YZ Engine Rebuild in Progress

As anyone reading would note, YZ hasn’t been happy recently. Its been making noises I didn’t like the sound of so I decided to pull the barrel off and take a look, the first time I’ve done so. You can do this with the engine still in the bike. The first thing of note was the piston, the exhaust side was unremarkable but the inlet side had fairly deep scoring, above what I’d consider normal:

Its a widely accepted fact of life that two stroke engines do need maintenance from time to time and with two years of (ab)use, I can hardly complain and I’d expected it would need a piston. The barrel didn’t photograph well but I think its probably serviceable which is a relief as getting a new coating put in is a pain. I had removed the piston so I turned my attention to look at the bottom end of the engine and specifically the big end bearing:

The big end was fine however in checking it, I thought the little end felt like I’d filled it with sand. A closer look revealed:

Which is something I’d not expected, the little end is to put it technical engineering terms, knackered. I’ve damaged two stokes in a multitude of different ways but I’d never broken a little end bearing until now. First time for everything I guess. Sadly, with damage like that a new con-rod is needed and that means splitting the casings to get the crank out. That in turn means taking the whole engine out the bike. To do that there are a number of serious nuts that need undoing. It was one of these that I previously managed to snap ligaments in my hand whilst attempting to undo. This time around with having the barrel off, its possible to rather robustly brace things to stop them turning:

This may look abusive but the little end is already broken so it can’t really damage much else. The bike looks rather sorry for itself without the engine. You can see from the photo how spindly the frame is which makes more sense when you realise the engine is actually part of the frame (a stressed member):

So I’ve found it needs a new piston and a new con-rod but why was the bike rattling? My best theory so far is the power valves are also in need of attention. The push rod from the bottom to top end is loose and the free play in it could account for the rattle. The fact it doesn’t work directly as engine rpm changes also matches well with the symptoms. In looking at the valves themselves on the workbench, it was clear the left hand valve was not completely closing. Wear in the power valve cams and the cam following pins would appear to account for this. In an ideal world, I would just replace all these parts however to do so looks like adding hundreds of pounds to the repair bill. I think there is adjustment which would allow the free play in the cams to be taken up, the push rod may need to be replaced however.

A photo of the engine partially dismantled on the workbench. I can’t split the casings until I find a puller to take the ignition off. The cams are on the left and right of the square oily opening on the barrel. The followers are on the ends of the forks on the black thing on the workbench on the bottom left.

It could be a lot worse, something could have seized whilst it was running and caused considerably more damage. Finding reasonable priced spare parts seems to be a bit of a challenge and I haven’t figured out what to do with the power valves yet. The YZ has some life left in it yet and will live again!


My Centennial Rally Experience

A while ago I volunteered to help out with marshalling at the centennial rally which is up in and around the north this weekend. Saturday they were going into Kielder/Wark forest so this morning it was an early start. I met up with some fellow TRF members and together we made our way out to Gisland and up past Spadeadam. I volunteered to take the fuel for the group in the discovery into the forest. So far so good.

On the way in, I hit a deep pothole and stotted bike off the back window of the discovery. On the one hand it has marked the glass, on the other it didn’t smash it, how I don’t know. I made a mental note to take it easy even if at this point crazy forest worker come marhsals towing trailers with quads on appeared and were flying around and asking if I’d left the hand brake on.

So we found where we needed to be, I unloaded, kitted up and found the others. We were to be on course in the special test. Two roving posts at the start/end and a static in the middle. I took the first stint on the static and was there for a couple of hours, I had been promised some relief and it did come. I then roved around the end section a bit. There was a corner the bikes seemed to be having trouble with where many were going straight on into the grass and a nice deep ditch which I helped pull several out of.

The day had started off dry, turned into a drizzle and then by now was a near constant light rain. The rain eventually ran into the boots since I’d put the trousers into them, to try and avoid ripping them into any more shreds on the YZ kickstart. I gave up on the googles and just let my glasses get wet.

At one point I was offers a trip down a “hard” short cut, I suspect I made a bit of a fool of myself since I was going slowly, coming off and then was too worn out to continue. At this point someone else got the bike out of the rut I was stuck in, making it look easy. They did check it if was a 125 or a 250 to know how much throttle to give it 🙂 I’m sure I could have done that myself, had I been able to get enough oxygen into my blood stream to think clearly. Anyone who is honest about their first off road experiences on bikes will know the vicious circle of come off, tire getting things back on track, come off again because you’re tired and so on. Its been a while since I suffered quite like that. I couldn’t suppress a chuckle when the two I was following both came off themselves.

By this point, the YZ was making worrying engine noises, there is something wrong, the next suspect is the power value mechanism since it doesn’t seem to be coming into the raw power it should (not that is mattered on a day like this!). I also found I’d run out of back brake pads.

Being rather wet by this point, it was good when we figured out the course was closed and we helped demark it. It was then a case of loading the bike onto the discovery, finding some dry clothes and heading home. I went back out via Spadeadam so I could drop the fuel back to the others.

Driving on the forest fire roads on the way out, I wondered if something wasn’t quite right. I’ve had this feeling on previous occasions driving the discovery off road and this time told myself to ignore it, every little noise makes my jumpy. I could see the bike was fine in the mirrors and the car seemed level and all that. The stability control light did briefly light on one occasion accelerating which seemed odd.

As soon as I reached tarmac, I knew something was very wrong. Having stopped and walked around I noticed a not very happy looking tyre which was clearly written off. No problem, reverse into the layby to get off the road and I’ll have to change it for the spare.

Reversing into the layby totally destroyed anything that remained of the tyre. Ok, no use crying over spilt milk. I calmly flicked through the owners handbook to the section on changing a tyre. Firstly, I have to say that whoever wrote it should get a different job, preferably after being made to change a tyre in the pouring rain. Its full of things like explaining how to jack the car, then mentioning that before jacking you should loosen the wheel nuts. The main reason I was reading it was to figure out where the tools were, how to release the spare wheel and what to do with the self levelling air suspension.

Obviously the jack and tools were in a compartment in the rear of the car, with piles of wet bike gear filling the boot and the boot door inoperative due to the bike on the rack on the back. There was also 85L of petrol in the way amongst tools and all kinds of other junk. I also noted with dismay that to lower the spare wheel you need to access a winch under the rear two pop up seats, which have all this stuff on top of them. I would also note it is raining, it would be, right!

To cut a long story short, I did manage to move things around, I was able to jack the car up, put the spare on, stow the shredded wheel and continue home. The self leveling suspension did quite an amazing job of hiding the flat. I bought the discovery to use and have a bit of adventure with so I guess I’m getting that and these things happen. Nobody can accuse me of not using it as it was designed or call it a Chelsea Tractor! 🙂

I am now totally worn out, I think I’ll need to take it easy for a few weekends and I’ve some work in the garage to do now. I haven’t dared closely inspect the rim yet, if I’m lucky, it might be ok, we’ll see tomorrow. Marshalling tomorrow? I think not.


The 675 for a change

On Sunday with Cadwell coming up it made sense to check the 675 still works and scrub in its new tyres a little. Scotland seemed the logical direction choice. I’d started heading for Morpeth/Rothbury and then found myself in the middle of a cycle event which seemed to head to Bellingham. I’d not have liked to be cycling up some of those hills. The roads seemed otherwise quiet.

Going past Kielder, the fuel warning light came on, I’d evidently incorrectly ‘remembered’ filling the bike last time I used it :(. This is about the worst place to run out of fuel as there isn’t any for many miles, particularly on a Sunday. I was closer to Scotland at this point so continued to head for the border, it being touch and go whether I’d reach anywhere selling fuel. I remembered someone telling me the old garage at Kielder had reopened so there was a small chance that would be open and I’d be passing it anyway.

Going past the garage at Kielder the garage looked deserted and shut, the signs said open. The fuel pump looked odd. I’m pleased I stopped and checked as its now an automated self service one and I could get fuel there which solved my worries about running out.

It was then into Scotland and onto roads which were mostly single track with passing places ending up in Hawick which was the planed refuelling stop. Since I wasn’t in a hurry, I then looked around some roads over to Langholm and Newcastleton using some further minor single track roads going from the Scottish Borders into Dumfries and Galloway and back before heading back to Kielder in my native Northumberland and then home via Chollerford. The weather was mostly good with odd rain showers, the only one I really got wet in was near Langholm (hence the dark photo) other than that there were just wet roads as evidence of them.

It was nice to use the 675 again, I do love that bike although I’m not used to the riding position any more which was comparatively painful, particularly after the couple of hundred miles I covered on this trip. The 675 behaved well and the new tyres seem good although it has a few squeaks for example in the air intake mechanism and will benefit from a good service.



I’ve had some extended vacation time recently and shortly I’m probably going to get questions about how I enjoyed it. It would be tempting to nod and smile and quickly change the subject since the answer I’d truthfully give is hard to understand and not what people would want to hear or expect, I’ve actually found it rather like a form of torture.

Its an open secret that for whatever reason I seem to suffer from some kind of fatigue. There is no known medical explanation for it, the catch all “we don’t know” of chronic fatigue syndrome (CFS) being the “diagnosis” once you rule out everything else. So what does that mean in practise? Imagine having a finite store of energy which replenishes at a fixed rate. As long as I use it carefully at a rate approximating the replenishment rate I’m perfectly fine. If I do something strenuous, I need to go easier for a while to allow the store to replenish and for example with the motorcycle trail riding, there will be a mild price to pay (say approximating flu like symptoms the following day). The real problems start if you use up a large amount of the store, I’ve experimented to varying degrees and near involuntary collapse followed by a week of feeling like you were badly beaten in a boxing ring is a possible outcome. I’ve carefully improved my general health and fitness over the past few years in the hope it would help. Sadly the size of the store or rate of replenishment doesn’t seem to change, even if I’ve noticed significant other improvements in my general fitness.

A colleague recently posted about being unable to do nothing and I had to smile since I share this “problem”. Combine this with the fatigue and you can see where this is going. There are a ton of things I want to do yet I know that if I try and do them, there will be a price to pay. The availability of extra time puts temptation in place and to be honest, I’ve totally overdone the activities and physically feel like a wreak now, yet I haven’t used the time as fully as I’d have liked either.

So if you ask me if I enjoyed my vacation and I laugh you might better understand why. That isn’t to say I haven’t done some things I’ve wanted to do for a while or enjoyed. I also appreciate things could be much worse too!


Historic Karting at Rowrah

For five years my kart (CR250 powered) has been buried behind mountains of “stuff” at the back of two different garages quietly dreaming of once again driving on open tarmac. Partly this has been a time issue, partly its due to not being able to drive it on any of the local circuits after they deemed gearbox karts too dangerous on them.

The kart is “only” 19 years old and is water cooled so is frowned upon in historic kart circles however I was invited to attend their annual meeting over at Rowrah last weekend. The circuit is my favourite kart circuit since its somewhere unexpected (a national park) and is picturesque, nestled in the bottom of an old quarry. Since I was last there (must have been years) they have built a new clubhouse replacing the corrugated iron shack I remember of a canteen and generally improved facilities there.

Prior to the event I’d cleaned out the carb and fuel lines, found slick tyres for it, filled it with coolant and was pleased to find it started up on the rope without any real issue. My Dad was also there with two karts, one a Bellotti with a air cooled ‘red rocket’ CR250 on it, the predecessor to my kart’s engine and the other, the cougar, a kart from 1979 which has its main components manufactured then but was only recently brazed up on the jig which was dug out from under a compost heap. This was the Cougar’s first outing after several late nights last week finishing putting it together.

After arriving on the Friday night and meeting some people I’ve not seen since the School’s Karting Association (SKANE) days and a good night’s sleep on the top of a hillside, the Saturday had beautiful weather. The sessions were alternating between class ones and class fours, 20 minutes each. That is ancient terminology for 100cc direct drives (ick) and then anything with a gearbox (the proper karts).

Basically my kart performed wonderfully given its condition, the only issue was that it was geared for long circuit (26:30) and I was only using the first 2.5 gears. There were some modern 125cc karts there which were thrashing me on acceleration. Initially I decided to ignore this but I appear to have some kind of competitive spirit as I ended up taking the sprockets off and changing to 26:36 which was chosen from the available sprockets and chain availability. This gave me 4 gears and made a massive difference to keeping up with the modern 125s as I could now act as a road block and keep up with them. I’m not sure I could have overtaken one, would have needed better gearing again for that but I was happy enough.

I played in various sessions, torn between pushing the kart and not wanting to break it, particularly the engine. I soon realised that the back bumper had cracked around the radiator mounting on one side, an age old problem its suffered with since forever however I decided to ignore that. I was less able to ignore the squealing the kart was now making under braking. A quick check showed the rear pads were not looking healthy, it turned out one has partially disintegrated:

thankfully, I’d taken a set with me having realised the pads were low and even had the cordless drill to make the oval hole round on the new pads to fit.

I tried Dad’s red rocket and it was fun, the engine makes much more sense on that chassis that some of the others we’d had on it 10 years ago in the SKANE days (2.5 YZ125s reduced to shrapnel in the end). We then turned attention to the cougar, the engine fired up no problem although pushing it up the hill to start it was hard work as the brakes were new and binding a bit. Dad took it out onto the track and it threw the chain. Hmm. We replaced that and tried again. As I was push starting it, I had a hand on the engine and as it fired and set off, I noticed the engine move 4″ sideways. My brain registered that it shouldn’t do that, ever. I signalled for Dad to stop and we found the engine mounting posts had sheared from the chassis, the engine literally now able to fall off. Game over for the weekend but it can and will be fixed and the weekend was always meant as a shakedown for it.

The memories of how to drive a kart came back, I only spun once over the weekend and kept the engine running. When chasing 125s, I did run wide off the chicanes onto grass on a few occasions and despite effectively rallying the kart, kept it on full throttle and didn’t lose ground. I suspect I’m channelling some of its former rally driver owner there (who’s name is still on the front bubble).

At this point I was bruised and battered from bouncing around in the seat, a seat bolt finding a particular connection with my ribs which were now visibly bruised along with my left shoulder blade. I had quickly resorted to driving with a towel wrapped around my waist but even that didn’t stop things. Dad took plenty of photos and I also swapped roles and took from photos of him in kart for a change, venturing out onto the circuit in the high-vis with a camera much to the bemusement of people (its usually Dad doing this).

It rained heavily over night and part of the Sunday morning, I wasn’t optimistic the track would dry but it did. I hadn’t slept too well due to the bruised ribs and shoulder. I did get out a bit more on the track and was pleased with the kart holding its own apart from against a particularly quick twin 250. One of the things which I regret from the SKANE karting days is there weren’t many photos despite hundreds of hours in the various karts. I now at least have some photos of my in the 250 thanks to Dad, its only taken 20 years to get them!


More wheels than normal

I’ve been wanting to try this since I brought the Discovery. Last Friday on my way elsewhere with a full load of karting stuff in the back I took it over Long Cross since I was passing. This is a steep rocky climb with no tarmac surface, just rocks. I decided not to stop for photos on the steepest/most technical bits and the sun was in the wrong direction but you get the idea from these. I was impressed with the way it handled things as it never missing a beat. Stopping and starting again wasn’t a problem anywhere and it slowly but surely crawled its way up and over everything.

One thing which didn’t impress me is when I took it out of low range and the rock crawl mode at the top of the hill, it also decided to drop to normal suspension height itself without prompting. This lead to the vehicle grounding out which was annoying, the towbar/bike rack mount took the brunt of it.

I think the weirdest feeling of all was after this, feeling bumps and twists through the steering, driving back onto tarmac and resuming 60mph cruising of twisty roads up and over Hartside and into the lake district. It feels so at home on both.

The size does make things interesting on some of the narrow roads over in the lake district but it also has its moments where it shines. For the trip back there had been heavy rain which had washed large gravel onto the A686 but this wasn’t a problem. Hitting a few inches of water flowing over the road at speed was also interesting, its the first time I’ve felt it thinking about aquaplaning but the main issue being its tendency to seemingly remove all the water from the road and put it on the windscreen making seeing where you’re going trickier. All in all I’m quite enjoying it!