Monday 8 January 2018

The new TR1 motor - uber-clutch and some lathe testing (part 17)

As the stock clutch is somewhat prone to slipping under normal use, even slight power-increases mandate improving the clutch. Luckily the Yamaha engineers made this very easy as the clutch basket of a XV1100 is just a tad higher and once the innermost steel-disk is replaced with a standard disk, a 9th clutch disk can be fitted. Unfortunately the spring mounting posts are somewhat taller, because the later 1100 engine uses a diaphragm- instead of coil-springs.


But once you shorten the posts, it works just fine. In order to reduce time on the mill (and prolong the lifespan of my milling cutters), I hacksawed them off with some three to five millimetres extra.




Then I dialed in the mill to be precisely on zero with a sheet of paper, knowing that the paper of these sticky notes is about 0.1 to 0.2mm thick. And then milled the basket down to final height. 



As space is really tight, I also opted to turn down the ribs on the clutch'es pressure plate, which is way trickier than it sounds, as you can only take very light cuts, because the backside only offers some rather inadequate room to clamp it in a three-jaw and I didn't want to make a fixture.




The 1100 clutchbasket is indistinguishable from the original one on the 1000, but in order to make clutch adjustments a bit easier, it is advisable to use two washer on the clutch pusher mushroom.




This really concludes the right side of the engine's bottom to be honest, not much more to do than install the engine cover and an oilfilter.

2 comments:

  1. Hi Greg, one question:
    I take a somewhat critical view of the last clutch disc. Don't you think that this might twist when the clutch is activated and thus prevent the clutch from engaging? Finally, the disc is only guided on a small edge on the clutch basket. Have you already tested this in continuous operation?
    best regards,
    Dieter

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    1. Hi Dieter, sorry for the late response, but your comment notification drowned in a sea of spam-messages. Yes this is a tried and tested mod, not only by me but various others as well. On my own bikes I probably tested it in excess of 30,000km so far.

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