Aermacchi/Harley Baja Project

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By reference to the Vintage Motocross Restorer thread on the Wanted board, we briefly discussed the early 70s Harley-Davidson/Aermacchi Baja as one of my top restorer searches. A rare and a very strange motorcycle, it placed in the top ten on Rick Sieman’s (aka Super Hunky) All-Time Worst Dirt Bikes. Yet I’ve always had a keen eye for this model…I distinctly remember it sitting on the showroom floor of our local AMF (…oops, I mean Harley Davidson) dealer in Upstate New York when I was a kid. Anyway, one popped up on eBay last week. It was a 1974 SR100; a matching numbers restorer. The Baja came in two models, the SR and the MSR (M for motocross). They’re the same bike according to Aermacchi World, except the SR was fitted with a head and tail light, different fenders, and a few other design differences.

When I saw the auction, I hit the web to see what’s out there information-wise, parts-wise, etc. and made a few phone calls. I found that the Aermacchi Harleys have a fairly broad network and following, although principally as to the Sprint line. There appeared to be quite a few people to talk to when needed (e.g. Aermacchi Yahoo Group of over 1,200 owners) and parts, while not easily acquired, are out there; just need to find them and probably be patient in the process. I was even able to download the entire 94 page workshop manual off the web.

So, I lobbed in my $500 bid with about thirty seconds left (that’s called sniping btw) and the auction didn’t hit the reserve. Fast forward…I contacted the seller directly and we worked out a deal for $750, me knowing fair well that it ultimately could turn out to be a basket case. Did I mention the bike was located in Alpharetta, Georgia, north of Atlanta? Yeah, I drove up and picked the motorcycle up yesterday…14 hours round…and here it is.
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Drained from the drive, I haven’t been over it in the greatest detail, but to toss some reference point out, I’d say the bike is over 90 percent there. Missing are the flywheel for the magneto, the left crank cover and the air filter cover. Obviously, there’s quite a little there that will need to be replaced, but it’s always a good idea to start with something mostly intact, and preferably running, although not the case here.







Probably the coolest thing on this bike is the rear sprocket…or sprockets. Check that out. I’d looked over two dozen photos and didn’t notice that until I picked it up.







Here we go. Don’t hold your breath. This is going to take a long time.  

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[dcameras]

Congrats on your find and good luck with the project. Keep us updated on the progress.

[dt]

Congrats on your find and good luck with the project. Keep us updated on the progress.

Thanks and will do. I took I75 to I475 to I75 to SR400 up to Alpharetta. Did I come anywhere near where you are?

A rare and a very strange motorcycle, it placed in the top ten on Rick Sieman’s (aka Super Hunky) All-Time Worst Dirt Bikes.

btw, I guess I shouldn’t assume everyone knows who Rick Sieman is. Rick is the retired former editor of Dirt Bike Magazine and three time (1984-1986) No. 1 Plate holder in District 37 (i.e. Baja California) Motocross. After retirement, he runs the Super Hunky forums and the famous “Don’t Ask” column, where people lob in questions on about any dirt-bike topic and if they’re off base even a little he flames the crap out of them. It’s funny.

btw, again, I now own two of the models on Rick’s top ten. 

[mrbones]

Congrats on finding that old bike! I noticed the rear sprocket is different from yours and the one in the photo with the plane. Any significance?

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I noticed the rear sprocket is different from yours and the one in the photo with the plane. Any significance?

The Baja in the photo with the plane is the competition model MSR but, except for the lighting, that and my SR are supposed to be the same bike. Obviously, that’s not the case with the sprocket. All photos of the MSR I’ve ever seen have the one pizza-sized sprocket like the plane photo. The rear sprocket on the SR looks like its set up for two different final drive gearing ratios. The inner sprocket for speed/street and the outer sprocket looks to be the same size as the MSR so power/torque. I guess it’s just the way Aermacchi put the thing together and you pick the gearing you want. What a weird thing to do, but it’s those weird things that make these old bikes cool. 

[mrbones]

That's pretty cool. Maybe the chain had two master links so you could shorten it?

[dcameras]

I took I75 to I475 to I75 to SR400 up to Alpharetta. Did I come anywhere near where you are?

Coming up I75, if you had gone west on US 84 at Valdosta, you would have been about 40-45 miles from me.

[mrbones]

Looks like you're off to an excellent start. Can you still get carbs kits for the Dellorto?

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I’ve found the diagrams for this model and several other Italian models (mostly scooters lol) that it was on. I think we’ll be able to run down OEM parts. More expensive than a kit, but so far, I haven’t found one like Keyster or any of those guys.

btw…that NOSParts outfit was actually pretty good to work with so far, notwithstanding their “turnoff” website.

[Drod13]

congrats on the find...I know I haven't updated on my project,But I will tomorrow.
I was looking through craigslist and found this....Thought you would like to see it.

 http://miami.craigslist.org/mdc/mcy/1770195910.html

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That's another model that Aermacchi made for Harley/AMF back then and probably the most popular, probably because it actually looked like a real motorcycle compared to some of the strange stuff they produced. I know I just saw one up at Barber, but can't seem to find the photo. I remember thinking how big it was for a 250. Cool bike.

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Yahoo! Groups > Mag Cover > Great Condition > $40 > 

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<a href="http://www.youtube.com/watch?v=ZnwIIKnWJtg" target="_blank">http://www.youtube.com/watch?v=ZnwIIKnWJtg</a>


Yeah, my son and I got the Baja running today…finally…but we can’t keep it running yet. I’ve got something going on in the carb that floods it out with gas dripping out the back of the throat, but when it’s running (for 30-45 seconds) it runs and shifts good. Like I mentioned earlier, you’ve really got to get these things running before putting any dough into the restoration. Here’s the rundown so far. Not much, but I thought I’d give an update after two and a half months.

Hey, I did say this was going to take awhile.

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The first order of business was checking everything and seeing what all was inside the crank. I didn’t pull the right cover off, because I don’t have a replacement gasket yet, but I did drain the crank to see what all was in there. Here’s what came out.



Yeah, that was pretty gross. After draining that goop out, I loaded up the crankcase with 20wt and left it in there for a couple months kicking it over and pushing it around in fifth once and awhile. I drained it and put the proper 30wt in this morning. The good news…no leaks in the crank.

The big issue was that the magneto was shot. The mag cover (left crank case cover) was missing, as was the flywheel. The stator was intact, but it was just a mess. Clearly it was exposed to weather for a long time, the points were frozen and the ignition coil (top coil in photo below) was missing three quarter of the wire. Here’s a photo of what it looked like.



I was able to find a NOS flywheel, a complete (used) stator and a guy on the Yahoo! Aermacchi Group sold me a used mag cover. Sweet! I also had to buy a special flywheel nut from a NOS parts supplier. All that was under $65!

The one thing that really concerned me was the tip of the crank that has the threads to hold the flywheel was really rusty and I was concerned whether the threads would hold the nut. I got after it with a wire wheel and all was well. The nut spun on nicely.





Once installed, I set the timing and the points as best I could with a non-running engine and no markings on the flywheel (I needed some input from the Aermacchi guys on that one and got a nice diagram to help me through it). Then I tested both the spark (with a simple circuit tester) and circuit path with an Ohm Meter. The test for juice of the stator coil is to use the circuit tester to ignition lead and check for a flashing/flickering light. I have the wiring diagram in a workshop manual. The path (open or closed circuit) is tested through all points leading to the spark coil wire to the spark plug. I also was able to test the lighting coil (the lower coil on the stator) to make sure that’s throwing off juice to the lights.





All that was actually a month or so ago. Anyway, like I said…there are three things needed to make an engine run: fire, fuel and compression. That was the fire part.

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Today, I worked on the fuel part. First I yanked the Dellorto S2 Carburetor out. It’s a 24mm throat with a square piston. I’m used to round barrels, but this had all the same stuff, just set up different. It’s a neat little carburetor. More below.



There was no fuel line on the fuel inlet (red arrow above ^) so it was full of crud; may have been a bug nest or something. However, once past that little mess, the inlet screen was very clean and when I pulled the float bowl off I was actually a little taken back how clean it was in there (see photo below). When I get inside old Keihin or Mikuni round barrels, I usually find a huge mess after someone left fuel in there, and premix at that! Anyway, that was a pleasant surprise.

The three jets you see inside the float chamber are, bottom to top, the low speed jet, the main nozzle and the starting jet. The starting jet opens when the “starting valve” is opened (see red arrow in second photo below). I’d liken it a choke, but it’s not a choke in the traditional sense. I’m not exactly sure how it works, but it did when we cranked it up.





As mentioned, the carb is flowing too much fuel into the throat and choking out the engine. I’ve encountered this before and it’s usually the float valve. That’s in the normal location under the square float. I pulled it apart twice, cleaned the valve and it really seems to be working okay. The fuel is coming up through the main jet and nowhere else as best I can tell. Any thoughts?

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Okay, here’s where it got real fun.

It seems like the last several restorations I’ve done, I’ve installed a new, aftermarket gas tank; usually a Clarke. But much of the character of this old bomb is that mail-box looking gas tank, so the plan is to restore it, and it’s not in very good shape for that. Anyway, rather than rig up a surrogate, I decided to start on the tank, clear out as much as possible and use it in the first start.

First was getting the gas cap off; let’s just say that thing was on there so hard I used half a can of liquid wrench before I got it off. Then I pulled the petcock out…damn thing had reverse threads. I hate it when they do that shit! After figuring that out, I got the petcock out and it had a long filter that was packed solid with brown crud (photo below). I’m generally not surprised about what I find in tanks, but that was like dirt. It gets better…



So with the cap and petcock out I shook the tank around and heard some stuff sloshing around…dumped it out…here you go! (btw, the red arrows mark pin holes in the tank.)



You’re thinking rust, right? Well some, but there was simply too much mass, and with the exception of the front of the tank top there isn’t that much rust. Look at the chunks ^^, they’re not metal. Fast forward…I did the “shake nuts and bolts inside the tank” exercise the dry tank for the better part of an hour and this is what I got. THREE TIMES! To clarify…add up the crud in the picture above with three times the stuff in the picture below, and that’s what came out of there…so far.



After I got all that out, I flushed the tank with a high-pressure garden hose…and shit was still coming out! I’m holding just the larger chunks! Well geesh, I probably spent three hours cleaning all that shit out of there. So what was that stuff? There was way too much mass to be rusted metal from the tank. I’ll tell you what, it was more like dirt than anything else. I suppose it could be the remnants of some premix someone left in there, but I’ve never seen that before. I really don’t know what it was.



After I felt that I got all the crud out (I’m still not really certain) I flushed it with some super strong solvent (Methyl Ethyl Ketone); this is stuff that’s usually for cleaning out the old premix that turns to something like a shellac. Not sure why I used it here, but I kept with the process thinking it still needed some cleaning out.

All that work cleaned the tank out enough to be able to use the tank to start the bike. However, as you can see I’ve got a ton of work to do on that tank, including cutting out the top-front, and getting my welder dude to braze a big patch on there. Other than that portion (top front) the tank is fairly solid, no leaks anywhere else, and I’m confident that I can restore it. After the cleaning and the plate, I’ll probably go the Kreem route.


I put the tank on and ran the fuel line (and a little “just in case” equipment) and kicked it. Started right up…then pooped out. As mentioned, I pulled the carb off and tinkered with it, but it’s still sucking way too much fuel into the carb throat. If you’ve got some thoughts other than the float valve, which seems to be working, let me know. Otherwise, it’ll wait until I’m next motivated to work on the old bomb…hopefully a cooler day.

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Well, I was all stoked to go get that tank knocked out pre-paint today…probably only got a quarter of the way through because it was another miserably hot day but I made some good progress with the help of my son.



I knew I had a rusted out section on the front top with pin holes (around the vent pipe), but the only way to find all the holes is strip the tank down. I use aircraft coating remover that comes in a rattle can over at Autozone. Any paint remover will work. Spray on…rinse everything off. If you get any graphics/decals off first as in the photo above the aircraft stuff usually requires only one application. Here’s the stripped down tank, but after the paint removal, I went over the tank pretty good with a medium wire wheel, AND covered it with etch; a rust preventer that’s also available in a rattle can at Autozone.

Clear view of the rusted out area around the vent. S means suspect…that is, no holes, but needs a peek on the other side.

Note the magnifying glass. You need to look real close for pin holes, they’re hard to see. D is for dent; you probably figured that out.

See…wouldn’t have seen that bad boy without stripping it down.


Anyway, with the exception of that little section on the front end, which needs to get cut out, this tank is rated barely salvageable. It’s really not that great, but as mentioned, it’s part of the bike’s overall character so I need to try and save it. So I’ve cut the bad section out with the Dremel cutting wheel. That actually opened up a nice big hole to get a bird’s eye view on the interior AND to scrape/grind the rest of the crud out of the inside of the tank. Good view of that hole in the bottom. The “suspect” was not a rust through, I can get to bare metal on the other side, but it’s pitted enough on the outside that it will need to be ground and take a fiberglass patch. I will be using bondo on this, but any risk area needs fiber ‘cuz we don’t ever want fuel and bondo to come into contact.



Oh one other thing, I’m still not sure what to do about the vent, ‘cuz that’s the only vent and the one on the tank is fubar…and I hate its location. I did find a neat fuel line fitting that will work, but I’m thinking about drilling it into the top of the gas cap. Problem is, the gas cap has this neat little measuring cup on the bottom for premix measure. We’ll see. Here’s a photo of my 15yo son working out the rest of the crud inside the tank with a Dremel attachment…Dremels rock!



So that’s as far as we got before we bombed out from the heat, and it was time for AMA Lites anyway. The next step is to braze a patch into the hole and do the fiber work. Then it’ll be Kreem time. Based on what I saw inside, the Kreem rust remover is going to rip everything that’s left out and I will use the inside coating or maybe consider that smelly, bee-attracting crud bones used on his Café tank. Then primer and we’ll be ready for some color, which will come way down the road at the end. I’ve got a surprise in store.

Until next time…

[mrbones]

Nice progress!

[bagobones]

I'm left speechless over what came out of that tank. It's beyond words, other than WTF?

I like the look of the bare tank, and am thinking that I should strip all the paint off of my Virago tank, seal the inside really well, and then just let it rust on the outside. Ratbike style.

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I like the look of the bare tank, and am thinking that I should strip all the paint off of my Virago tank, seal the inside really well, and then just let it rust on the outside. Ratbike style.

Oh yeah! Or sealing the bare metal with some mat clear coat could still be ratish depending on what else is going on with the bike.

Nice progress!

Slow, but maddening just the way it should be. I am looking ahead though. Yesterday, I ran down some fork tubes…remanufactured, but get this, it used the same forks as the 69-74 Sprint. Wish I had a parts cross reference guide like for my Yamaha and Honda restorations. I’m trying to salvage as much as possible…air box, seat pan, things like that just aren’t out there. I’ve also been kind of stuck looking around for vintage-looking 6V blinkers that’ll run off the mag.

Hey, btw, did you guys see Drod’s progress on his bobber?

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Okay, I think we can get off this tank and move on to something else.

After cutting out that big rust area, we decided to solder in a metal mesh screen and fiber glass…then bondo it. My son is more interested in helping out this time (he’s in auto tech at Tampa Bay Tech) so I’m cutting him loose. Here he’s soldering the mesh screen in. This screening is available at auto part stores and is usually used for a bondo patch, but it creates a real nice base for fiber glass. Just to be clear, brazing a solid metal patch is better than this process, but this tank just doesn’t justify sending it out for that.



Once soldered in place, we laid two sheets in the cut area and two overlaid, ground it down and bondo’d.





However, before the bondo, we ran the Kreem Drill ($50 at Cycle Gear)…messy, awful, horrible, but it gotsta be done. If you’ve never done it, it’s a three part process. First is a rust removing cleaner solution (Tank Prep Cleaner) that mixes with warm water and fills the entire tank (need a good seal, I use rubber corks from ACE Hardware in the fill and petcock holes, see second photo below). This solution requires anywhere from four hours to overnight…we needed the later…do this outdoors. During this process, there is a tremendous amount of pressure built, which needs to be periodically relived, but as it cleans and dissolves the rust it also finds those elusive pinholes…there were another three pinholes in the tank that got fiber patched before all was done. As leaks pop up during the cleaning process, you plug them with tank repair putty; it’s just temporary. If some big holes pop up (should have found those before starting), dump out the solution into a bucket, patch the holes and start over. The second stage is the etching (Tank Prep Conditioner). This stuff is methyl ethyl ketone (MEK) and if ever you just need to etch, it’s available in the paint thinner section in hardware stores. Lastly is the liner…a nasty, messy, gooey treatment that lines the inside of the tank to prevent any other pinhole leaks. You don’t always need this, but in this case it was necessary. Yuck, glad that’s over.





Once that’s done, the remaining fiber patches were applied, plus the bondo and then sanded and ground. One light coat of primer is applied just for storage. There will be more touch up work necessary to prepare it for paint, which I’m going to have someone else do because I have some custom ideas planned.



Pheew, this tank was a pain…glad to be able to move on.

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The Baja is mostly apart and I’m in the process of running down parts. I’ve got upper fork tubes along with seals and wipers on the way, as well as a set of shocks. The forks worked okay, but had a lot of real unsightly pitting up between the triple clamps. The shocks probably could have been recovered, but the left side coil and shaft is really bad and I really don't feel like dealing with them (at least for now). I have had a lot of luck with the LegendsMC shocks, cheap and work good, so I have a set on the way. Same ones I have on my CR as a matter of fact. It seems like everything on the left side of the bike is in much worse condition than the right. The bike probably sat outside up against a barn someplace with the left side exposed for a long time. The left shock, the stator and flywheel shaft...all a mess. Unfortunately, the exhaust pipe is on the left side, too, and that took it real bad. I’ve got some unique plans to try and rescue the pipe. I'll get to that down the road, but not too far because if it's fubar, I need to come up with a plan sooner rather than later.

While I’m waiting for parts, I’m cleaning up and repairing the parts that I’m saving. Finished the seat pan tonight. Finally found a seat cover, which is on the way, so I needed to get the pan ready. Believe it or not, the foam is in great shape; not a tear. The pan was a whole different story.





Nothing real special here. The pan surface was accessible, both top and bottom, to get after with a course wire wheel on my variable speed drill. Once I ground off the rust, I applied some rust neutralizer and let that do its thing. It was really pitted, so I mixed up some fiberglass resin and applied it with a paint brush; no sheets, just the resin. A little grinding with the dremel and then some high gloss black. The edges were very rough and would have cut and ripped my seat cover, so I got some industrial grade edge trim from an eBay vendor. It’s the kind that has an aluminum core so it molds nicely to the curves. It'll probably show a littlewhen I get the cover on, but it'll be okay. There you go…



I’ll tell you one thing…that damn seat pan is the heaviest pan I’ve ever worked on. It was super thick and heavy steel. I guess that’s a Harley thing. If you’re going to make it…make it heavy!

[mrbones]

Wow! That seat looks like new again. Great work.

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I got the seat cover in the mail last night. It took me quite awhile but I found it through an eBay vendor inquiry. It wasn’t listed, but the dude had one. So I was all excited to slap it on…and it doesn’t fit. Not too bad, but the front panels (see arrows in first photo) are too short (i.e. not enough fabric). I tried like crazy to get it stretched, but I couldn’t get them pulled out enough. So I took it down to my boyz at Anthony’s Upholstery after Croom today to have them take a look. Basically, they agreed that it couldn’t be stretched enough and believed the best fix was to sew extensions on the panels. So they’re doing that, cuz me and a sewing machine really shouldn’t be in the same room, and then they wanted to put the cover on to make sure it works, so I’m letting them do that too. Should have it back early next week and I’m sure it’ll be sweet. 



Although it’s now in someone else’s hands, just a couple side notes on seats and covers. First, always make sure you lay down a vapor barrier between the foam and the pan (photo below), properly vented same as the pan. This keeps the foam from rotting and helps preserve the pan. Second, the seat cover doesn’t just lay on there and get glued/tacked down, it needs to me stretched. If you don’t stretch it, the cover will wrinkle, bunch up, slide around on the foam and look like crap. Enter mom’s hair dryer. Yeah, you can muscle it, but a little heat from a hair dryer does the job.



Lot’s going on now…all at once. I’m actually painting. Should have some more substantive reports soon.

[dt]

I’ve aggregated almost all the major parts for the restoration. The last big thing I’m waiting on is the upper fork tubes, seals and wipers. Wish I’d had them for the weekend, but I found out on Friday that the wipers are on backorder, so they’re holding up the whole order. I told them to ship out the tubes and the seals and send the wipers when they get them. I definitely need the wipers but I can always put them on later. I still broke down the steering head, though. It took hours. What a pain! So, right now, it’s kind of restoring all the keeper parts and getting all the pieces ready to put back together down the road. I haven’t started on the frame at all, but I did have the bead blaster working this weekend.

I fully intend to relace the wheels, but later down the road. I’d like to do that now, but the spokes for these wheels are simply not available; maybe one or two here or there, but nothing like a set anywhere. So down the road, I’ll have RTR Wheel Lacing make a custom set for me. I've used these guys about three times; good guys. I’m putting it off because that’s going to take a long time from past experience and I don’t feel like putting everything on hold. In the meantime, I put the beadblaster on the wheel/spokes/hub, just on the front so far, but it came out pretty good. Also, I think someone put a new set of Pirellis on before they leaned it up against their garage for twenty years. They’re dirty, but no rot and they still have the little nubbies. I think I can salvage them and that’s good, because they’re nice enduro tires.



Before Blasting


I also blasted the engine this afternoon, which came out so-so. The head/jug cleaned up well but the case still really shows its age even after blasting. I might need to paint it.



Before Blasting


I also blasted the pipe and a dozen smaller parts. The pipe is in decent shape up to the stinger. The stinger has these enormous pits. It’s a good thing its such thick metal or it would have rusted through. What I’m doing on the stinger is something I’ve never done before. I purchased some stuff called Hi-Temp Lab Metal. It’s essentially a high heat filler putty. Among the applications is exhaust pipes. So it applies kind of like Bondo (without the mixing) and then it’ll get sanded down. I found this stuff by doing some Google research, so I have no information for how it works. You can read the info in the link. Hope it works out okay.





I’m also doing a little painting. Recognize the color?