Tuesday, March 10, 2015

Clutch adjustment and a few upgrades.

The clutch lever on the Honda had an enormous amount of slack, so a good few Saturdays ago I thought I would be clever and correct the problem; instead, I managed to snap the clutch cable, bend a bracket and strand myself at the garage in the process, what an idiot.

After berating myself at length, and thinking I should just get rid of all my motorcycles and be done with the whole thing, I realised what had actually happened: I was not properly dressed for the garage (i.e. I had clean clothes on), it was cold in the garage, despite the heater being on, and I had the flu. Bad combination.

I also wonder if that cable wasn't about to break anyway, and it could be that that's what it was: since I took the Honda back in January, I've had to adjust the clutch lever twice, which I thought was odd. Perhaps the cable was fraying and it would have snapped anyway soon, and I just helped it along. No matter, I've replaced it and there is a spare under the side panel that I've already cut to measure so I won't have to waste too much time next time it happens.

There are actually two adjusters for the cable, the lower one (shown in the photo below) takes up most of the slack, while the one at the handlebar lever is just to finish it up. The important thing to look for is that both the handlebar lever and the clutch actuating lever reach the end of their travel at the same time: if the clutch actuator is fully engaged but the handlebar lever is only halfway in, you would end up pulling against the actuator, damaging it, and/or rip the cable end, a bracket or who knows what. Just because this is a virtually maintenance-free machine, doesn't mean it doesn't deserve the same care we bestow upon our classics.

Next, the carburetter (and a whole lot of other stuff) comes off, but not all the way because some screws are just stuck solid so I can't disconnect the throttle cable holder, and heating a carburetter full of petrol with a propane torch is not exactly the smartest idea in the world.

This is where you appreciate British classics, where almost everything is usually easily accessible...
Off comes the manifold, and I drill a 4.2mm hole, then tap it to 5M and install a brass spigot (just to be clear, I did this with the manifold on the bench and removed all the swarf before refitting it to the engine):

Why? to create a vacuum point for this nifty bit of kit:

It's called a Scottoiler, and on a chain-driven daily driver bike, it's more than just an accessory, in fact, I don't understand why motorcycles aren't fitted with a chain oiler as standard. After all, the Norton Commando had one, and it worked well if it was adjusted properly.
This particular type is a bit more sophisticated and makes use of the vacuum at the intake to open a metering valve in the reservoir when the engine is running, feeding oil to the rear sprocket; the flow can be adjusted.
The kit is comprehensive and well made, there are plenty of "bits" to take care of the vacuum end, as well as routing and fixing tubing. It takes a few "dry runs" to figure out where everything goes before you commit to actually installing it, but it's easy to do.
For the reservoir, as long as it's not horizontal, you can mount it pretty much anywhere, you just have to leave yourself enough room for filling and refilling as needed.

If you look closely at the next photo you can see the delivery tubing routed underneath the swingarm, and the nib that feeds the rear sprocket bolted to the hard plastic chain guard. If this actually works, it should pretty much be a "fit and forget" type of thing, and the chain should be clean and properly oiled all the time.

After that, I fitted the Dynojet kit, very exciting:

When you come right down to it, it's a bit underwhelming, after all what you get is a main jet, a titanium needle and a couple of washers, that's it. Installation is dead easy, but you have to be extremely careful, especially with the vacuum diaphragm: those suckers are expensive to replace. (Suckers, ha ha, get it?)
That said, if this thing works like it's supposed to, we should see smoother acceleration, taking care of a bit of a flat spot that's usually around the 2.800/3.000 rpm mark. It means that you either have to go really slow, or whack the throttle open to get past it and unleash all the torque and power of the big thumper. Guess which one you end up choosing every time. Go on, guess.
In addition to the main jet and needle, the kit specifies a setting for the air mixture screw (which actually meters fuel rather than air, which is what I'm used to on Amal carburetters). After I took care of that, I refitted everything, all the various rubber hoses (overflow, breathers, etc.) including the rubber manifold that connects the carburetter to the air box. It's actually a beautiful piece, shame it gets covered up by the side panel, but it takes quite a bit of effing and blinding to get it back in place.
With the carburetter sorted (of course I still have to test it properly, and it may need to come off again for further tuning), and the chain oiler filled and primed, I turned to the exhaust headers.
I've never really liked the stock ones, they're small and... droopy.
Amazingly, considering this really isn't a popular motorcycle, there are these really good looking and well made after-market headers, made in Germany to the exacting engineering standards you would expect from them, all stainless steel and larger diameter; 32mm compared to the 29mm of the stock parts. They look great.

Bigger diameter should mean better gasflow, slightly lower temperature for the cylinder head and better throttle response. The manufacturer claims they're worth an extra 3hp...
The Dynojet kit I fitted is a "stage 1" and good for a theoretical 5% increase in torque and horsepower (2hp). The main point of a stage 1, however, is to optimize what is already there, so you get an improvement in torque delivery and smoother action.
I honestly doubt that just a jet kit and exhaust pipes are worth an extra 5hp here, but even if I gained just a couple more - and most importantly more usable torque and smoother throttle response - I'll consider it a worthwhile investment.

And finally, the bike gets tagged before it is released back into the wild:


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