Lots of work faces now, but an interim look at the cylinder head reveals that the valves and guides are beyond use - there is a couple of millimetres of rock at the edge of the valve head, with the valve half out of the guide.  So, while I wait for a new set of guides, valves and springs let's start on the timing gear. Fitting the pinions is straightforward once I have deburred the Woodruff keys. The timing is set to the marks: I've cleaned the dynamo straps since you have to have the inner timing case off to fit them. I'll plate these at some stage if I'm not too busy riding the b ..read more

Over three years ago now I pulled this sludgy oil pump out of the timing case, planning to look at it and consider it for further use. It would barely turn. Since then, much has come and gone (some of it twice) but I have stripped the pump and freed the high spots in the drive that caused the seizure. With these Mazak/Zamak castings, impurities in the alloy corrode and cause the casting to swell and crack, in this case causing high spots in the drive gear bore and damage to the circlip recess - though fortunately nothing irreparable.  The body casting had a bit of carbon in the smal ..read more

Strangely enough I enjoy this job. It’s methodical, I have six mops with their associated compounds and if you have the time it’s quite fulfilling to see a mirror shine appearing before your eyes. These are the two halves of the timing cover, currently going through the process with 300 grit on a stitched mop ..read more

 A nice little jaunt this evening to see the grandchildren and to help son Thomas replace the chain and sprockets on his 2019 RE Interceptor, supplemented by spaghetti & meatballs to keep us going. The gearbox sprocket is easily accessible under an alloy cover retained by three screws and the gearchange lever: It's high time it was replaced. The tab washer and nut were removed with a socket and breaker bar before we removed the chain. We slackened off the rear sprocket bolts as well. The chain is endless, so we get the Dremel out to slice through a side plate and grind back a rivet ..read more

 If any of you recall this post from last year, you'll know that the Huntmaster kit arrived with an Amal 928 Concentric carburetter: Now that we are getting around to fitting the cylinder head, we'll need to sort out the jetting for this carburetter. A plea to the AOMCC forum revealed that revered Huntmaster rider Steve that his FH is fitted with a 626 Concentric with a 200 main jet and a 3 1/2 slide with the needle clip in the middle position. The difference between a 928 and a 626 is the body size - the 900 series is the larger. The 600 Series comes in 22mm, 24mm, 26mm and 27mm bore si ..read more

While waiting for bits for the QR50, I took the opportunity to refinish the horn for the Huntmaster. It tests OK in that it pulls a current and deflects the diaphragm, so some adjustment will have it working. Lucas catalogues are very useful. This is catalogue 716A, section F - six pages of horns and horn pushes. The application page tells you which part number you should have: In the case of my 1958 Huntmaster, it's a HF1441 model horn, part number 70048. The spares list tells us a bit about it: It's black, and looks like this: So, I had the correct horn (bought from eBay I think - it w ..read more

 With the little QR50 out of the way and the FH back on the bench, we can get on with the build. The barrel has been painted for a while, the bottom end is in the bike, there's no primary or timing side and no pistons. Off we go: First step is to fit a circlip to each piston; the gudgeon pins come out with some mild warming and are refitted just as easily. As you can see, I've put a large rag under the pistons as I don't want a circlip in the crankcase at this stage, and the pins go back in and the circlips go on without any drama. Next, we can refit the reground cam followers. I've gro ..read more

 After three years in the field, the little beast is back. The boys are complaining the bike has no power after ten minutes running and with busy lives, my son and daughter in law have no time to check it out - so it’s back to Grandad’s workshop. The Square Four is now off the bench to test the kickstart against the clutch, and then close up the clutch, refit the exhaust and test ride it. All went well with that, so the QR can go on the bench: The first thing to attend to, and rather alarming, is the fact that the fork top threaded inserts are both loose. Now, these had a ring machined ..read more

 After spending the winter rebuilding the gearbox and the clutch, I'm pleased to be finishing the job as the weather warms up. First job, before finally closing up the gearbox is to fit the kickstart stop rubber that has been waiting on the bench for literally years. I needed to remove the metal part of the stop and reduce the 1/2" OD to about 7/16" to get the rubber to go over it. I mangled one in the process of realising that, which delayed the job by a week: Next, when the kickstart is on and the gearchange mechanism is timed, I need to fill the gearbox. This is easier said than done ..read more

 While waiting for the kickstart rubber, I've degreased the FH barrel in the cleaning tank and given it  good scrub and scrape. Removing the rings from the new + 0.060" IMD pistons and testing them for fit reveals a nice 0.004" clearance in both barrels, per the IMD recommendation. Therefore, it's time for a coat of engine paint. This is the same stuff I used on the W/NG which seems to have survived OK ..read more