. It hasn't had anything but ratty silicone for a gasket for god knows how long and looked to be filled with muddy water at some point. I have cleaned it, but who can say if it will make fire. Searching for an affordable new one now.

 

Close-up of the side panel bracket I had to fab up. Don't laugh at my welding skills, I'm a computer nerd by trade.

Striped frame with new bracket

Hey! It works! Yippee! Now it's off to Mr. Powdercoat-man!

Reverse side showing the beads I ran as reinforcing gusseting.

I have no clue if this will actually work, but it seemed like a good idea.

I never said I was a metallurgist either.

Motor after the first coat of pretty-up.

I used Dupli-Color Engine Enamel "Low Gloss Black" (DE1634) this time.

I thought it might be a close approximation of stock. It's close.

Some paints I've tried in the past are too glossy, and others too flat.

I guess if I did ten minutes of research I could FIND the right color, but I have long been prone to shotgun solutions.

BLAM-O!

I plan on eventually replacing all the engine bolts with plated hex bolts. Suzuki's Phillips head bolts have long been a source of vile hatred with me, but I do like the silver on black contrast they provide. It remains to be seen if the same effect can be reached with the hex bolts. I think it might not, as there is something rudimentary 'period RM' about the silver Phillips screws on these old steeds...Hmmm.

Here's the frame fresh back from Olympia Powder Coating.

They did a GREAT JOB, at HALF the price the other place in town quoted me.

Four day turn around. Good guys!

 

It's like Christmas in February. Look at all this stuff! Project has now OFFICIALLY exceeded planned budget.

But we're doing it RIGHT!

 

See?

Biggest "bitch" to date: Removing the old swing-arm bearings.

Once I gave up pounding them out, and bought a cheap die-grinder at Harbor Freight, it was a ten minute job.

Whirrrrrr! Gnock! Done!

Here we are in the middle of February. Reassembly progressing. I've had to order another swingarm bearing, as I trashed one while pressing it in. I pressed them in using the all-thread & washers technique which really was a snap. However, when I pressed the second one, I mistakenly had the perforated swingarm bushings in place, which are supposed to protrude on either side. I didn't know that and reefed and reefed and damaged one of the bearings. Oops. Education is expensive.

The next problem appeared when I tried putting the rear fender and seat pan in place. The rear sub-frame was split too far apart by about an inch. Too bad I didn't notice this BEFORE powdercoating the frame!

I spent the better part of a week trying to figure out how to fix it without screwing up the powdercoat. I thought about grinding the coating off and using heat and bending it. I thought about using a sawzall and making a thin cut and rewelding it. I thought about just getting a big ol' cheater pipe and bending it. I thought of all of these, and discarded them. I thought about straps and come-alongs, and trucks. I thought about commercial shops and presses. I discarded those ideas too. Then one day, as I finally got all the hardware to bolt the airbox in place, I was walking out of my shop and noticed the tool that ended my misery. There, propped in the corner next to the door, covered in cobwebs and grime, lay my fathers old barbed wire fence stretcher. For those of you who didn't have the wonderful occasion of growing up on a farm, this device is about four feet long, and resembles a high-lift jack more than anything else. Except it has two large hooks that you snap each separate length of barbed wire to, and then you jack it together until its nice and tight and you can tie the ends together.

As soon as I saw the thing I knew my prayers had been answered. It was almost as if it had been designed for this job.

I wrapped each end of the frame in shop rags and put a cheater pipe on the stretcher's handle. I few jacks and the ends were perfectly lined up. I can't imagine a better tool. I would have prefered to have heated it with a torch and done it that way, but the powdercoating precluded that sort of deal. As it is, there isn't a blemish to the coat. Hopefully due to the not so critical area of the frame there isn't any sever stressing from this. (it was actually clamped farther back than shown above, this picture was a re-creation of the historic event, kind of like Civil War re-enactors).

My ordeal with the swing arm bearings is finally over. I finished it all up, and bolted the Íhlins on. I still need to have them rebuilt, but I couldn't resist. I am also searching for a swing-arm in better condition, but they are as rare as the proverbial 'hen's teeth', and so that search may be in vain. Perhaps this one can be buffed into shape, but it's got some deep gouges and dings. My plan at this point is to get the bike back together and tested before I send the shocks out. They were reported to be serviceable when I bought them, but they need bumpers at the least, and I'd like to have them rebuilt just because. However, I'm getting impatient to ride this thing. I still need to reseal the forks, and I haven't started that yet, so I may just send the shocks off while I do that. I also want to refinish a lot of things before final reassembly. So I have to remind myself not to hurry. As you can see, I STILL haven't stapled the seat cover on...

New parts are STILL arriving daily.

I finally found the correct rear axle, and (while I wish I photo'd it) I used a wire wheel on the magneto coil and it cleaned up very nice. I replaced the four Phillips bolts (see above...Grrr!) with new OEM ones, put on the first OEM magneto cover gasket this thing has seen since 1986-ish, and gently prodded the kick with my hand on the plug. SPARK! Yep. Life giving FIRE!!!!

Here is how the monster is taking shape - Still FAR from done, but at least it's starting to look like a dirt bike!

No carb. No silencer. No chain...

No grips. No brakes. No footpegs...

Lot's to do, but I'm happy with how it's looking so far.

Now onto the carb...

Haven't sent the Íhlins off to be rebuilt yet, as I am wincing from bills. Neither have I started playing with the forks. I'm still hum-de-dumming about stock 38's, or more lavish 43mm's. Hmmm...

I still haven't found the correct silencer. DG bolt-on steel is available, and looks sort of period, but I want an aluminum repackable unit.  This isn't a "restoration", it's a "refurbishing". I'm not building a museum piece. This is going to be a "Racing Machine" ("RM" -Get it?).

The "New Program" is well afoot! Stand by for intermittent updates!

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