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Thread ID: 87621	2008-02-27 21:06:00	2 stroke motorcycles	Thomas01 (317)	PC World Chat

Post ID	Timestamp	Content	User
644508	2008-02-27 21:06:00	Years ago in desperation after a year or so trying to get my S8 Sunbeam to go at least a few days without breaking down I bought an Ambassador Popular. Made down to a price this featured solid back end - pressed steel girder forks - all black finish - direct lighting and the usual 200c Villiers. It turned out to be the best bike I ever owned and we kept it for years. Took us all over the UK and to Scotland hopelessly overloaded with the 2 of us and masses of luggage, tent etc. It easily out performed my friends scrambles OEC even though mine was fully equipped with legshields and windscreen etc. We reckon the cheap silencer had by sheer luck introduced the "feedback" the Japs were to work out and utilize many years in the future. It had one fault - the plug would oil up occasionally - always of course in the worst spot, time, weather etc. I never fixed this problem. But read the other day that having the head adapted to run 2 spark plugs can cure this fault. It would be rare for both plugs to oil up at the same time and the constant running should clear the bad plug quickly. Seems so simple. I never thought of that. Have any readers tried this - and did it work. Just curious - I doubt that I will ever ride again myself. Tom	Thomas01 (317)
644509	2008-02-28 02:33:00	Try this group: http://www.kiwibiker.co.nz/ ...you will surely get an answer... :D	Morpheus1 (186)
644510	2008-02-28 02:41:00	Hi Thomas. Had BSA Bantam in the early 50's which was similarly robust and went anywhere. From memory, the fins and webbing in the cast head would have made any adaptation for a second plug virtually impossible. I too always carried a second and somethimes a third plug and remember well the small sand-blasting machines that most garages had to allow the plug to be inserted and blasted clean - free, of course. Every handkerchief I owned for several years was heavily oil-stained until I moved up the bigger machines. Fond memories.	Scouse (83)
644511	2008-02-28 03:10:00	Years ago in desperation after a year or so trying to get my S8 Sunbeam to go at least a few days without breaking down I bought an Ambassador Popular. Made down to a price this featured solid back end - pressed steel girder forks - all black finish - direct lighting and the usual 200c Villiers. It turned out to be the best bike I ever owned and we kept it for years. Took us all over the UK and to Scotland hopelessly overloaded with the 2 of us and masses of luggage, tent etc. It easily out performed my friends scrambles OEC even though mine was fully equipped with legshields and windscreen etc. We reckon the cheap silencer had by sheer luck introduced the "feedback" the Japs were to work out and utilize many years in the future. It had one fault - the plug would oil up occasionally - always of course in the worst spot, time, weather etc. I never fixed this problem. But read the other day that having the head adapted to run 2 spark plugs can cure this fault. It would be rare for both plugs to oil up at the same time and the constant running should clear the bad plug quickly. Seems so simple. I never thought of that. Have any readers tried this - and did it work. Just curious - I doubt that I will ever ride again myself. Tom The British 2 strokes oiled up plugs for 2 reasons 1. They commonly used normal SAE 30 grade engine oil. 2. The ratio was sometines 20 to 1 Now days super two stroke (ashless) oil and up to 100 to 1 mix make plug fouling lesser a problem. But even now the life of a 2 stroke plug spark plug is not for long. Rotax on 582 say change them every 25 hours 2 plugs would help but needs a special double coil. Some CZ/Jawa and Puchs had 2 plugs but you knew when they were running on 1.	XRNZN (13406)
644512	2008-02-28 03:18:00	We reckon the cheap silencer had by sheer luck introduced the "feedback" the Japs were to work out and utilize many years in the future. " first discovered in the 1950s by Walter Kaaden, who was working at the East German company MZ" The Japanese did seem to work out how to make a decent spark plug.	PaulD (232)
644513	2008-02-28 04:11:00	" first discovered in the 1950s by Walter Kaaden, who was working at the East German company MZ " The Japanese did seem to work out how to make a decent spark plug. It was about 1954 I had the Ambassador. I didn't know about the two stroke feedback or whatever it was until very much later when I read about it on Japanese bikes. Discovering the tremendous power in my bike was quite amusing. My friend (a R.E. works assisted rider) wondered how much better his OEC scrambler was with its highly tuned engine against my standard motor. Working at BAC we borrowed the runway for a test. As I mentioned my bike had all the gear, electrics, windshield, legshields, etc. I knew I could raise the front wheel just by giving it lots of throttle, but it was a very short wheelbase. Even so we were both amazed when in several runs the CHEAP road bike kicked the pants off the racer finishing not just a little bit ahead but up to about 5 lengths over about 250 yards. We didn't understand why at the time. The OEC was his second " fun " bike but did have a large number of 1st places to its credit. And no we never did switch motors. I think as somebody has already mentioned that modifying the head to take two plugs then making sure sufficient electrical power was available would have been extremely difficult but not impossible. The bike was my only transport to get to work so I would never had considered taking it off the road. Gosh I wish I had it now! Tom	Thomas01 (317)
644514	2008-02-28 08:45:00	I used to use Gold Paladium plugs.	mikebartnz (21)
644515	2008-02-28 17:56:00	Sandblasting a plug to use on a 2-stroker was a no-no as the porcelain would then have a "tooth" or opened surface from the abrasive that would allow burned deposits to embed themselves into it and allow for much earlier flash-over of the spark . That made the plug useless as a spark traveling down the porcelain instead of across the electrodes was not conducive to ignition . And . . . yes . . . motor oil not actually designated for use in a 2-stroke engine is also counterproductive . It has not been designed to go through combustion and just leaves a nasty deposit on the plug . . . again with shortened life . Ask about the ports and the exhaust too . . . as a 4-cycle oil will build up some marvelous amounts of ceramic-like deposits all the way through them and they will put a crimp in performance too . Many 2-strokes however still run 32:1 with impunity . . . IF the oil and the compression and a slew of other designs and variables are observed . Back-pressure in the exhaust is one of the designed-in components of 2-cycle theory . Without it, the power band is too narrow and likely to cause lean-outs at certain on-the-pipe situations where extraction is more efficient because of Doppler and waveform/counterform values in the pipe . Positive/negative sonic and pressure waves in the pipe cause the performance to drop off excessively or to improve by what factor the engineers wanted . Modifying these shapes (bells, cones, recombinant platforms, "pea-shooters" and expansion zones) are all very counterproductive without some real seat of the pants or slide rule experimentation . . . not to mention time/money or personal frustration . A good streetable pipe has a rather broad range or "sweet-spot" power band and is not at all "pipe-y" for the driver . . . necessitating him to keep the RPM in a narrow range for max power and efficiency . Some very early designs . . when pipe tuning was not well understood . . . had some very complicated gearboxes with many ratios to keep the engine on the boil . . . for just that reason . The Yamaha YDT Series 1/250 Roadracer was one of these that had that famous "ripping canvas" sound that had the Isle of White roadracers all aghast . It was there in the very early 1960's with a little Japanese pilot on it who must've only weighed 65lbs/30kg and was all over the rider's seat to get it around the turns met the likes of some "serious" iron in the form of the AJS, Norton, BSA, Triumph pilots and crews who were laughing at the sound of the engine and the clouds or blue smoke until it ripped them a royal one in speed records and times . *I need a citation for this info . . I distinctly remember it well . . even the description of the engine sound in a magazine I was reading at the time . I have THIS LINK ( . yamaha-motor . co . jp/global/product-history/mc/1950/yds-1/index . html" target="_blank">www . yamaha-motor . co . jp), and THIS LINK ( . motorbike-search-engine . co . uk/classic_bikes/1963_yamaha_classic_racer . jpg" target="_blank">www . motorbike-search-engine . co . uk), but alas, it is not what I want to find . The Suzuki X6 Hustler ( . wikipedia . org/wiki/Suzuki_T20" target="_blank">en . wikipedia . org) was another one such bike that required (gasp!) a 6-speed transmission just to make it streetable and useful . It WAS very fast and powerful when it was boiling . The driver was constantly stirring the gears looking for the right combination of throttle and RPM though . Very busy! It had a new-unique "rotary shift" that allowed the driver to come to a stop in 6th gear and just pull up two times to hit first . The shift pattern was 1-2-3-4-5-6-N-1-2-3-4-5-6-N . . . and so one . Spark plug heat range, is of course, tantamount to performance, and the wrong heat range can hole a piston on the hot end of the scale or foul the plug(s) and engine on the other end . E85 fuel . . by the way . . is not to be run in a 2-cycle engine . Does anyone remember Castrol Caster "R" Racing oil? Or "Torco"? I ran them both in my Yamahas and early Kawasakis . Yummy smells and great performance . Torco smelled like hot peanuts . . . and Castor "R" was more like nitromethanol .	SurferJoe46 (51)
644516	2008-02-28 20:24:00	It had a new-unique "rotary shift" that allowed the driver to come to a stop in 6th gear and just pull up two times to hit first . The shift pattern was 1-2-3-4-5-6-N-1-2-3-4-5-6-N . . . and so one . That doesn't sound very usable, the last thing I'd want in 5th or 6th was a neutral anywhere close! Info I've found on the X6 describes a "positive stop neutral" that meant that the change up from 1-2 was as usual but changing down from 2 always went to N with neutral being between 1&2 as usual . Later models lost the positive stop but included an indicator light for neutral .	PaulD (232)
644517	2008-02-28 20:26:00	Sandblasting a plug to use on a 2-stroker was a no-no as the porcelain would then have a "tooth" or opened surface from the abrasive that would allow burned deposits to embed themselves into it and allow for much earlier flash-over of the spark . That made the plug useless as a spark traveling down the porcelain instead of across the electrodes was not conducive to ignition . Does anyone remember Castrol Caster "R" Racing oil? Or "Torco"? I ran them both in my Yamahas and early Kawasakis . Yummy smells and great performance . Torco smelled like hot peanuts . . . and Castor "R" was more like nitromethanol . A couple of points there . I am puzzled your comments on sand blasting of plugs . I follow the logic OK but do remember that it worked extremely well and no way caused problems . In those days plugs were too expensive to replace and sand blasting gave them a new life . I and my friends used the process regularly on both 4 and 2 strokes . Never remember being disappointed by the results . And Castrol R . Yes of course I remember . In fact it is impossible to forget . What a glorious PONG . The only industrial smell that was extremely pleasant . Do people still use it ? Tom	Thomas01 (317)
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