A crank case for Sherlock

After getting the engine out of the frame, decided to swap in the new engine, after re-rigging a new stator and rotor and matching up the connections to the ignition coil.

Two engines

Engine in and also went back to one of the original exhausts, as the mounts had broken on the Circle F I had. Made up a new bracket for the rear using great meccano strip metal which I’d found near Abergavenny station (not off the track) whilst trying to fix the Polo exhaust.

After that, decided to strip the original engine and see why the selector was stuck. Removing the clutch side and selector mechanism, demonstrated that the drum was indeed still stuck. Oh well, time to split the cases.

Doesn’t take long to split the cases, (with the soundtrack was Saint Etienne and The Seahorses) and the problem was revealed, with some pieces of metal lying underneath the selector drum.

Something inside the engine

Removing the metal, it look like the inner race of bearing, but a check of the the cases and all the bearings were intact. Strange. Time to call Mr Holmes. Cleaned out the cases and continued to search.. Hmm, no problems.

Mystery solved

Going to the Parts book and searching through the Transmission diagram didn’t turn up anything and check, all the bits that were meant to there, were there. But checking the balancer shaft diagram, which had been removed from the engine, showed a bearing with a detached inner face. Probably root cause, which hadn’t damaged the gears, but broken up and ended up in the bottom of the case.

Further work to be done, but the cases are back together, with clutch side and top end to be rebuilt.

Yamaha MX250 Engine Rebuild

Ready to start work
Radio On
In the frame
Head and barrel removed
Ignition
Engine of the bench

Clutch cover removed
Clutch centre
Removing crankcase bolts
Case splitting
Splitting the cases
Damaged gear selector
Removing the crankshaft
Inspection of the residue
Piston ring
Gear selector

Crankcase reassembly
Cases back together
Gear selection mechanism
Clutch baskets
Clutch side reassembly
Clutch side back together

Timing
Head and barrel back together
Engine back in
A running bike.

The bike started up third kick and ran, with a top-end rattle. However, nothing much under load, so something not right still, but it’s fuel or ignition rather than the engine.

Border Classic, Cilfronydd 5th May 2014

Picked up Paul Prosser and his Gori around 6.30 and then met with the Tredegar contingent back up in Bwlch, before heading north towards Welshpool. Though it’s a lot closer than the previous days trip to Dartmouth , the journey was going to take about the same amount of time.

Mass tea production

The track near Cilfroyndd is run by the farmer as a practice track and is in an excellent location in the rolling hills of the borders. The Border Club had done a lot of work to grade it the day before, so many of the ruts and compressions had been taken out. Looked good, even though there were some big stones in places. Time for a brew and I’d located a roofers burner in the garage attic which speeded up the boiling process for tea, especially for the larger contingent.

Cifronydd track near Welshpool; a lovely spot

Practice was, er…dusty, with about 50 riders on the track, but it rode well and those jumps that were there were uphill and nothing stupid. Perfect. The Husky was going well and I managed to perfect the knack of starting it, so it was going 2nd or 3rd kick. The SC500 less so and although I’d managed to fix the decompressor, but putting a blanked off one in place, it was running a little rough.

Ready for action

The race order had the pre75 races back to back, but that was switched around whilst they watered the track, which provided some time to fettle bikes and have another cup of tea. Graham came up from Cardiff on the KTM and arrived at the right time before the first race. Both the Husky and the Yam went okay during the first block of races, alas Paul’s Gori didn’t and destroyed the piston and ring. Not so good. Kevin was flying with his Husky in the twinshock race and after Mark had run over someone on a KDX, he also was getting into the swing of things.

Mark bottoming out the Cappra

Steve was out of his Metisse also and was also going well, though problems with a slipping clutch meant he was a bit further down the field than normal. Straight into the second and third blocks of racing and the Border Club were doing a great job in getting things moving after a late start, and the track watering had done the job and it was now perfect.

A rare picture of me

Kevin took my Husky about for the pre74 250cc race and after his usual poor start, was swiftly up to 3rd, getting past Trevor Hammond and Sam Gittoes. Time for him to show me how to ride the bike, but he stalled it coming into one of the downhill corners, so lost a few places after dismounting to restart.

A good day and some good racing. All finished by 15.30 and away at 16.00, after picking up the results and signing the marshalls sheet.

Dartmouth Classic, Harberton 4th May 2014

Managed to shake Saffron out of bed and we were on the road at 06.30, which turned out to be plenty of time. Though Harberton is near Totnes, the M5 and A38 made it a relatively quick journey and going on a Sunday on a Bank Holiday weekend meant there was no traffic of note.

It's a long way down the M5

Actually got to the track just after 08h30 and the fresh morning and long wet grass made it all a bit spring-like. Did the deal with the Husqvarna and then had a quick look at the track. Very much a traditional scrambles track round fields and through gaps in the hedges. To get the start in, they’d set in the middle of the big field at the top of the track, a really good innovation I like and one that gives you a bit of flexibility with track layout.

Alan Barnett's Cappra

Not a good start, when the Yamaha SC500 spat out the decompressor mechanism during practice. This an automatic decompressor connected to the kickstart shaft, and is located in the front of the cylinder above the exhaust. Bike seemed to run well, but was a tad loud. Managed to get it back to the van, but the internal plunger was missing, so even if I’d had screwed the unit back in, it wouldn’t have been usuable.

Doug's TM400

So the newly purchased Husqvarna was the weapon of the day. With only 4 races per block there was no rush to start, so I managed to work out how to kick start the thing and develop my technique. First time riding the bike, was in Race 3, the first pre74 and Circa75 race. Off we go.

Great stuff and though I wasn’t blisteringly quick, I put this down to the fact that I had brakes (front and rear), as well as an uncanny ability to find all the gears.

Harberton : a classic scrambles track

Some good racing in all 3 races, though I managed to drop it into a corner of the second race. The Marshall commented that there was a bike like mine on ebay in Cornwall; not any more there wasn’t. All in all a good event, and even if entries were not strong (I was the only person not from the South West racing), only running 4 blocks made the racing good. Nice meeting at an interesting track and it’s always good to race at different venues.

All racing done by 4pm, so back in Bwlch before 7pm and then spent an hour in the garage fixing the SC500 prior to the following days racing at Cilfronydd and the Welsh Championship round.

A long time coming….

A bit of an impulse buy off eBay (aren’t they all) and with the location being Cornwall, probably put a lot of people off. However it had the bonus of arranging an additional days racing at Harberton with the Dartmouth Club, as the seller was also racing.

Rising above the long grass of Harberton

The bike is a 250cc CR (Close Ratio) from 1975 and it sits in that funny ‘circa’ period where bike evolution was rapid. 1974 still has bikes with up right rear shocks, low seat height and (mainly) piston ported. By 1977, bikes were a good bit taller, laid down shocks (and in the case of Yamaha, monoshock) and reed valves as standard.

img_0004-2.jpg

You immediately notice that unlike a Yamaha, a Husqvarna is relatively hard to kick start. It’s on the wrong side to start with, so getting off the bike helps. Also, the direction of travel for the kickstart means the footrest is very much in the way. After working out a plan at Harberton during the afternoon, best approach is off the bike and standing well behind the footrest and kick forward. Tickle the Bing carb and hold open the throttle (again very different from the two stroke Yamaha’s) and go for it. Seems to work.

Compared with the Yamaha, you can tell that the Husky is a proper race bike; no frills and no concessions for trail or desert riding. Gears are all there (and I think there are 6 but haven’t counted them yet) with positive feedback for your foot. Handling is great and though the forks were dropped in the yoke, moving them up didn’t seem to affect handling too much. Indeed a pleasure to ride.