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Adventures with a 1986 KTM MX 500 Widowmaker

2727 Views 44 Replies 9 Participants Last post by  snowworks
The old girl arrived safe and sound have been spending the past couple of days getting acquainted with it in the garage. I finally fired it up and took it for my first ride today. If you'd like to get a firsthand experience of what it's like, then you can read my review below after the pics.



























The Basics
When you first throw a leg over it you realize how light it is. Really light. If you're used to riding two strokes and the weight wasn't so noticeable, the hard and unforgiving seat instead will catch your attention. It is probably partly this way due to its age. The gas tank is large and sits up high in front of you, but is unusually quite narrow and slim on the sides like an MX bike. Flick the kick stand up and you wonder if you almost broke it because it feels very light by the way it went up. You definitely feel like you're on something that's retro by the lines of the tank and style of the plastics, but the ergonomics are not so far vintage that you feel like you're on something from the early 70's.

You work the controls a bit to get a acquainted with their positions. The bar is nice and flat (it's actually an aftermarket bar) with a very comfortable reach that doesn't feel anything out of the ordinary. The Magura throttle system is quite heavy in feel with strong return spring pressure. Magazine editors back in the day had complains that it and the front brake lever required too much muscle to operate and could cause fatigue after a while. The clutch lever on the other hand (literally) is light. You then attempt to work the rear brake but you find that your boot rolls off the peg instead as if the brake lever isn't even there. What? The rear brake lever is somewhat oddly mounted inboard with the bike so you have to actually position your boot up and to the left in order to fully activate it smoothly. It's not mounted directly in front of the peg like most bikes so you realize you better work it several times to become comfortable with its orientation.

Starting it
This is where it gets fun. Kicking this thing over is downright scary; plain and simple. The good news is that it does seem to want to start (some bikes just plain don't and will fight you until the end) but it seems to actually be working on your side to do so which is good. You can either use your left leg, unnaturally, to do it while on the tall seat, or, kick it with your right leg standing off the bike while trying to keep it from coming off the kickstand at the same time. Whatever nonconformist style you chose produces a low and fierce sounding "glug glug" as you turn it over that growls through the exhaust like the echoes the clown in the movie "IT" makes in the sewer pipes. Stories you read of folks having their calves shattered in half or legs broken quickly dance in your mind. You ask yourself "what if" and question if the risk is worth the reward. You press on the lever about 1/4 of the revolution down just until it goes over compression. The feeling is like the kick starter all of a sudden engages what feels like a stuck rock that simply won't budge any further. I use the analogy of a rock because that's exactly what it feels like once the lever comes into compression. When you kick over a big 4 stroke and you reach compression stroke, it will still often feel somewhat "rubbery" with a tiny bit of give at that point. This... notta. Nothing. Zilch. The motor might as well be locked up solid. Even when you put your entire body weight onto the lever it still will not even budge a millimeter or give you any indication that it will. At this point you say a prayer, and jump on it as if your life depended on it with the hope that the lever doesn't spring back up with enough force that could land you on the moon. If your best Hulk impression still did not move the lever one or both of two things will have happened; you either put a nice gouge in the tread of your boot and/or the bike almost fell over.

If you think bump starting this thing is a second option, think again. I initially tried this but unless you are a heavy weight, it wants lock up the tire when you let the clutch out... even in 5th gear.

If you were successful with the kicker, the lever will have gone half way down its revolution and your ears all of a sudden begin bleeding with a very rewarding joy. I felt like I had just won a gold in the national Olympics when I fired it for the first time. The sound of it is VERY loud. POP POP POP, BANG BANG BANG, CRACKLE CRACKLE CRACKLE. You almost need ear protection standing next to it when it idles it is that loud.

What is it like to ride?
To be honest, I had naively been wondering just how "powerful" it was going to feel next to modern day machines and thus preparing myself that it may not exactly what I had been envisioning. I was just going to enjoy for what it is. Boy, could I have ever been more wrong.



I don't think I could ever post enough of those "yikes" smilies to justify this bike. It is hands down the SCARIEST bike I have EVER ridden in my entire life. I used to review motorcycles for a part time job and have ridden varieties from all over the spectrum. Forget 1000cc+ liter bikes. The acceleration this thing has is pure insanity to the tenth degree. Violent. Pure i-n-s-a-n-i-t-y. I was shaking after my first ride on it as if I had just gotten out of a cold shower. I have not even gotten past a 1/4 throttle yet as the bike just wants to explode out from under you. I'd describe it like a stick of dynamite. Again, pure insanity. Insanity! You almost ride the clutch on this thing more than you're on the throttle. As you give it a hair of throttle input it takes off like you're going down a roller coaster. Basically if you give it any throttle it says "oh, you want a piece of me?" You let off the throttle but then you don't slow down at all because it has hardly any engine braking. You reach for the brakes and while the front works, you totally miss the rear because of the akward positioning that you still haven't mastered yet. You've got a lot other things on your mind at the moment so you can forgive yourself for that.

As you're riding, you quickly begin to notice the heat from the expansion chamber on the left side begin getting hot so you have to swing your leg out to not burn yourself. It's hot, there's no heat shield, and it's easy to bump your leg on it which I seemed to repeatedly do. Eventually I'll get the picture. Surprisingly it is smooth in the low end, then as the revs build the vibes begin to come. Unlike some of the other 500 open classers of the time, this one came with a heavy flywheel which helps mask vibrations.

I go back to the noise because it is a lot louder than I expected it to be. The exhaust has a factory spark arrestor so it's not like it's running an open pipe either. I was even a little concerned this thing might sound a little too plugged up and already considering options of having a custom muffler made. Turns out you need ear plugs to ride it as the "BANG BANG BANG" makes you think there's bottle rockets going off inside your helmet. When it idles it's nearly as loud as a 4 stroke single that is running straight out of the manifold with no exhaust system. It's ridiculous, every part of it!

It is by far the most absurd and scariest machine I have ever experienced in my life. I can only wonder what the heck would happen if you were to fully open the throttle. The bike would probably shoot out from under you doing multiple backwards somersaults until it eventually crashed into some trees in the next state. I now understand why these are called "widowmakers."

Now for the serious question... will I ever be able to start it again? ;)
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Well written, I got lots of good information from the article as well as several solid laughfs.
I'm not an avid rider these days, but I assure anyone that particular ktm is an a** Skinner.
One point made regarding an older bike is the higher tank, the new bikes just don't have the same lines.
I'm glad you posted this because my interest has recently re- fired about a dirt bike. Mind you I am not one to say much about motorcycles, period. However I had a few years ago. I recently found an 87 xr100 that is a lot like a 1985 model I had as a kid. I'm not a big guy so I think it would be fun to putt around on it ... Anyhow, nice read.
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Sounds like you had a ......powerful experience. ;) Take it slow and get used to it...we don't wanna lose ya! :eek:
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Thanks guys.

I took it out for another brief ride today on a gravel road and gave her a little more stick. People online have been encouraging me to give it full throttle to experience what it's like "on the pipe" but you'd need a good mile or two of open stretch to do anything like that. I did get into about 1/4 throttle and the rear tire just spun into the oblivion.... brrrRRRRRAAAAAPPPP!!!!

I drained the coolant and ordered some Evans Waterless Coolant which will prevent corrosion from happening inside the magnesium water pump. The guy Andre from Andre Horvath's Enduro Klassiker - André Horvath's - enduroklassiker.at said that he should have the aluminum reproduction pump covers hopefully available mid 2016. Until then, the waterless coolant will at least stop any future corrosion.

I'm not sure how it would do riding in traffic if I ever were to make it street legal. It is kind of like riding something that's on nitrous and may all of a sudden just jump out at you at any given moment. I am nonetheless going to eventually install a headlight and brake light.
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Reminds me of riding my old Husky, at least you have disc brakes mine were drum. Yea, kick starting one of these old ones can be fun. Even with moto boots on, I've plowed my ankle into the ground more than once. And yes kick back can be a b----.You just sit there till you can feel your knee again. Ah the good old days. Have fun, be safe.
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Austen NICE KTM!! and the Ducati!! I have not been on any large 2 stroke Liquid cooled dirt bike like that.. What do you think the HP is?? But I do like my 2 strokes!! I have snowmobiles with 700, 800, 900 cc 2 strokes 165HP. So I know what on the pipe means and it is a rush!! Just take it easy and you will get the feel of the bike. I am sure you have ridden many bikes and some are just an animal to ride and that is what make it feel so good to harness it. Ride safe!! AGAT (All Gear All Time) I guess I need to get my 75 Yamaha RD350 on the road..
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Reminds me of riding my old Husky, at least you have disc brakes mine were drum. Yea, kick starting one of these old ones can be fun. Even with moto boots on, I've plowed my ankle into the ground more than once. And yes kick back can be a b----.You just sit there till you can feel your knee again. Ah the good old days. Have fun, be safe.
Those vintage Huskys are some of the neatest vintage looking bikes. Yeah, starting them is half the experience.

It's easy to see why the original owner may have gone MIA...

Austen NICE KTM!! and the Ducati!! I have not been on any large 2 stroke Liquid cooled dirt bike like that.. What do you think the HP is?? But I do like my 2 strokes!! I have snowmobiles with 700, 800, 900 cc 2 strokes 165HP. So I know what on the pipe means and it is a rush!! Just take it easy and you will get the feel of the bike. I am sure you have ridden many bikes and some are just an animal to ride and that is what make it feel so good to harness it. Ride safe!! AGAT (All Gear All Time) I guess I need to get my 75 Yamaha RD350 on the road..
Thanks! The seller included some factory literature and the specs list it as 62HP. KTM apparently also approved race fuel.

I'll bet your snow machines are an absolute blast!! Wow, I can only imagine how fast they are with that kind of HP. I'd love to experience one of those. You should start your own thread for them! :2th:

You've read my mind and you speak my language. There's something super rewarding about harnessing (as you state) an animal of a machine. It's what my two motorcycles have in common. There's never a dull moment.

Yup, this bike is one that you don't ride without gear. That is for sure.
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Nice looking machine!! All your toys together look awesome!
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As my dad always says after you purchase a vehicle, "what is the assessment." In other words, what surprises good/bad have come to light that you weren't aware about during the purchase.

1. Do not under any circumstances flood it when you're attempting to start it. I flooded it really bad earlier this week and it became a nightmare to get running again. Once it's warmed up, it'll start with 1 or 2 dynamite kicks. Just DO NOT flood it when you are trying to start it when it's cold. I've been trying to find little tricks to getting it started more easily so I've been trying to start it at least once a day to become comfortable with it and try and develop a system. I've found that charging the cylinder by rocking the bike back and forth in 3rd gear few times, then shutting OFF the fuel usually has positive results. Tipping it over on its side floods if you're not careful. If you leave the fuel on and she doesn't light off in 2-3 kicks, you best call it a night or find shelter if you're stuck in the mountains.

2. I've discovered there is a slight exhaust leak in one of the seams in the expansion chamber at the very bottom. I first noticed it when I flooded it real bad and fuel began seeping out of it. Apparently Andre from Enduro Klassiker may be offering reproduction expansion chambers later this year so I may wait to just get a new one instead.

3. The reed cage boot has some cracking from age. I was a little surprised the owner I got it from didn't address this when he went through it. I was concerned so I tested the cracks by spraying them down with carburetor cleaner but noticed no difference in running which is good. Eventually it'll need to be replaced and I'll install a Boyesen reed cage that has an aluminum tract vs. a rubber boot that can dry rot like the original.

4. I drained the coolant and installed Evans Waterless.

5. I learned there was a recall in regards to the ignition on these. Apparently in some situations timing could advance when you were kicking it over and the engine could actually begin running in reverse because of it. If that happened, the kick starter would slap back up and usually break the starting mechanism at the same time. I'm not sure if the recall was done on this bike. So far there haven't been any serious kickbacks.

6. I came across a couple of additional MX magazine reviews of the bike and learned that it has 18:1 compression which is largely responsible of why it is so hard to kick over. Apparently KTM suggested that if you were having trouble starting yours, that you could install a thicker head gasket which lowered the compression ratio a little bit thus making it easier to kick over. I'll buy an electric starter roller before I ever go that route, though.


7. It is the scariest sounding machine. The "pop" (or rather "bang") from the exhaust when it idles is nearly the same decibel level I'd say as a 4 stroke when it back fires. Almost like a shotgun going off. You really do almost need ear protection just standing next to it as it sounds like constant backfires going off. The sound of the engine itself when you're riding it sounds plain scary. It is very "echoy" and has a haunting/deep tone to it.

8. The power, again, is almost uncontrollable and takes your mind into another dimension. You really can't roll into any throttle at all unless you have at least a mile ahead in front of you. It is crazy thing it is. If you roll into it and it doesn't find traction it'll just burn a hole in the earth but then out of nowhere it all of a sudden slings you forward with a sledgehammer like force. When it finds traction it may all of a sudden wheelie or the back end might jump out. If you were to take your mind off of riding the bike for at least a second, there is the potential that you could be thrown off and not wake up again until you're in the hospital. Riding it in tight areas takes an immense amount of concentration.

9. Fuel consumption. It goes through fuel as if you drilled a hole on the bottom of the tank and let it run out. One little ride and you've already blown through a gallon of gas.
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Yea, every machine has its problems and characteristics. 18:1 Makes my leg hurt thinking about that. I guess you should use race gas. At least Prem fuel for a easy ride.

I would like to here that pipe 'pop' as you say. I have been to enough races and other shows that have open pipes on 2 strokes. Some motors really have a nice sound. It just make me want to go look at the motor and find out more about it. Now how about a triple 800 2 stroke with megaphones!! That is just plane LOUD. A guy I know has one..
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That thing scares me just reading about it.
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nice ktm austen, as a young teen with a hodaka wombat and riding a friends ossa 250 I wondered why anyone would want a larger two stroke dirt bike.
" I guess I need to get my 75 Yamaha RD350 on the road "
yes you do, I got a chance to ride one of these and while not dirt bike scary it made my cb 350 look bad, real bad
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Yea, every machine has its problems and characteristics. 18:1 Makes my leg hurt thinking about that. I guess you should use race gas. At least Prem fuel for a easy ride.

I would like to here that pipe 'pop' as you say. I have been to enough races and other shows that have open pipes on 2 strokes. Some motors really have a nice sound. It just make me want to go look at the motor and find out more about it. Now how about a triple 800 2 stroke with megaphones!! That is just plane LOUD. A guy I know has one..
Premium for sure! I'll have to mix up some race fuel for it. The engine does not have a power valve either.

I'll bet the triple 800 sounds nice!

That thing scares me just reading about it.
It's a trip!

nice ktm austen, as a young teen with a hodaka wombat and riding a friends ossa 250 I wondered why anyone would want a larger two stroke dirt bike.
" I guess I need to get my 75 Yamaha RD350 on the road "
yes you do, I got a chance to ride one of these and while not dirt bike scary it made my cb 350 look bad, real bad
Thanks, I know what you mean there!
Boy, I've caught this "vintage" open class 2 stroke bug hard. It's a totally different breed of bike that I've never owned or experienced before. I think back to riding bikes like modified CBR1000RRs that were complete monsters to ride on the street, 190HP Ducatis, and this is just a whole different level of scary excitement that no kind of bike can offer. I'd love to see it find a CR500 garage partner. I guess there was a reason why a lot of times the teams had to literally help the riders off their bike after race due to complete fatigue.

In proper gearhead fashion, a new set of motorized wheels doesn't remain in its current state as he bought it for long, whether that be dramatic or subtle, after the papers are signed.

There were a few "pressing things" that I wanted to do to get the bike fully ready before I really took it out this summer in the mountains. I've listed them below.

Boysen Rad Valve


vs



The original reed cage was beginning to develop cracks in the rubber intake track. Boyesen fortunately offers one of their rad valves for this motor which has an aluminum track that eliminates the issue of cracking. Reason enough to justify the "need" over "want" for one of these. The Boysen Rad Valve is a dual stage reed valve system, a design Boyesen apparently discovered several decades ago. A stock single stage reed valve system works similar to a powerband in that it works most effectively at a certain RPM range. The dual stage design solves this by incorporating two different style valves with different tensions that react effectively at separate RPM ranges. The carbon reeds (low tension) are lighter and open in the lower rev range and as you increase the throttle, the larger and more heavier (high tension) fiberglass reeds (yellow portion in the photo) open up at higher RPMs. The design is supposed to offer better throttle response and smoother power delivery.

Additionally, the Rad Valve straightens out the angle of airflow from the carb to the reed valve which helps reduce turbulence by smoothing out the airflow which provides a more constant velocity. With the development of the mono-shock, the carburetor was now required to be offset to one side so it no longer had a straight airlow track from the carb to the reeds resulting in the air flow having to change directions.

Differences?

After putting it back together, I was able to get it started on the second kick which was a pretty cool feeling. The carbon fiber reeds are definitely more responsive right off the bat. I could notice it when as soon as I twisted the throttle in neutral by how quickly it revved compared to before. These vintage big bore KTMs have a heavier flywheel and it seems to have made it respond a lot quicker as if it had a lighter weight flywheel. In terms of overall power, it seems the same. I guess the only other thing is that it may have smoothed out the powerband a little bit down low.

Airbox to carburetor boot



vs.






The PO who definitely performed a lot of good in bringing this bike back to life such as installing an upgraded Keihin carburetor also took a few shortcuts along the way I've discovered. An example of this is in the custom airbox- to-carburetor boot that had to be made to accept a CR500 Keihin carb. The problem was that he used an automotive tire inner tube which wasn't holding up well to the heat of the motor. I ended up replacing it with an automotive silicone hose reducer and trimmed it length. It should be a permanent solution.

The other notable shortcut was that he seemed to have a love affair with gasket maker instead of ordering the correct gaskets (many of which are still available) from a company overseas. I'm slowly addressing this as I go along.

New front tire & wheel bearings

The original front tire was dry rotted and needed to be replaced. While the wheel was off, I replaced the front wheel bearings as one of the outer was dry and becoming to fall apart. One thing always turns into another!

Odometer:



I wanted a way to track mileage without always having to stop and pull my phone out while on the trail. An odometer was an optional feature on these bikes but not already outfitted on this one. A period correct look is what I was after over the practicality of a modern computer like a Trailtech so I did a little research and happened to find a complete used take off odometer system from an '85 MXC500 on Ebay. The issue was that the meter itself read kilometers instead of miles so I ordered a new, OEM, meter that reads mileage instead. Again, I know this is a very old school system instead of running a small computer that has a lot more features but I wanted the period correct look and want to keep things really simple on this bike.

Also, I've decided for now anyway that I'm not going to make it street legal. I really like the vintage styling and don't like the idea of mucking it up with a headlight, taillight, probably signals, and having to run a computer system with wiring to run the electronics. I may feel differently in the future but I don't picture myself riding this psychopath on the street anytime soon.

An extra touch to the right side panel

Can you spot it?

I think I've mentioned before that a certain recall was performed to eliminate the issue of deadly 18:1 compression kick backs that would more importantly break the starting mech due to timing advancing too far on start up. When the timing advances too high, the engine tries to run in reverse and can if it starts. I've read of one case where this happened and the rider got a chest full of handlebar when the bike unexpectedly went in reverse when he tried to get the holeshot! Note to self; let the clutch out slowly after starting to confirm engine is running in the correct direction.

What's next?

Not too much. After said work I told myself it's just about done. I will have to replace the front number plate with a reproduction because the top mount can no longer be used with the odometer meter and more importantly, it's missing the top straps that wrap around the bar. Right now the top is just secured be a zip tie. I may replace all the plastic with reproduction and put a green number instead of blue like pictured below but we'll see. I'll have a new expansion chamber made sometime in the future.


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Austen, There is always a reason to put performance parts on. At least that is what I tell my wife. You are probally correct on the Boyesen rad reeds that they will give it more bottom end and smooth out the power band. A little more HP on top end never hurts either!! They need to make Boyesen reeds for our Lawn Boys.. More Power YEA !!
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JEEH Austen, your like me can't leave her alone! ;)
Nice upgrades and write up! I kinda know of some of this stuff now. I helped my friend Bob buy a old Polaris Scrambler 4x4 from a co worker. Was sitting in shop all apart for over ten years. Engine in box. Bob just got her running Friday! Two strokes sound so cool! I MIGHT take it for a ride!! :)
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I sure do enjoy your write ups. It's like being there, and I have to say, I'm not sure I'd get on that KTM a second time myself. I did chuckle a bit while reading about the Boyesen reeds. I had a set of dual stage carbon fiber Boyesen reeds on the Honda PA50II that I had tricked out a few years ago. They made such a noticeable change in it, yet I can't even imagine what yours have done for your KTM.
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Wow, you're really going the extra mile to make it super special! I'm impressed by how clean the engine is in the closeups, but I suspect that won't last long. :ROFL
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Austen, There is always a reason to put performance parts on. At least that is what I tell my wife. You are probally correct on the Boyesen rad reeds that they will give it more bottom end and smooth out the power band. A little more HP on top end never hurts either!! They need to make Boyesen reeds for our Lawn Boys.. More Power YEA !!
Haha, agreed! I like the idea of performance reeds for 2 cycle OPE. :idea:
JEEH Austen, your like me can't leave her alone! ;)
Nice upgrades and write up! I kinda know of some of this stuff now. I helped my friend Bob buy a old Polaris Scrambler 4x4 from a co worker. Was sitting in shop all apart for over ten years. Engine in box. Bob just got her running Friday! Two strokes sound so cool! I MIGHT take it for a ride!!
Nothing wrong some personalization. :2th:

Nice! Yeah, you definitely should take it for a spin. You might find yourself in the market! :ThumbUp:
I sure do enjoy your write ups. It's like being there, and I have to say, I'm not sure I'd get on that KTM a second time myself. I did chuckle a bit while reading about the Boyesen reeds. I had a set of dual stage carbon fiber Boyesen reeds on the Honda PA50II that I had tricked out a few years ago. They made such a noticeable change in it, yet I can't even imagine what yours have done for your KTM.
Thanks Bruce,

I guess I try and write them in a way so that I can vividly go back and remember each step of the project.

I'll bet the Boyesen reeds made a noticeable difference in your Honda! :2th: It's pretty neat and effective design. I'm surprised the dual stage setup isn't a standard setup with the OEMs today.

Wow, you're really going the extra mile to make it super special! I'm impressed by how clean the engine is in the closeups, but I suspect that won't last long.
It'll be detailed after rides. :2th:

This is kind of a cool documentary a 1980s open class 2 stroke bike dezert race that I think captures what these bikes are about.
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