Montesa 315R: The project begins...

The work begins on my 1997 Montesa Cota 315R trials bike. Made in Barcelona, Spain and powered by a water cooled HRC (Honda) two stroke. It only weighs 160 pounds.

I got a chance to clean it up today so that I can get an idea of what I'm starting with. Here's where I found it:

It was in a side room at my friend's shop. Is it any wonder that both he and I had forgotten that he owned it? It looks worse than it is. He makes Kydex holsters and it was parked near his scroll saw so it's covered in black plastic dust.

I stripped it down a bit, which took moments, hit it with some compressed air and then gave it a good washing, followed by more compressed air.

It originally came with white fenders, but the first owner bought the red ones to update the look. It also came with a headlight and taillight so that it can be registered. No seat, though...

The half gallon fuel tank is really nicely made and much more robust than I had expected. About a pint of old fuel was emptied into my lawnmower.

The old air filter was pretty sticky and doesn't really look like an off-the-shelf piece. Hopefully, I won't have to order a replacement from Barcelona. I suppose that I could use the old one as a pattern and make my own without too much trouble.

The bike cleaned up pretty well.

I've left it apart for now. Immediate plans are to rebuild the clutch master cylinder, flush and replace the coolant and brake fluid, clean the carb and find some new tires (they have lots of tread, but they're dry rotted). I don't even want to attempt to start it until I get the clutch working.

I'm not sure if this belongs with Build Threads or here in Sprockets, but feel free to move it if necessary.

I have never ridden even a dirt bike, but I would love to give one of these a go. How far will that half gallon take you? Is the fuel mileage closer to a modern scooter (pretty good) or a two-stroke sport bike of yore? I have no clue how economical dirt bikes typically are.

I can't answer that question yet, but I can tell you that 10 miles in the woods can be a long ride. This bike was designed to climb over things, though, not to cover significant distances.

Those have always highly amused me. I kinda sorta really want one.

Woody wrote: I can't answer that question yet, but I can tell you that 10 miles in the woods can be a long ride. This bike was designed to climb over things, though, not to cover significant distances.

Silly question can you put a seat on a trial bike. I mean at 160lb's and maybe a bit bigger gas tank and that would be a perfect city attack bike.

wearymicrobe wrote:

Woody wrote: I can't answer that question yet, but I can tell you that 10 miles in the woods can be a long ride. This bike was designed to climb over things, though, not to cover significant distances.

Silly question can you put a seat on a trial bike. I mean at 160lb's and maybe a bit bigger gas tank and that would be a perfect city attack bike.

I just learned of these today, I really want one:

http://advrider.com/forums/showthread.php?t=826491

Yeah I did some research after reading this thread. One company makes a 2 gallon tank and seat for em. 125cc with a 5 or 6 gears, that should provide plenty of range for an urban assault platform.

wearymicrobe wrote: Silly question can you put a seat on a trial bike. I mean at 160lb's and maybe a bit bigger gas tank and that would be a perfect city attack bike.

Yes. I'm going to try to find one of these, just to give my legs a rest on occasion. There's not a lot to support it underneath, though.

Talk with Mike Komer at the trails shop in Locke NY. http://www.tryalsshop.com/index.html

Stand up guy, well versed in all makes and a true american trials race team suporter.

He will have the air filter and other parts on hand and he's close. Other places to look are Ron @ Rascals Cycle but it will not be on the shelf but ron will get what you need he's in sturbidge mass area.

In reply to 44Dwarf:

That's awesome! Thanks! I didn't know about either of them.

I have always wondered what one of the old trials bikes would be like to ride as a off roader. Like one of these.

http://cgi.ebay.com/ebaymotors/VINTAGE-MONTESA-COTA-TRAIL-1975-STORED-IN-GARAGE-FOR-30-YEARS-/251149913933?forcev4exp=true

EvanB wrote: I just learned of these today, I really want one: http://advrider.com/forums/showthread.php?t=826491

Whoa.

Half gallon tank on a 250 at that weight ought to give you around 35-50 miles, depending on gearing and throttle input.

There's a very similar new bike about to hit the market. I'll start a new thread about 'em tomorrow when I'm not dead tired.

In reply to Woody:

Welcome. I got to meet Mike in the Isle of Man i went to watch the FIM Trials, Mike was the team tuner. At the time i was looking to buy in to the Montesa brand and be a dealer but could not make it work.

theirs Ryan Young's too but he's down south somewhere.

alex wrote: Half gallon tank on a 250 at that weight ought to give you around 35-50 miles, depending on gearing and throttle input.

I don't really see myself standing up on a motorcycle for much more than 35 miles anyway.

I didn't really trust the aluminum kickstand, so I bought a dirt bike stand from Harbor Freight that's solid, but looks like it was welded together by Chinese school children, which it probably was.

The bike hasn't been kicked over in a long time so, as a precaution, I removed the plug and added a tiny bit of Marvel Mystery Oil. I suspect that it's what old guys in Spain use in the cylinders of whatever kind of old engines freeze up on them over there. I didn't want to use too much, so I used a drinking straw as a pipette and dribbled a small amount onto the high side of the piston. I let it sit for a while and turned the engine over by hand with the plug out. Nice and smooth.

It took less than 36 hours to get parts for my obscure old Spanish motorcycle. I don't think I could have found them that quickly if I was living in Barcelona in 1997. I love the internet!

Started changing fluids today. The transmission oil came out fairly easily, but the specified replacement oil is ELF HTX740. Not sure where to get that outside of France, so I went to the bike shop and picked up a bottle of Honda Transmission Oil.

I removed the coolant plug and nothing happened, so I initially thought it all might have leaked out. Once I removed the radiator cap, it shot across the garage.

I ran into a bit of a snag when I reinstalled the drain plug bolt. Even using my inch-pound torque wrench, I could tell that the threads were stripped; not surprising with a steel bolt into aluminum. I chased the threads with a metric tap, but it looks like the remains of a heli-coil came out. I suspect that I am not the first to have this problem. I'm not really worried about this, though. There's some bite, so first I'll just try reinstalling it with some thread sealant. If that doesn't work, I'll drill it out, tap the hole and install a fatter bolt. Worst case, I'll have to replace the tiny water water pump. Fortunately, the drain is in the pump, not the block.

Cool bike. My neighbor has some sort of trials bike. It is interesting to watch him ride in through the trees in his back yard.

I removed the water pump cover and made an effort to salvage the threads for the drain plug

The cover and the gasket are Montesa specific parts, so I can't just get replacements from the Honda dealer. I didn't feel like waiting a week to get a new gasket from Europe, so I decided to make my own.

I had some old gasket paper laying around from the '65 Mustang project (1997), so rather than get a new gasket from Europe, I made my own.

I'm waiting for a few parts to arrive, so I thought I'd tackle some easy stuff.

The aluminum bar ends were pretty hacked up, so I removed them, chucked them into the drill press and hit them with a file. It wasn't worth a trip to my buddy's shop to use the lathe.

Next up was flushing the fluid out of the brakes and the hydraulic clutch.

I needed to stabilize the front end to prevent fluid from spilling out of the two handlebar mounted master cylinders, so I carefully fabricated a precision brace out of a small air compressor and an old turbo.

I may have an issue going on with the clutch. It's either incredibly light (which I think it is), sticking a bit (probably is) or the slave cylinder has failed (hope not). I won't know for sure until I get the engine started (haven't tried yet). At that point, I should find out very quickly.

For the past week, I've been sidetracked with other projects, as well as waiting for some parts, but today I was finally able to spend some time on the Montesa.

I had already changed the transmission oil, brake and clutch fluids and lubed the chain. I decided that I wanted to make sure the cooling system was 100% right, so I found a brand new water pump cover, proper gasket and new radiator hoses. This was all very straightforward stuff. I added fresh coolant, bled the system and was pleased to find no leaks.

I also changed the fuel and breather lines. The fuel line was a little trickier than I expected, as there is absolutely zero extra room for anything on this bike. You soon realize that this was a world class competition machine in it's day. I had wanted to add an inline fuel filter and bought the tiniest one that I could find, but soon found out that fitting it in there was not an option.

I ran into a couple of minor snags along the way. I wanted to replace the grips, but ordered the wrong ones. The replacement air filter is quite a bit smaller than the original, but it fits and I don't think it will be an issue.

I've rejuvenated dormant motorcycles in the past and, almost without fail, the fuel valves tend to leak because the gaskets dry out. Occasionally, the old seals will leak at first and then stop once they get wet and swell. The Montesa has a small wire fuel filter inside the tank and I wanted to clean this anyway, so I ordered new seals for the valve. Unfortunately, I wasn't able to remove the old one. The tank is fiberglass and it appears that the valve is bolted to embedded nutserts. When I tried to remove the bolts, the nutserts just spun, so I decided to take my chances.

I reinstalled the minimal body work (four bolts) and gave it one last survey before pushing it outside.

I bought some fresh gas and two stroke oil. The shop manual calls for 80:1 for competition use, but I wasn't really comfortable with that, so I whipped up a batch of 60:1. It may be slightly harder to start, but I think the extra oil is a good idea. That's still a pretty light mix.The tank only holds half a gallon and I was happy to find that the valve (which is almost impossible the get to once the tank is installed) wasn't leaking a drop.

Another problem with the tight packaging is that there wasn't really a good way to drain the old fuel out of the carb without removing it, so, again, I was taking a bit of a chance. For this, I was rewarded with the opportunity to kick the starter at least 50 or 60 times without success. I finally gave in and tried a little starting fluid.

After another dozen or so kicks and a second shot of fluid, the engine came to life. It was smoother and quieter than I expected, with no noticeable smoke out of the thin, aluminum exhaust. I immediately recognized the smell of the eight year old Cam2 that was still in the carb's float bowl. The bike quickly settled into a nice smooth idle.

I still wasn't sure of the clutch status, so after the engine was warm, I cautiously shifted from neutral into second to see if the bike would try to pull away or stall, even with the clutch in. There was no problem, so I went back down to neutral and into first, keeping my thumb on the kill switch just in case. Once again, no problems. It just has an incredibly light clutch.

I spent the next half hour riding around my lawn and climbing over anything that I could find. It's completely different from anything else you'll ride. It's also a good workout. I don't foresee the higher gears getting much use. Most of the riding will happen is second gear. Shifting while standing up is going to take some practice.

So, it's up and running, but I'm not done yet. It will need tires and I'd like to have the rear wheel trued, but that will all happen over the winter. The tires have a lot of tread, but the sidewalls are pretty dry. Most of my riding is going to happen at ten miles an hour anyway. I'd like to replace the peeling decals and grips but that's easy stuff. I also want to move the kill switch to a more convenient spot and change it from a button to a switch. I'll take care of that in the next day or so, and then it's time to have some fun in the woods.