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My my, that is a real interesting + goodlooking Gold Star; the fuel tank is a beauty, subframe too.

The big retail website where everything comes from that doesn't come from the big auction website sells a small little universal-fit multifunction instrument for bicycles. One of its functions is, uh, odometry. Down at the wheel, looks like the moving part (a magnet) simply crimps onto a spoke and the corresponding sensor is mounted to a fork leg with a couple of cable ties. The display at the 'bars is 52mm dia. Price is $18.
 

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Discussion Starter · #142 ·
Small update, with the recent heat wave (hit 120º+ a few times) there hasn't been much riding, so far about 60 miles on the bike.

Tachometer works now, picked up a signal adapter per recommendation by a Smiths rep.
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Used a gearing calculator to figure out speed based on rpm, white lines are 50 and 70mph in 4th gear.

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Early morning car show last month.

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Took a cruise yesterday evening, ran well though under-powered....and heard a noise.
Got it home to find oil all over the place that appeared to originate from the cylinders, and the nuts loose. Pulled the heads and found a shiny ring around the pistons and head surface.

Question is should I get thicker headgaskets, or take a rotary tool and shave the areas on the head where the piston meets? About 1/16" overlap where the bore is larger than the combustion chamber diameter. Would rather grind the areas instead of dropping compression with a headgasket.
 
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Discussion Starter · #143 ·
Fixed the piston - head clearance issue, instead of a thicker head gaskets the combustion chamber was matched to the cylinder bore, I used the gaskets as they fit very closely. After scribing a new pattern it was evident the bore vs cc wasn't concentric, one side offset about 1/16".

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Got the bike buttoned up in time for the early Saturday cars & coffee meet.
Halfway home from the throttle cable decided to break, luckily at the ferrule twist grip side giving me enough to yank on and get it home.

Spent a few hours trying to fix it but couldn't get the solder to stick, apparently nobody in the US sells replacements that's compatible with an Amal 364 throttle and twin Mikunis....so I had to order one from Mikunioz in Australia.

Having some time to kill till it arrives decided to start pulling apart the ign/alt bracket to fix a small oil leak, pretty sure it's the threaded hole used for the primary chain tensioner, I forgot to re-tap and put a helicoil in before assembling the engine. Also need to fix a transmission leak, pukes out the kickstart shaft all over the frame and exhaust which I'm sure is just a worn kickstart o-ring; damn headache for a 75¢ part from Hitchcocks in England that I can't find a suitable replacement from McMaster (1" ID x .07" thick). Situations like this makes me regret not buying a Triumph...something that's easy to source parts for.

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Any tips for fixing the chain tensioner case threading? The hole goes through into the crank case and want to keep any shavings out.
 

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Any tips for fixing the chain tensioner case threading? The hole goes through into the crank case and want to keep any shavings out.
Is there an adjustable hand reamer that would go big enough for the helicoil tap, plus suitable access for the handle? Pack it and the tap with grease and clean and repack often.
 

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Discussion Starter · #145 ·
Thanks for the tip, fortunately the threading was buggered enough not to need reaming before tapping. The bolt had finally stripped any remaining holding it torqued down causing some of the oil leak, behind the bolt was a small reservoir flushing any remaining shavings after tapping. Helicoil is in but now need to find a 5/16 bsf countersunk screw, bolt stuck out too far barely contacting the belt.

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Noticed a loose crank nut, factory manual listed no torque specs, Hitchcocks recommended "tight is good enough" as they "rarely come undone" which it still did after I gave it a couple taps with the rattle gun; tearing the drive side down in retrospect was a good idea.


Since it's apart might as well breakdown mounting the Electrex World alt/ign and sealing up the crankshaft in an open primary system, the former had not been engineered for belt drive compatibility.....this was a real head-scratcher.


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Base started from 6"x 5" 3/8" 6061 plate. Locating center hole, 3 mounting holes, spacer holes, and the corner took some time measuring out using a set of calipers, some maths.

Crank seal is a factory Enfield part meant for an Interceptor. Spacers are 2" threaded standoffs from McMaster, one side is 1/4-20, the other I retapped to fit 5/16 BSF studs. Rotating the spacers around or changing mounting holes allowed fine tuning the rotor to coil clearance. Assembled the coil base is about 1/16" from the front pulley.

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Pulley to spacer clearance is pretty tight too.

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Next challenge was the original rotor to crank adapter.

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Electrex World designed this unit to fit standard chain drives and still fit under the primary housing, since the belt pulley is significantly wider the rotor adapter needed extending. The rotor gets pressed onto the adapter shaft using a tapered split sleeve, held in place by friction and doesn't require a key.

The local hardware store carries a selection of chromed spacers, the 3/8"ID x 3/4"OD x 1/2"L was the perfect fit. I used the tapered sleeve for alignment and vise to hold in place, tig welded them together, then ground the weld flat. Spacing the rotor from coil base was done by a 7/16" long bronze bearing from McMaster.

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It works so that's cool. Might be helpful for anyone else wanting to run the same set up.
 
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