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Messages - john.k

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1
British Bikes / Re: BSA Gold Star misfiring
« on: May 18, 2019, 06:52:18 PM »
Assume you have checked that you have no supressed/high impedance ignition components?......also will assume you are aware they double magneto voltage and cause failure even in rebuilt mags?......but symptoms sound a bit like a faulty spark plug.

2
British Bikes / Re: Spronging forks question
« on: May 13, 2019, 09:57:00 AM »
Join the Owners Club.......very likely they are remanufacturing hard to find items,and certainly will know where to find stuff.Im pretty sure they have a forum,where you could ask ,even if not a member of the club........which you should be.

3
British Bikes / Re: JAP 750 v twin ,type MTS
« on: May 12, 2019, 12:35:22 PM »
The owner is a millenial.......and if he says "cool" one more time ,he will be walking funny,with Jap parts inserted.

4
British Bikes / Re: Spronging forks question
« on: May 12, 2019, 12:32:15 PM »
I would think that by 55,there should be the girling units ,but with the alloy forked cast lower end.........I assume the ally emds are threaded onto the girling  shocks..............You cant fit standard girlings ,as the mounts are different........The red oil will be Dexron autrans fluid........which is what I use........I find that Matchless forks have stanchions of vry soft steel,and easily bendable.................with the advantage ,easily straightenable,without worry about cracking heat treated  high carbon steel,like BSA s......seals are no problem......but wear in the alloy sliders is.......if worn excessively,they will need to be replaced........seen prices for new of around 200 quid each......kinds steep.

5
British Bikes / Re: JAP 750 v twin ,type MTS
« on: May 11, 2019, 02:38:37 AM »
Ive looked at all the options ,main problem is the case is  not very strong..........same as the rest of it.......Anyhoo,Im thinking the cheapest option is to make a new outer race,and skim the case bore just enough to round it up........fortunately the 22mm mainshaft is good......looks like it was replaced....................the rebuild with INA bearings is probably the best,but  too costly........The main bearing is somewhat similar to a WLA part,similar dimensions ,and I could use WLA cages ,but the JAP alloy cage is still good........................I suggested to the owner to rebuild the whole motor with new WLA parts,including flywheels,rods, shafts ,bearings..........but cost is an issue ..... and its only a sidevalve................the conrods are also problematic,but the owner wants the JAP system retained..........in fact the outer forked rod is completely wrong since day one,and machining out the centre rod space has made part of it paper thin ,and its cracked.......every non racing JAP ive ever worked on had serious issues with poor quality and bad design.

6
British Bikes / Re: Coventry Eagle
« on: May 10, 2019, 04:34:06 AM »
Its a pretty little bike,which is not often said about CE s.............the racing primary means you will never need to trim your toenails.

7
British Bikes / JAP 750 v twin ,type MTS
« on: May 10, 2019, 04:30:54 AM »
I have a JAP 750 to rebuild,and I m wondering about the drive side  mainbearing........the shaft is OK,but the outer race is chewed,and been turning in the case..............My old fallback of using INA races and rollers has hit a snag....SKF.......seems Skf have taken over INA,and prices are now astronomical,as in 2.FN.DR!...........inner race +caged roller +outer race..(need to be trimmed) is over $200.............but big advantage is it all fits in the case.......which case IMHO is a bit weak to be enlarging bearing bores.........However ,a 62/22 ball is 50mm od,needs about 4 mm enlargement,say 2mm  cut from the housing.(original bore is oval ,and needs skimming anyway,at 46-47mm........but a 62/22 is 22mmID,fits the shaft ,and costs around $20 depending on brand............one other option considered is tapered rollers with 22mm bore /44 mm OD,but obviously needs two opposed bearings ......not impossible,.....but.

8
British Bikes / Re: Excelsior Universal 125cc - Rear Plunger
« on: May 07, 2019, 08:16:42 AM »
OK,so what does the inside surface of the tube look like..............it should be a plain cylinder ,probably with the natural finish of a solid drawn tube ..............the rods should have a thread or a boss in approx the centre ,for a spring seat to go on ........from here it looks like the rods are replaced with plain ,and springs outside...........I must say its a strange bodge,but british bikes are the natural habitat of the strange bodger,and sadly,the true bodger is becoming extinct due very high prices for new material to bodge.

9
Identify these bikes! / Re: Barr and Stroud mystery bike
« on: May 07, 2019, 02:24:36 AM »
About the same time as the Arblaster patent ,Ricardo &Co patented and licensed a simplification of the Barr and Stroud system ,do ing away with skew gears altogether and using a link driven by a single eccentric and lever,achieved the same rotary motion of the sleeve and applicable to inline multicylinder engines ........engines were built by Peter Brotherhood &Co ,and by Mirrlees ,Bickerton  and Day..............The Mirrlees engines were quite common once .as they were a WD contract item genset .....and built in hundreds.................incidentally ,the Day mentioned was Charles Day,who invented the crankcase compression two stroke .

10
Identify these bikes! / Re: Barr and Stroud mystery bike
« on: May 07, 2019, 02:13:30 AM »
Any US patent is searchable by the inventors name .......you usually need a full name ,but something uncommon shouldnt be hard to find.......if indeed it was actually  patented,and not applied for and rejected. .................you will notice G.Brough stooped to the device of applying for patents that he had no hope of getting issued,and then advertized "Patent pending",or "Patent applied for" .

11
British Bikes / Re: Excelsior Universal 125cc - Rear Plunger
« on: May 06, 2019, 12:07:59 PM »
Is the springbox saveable?...What about the endcaps?...........the rod is easily replaced ,remaking the plunger unit ,a fair job of fabrication and machining.

12
Identify these bikes! / Re: Barr and Stroud mystery bike
« on: May 06, 2019, 07:06:46 AM »
There is a more interesting sleeve valve called the "Fischer ...Magic -crescent valve".........manufactured in Zurich from 1908 to 1914.......invented by watchmaker  Martin Fischer............produced .apparently by a "Turicum Co"............there is one example in the Zurich transport museum,and also a cutaway salesmans sample.......The valve was in two halves (of a liner),each reciprocating independently.............200-400 cars made ,before war work became much more profitable.

13
Identify these bikes! / Re: Barr and Stroud mystery bike
« on: May 03, 2019, 09:02:59 AM »
There was a B&S powered bike for sale about 10 years ago,IIRC,it was locally made ,and for sale on either ebay or just bikes.I think it was a 350,and the price was very high for what it was.

14
British Bikes / Re: Correct Ignition Position
« on: April 26, 2019, 01:44:41 AM »
Its usually pretty easy to tell where a low powered motor pulls best,and run with that advance.........I suspect you have probably set the timing well before TDC,and are getting plenty of advance..............a motor on full retard generally has no power ,and wont rev if you snap open the throttle................the biggest risk is excessive advance with high octane fuel.....no knocking,but enough extra load on the engine to break something.

15
British Bikes / Re: Stops When Hot
« on: April 26, 2019, 01:37:29 AM »
Heat does sound right....on  along downhill with throttle closed,no air or fuel to cool carb..................a lot of early SV s had the carby on a long intake pipe......maybe a good reason why,although it seems the pipe is needed to clear a magdyno.

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