Saturday, March 28, 2009

Clutch (updated, with pics too)

The IC engine clutch, perhaps the most important piece of equipment on a bike, the part which makes the power produced by the engine usable at all speeds, partially, along with the gear box that is, is a simple yet sophisticated arrangement, the working of which if you think for too long will drive you crazy! it is to the most part inefficient, purely frictional, heat producing, energy consuming and not-fully-work-transferring set-up, but it works, as in the heat produced is acceptable and is used, with the engine oil, to heat up other things in the engine which do require heating, and the frictional slippage is negated by using many plates and tough springs.
All said and done, what it is, is this. It's a jigsaw of thin circular metallic discs, some toothed on the inside and some on the outside, sitting alternatively in purpose built slots on two different cylindrical drums, one driven by the engine and another driving the gears, bolted to a single shaft and rotating concentric to the shaft in its axis, held together with strong bolts to make sure relative motion when they're engaged is zero, at least that's the aim.
Here're are a few pics

1. This is how the whole arrangement looks like from the outside.

2. The tabs of the cork plates, slotted on the outer drum driven by the engine

3. The alignment arrow-mark to help reassembly

4. You're supposed to align the arrow mark to this punch mark.

5. Look how badly burnt the plates are, they're almost black, and tused to stink like crazy when i rode the bike hard, stench of burnt cork!

6. The friction plates, from the RX on the left and pulsar no the right. See the the arrangement of the tabs in the set at the left, and the marks on the plates for better bite. the pulsar's plates are bald! the pulsar 150 cc old (4 cork and 3 steel) clutch is the worst clutch I've ever ridden! and the Suzuki fiero's, the best!

7. The suzuki fiero's clutch during disassembly, it has a unique 'old school' way of fitting the clutch springs. This is one very effective piece of kit, the whole bike in fact!

8. The clutch bell (the outer slotted thingy) and clutch boss (the inner slotted thingy) of the suzuki fiero, after removing the plates.

And that aim was what was not being fulfilled in my bike, thanks to a crappy mechanic job which was done to it while it was with it's previous owner...
So I decided to put in a new clutch, finally got the heart to open the bike up to do some work, after growing into it for almost a full year , letting it gather dust without an oil change! :| Asking a word with my friend revealed that, apparently, the clutch costs 195 bucks a set! So I thought "why not" and went to the Yamaha Showroom and ordered a set, he said 53 a plate! now, I don't know whether I was ripped off or whether he got lucky or whether he god low grade stuff... but I was really shocked, and there was no turning back, I wanted a new clutch and I almost wanted it yesterday! so, "bill it" I said. along with some other necessary stuff. Came home, got into my mechanic clothes and drained the oil... my first surprise, the oil nut wouldn't come out easily! did someone jam the crank case??? well, with a little tug of war, I got it to separate from the engine... then my second surprise.... the oil is black, greenish and flowing like water! was it running on 2T oil?? or a synth blend?? this was preparing me to face some weird stuff inside. Then I unscrewed the screws of the clutch cover and open it up.. I see the case looked clean, but the big problem!!
what had happened is this. he'd gutted the baffles of the exhaust, increased the port heights which effectively increased the power band to much higher up in the rev range, therefore making it much violent in full throttle acceleration, so to counteract the clutch slip, he'd put in 6 friction and 6 drive plates making two metal plates rubbing each other, this extra plate had caused the clutch to open up unevenly in the clutch-boss and clutch basket thus increasing uneven wear on the clutch and increasing slippage.
The clutch change went well, the friction plates were burnt black and the metal plates were scored, so had to run to the showroom again and get new metal plates! each plates costs 81 bucks and I needed 5! Already 750 spent in a few hours and counting, cause I knew I would need engine oil later! After coming back home, I forgot how the clutch plates went back into the basket! In the Yamaha, the clutch plates are weird, there's a tab on each metal plate and I was confused whether all the tabs were supposed to be superimposed or should they be staggered. I tried to think up some logic to guess how they'd fit, but nothing worked. It then came to my mind that I have an old service manual of a Yamaha DT125 dirt bike. I opened it up and saw that it had the same clutch as my bike, so the tabs go staggered at approximately 60 degrees relative to each other. I put that back and sealed up the clutch basket.
While trying to put back the clutch cover, disaster struck, the kicker shaft, gear and return spring fell down from the crank case while I was struggling to fit the cover and I didn't know how it went back it. I tried a few alignments, but couldn't crank the engine at all! it was frozen solid. Went back and forth to the manual trying to search for the kicker assembly diagram, they'd given it, and explained it too.. but I had already panicked and so couldn't understand a word of it! called up a friend, wasn't of much help since he'd never worked on this bike. it took me more than 3 hours by the time I figured out how it fit! then whatever I had read earlier in the repair manual made perfect sense! so much for my state of mind! I went, got another can of oil and started her up... the clutch bites well now! hope it holds for long too! Anyway, I learnt something new! small mistakes matter a lot, and consume a lot of time if you're not familiar with doing stuff or don't have resources at hand! Till next time, happy biking!

P.S. The guy who told me it was 195 for a new clutch, well, he was right, it's Mr. RX by the way, and his bike has four cork plates compared to the six of mine! and plates were cheaper a year ago, so, clarification. Sorry Mr. RX :)

Wednesday, March 11, 2009


This weekend there's a run for peace with anti-terrorism being the main theme, It's a course covering 12km according to the papers. So this would be a good thing to start off with for the preparation to the Sunfeast 10K in may. I'd been to register for the event a few hours ago and a peculiar incident happened. As soon as I entered, I was rushed to a counter by a guy with curly hair (if I remember correctly) where two girls stood, both of them, in turns, were trying to talk me into participating in a slow-bike race which was either happening or going to happen later in the day. At first I asked whether it was bicycles, as I planned to go and get my bicycle from home (little did they know they were talking to a two-time slow-cycling podium finisher, mere mortals, ha ha). But they immediately revealed that it was motorbikes, with gear, without gear, anything goes they said, “just go and participate” was the word of motivation given by the tall girl who pointed out where the event would happen, inside the campus in the shade of the trees I assumed. As badly I didn't want to dampen their spirits and be snobbish, my heart also went out to my bike, the Yamaha, it wasn't in a good condition at all, it has a bad clutch slip, bad handling, a bad cooling problem, so much so that you could smell something burning when you parked the bike after a ride, probably more of that old clutch! Most of all it had no brakes, or very little of it to be precise. So I didn't wanna keep blipping away to glory in first gear while the bike would burn its insides out by the time I'm done with the race (and thus give me a 2000 Rupee repair bill, which I'll have to bear apart from fixing it myself!). So, what could I do, I had to tell them, the bad truth, well, I say bad cause, me being a big bike freak apparently, it's a insult to say your bike is not in a good condition, but I went ahead anyway and told them “my bike is not in a good condition, technically” in a sheepish voice and a smile to go with it to break any possibly perceived “attitude problem” and make them understand that I was avoiding it intentionally but sadly inevitably. Then the second girl standing a little further away from me behind a table and leaning into it who had the bluest crystal-like crisp eyes I've ever seen on a person came forward to stick her oar in the negotiation. Try to be a sport, as was the guy and the other girl, she said with a smile that it's a slow-bike race and slow-bike race doesn't demand the bike be in perfect condition, I guess that's what she thought. Well, I couldn't explain the technicalities of my ordeal, so I stood my ground, albeit with half a heart to go and enter the race, one eye on the lookout for the marathon stall and another eye firmly planted into this girls eyes!

Alas, finally, even when the girls had almost torn off the participation ticket from the book, I made some lame excuse, for which I certainly feel bad, that I'm hard-pressed for time, not that I wasn't but not so bad that I absolutely had to miss this event at all cost! They looked disappointed too, all three of them, and they pointed to the marathon stall with a cold glance. I could do nothing but smile and really appreciate the spirit something which I lacked today and I'm ashamed of it.

The marathon guys on the other hand, were more than happy to welcome me and since I already knew the route and other details, the transaction was very brief and quick. I would report at 6AM and get my number and a tee shirt. I said a big thank you and was on my way. Heh, I felt bad and my memories were going back to my college days where I was the silent rebel, almost an outcast. I used to wake up at 8:15 for the 8:30 college, leave home at 8:22, 8:23 would be too late, and would red-line my bike on the revs all the way to the college, many times with an 85 kg ballast in the back seat, managing to reach at 8:29. In college, I never talked much to anyone, kept all to myself and my mind, never participated in anything except being an audience at the rock show every year during the college fest, which I followed quite religiously.

But after I left college I changed my outlook towards the world, became more social, probably more approachable (as a close friend puts it). And learned never to say no to any invitation which came from the heart, in true spirit. Learned to be a sport. But I guess sometimes old things are hard to forget, cause while I was standing there, I was thinking “why don't they just let me go”!! I know why they didn't let me know! And it was a good thing!

Well, you three, the two girls and the guy, if you're reading this, just know that I wanted to, but couldn't. Will hopefully run into you on Saturday. Till then! Cheers!