Friday, March 15, 2013

Fat tire fun in the snow

I finally got a chance to trail ride on one of the new fat-tire trail bikes, thanks to my buddy Phil who bought one last fall (his is similar to the one in the pic). We took off onto our Almonte Riverside Trail this afternoon in the midst of snow squalls and biting wind, over a mostly packed snow surface hiding postholes and icy stretches. Phil gamely rode his 26" dually with studded tires while I practically cruised along on 5 psi balloons.

If you haven't tried one of these bikes, I highly recommend it. The contact patch has to be around 48 sq in, which means you can float over almost anything like you're on suspension and find traction in the most ridiculous circumstances. For instance, this was the first time I'd ever managed to pull a burnout on a bike. I just pedaled like mad in circle on undisturbed snow, and carved an awesome lazy donut--complete with roost. Serious giggle factor. No motor needed for this kind of hooliganism.

The trail has some steep twisty sections that were completely eaten up by this thing. Cornering was a little weird at first, but once you get used to the side-slip you look for little berms to bounce off of and trust that the massive contact patch with its little knobs will snuffle out and engulf any tiny features offering traction under the snow. It was almost as easy as riding in the summer.

A bike like this opens up a whole new season for knobby fun when skiing conditions suck, there's not enough snow for snowshoeing and too much for trail running, and you don't want to take a bike on the roads because of the salt. Definitely on my list for next bike to buy.

Update: Rode the same sections on 26" duallie today with tires at 25 psi. Snow was hard frozen so it was surprisingly good to ride. Managed to do almost everything without dabbing, but icy sections were sudden death because I didn't have studs.

Edit: Contact patch size.

Wednesday, March 13, 2013

Jet engine project - Part 3

After spending several nights experimenting with some ghetto homemade tooling to bore out my replacement main journal bearing, I couldn't rig something that gave a smooth enough surface over the length of the bore. So reluctantly, I took it to a reputable machine shop to see if they could complete this step for me. Surprisingly, they fared no better despite three hours of trying. Worse, now the bore hole is about 0.001" larger than I'd like and a bit rough. Can't fix that! What a bummer, because I'd managed to machine the outside to within 0.0002" of the original part.

So much for "saving money"... now I'll just buy the tooling myself and have another go. That means making a new bearing from scratch. However, this time I'll start with the borehole and work to the outside. There's still the question of how to accurately mill the end cutout without a milling machine. I may be able to do that on my drill press--slowly. It's only brass, after all. None of this stuff would be a challenge on a CNC lathe but it's surprisingly tricky to do on a manual lathe. I've even tried maple jigs for offset turning the end mill. I could machine the maple to within a few ten thou of runout, but just could not get a decent interrupted cut in the brass with my makeshift tooling.

Thursday, March 7, 2013

KLR 650 for sale

Yep, I've finally decided that this most excellent steed needs a new home. Bombproof reliability and rugged good looks aside, something smaller is probably better suited to the type of riding I would like to do now.

2000 KLR650
40,780 kms
$2500 safetied

- Doohickey replaced with Eagle Mike (don't believe the BS: my original chain tensioner was broken, as were those in two other KLRs I've inspected and fixed.)
- Progressive fork springs
- Braided stainless front brake line
- Upgraded subframe bolts
- New maintenance-free battery
- IMS foot pegs
- Moose aluminum skidplate
- Water pump seals replaced
- Maier handguards

When I first bought the bike at around 25,000km, I replaced all the wheel and suspension bearings with better parts, replaced the chain and sprockets, and generally tuned it up. I also inspected the clutch and valve shims not long ago, and both were in spec. Bike runs like a champ and pulls strong. I'll include the original fork springs, skid plate, and a smaller sprocket. Maybe some other odds and ends as well. If you've ready my blog you know what this bike looks like and can do, and it's never let me down.

Edit: Just to sweeten the deal, I have now installed a new Moose front rotor and new Galfer brake pads (green on front, black on rear). I've also disassembled and cleaned the calipers, changed the brake fluid, changed fork oil, changed engine oil, and cleaned and oiled the air filter. Bike is in heated storage and ready to ride.