Synchronizing the Carburetors (Part 1)

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For our next project, we're going to be synchronizing the carbs. If you haven't already, please follow our blog so that you can get updates on new posts.

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This bike is pretty smooth when I bought it, at low RPMs at least. But once you start to crank it up, I can feel vibrations coming on through the grips on the handlebars. So this was a job that I've really been wanting to do for some time. Well, enough talking, let's jump right in.

First, remove the seat. I assume everyone knows how to do that, but in case you don't, insert your key and unlock the seat lock.

 Next remove the seat. Just slide it back and up, and it should come off.

 

The next thing to come off are the side panels. There are no screws holding them on. These panels have protrusions on them that plug into rubber grommets on the frame of the bike, so you just pull them off. 

However, make sure you pull them off in the correct order or you might risk breaking the hinged tabs. I'll tell you what I mean as we go along.

Grip the panel as shown in the picture, then push with your thumbs and pull with your fingers. It should release the top of the panel.

Next grab the bottom like this, and pull gently.

 That should release the front of the panel. 

The back of the panel has a hinge, and it hooks onto the rear cowl. You need to be gentle with the panel because the hinge is fragile and it's not difficult to break it. So the rear of the panel comes off last.

Here's another view of the hinged catch.

Do the same for the other side.

Here you can see the protrusion of the panel which goes into the rubber grommet.

 A close-up view.

Here's a close up view of the hinged catch again.

The grommets where the protrusions plug into are circled in red here.

And a close-up shot of the protrusions behind the side panel.

Next we need to remove the fuel tank. The first thing to remove is the bolt holding down the rear of the tank. It's as 12mm bolt on my bike.

Wrench or ratchet, your choice. I chose wrench this time. Remember, righty-tighty, lefty-loosey. So that's anticlockwise to remove, clockwise to tighten.

This is where that bolt screws into.

Next remove the vacuum hose from the petcock. The circled part is where the vacuum hose fits onto.

The fuel tank on this bike is a gravity-fed tank, meaning the tank feeds fuel to the carbs by gravity. There is no fuel pump on this bike.

However the bike has a safety feature in case the bike is overturned in a drop or an accident. If the engine is cut-off using the cut-off switch on the handlebar, the fuel will stop flowing.

Why? Because there is a valve in the petcock that stops fuel from flowing out when the engine is not running. It's called a diaphragm valve I believe. When you start the bike and the starter motor starts cranking the engine over, the motion of the pistons moving downwards and the exhaust valves closed and intake valves open, creates a huge sucking force, or vacuum.

This vacuum goes through a vacuum tube into the fuel petcock, sucking the diaphragm valve open, allowing the flow of fuel into the carbs.

With the vacuum tube removed, it's time to prop the tank up. Here's a useful tip, especially if you're doing this alone. It is very challenging to try to prop up the tank and remove the fuel hose at the same time. So it helps if you can prop the back of the tank up with an object (I used my trusty rubber mallet) so that you have enough room to remove the fuel hose. Just shake the tank around and make sure it's stable.

Next turn off the fuel tap. If the diaphragm valve is working it shouldn't matter, but just in case it's not working, turn it off.

I'll have to admit that I always forget to turn the petcock back on when I go to ride the bike after taking the tank off, so remember to turn it back on again after you're done.

The fuel hose comes out from behind the petcock and it isn't normally visible or accessible when the fuel tank is sitting on the bike. That's supposed to be a good thing I suppose. It will prevent some low life from unplugging your fuel hose and trying to steal your gas. Yes, I've heard of that happening, what more with the rising fuel prices nowadays.

Here's a view of how the fuel hose attaches to the petcock viewing from the back of the bike. The red arrow points to the fuel hose. The blue arrow points to the attachment point for the vacuum hose that you just removed.

Here's a far out shot so you can get the context of where the fuel hose goes on. You can't really see it very clearly in this shot, so I've circled the petcock for you. Notice how the fuel hose runs towards the centre of the bike.

The hose will be tight, but you should be able to grip the hose clamp with your fingers to open it, and then pull out the fuel hose.

 

Once that's done, all you have to do is to lift up the back of the fuel tank, and pull it back and up, towards the back of the bike. Before you remove the tank, lay down some cloth on where you're going to lay the tank down, to prevent scratching it or the bottom of the petcock. Did I mention laying it down really slowly and gently?

The front of the tank rests on these rubber grommets.

And with that, we'll conclude part one of our series on synchronizing the carbs.

Please follow this blog so that you'll get notification of updates.

If you have ideas or advice on how I can do this better, please comment on the blog!

Thanks for reading, use your tools, and happy wrenching! Oh, and stay tuned for Part 2. :)

Corrected Fork Oil Specs

I've updated the fork oil specifications in the fork oil seal replacement post with the correct numbers. The amount of oil was correctly stated as 472ml. However the height of free space from the top of the fork to the oil should be 137mm, not 147mm. Should have got my lazy behind off the chair to go check it in the first place.

Greasing the Speedometer Cable Housing

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First off, if you've been following this blog, thank you, and please leave some comments because I'd love to hear from you. Also, if you have tips to share on how a particular job could be done better, please share it with me.

In my last post, I had the forks apart to change the oil seals. When I did that, it gave me the chance to clean out the speedometer housing.

I'm not sure if it's ever been cleaned, but it was really dirty. Filthy would be a better word. So I dismantled the housing and cleaned everything up with paint thinner.

The housing is a simple assembly. There's the outer aluminum casing and a plastic geared centre. This geared plastic piece is splined to the front axle, and it spins when the wheel spins. This plastic piece in turn spins the speedometer cable, which tells the meter how fast you're going.

There are two very thin washers that sit between the plastic centre and the aluminum casing. I guess this is to prevent wear and to prevent the plastic piece from spinning directly on the casing itself.

Today, I had some help from my lovely assistant. She starts by lubricating the inside of the speedometer cable housing. This is where the washers are going to sit, so it's important to get some grease in there. She does it by squeezing the grease in with a stick.

Another shot.

Next she lubricates the washers with waterproof grease before assembly. I used brake caliper grease for this. Apologies for the poor picture quality.

Now the other washer.

Next the centre plastic piece is lubricated. You can see the gear teeth cut into it.

Here's what it looks like fully lubricated with brake caliper grease.

And here everything is fitted into the housing, and a final dollop of grease gets squeezed into whatever space is left.

And that concludes this short post on how to lube the components in the speedometer cable housing.

If you haven't already, please follow this blog.
If you have ideas or methods to do this better, please comment on the blog!

Thanks for reading, use your tools, and happy wrenching!

Replacing the Fork Oil Seals (Part 3)

Now that everything's apart, it's time for some cleaning. I bought one of these BBQ containers they sell at the supermarket for $2. It's big and relatively firm, and is not so light that it flies away easily.

I also got a paintbrush for cleaning for 80 cents. I tried to pick one with firm bristles.

I used paint thinner for solvent. It works very well for getting rid of dirt, oil and grease, but it really stinks. However, paint thinner doesn't leave any residue once it evaporates. If our local thinner is made from acetone, then it should also be a safe chemical to use, because acetone isn't harmful to health unlike things like gasoline (i.e. petrol). If it isn't, then there goes whatever's left of my brain cells.

You can also try kerosene or diesel, but please wear gloves. Some, if not most of these chemicals are carcinogenic (i.e. it causes cancer on prolonged contact).

I bought these nitrile gloves because I read that they work really well as a physical barrier against chemicals. These were a nice pair. I think they cost me around $5 a pair.

Cleaning the spring seat, spacer and bushing.

Cleaning the damper rod.

Being the tightwad that I am, I didn't want to waste a lot of thinner. So I saturated the brush with solvent, then dripped it into the interior of the damper rod to try to clean out the old oil.

The forks had some rust spots on them. So with the forks apart, I attempted to polish them up. My first attempt at using power tools for polishing.

I clamped the fork to the table and put some metal polish on it.

Then I attacked it with a teeny buffing "wheel" on the end of a drill.

Here's a close up shot.

Honestly it didn't work very well. I realize that I need to get proper polishing wheels and compounds, and this just isn't going to cut it. Another project for another day I guess.

I didn't take enough pictures for this project, so I don't have all the pictures for re-assembly. I'll take better pictures next time, promise.

But here's some other stuff I did before the forks went back on the bike. Here're all the parts cleaned up and laid out on the table. I lube the damper rod spring with fresh fork oil before re-assembly.

Then I lube the damper rod. I'm wary of that hole because of how much blood it's caused me.

I torque the screw according to the specifications in the manual.

I saw this torque adapter on sale on Amazon, and I thought it'd make a really neat tool. The reviews said that it was really accurate, so I actually bought it as a replacement for my torque wrench. Here's a closer view of it.

You can set the torque in various units, Kilogramme-meters, Newton-meters, Foot-pounds, or Inch-pounds. The torque readings only start to come on at 29 ft/lbs, so it isn't going to be able to measure anything below that. For working on a motorcycle, this just isn't going to cut it.

Moral of the story? Get a proper torque wrench.

After spending some time messing with it, I realized that it isn't very practical for several reasons. First, physical feedback is important in a torque wrench. This one beeps, and the LED changes colour when the torque setting is neared. That means you have to pull really slowly to hear that beep before exceeding the torque setting, and you need to be able to see the readout at all times. Besides, if you're working in a noisy area, things will go wrong.

Secondly, it's tricky to set the torque settings. The increments either move too slowly, or too quickly if you hold down the button.

Third, it's bulky and it doesn't ratchet. I cannot recommend getting this if you're thinking of using it as a replacement for a torque wrench. It might work as a calibration device, but not a tool for regular use. You'll also need a vice to use it as a calibration device for your torque wrenches.

To prevent damaging the inside lip of the new oil seals, I wrap a plastic bag over the top of the fork, and coat it liberally with fork oil. This is to enable the seals to slide over the top of the tubes without damaging the lip.

Next, you need to hammer in the fork oil seals. You're supposed to use a special tool for this, a fork seal driver. This is what the special tool looks like.

Before you do that, I highly recommend that you lube the inside of the fork lowers before you bang those seals in there. The fork oil is going to help the seals go in much easier. And they don't go in easy. On my first attempt, I spent close to 20 minutes hammering on the seal and didn't even get it to clear the retaining ring groove.

The picture below shows you where to apply the fork oil.

I didn't want to spend so much on a tool that I'm only going to be using very infrequently, so I made do with some PVC pipe. I got some 40mm PVC pipe and split it down the centre. Here's my improvised fork seal driving tool.

 Here I used my improvised seal driver to hammer in the fork oil seals.

 

Here's another shot of me driving my neighbours downstairs crazy.

Frankly, this plan didn't go very well. Problem was, the short PVC pipe was too light, and it just didn't give me enough leverage to drive the seals in properly. So I had another idea.

Introducing the "Big Kahuna."

It's a half a metre long 40mm PVC pipe. I suggest getting a larger size, perhaps 42mm. This one didn't fit the OD of the seals perfectly, although it did the job very well.

In fact, with this pipe, I took less than 15 seconds to bang the seals in so that they sit below the retaining clip's groove. Contrast that to the 20 mins I spent with the previous tool.

Here's another view:

I probably should clean up the edges with a file.

After I re-assembled everything, now it's time to fill it up with fresh fork oil. If I remember correctly, it calls for 472ml in each fork. I didn't want to dirty the only measuring flask I had in the house, which my wife uses for baking (I don't really fancy the taste of fork oil in cookies, do you?), so here's what I did.

I took a regular drinking water bottle, and cleaned and dried it. Then I measured 472ml of water with the measuring flask, and poured that into the bottle. Then I marked off the level of the water with a marker, and poured out the water, and let the bottle dry.

When it came time to refill the oil, I just poured the oil to the mark I made, and there should be 472ml in there. See? I didn't sleep during physics class.

It's important to get equal amounts of oil in both forks. I've read that unequal amounts will cause handling problems. Initially, I thought I'd just eyeball the oil level using a tape measure. I think the manual calls for the oil to be filled up to 137mm from the top of the fork.

At this point, I actually put everything back and fixed the forks back on the bike. But I kept having the nagging feeling that the levels were not level on both forks.

So I made tihs tool instead to help me accurately measure the level of oil in there. First you need a big syringe.

Then I get some clear tubing and fix it to the syringe. I taped a wooden chopstick on the end to make the tubing straight, so that it measures the level accurately. Then I mark off the required measurement (137mm) from the tip of the tubing.

With more time, I'll probably scrounge up some parts to make a better tool.

To use this, I just insert the tubing into the fork tube till the mark aligns with the top of the fork. Any excess oil can then be sucked out with the syringe, so the final level of oil in the fork is 137mm.

After that's done, the spring, spring seat and the spacer gets put back in.

 

The easiest way I've found to get the fork cap back on, is to push the fork cap down, and turn the fork tube (not the fork cap) anticlockwise, until you feel the threads engage. I found this much easier then trying to push down and screw in the fork cap at the same time.

Tighten it up, and that's one side done, and ready to go back onto the bike.

Well, that concludes our series on fork seal replacement. If you haven't already, please follow this blog.

If you have ideas or methods to do this better, please comment on the blog!

Thanks for reading, use your tools, and happy wrenching!