Motorcycle maintenance

On Saturday I changed the sprockets on my bike and had a brand new chain which I'd been keeping as a spare in case of breakdown. In fact I'd bought the chain from the main Jawa dealer here in BA, but when the time came to fit it, I was one link short. 107 links instead of 108.
That was definitely a wtf! moment after hours of toil.
Anyway, I cleaned up the old chain, put it back on and will have to buy yet another chain.

All chains are different sizes in length, link width etc. Not to mention the sprockets, where you have a small one at the front and a larger one at the back.

The sprocket sizes and amount of teeth influence the RPMs and other factors. In my case, I asked for a rear sprocket that would result in lower RPMs at cruising speed and so I bought one with 34 teeth.

The front sprocket has 14 teeth and this combination is recommended for my bike apparently. However, I preferred the rear sprocket with 32 teeth and I may put it back on, as it's actually in pretty good shape and hasn't fish-tailed.

Here's an explanation from Roberto Martinez, Jawa Argentina. (The pinion is the front sprocket and the crown or corona is at the rear)

Quote

"The larger the pinion or the smaller the crown the engine runs at less RPM than at the same speed with a smaller pinion or larger crown.

This seems ideal, we put a smaller crown and our engine runs rested ... But: as we increase the speed, the air resistance increases and we need more and more strength (+ CV) to overcome this resistance.

With the long transmission (crown girl 30) we need more CV to reach 6500 rpm than with a short transmission (big crown 34).

The bikes are delivered with different crowns, 30/32/34 because it is not known what the use that each customer will give the motorcycle.

In the city it goes very well with the 30 teeth, but in the route, when one seeks to overcome the resistance to more than 100 km / h, it increases speed better with that of 34 teeth.

Be aware that there are many cases of speedometers that have difficulty climbing after 100 km / h but the RPM continues to rise. "

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Here are some shots which may interest you Rice

When I returned from the UK, as expected, the bike wouldn't start, so I charged up the battery and got it running. However, it ran like a dog, was coughing and backfiring, with fuel coming from the carburettor overflows. This meant that the floats in the carbs had stuck, so I turned off the fuel, opened the screw and drained the fuel into a bottle, whilst tapping the carbs lightly with a piece of wood.

I did this about five times and finally the engine began to run normally. I hasten to add that I like to do all these jobs myself, not only to save money in this rip-off country, but also to understand how my bike works. This is especially important when going off on a long run by yourself, when you have no one else to rely upon.

I had some trouble changing the rear brake pads though, as one of the two hex screws which you open with an Allen key was locked solid, so I'll have to work some more on that.

Next, I'll be changing the oil and sourcing an LED bulb for the headlight.

I've always believed that the best way to learn is by teaching yourself.

I went back to Jawa, Lugano this morning having reluctantly accepted that I'd have to shell out AR$2000 for a new chain, but at the last minute put the 106 link chain in my backpack with a view to pleading a free replacement.

Bearing in mind that I'd bought the chain three years ago as a spare, but had never used it. Anyway, as the assistant brought the new 108 link chain to the counter, I asked if they could simply exchange it. This was a bit tricky since I had no receipt and had paid in cash, but since it was still in brand new condition, they said 'no problem', since the chain was supplied in error and in fact was meant for a Jawa R40.

That doesn't often happen here, so you can imagine my delight.

I couldn't change the rear brake pads, as one of the caliper pins was completely seized in and in my efforts to remove it, I'd rounded off the hex head. I then bought a set of bolt extractors, but the one that I used snapped off, leaving me no choice but to remove the caliper and take to my local bike shop.

Leaving it with them, I wasn't expecting to get it back till Thursday, but ten minutes later they phoned to say they'd extracted it, much to my joy.

This was a blessing in disguise, since the brake fluid had turned dark brown, so I changed it, bled the system and spent the next few hours bleeding the air out, testing the brakes, bleeding etc etc.

Anyway, they now work at about 75%, so I'm using a trick which involves leaving the pedal jammed down overnight, so that any tiny air bubbles might find their way out.

That's the theory anyway.

The rounded hex

Forcing the pistons back

The old fluid

Bleeding

Jamming the pedal down with what was at hand

That should be it for next few thousand miles.

A couple of weeks ago Jawa did a superb job in replacing the crankshaft, pistons, seals, bearings, clutch and front fork seals on my bike and frankly, I can't praise them enough. They completed the job in less than five working days and the bill was half of what I would have paid elsewhere, bearing in mind that Jawa, Lugano is the main dealer as well.

I replaced the rear tyre with a Pirelli in December and now have the same make, both tubeless, on the front. I have to go back to Jawa early on Monday morning for them to make some adjustments as I've been running it in for the last 1000kms. Mind you, that indicates that that I'm now doing more than 500kms a week, so maintenance is even more important now.

Oil change to semi-synthetic in 1000kms.

My eyes shut as soon as my head hits the pillow, that's for sure.

The headlight on the bike has always been woeful and I've been wanting to change it for ages. It's so bad that it's about as effective as strapping a small torch to the bike and the quality very bad, being made of cheap plastic. That's mainly why I put a couple of powerful LEDs on the leg protectors.

Anyway, yesterday I bought a new one at Jawa and started fitting it today, with a few modifications required to the front support bracket and some of the wiring.

No doubt I'll be counting the minutes for dark to come tomorrow so I can try it out when it's all finished.

It's taken me a while to get my head around gear ratios, i.e. the relationship between the sizes of the front (countershaft) and rear sprockets. The number of teeth on each determines the size.

The gear ratio is the number of teeth on the rear divided by the number on the front. The gear ratio equates to how many times the front sprocket needs to turn to turn the rear sprocket.

At the moment I'm running with F14 R34 - gear ratio =2.43, but this is giving me faster low down acceleration but much higher revs at faster speeds, thus higher fuel consumption and the engine feels like it's working too hard.

It's worth noting that for every one tooth you change on the front is like changing three or four on the rear.

Up until now I've been using a 32 tooth rear, but there weren't any available, so I changed it to 34. However, I still have a couple with 32 teeth and they only have minimum wear, so I'll be doing that shortly. That will also mean shortening the chain which only has about 1000Kms on it and I've recently acquired a chain cutter for removing links.

Ideally I'd like to get down to a 30 tooth rear to reduce the revs even further, but I will need to have one made especially.

Here are some handy diagrams:

Anyway, I'll go down to 32 on the rear today or tomorrow and report back.

I've just added a shiny new tachometer (rev counter) to the bike, as well as a couple of foot supports for those long rides.

I also removed the chain, cleaned it, removed a link, cleaned up the rear brake calliper and replaced the pads. I also made a rubber chainstop for the swing arm.

Have to keep the machine in good working order.