502 Refurbishment

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Re: 502 Refurbishment

Post by Go Go Diablo » Tue Jan 19, 2016 11:11 pm

The Hirth recoils are nothing to be scared of. They are far more simple than the JLO recoil.
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To pull apart:

- If your recoil has the three angled tabs, you will need to slightly punch the roll pins in to get the tabs off.
- Remove the starter cage with the rollers.
- Turn the spring housing and you will feel it rotate off those three pins.
- Carefully remove it with the spring.
- Pull most of the cable out, then pull the cable reel out.
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Don't worry about the spring getting out of the housing. Just hold on to it, remove it and let it unwind.
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So now you have it all apart. If you punched the roll pins in, punch them back out so they are centered in the rim (sticking out on each side of the hole). Clean your parts. Lets start with the cable and cable reel. If you have an original metric cable, it is about 0.113" in diameter (not sure what millimeter it is) and is about 88" long. If your cable is shorter than 88" long, then someone probably cut it off because it wore at the starter handle. If the cable is significantly shorter (more than 8 inches), you may have a problem.

The thing to know about these recoils is the dead end of the cable on the cable reel is not secured to the cable in a firm fashion. If your cable is short and you make long pulls on the recoil, you can easily pull the cable right out of the recoil. So if your cable is short to start with, that hurts your cause.

Another challenge is if someone put in a standard cable that they got here in Northern America, chances are it is a domestic cable which is not as bendable as an original cable and is larger in diameter by more than 0.010" That does not sound like much, but the most domestic cable you can get on the cable reel is about 77", so already, you lost 11" of pull length. I have the correct Hirth cables if needed.

One technique I use to keep the cable in place on the reel is to put the cable under the tab, and then punch the tab down on to the cable with a thin chisel. This clamps the cable end and you are less likely to pull it out if you get to the end of the stroke. If you have an original size cable and can get the full 88" on the reel, then you can make a pretty significant pull on the cable and still have some cable left on the reel which is the best of both.
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Pull the plastic grommet out of the recoil so you can route the cable through the outlet throat. Have 1/2 the cable out of the reel and install the reel in the housing. Wrap the cable on to the reel.

Clean your recoil spring. Then put a light coat of thin oil or lubricant on it.
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Put the spring back in the spring housing by putting the circular end on the post and wrapping it clockwise, walk the spring in to the housing. Before installing the assembly, it helps if you bend the tab that the spring's live end will grab out slightly so you can get the spring "hook" to grab the tab. Insert the spring housing into the assembly. Pull the cable outward and you should see the hook of the spring against the tab. Using a screwdriver, put the hook into the tab. Fully insert the spring housing. Now you can turn the spring housing in 1/3 turns and you will see that every 1/3 turn, it will grab those roll pins and tighten the spring. I usually tighten the spring by rotating the housing a turn to a turn and a third or so. Don't overdue the tightening because if it is too tight, when you pull the cable, the spring could run out of travel. You can pull the cable out and let the recoil pull it back in at this time to see how it is working.

Next is the starter cage. The important thing about the starter cage is not to get it full of grease and do not lubricate the spring washers under the snap ring. The rollers do not need much lubricant to keep them free and the spring washers are a brake for the cage.
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So install the starter cage with the spring on and install one roller by pulling the spring outward with a pic and setting the roller into place. Pull the cable and the roller should pop out. If it does not, pull the starter cage off and turn it 1/2 turn and reinstall it. It has a left hand and right hand position and when it's correct, the rollers will pop out when pulling the cable.

There are typically two spring washers under the snap ring. Usually one does not provide enough friction to get the rollers to pop out properly. If the rollers do not fully pop out when pulling the cable, it will occasionally not catch when you are trying to start the motor and everyone knows how frustrating that can be. If you grease this cage up, you will have the same issue with the rollers not popping out their full distance.

Put the clips back on if you had them. Reinstall the recoil on the motor and route the cable through the dash.

That is it, you have a good recoil. About 1/2 to 1 hour.
Too many Diablos and parts to count.
Yamaha 600 SX

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Re: 502 Refurbishment

Post by Go Go Diablo » Wed Jan 20, 2016 9:38 pm

The Primary Clutch is a Salsbury. Not much that goes wrong in these clutches other than a broken spring here and there and the need for some lubrication. Original clutches have these small Allen headed screws and they are difficult to get out.
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My method of getting the screws out is to cut a 3/8" nut in half and weld that half directly to the top of the screw. If you have a wire feed welder, hold the nut half in place and aim your arc right at the screw so you weld the screw head to the nut. This heats the screw and when doing this, I've always been able to get the nuts out without hurting the clutch.
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Remove the ramp plate and look at the springs. This is a picture of a good spring:
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And this is a picture of a broken spring:
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To replace a spring on an arm, you need to unhook the opposite spring by just pushing the spring end off the arm. That is the easy part. Then push the movable side of the clutch down and this gives you access to the bolt.
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Remove the bolt and install your new spring. Now the challenging part is to get the springs back up on the arm. I've found this muffler spring hook works good. I am right handed, so I naturally hold the clutch with my left hand and grab the left spring with the spring hook and pull it in to place. When you try it, you will understand that this seems the only way to get enough leverage and also pull the spring over and on to the arm. For the other spring, you have to switch hands and do it opposite for the same reason to get the spring over and on.
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I use a Comet Clutch Lubricant and spray the springs and the rollers spinning the rollers to make sure they are lubricated. When you put it back together, install new Allen headed screws. Install it on your motor. When you start your motor, you can use a piece of emery cloth on the clutch faces and they clean right up easily. You can also spiffy up the ramp plate of the clutch.
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Clutch takes about an hour.
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Re: 502 Refurbishment

Post by Go Go Diablo » Thu Jan 21, 2016 9:39 pm

The wiring on a Diablo 502 is very simple. Coming from the motor you will find:

- A brown wire that is the motor ground
- A black wire that is connected to the points to ground them out and stop the engine
- A yellow wire from the motor lighting coil
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I route new wires and use a new key switch and a light switch. The key switch has continuity between the poles when the key is in the off position. This is different from typical 2-pole key switches found. A wiring diagram is available if you need one.
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Couple of comments are:

- If you have a diode in the lighting circuit, it will be right above the top motor mount. I typically take this diode out and that brightens up the headlights. However, if you lamps are original, you take a chance of burning them out.
- Ground the hood to the chassis and the motor to the chassis for best results.
- Use 2-terminal quick disconnects at the hood connections and at the sled connection.
- Have solder on the wires leads that go to the 6 terminal connector on the motor. If you don't solder the ends of the wires, they typically will just break off from the vibration.
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Wiring is about an hour.
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Re: 502 Refurbishment

Post by Go Go Diablo » Fri Jan 29, 2016 8:56 pm

The original carbs on a Diablo are a Tillotson HR3A or HR14A. To my knowledge, there is nothing different about them. Just the year they were made. If you look at carbs of the same era (HR1A, 2A, 5A, 8A, 9A and others), they all look the same. Studying over the breakdown of these carbs, the only differences I see are things like the choke linkage, carb linkage, the choke plate has a hole or it may not, things like that. So I believe the internals are all the same. So you can use these other carbs if you set the linkage up correctly.

My advice to everyone is to use your original hardware if possible. Original needle/seats, levers, springs, hi and low speed jets seem to work better than to get one of those fancy kits with all the parts you put in your carb. In almost all carb rebuilds, I'm just using a new diaphragm kit along with new flange gaskets and the cork gasket behind the plastic inlet. In the end, there are a few things in my mind that are important:

- Clean parts well. I'm not talking about soaking in carb cleaner. I mean use a wire brush and clean the surfaces. If there is gasket material, carefully scrap it off.
- On the center plate of the pump, don't scrape the raised lines off when getting aggressive with a sharp scraper.
- When clean, you should be able to shake the body and hear the plastic ball on the fuel check valve rattle.
- Do a "Pop Off" test if possible.
- Make sure gaskets are in the right order (you can't put them in upside down).
- Evenly tighten the pump plate screws.
- Make sure the plastic inlet fits within the circumference of the carb plate. It seems they can swell and then not fit well causing you a headache when they have a vacuum leak.
- Install a new pulse line. Note that the nipple in the carb is just pressed in. If you need to tweak to where it points, you can just turn it with a pliers.
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One thing about carb cleaner, you tend to get the black soaked into your skin and it takes days to wash your hands!

My pop off tester is a 0-15 PSI. Here is one like it, but it is 0-30 PSI. I like to set the spring tension to pop the needle off the seat around 12 PSI and if it then drops and holds pressure around 6 to 8, your golden. Spray WD-40 into the seat first by putting the WD-40 tube down into the carb inlet port (see where I have the pop off tester placed). Spray while pushing down on the needle lever and watch for the lubricant to come up through the needle. Now test it.

https://cometkartsales.com/Carb-Popoff- ... 30psi.html
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Reassemble the carb and away you go.
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One more thing I like to do is add an additional return spring. If the shaft spring on the carb breaks, you best have a good brake or be able to reach the key switch. The more I think of Jesse's kill switch modification, the more I like it.
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That is it for the tractor end refurbishment of your Diablo. On to the ski seater next.
Too many Diablos and parts to count.
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Re: 502 Refurbishment

Post by Go Go Diablo » Sun Jan 31, 2016 8:45 pm

Seats are an expensive piece. If you can save your cover (even if it has a few rips), it might be just fine for an unrestored Diablo. Most often what I see is the backrest and the angle are gone. This seat's wood was completely rotted away, so I am reusing the foam and the cover and installing a new seat frame.
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Cut your wood to match what is left. Use a 9-ply plywood. If you use anything less, you will be disappointed as it will warp. Now is a good time to install new Tee Nuts for the mounting screws too.
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https://youtu.be/cZoHE3yshMw

The old cover is going to have hundreds of old rusty staples in it. I found if you have the cover upside down on a surface with those rusty staple ends up, you can just rub a wrench or something over them and bust them off. You can pull each one too, but we will check back with you in about a week and see how that is going :D . Then like in the video, pull your new cover on and staple it down.
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https://youtu.be/hxnPuOjtPoY

I always install a new piece of vinyl on the back. It makes for a good back end and can cover up some flaws in the original cover.
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Re: 502 Refurbishment

Post by Go Go Diablo » Tue Feb 02, 2016 9:46 pm

Skis are another costly piece and so often the skis on these things are rotted away. So you have to get creative on skis. Buying new ones is always an option (unless Barrie decides to only make Hus Skis). I'm also trying options to make some economy skis. I think most of you know that I am a big proponent of putting the Durasurf Wear Skins on all my skis.
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It's a process to get the right material that can be glued and then get them glued tight to the ski bottom. The challenge is this material and the adhesive is not sold over the counter that I know of. I got my materials from Crown Plastics and I had to prove I was a business before they would ship me the materials as the adhesive is considered "hazardous" (did you see those air quotes).

I've primed and painted skis for many years and that works ok. Jeff C from Canastota stains his skis black, so I tried that this time to see how they hold up.
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I use elevator bolts for the fasteners. The Durasurf is countersinked just a tad and the elevator bolts fit right in place. You have to put some kind of runner on the ski bottom or your seater will just get pushed around when you try and steer. I use solid rivets to attach the runners.
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Adjust the skis so they are square.

The last thing I do is install a 2-pole plug so there is a direct ground to the seater. Without this, you are relying on a grounding circuit through the ball joint connection.
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The seater is complete.
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Too many Diablos and parts to count.
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Re: 502 Refurbishment

Post by Go Go Diablo » Sun Feb 07, 2016 5:33 pm

I started this post by mentioning that this is not a cosmetic restoration, but the hood on this 502 had some serious paint issues. It had the decals taped off and then a poor coat of paint and did not even have the white stripe on the hood. When I peeled the decals off, it looked terrible. For this reason, I gave it a quick sanding and a coat of paint. Unfortunately what you end up with is a hood and chassis that is different colors, but in this case, I prefer the look of the hood to what it was.

So that is how I refurbish a typical Diablo 502. It should be far more reliable that is was. It took me about 26 hours, but I have a bit of an advantage over someone doing this for the first time. But even it you put twice as much time in to the refurbishment, that is still not a bad investment to be able to drive your Diablo and feel confident is won't break down before you get back.
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Since starting this post, I have had at least several people tear their Diablo apart and are in the process of doing the same. I hope it helped inspire a few others to do the same. In a future post, I will try and describe the differences when refurbishing a 500 or 503. Until then, if anyone has any questions, suggestions or observations, I'm sure the forum would like to hear them.

Thanks all for watching,

Bruce
Too many Diablos and parts to count.
Yamaha 600 SX

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