Sunday, 14 April 2019

JT Z3 chain review

Back in December 2017 I fitted a 520 Z3 "Black Steel" chain made by JT, a company who are well regarded for their sprockets but not their chains. The Z3 looks to be an attempt to change that with JT boasting X rings and an average tensile strength of 4240kgf (41.6kN) which is very high for a 520 chain. The "Black Steel" version is the standard plain steel, you can also get "All Silver" which is nickel plated to combat corrosion and now "Gold & Silver" which is nickel inner plates and gold coloured outer plates. So, when first fitted it looked like any other standard chain:
As it was fitted in December it wasn't on for long before the bike stopped moving due to work shutting down for 2 weeks for Christmas. When I came back to it the half underneath the swingarm had corroded quite badly, leaving half the chain tight and half loose! Not a great start.

I carried on regardless, with the chain always a little on the loose side to accommodate the tighter half and after around 2000 miles it seemed to stop stretching and settled down, just like most chains. I was quite pleased with this as I'd paid £45 for the privilege of being JT's tester which is not far off decent D.I.D money. The chain also felt the full force of some unusual weather we received here in the UK, the so called "Beast From The East" which bought freezing temperatures and therefore huge amounts of salt on the roads for around a month. This did the chain no good at all but I wouldn't expect it to be wrecked, especially since the bike was used every day. At around 8000 miles it started to stretch a little more, until by 9500 it was stretching an unbelievable amount. At 9700 miles I tightened it again, and at 10,000 (exactly!) it was again hanging off the sprockets:
It had stretched so much I was starting to run out of adjuster.

JT also boast about the width of the side plates, as you can see they really are quite thick:
I don't doubt the chains are indeed very strong, but that apparently doesn't guarantee them a long life.

Upon splitting the chain the cause of demise became clear, no grease:
Given the way the plates had corroded it's little wonder the seals no longer worked well enough to hold the grease in, probably only helping hold water in there instead. As always, bend the chain sideways for a visual display of wear:
Not quite the full 180 degrees but not far off! For a chain that has done 10K I find this quite pathetic but it may be that the Kawasaki Z250SL destroys chains so I can't quite call it just yet.

So, thoughts - probably a really good chain in the coated versions, not so good in the basic Black Steel version because the steel JT have used is far too prone to rust and ruins the seals. Problem is, at the time of writing the coated versions are priced well into X-ring D.I.D territory so why bother?

Saturday, 16 February 2019

Avon AV83 Streetrunner review

With the happy demise of the horrible Mitas MC25 I was in need of yet another 130/70-17 rear tyre. There's plenty of choice from the likes of Duro and Vee Rubber but I am put off from third/fourth tier manufacturers somewhat and decided to treat myself to a European tyre. In fact to heck with it, I work in British manufacturing and should support it! Also there are precisely no reviews for this tyre from Avon so that'll be interesting. £55 later I had one in my possession, ahh feel the quality of this fine thing. "Made in England" it will surely say..
Oh, okay then. The Mitas/Sava was also made in Slovenia so alarm bells were ringing loud and clear. The tyre is also really stiff, to handle it I would put it on par with the Metzeler Sportec Klassik - if this tyre is for 125s then why make it this stiff? Turns out it does indeed have all the plies:
At least it shouldn't struggle to keep the bike in line. More pictures for your delectation, this is a review after all..
After some faff the tyre was fitted to my Z250SL:
And it seems to have quite a lot of tread depth, which is marvellous:
So, what's it like? First impressions are that it is indeed really very stiff, I wouldn't mind putting one on the back of my K100 let alone a 125. Letting the pressure down to 15PSI still didn't have the tyre squishing at all when I bounced up and down on the seat, it's almost like a run-flat.

At an initial pressure of 32PSI (as per Kawasaki's recommendation for the original Dunlop TT900) I set about testing and found it to be a great improvement over the Mitas, wet roads are no longer a test of Speedway skills and dry grip is even more plentiful. It has behaved impeccably on the frosty roads that we lucky Brits get to use in Winter and wet weather grip is perfectly adequate if not astounding - if really "making progress" on slightly wet roads the tyre can slide a bit on corners (particularly if you hit a polished surface at the same time), but stick to normal speeds and it's absolutely fine. In the first 500 miles it also seems to have softened up a touch, it's not as chattery now but I would still say it's a very stiff tyre.

Wear updates will of course come in time, stay posted.


I ended up running this tyre at 28PSI, it's so stiff that it still doesn't wobble all over the place at this pressure but it at least isn't too hard and chattery. As far as wear rate goes, well, at 3110 miles I can only describe it as disappointing..
You can also see how it has squared off, it wasn't bad at all until the tyre saw some motorway miles and after a few trips up and down, well..
I'm also sad to say that after around 2000 miles the tyre became really quite slippery in the wet and I can spin the rear up in 4th gear, yes it's better than that awful Mitas MC25 but not by a lot. Given the not-too-cheap price of these I'm really struggling to find any reason to recommend them to anyone right now. Further updates to come..

Saturday, 3 November 2018

A tale of a puncture

You know how it goes, you get to work one day and find a great big screw in your rear tyre.
I fretted about it for a bit but it didn't seem to be leaking so I just rode home on it, no bother. "I know" I thought, "I'll fix it wi' me plug kit! Yeahhh". The tyre is that horrible Mitas and there's bugger ll tread left on it but I don't have a replacement and I need to get to work so..
And all is well again. Okay so the first mushroom fell back inside the tyre but I lopped the end off before I blew the tyre up, the second time I blew it up and then lopped the excess off and it seemed okay. Is that normal? I can't remember, maybe it is. Confident in the mush I leave the pump and kit at home and set off on the commute in the morning.. Ohh how short my memory is. This happened previously on the CB250. About a mile from work the plug falls inside the tyre and a very quick deflation event occurs. I stuff it in the entrance to a farmer's field and walk the rest of the way, rasser frasser nasser..
I decide the only sensible course of action is to borrow (ahem) a large screw from work, turn it into the hole and push the bike all the way to Morrisons where I can blow it up at their petrol station.It's only 0.9 miles away, how hard can it be?

While I'm sweating buckets pushing it to the supermarket (okay it's pushing itself on tickover in first but it's still hard!) a bloke zips past on his Triumph, turns around at the roundabout and comes back. He has the audacity to ask if everything is okay. I point at the rear tyre. He gets off his bike, delves into his fancy Kriega bag and chucks a string-type puncture repair kit at me with instructions to just drop it back at the gatehouse at Triumph which is where he works. He then has the audacity to mention he's never had to use it.. I was conflicted. Anyway! Rasp the hole, thread the sticky rubber string dog treat thing through the eye of the needle and shove it in the hole, then lop off the excess. The result:
Many thanks also to the other man who works for Triumph who stopped his run to help me with this, he held on the front brake while I shoved into the rear tyre - it takes a surprising amount of shove but if you're on your own you may get away with just sticking the bike in 1st gear.

More pushing, 0.9 miles is sooo farrr..
The plug worked a treat, it's still blown up just fine 1.5 weeks later. I think I am converted to string repairs now, I've had the mushroom kit fail twice with plugs falling back inside the tyre and you need a pair of pliers to pull on the stem of the mush which isn't included in the kit. With the string repair you have everything, and the rubber is so sticky it's not going to just fall inside. I always expected the rubber to be messy, but it wasn't at all - the hardest bit was threading it into the eye of the needle, and that wasn't too hard.

Thanks Triumph people, anyway. I set off straight to the gatehouse where I handed the kit in, such was my enthusiasm at the time.

Z250SL caliper clear out

Get a new bike, they said. You won't have to fix it all the time, they said. Liars! I knew the brakes were sticky after the long, looong winter of 2017/18 but we also then had the best, driest summer in 2018. Nevertheless, after coming back from the annual Germany trip on the TRX I found that the Kawasaki's brakes had taken much umbrage at sitting still for so long and the bike barely rolled. Oh joy, a mere 10K on the clock and another year before it needs an MOT and here we go already.. the front caliper can be my first victim..
It didn't look too bad in there considering how well the brake was sticking on, but clearly the dust seals are being pushed out of their grooves. Of course I find it so very fun that my ancient BMW K100 has dust seals that extend with the piston, covering it all just like a caliper from a car, while this here 2016 model is the same as all the normal crap. Pluck the seals out with dentistry tools..
Lovely stuff. Scrapey scrape, grease grease, pop seals back in (they're practically new!), pop the pistons in (eventually, I wouldn't mind a bit more chamfer if you're listening out there Kawasaki!)..
The pistons slide in and out easily, just as they should. You all know the game that follows this bit.
It took so long..
What does that hairy bloke from the 90s shout, DONE DONE ON TO THE NEXT ONE? Hello rear.
This was actually disgusting, quite a lot worse than the front. No wonder it was getting difficult to spin the rear wheel by hand! Of course if it had drum brakes that wouldn't happen, they could even by hydraulic like a car and use the cast wheel as a heatsink just like Bill Fowler was banging on about way back in the 80s but never mind, here we are in 2016 with nothing changed or improved. Yay.
Look at this.
That is a pin that the pads sit on, and rattle around on, and basically bite into. What a terrible design. Thankfully it can be replaced but all the other calipers I've seen don't have this "feature". Anyway, where are those dentistry tools I was just using..
Look at what I managed to scrape out, and this doesn't include what I freed from the body of the caliper - this is just the seal grooves!
Grease the seals, pop them in, lightly grease the pistons, pop them in, put it back on the bike, play the game.. You know how it goes. The result is a bike transformed, it rolls, stops better, goes better, handles better with freer moving suspension, more economical.. Seriously can we get those hydraulic drum brakes yet, they'd be like this almost all the time. And don't tell me it'd be heavier than a caliper and great big disc.

Satisfaction/transformation rating: Super.
Engineering rating: Pathetic.

See you again next year, seal grooves.


Fitting a Loobman to a Kawasaki 250SL

It's no secret that I like chain oilers, or that I'm too tight to spend out on a Scottoiler. I've had an old squeeze-and-go Loobman on my CBX250RS for many years, which impresses me with not only its simplicity but also its effective.. ness. The obvious answer was Loobman's new AB Dynamic, not as simple as the squeezy bottle but a similar price and supposedly it shouldn't cover the works car park in oil where I park up, which the squeezy one definitely does. On we go..
Time to unpack this neat little parcel!
The instructions are a bit too long and confusing, I think the squeezy version was slightly better in this regard but if you're of average intelligence like myself then you shouldn't go wrong too many times. First, thread a fat cable tie through the wirey snake thing like so:
Then inflict it upon the inside of your swingarm and secure in place, like so:
Simply snip the excess from the tie. Next bend the end of the wirey snake thing until it's kind of looking down at the sprocket, push the oil tube into the end of the delivery head and cable tie it all into place with a small cable tie.. Like so:
I chose to thread the tube underneath the cable tie that is holding the wire snake in place, if you've done it up too tight to squeeze the tube under then you'll have to think of another way! I also tied the reservoir to the pillion footpeg hanger, this gave me a nice short and vertical delivery which allows me to use gear oil (because it's thicker and doesn't fall down the tube so fast, y'see!).
The next step is to poke/burn a hole in the delivery tube - the length of tube after the hole will empty itself as you ride along, but the rest will stay in place due to the reservoir not letting any more flow out. This is what sets it apart from the squeezy bottle which was total loss once you'd sqozen the oil into the secondary reservoir. I gave up at this point and removed the chain guard, of course this being a modern bike that is manufactured in the cheapest way possible it's all one piece with the mudguard so off it all came..
With that out of the way it was easy. I used one of them oversized needle thingers, not sure what they're called. Some people use a soldering iron with a fine tip, whatever works for you.
With the tube successfully punctured just faff about a bit more putting all the muduard assembly back into place, fill it with oil and..
Success. After a few trips to work and back the chain looks lovely and oily:
Sure I have to remember to press the button on the reservoir before setting off but it's just part of the routine now. Hopefully this will cut down on all the rolling around on the floor, trying to tighten/oil my chain.

Oh by the way, Loobman themselves do state not to fill the reservoir to the top because oil will leak out the top - this is true! Not a terrible thing, but I'll just half fill it from now on..