brian h Posted July 29, 2007 Report Share Posted July 29, 2007 Can anyone tell me if there is an alternative solid state ignition system on the market that wil fit straight into a 1973 Mk1 Ossa MAR to replace the troublesome Motoplat system ? I am aware I can get my Stator and HT Coil repaired in Spain, however, I am interested to know where I can obtain Mk1 Ossa MAR ignition parts ?? Thanks Brian H Quote Link to comment Share on other sites More sharing options...
swooshdave Posted July 29, 2007 Report Share Posted July 29, 2007 (edited) PVR? or is it PVL? Edited July 29, 2007 by swooshdave Quote Link to comment Share on other sites More sharing options...
dabdab Posted July 29, 2007 Report Share Posted July 29, 2007 I know nothing about MARs, but if the ignition mounts on the same side as a Bultaco ( rotation etc ) and the taper is the same as a Bultaco, then, failing other options, take a lok at fitting the Sherco (Ducati) ignition. I have fitted the Ducati ignition to a M199a Sherpa & a Frontera - fantastic Quote Link to comment Share on other sites More sharing options...
woody Posted July 29, 2007 Report Share Posted July 29, 2007 I know of someone who once fitted a 250 Sherpa ignition including the flywheel to an Ossa (they are on opposite sides but doesn't matter) I've no details on this but I'm assuming the Sherpa flywheel must have fitted the Ossa taper on the crank ok. If the Sherpa ignition does fit an Ossa ok - you'd need to establish this - then another possibility is the Sherpa electronic ignition that is now available, you'd need to get a Sherpa flywheel too - 325 is a heavier flywheel than the 250 but both probably lighter than the MAR flywheel so engine response whould be quicker because of that too. DabDab - did the Sherco iignition go straight on your Sherpa without the need for any mods. Does it fit in the Sherpa flywheel ok. Which model Sherco does it come off (I know nothing about Shercos) - basically what does fitting it to the Sherpa involve? Quote Link to comment Share on other sites More sharing options...
brian h Posted July 30, 2007 Author Report Share Posted July 30, 2007 Thanks for the inputs guys, The Sherco ignition system sounds worth looking into. I do not believe any PVL system is available for Ossa MARs unfortunately, all suggestions are welcome to enable me to get this bike going reliably once more. Athough I am not completely confident yet - I may have a serviceable stator, however, I believe the HT coil is defective and may be the reason for no sparks. Does anyone know if there is another HT coil with the similar connections on the market that will suit the Mk1 Ossa MAR ?? Thanks Brian H Quote Link to comment Share on other sites More sharing options...
woody Posted July 30, 2007 Report Share Posted July 30, 2007 Not sure about where you are but replacement motoplat coils for the Ossa electronic ignition are (or were) available from Bultaco UK. Quote Link to comment Share on other sites More sharing options...
scotty Posted July 30, 2007 Report Share Posted July 30, 2007 you must have had a bad ignition! ive had 4 ossas all weve motoplat ign, and all have been excellent!!! i'd go weve a good secondhand motoplat unit from Ebay etc! they do come up now and again! incidently my stepdads ossa had been outside everyday in all weathers for 10 years and that still starts and runs well! so that must be some test of a good ignition system in my book! Quote Link to comment Share on other sites More sharing options...
woody Posted July 30, 2007 Report Share Posted July 30, 2007 Ossa Motoplats weren't prone to regular failures, but they definitely weren't failure free. I've had a few go over the years. It wasn't unknown for them to fail when they were new although not to the extent that the Beta ignitions seem to do these days. Buying one off ebay is a real gamble as there is no way of knowing its condition - most are pushing 30+ years old now after all. Even if it came off a running bike it doesn't mean it is working 100% correctly. Two of mine gave a weak spark at low revs, typically after rolling down a descent with the throttle closed with the engine close to stall speed. Opening the the throttle at the bottom resulted in a flat spot or the engine dying completely, just like a weak mixture from the carb. It was also a sod to start sometimes. Swapping the stator for a good one cured the problem. Would it be right of me to sell that stator on ebay as working ok as it came off a running bike. A buyer would have spent ages trying to cure the hesitation in pick-up by messing with carburation, which obviously would never sort it. Personally I wouldn't buy a used one unless it came very cheap, as then it would still be cost effective to send it off to MotoplatUK (now in Spain as mentioned before) to have it repaired if it was faulty. I had a couple done a few years ago and they worked fine afterwards. Quote Link to comment Share on other sites More sharing options...
brian h Posted July 31, 2007 Author Report Share Posted July 31, 2007 Woody, I have to agree, anything second hand in the ignition line over 30 yrs old is a gamble indeed. It would seem that the Spanish repair of both the coil and stator may be the only solution, however, it is a costly exercise to ship parts to Spain from N.Z. for repair. I was hoping someone may have done a ignition upgrade on the 244 Ossa MAR utilising an ignition sysytem from the new breed of Trials bikes. Brian H Quote Link to comment Share on other sites More sharing options...
woody Posted July 31, 2007 Report Share Posted July 31, 2007 No, unfortunately there is nothhing at the moment to replace the Ossa ignition unless you can explore the Sherco or Sherpa options mentioned previously. However, there is someone here in the UK who makes ignitions for the TY250 (not the same one that has been available for a couple of years, this is a different system) and he is looking at making one for the Ossa as he has a couple himself (very rare TR303 Rojas no less.....) Nothing definite and no timescale but hopefully it will happen and it would suit all trials Ossas which have the electronic motoplat fitted. Not sure about the points models. Quote Link to comment Share on other sites More sharing options...
dabdab Posted July 31, 2007 Report Share Posted July 31, 2007 Woody, the crankshaft taper is the same-Sherpa to Sherco. Use the Bultaco woodruffe key. The Sherco is any model with the Ducati ignition ( up to 2003 when the Leonelli unit was introduced ). Ignition goes on as an assembly-flywheel, backing plate & coil unit ( under tank) According to my dodgy kitchen scales, Sherco flywheel is slightly heavier than genuine Femsa Bultaco Flywheel. Thats good, because most fittings involve skimming a half mm or so off outside diameter and machining a bevel off the inside rear edge to clear the inside case mouldings Worth the work, believe me. I have tried to put photos on this post, but I don`t think it worked. Send me your email address & I will provide photos Quote Link to comment Share on other sites More sharing options...
woody Posted August 1, 2007 Report Share Posted August 1, 2007 Thanks for that Dab Dab. It's ok about the photos as I doubt I'll ever do the conversion, was just wondering whether it was a straight fit on the taper or not Quote Link to comment Share on other sites More sharing options...
swooshdave Posted August 1, 2007 Report Share Posted August 1, 2007 Woody, the crankshaft taper is the same-Sherpa to Sherco. Use the Bultaco woodruffe key.The Sherco is any model with the Ducati ignition ( up to 2003 when the Leonelli unit was introduced ). Ignition goes on as an assembly-flywheel, backing plate & coil unit ( under tank) According to my dodgy kitchen scales, Sherco flywheel is slightly heavier than genuine Femsa Bultaco Flywheel. Thats good, because most fittings involve skimming a half mm or so off outside diameter and machining a bevel off the inside rear edge to clear the inside case mouldings Worth the work, believe me. I have tried to put photos on this post, but I don`t think it worked. Send me your email address & I will provide photos Send me the photos and I'll post them. I want to see this! Quote Link to comment Share on other sites More sharing options...
peterb Posted August 4, 2007 Report Share Posted August 4, 2007 Hi Brian, Give me a call at home, I have a brand new Motoplat electronic coil unit for a Bultaco Pursang, might be the same one as the Ossa unit. Also, Ray C and I have all but completed fitting a Kokusan digital system to my 325 Bult and may be able to perform a similar operation on your Ossa. (Ray made a new centre for the Kokusan flywheel with the Bult taper. I have a few bits left to make up another system. Ta ta, PeterB. Quote Link to comment Share on other sites More sharing options...
woody Posted November 6, 2007 Report Share Posted November 6, 2007 I've just been trying a new CDI unit and HT coil on my Ossa MAR which is a replacement for the original motoplat HT coil. The CDI unit is made here in the UK and is built to provide 26 degrees of advance in the higher rev range, say at two thirds throttle (I may be a degree or two out on the advance due to my next to useless memory but it is thereabouts) Give it full throttle up a climb or through mud and that is where I could tell a difference. When the revs get higher there is a reasonably strong surge as the ignition advances and the motor really revs out. I was a bit concerned that I wouldn't be able to notice any difference over the standard set up, partly because sometimes you believe what you want to believe and also because the Ossa can really rev its nuts off anyway, but after riding 2 trials on it and playing about on it afterwards up some big climbs I'm happy that the unit does what it is supposed to do. At low revs the ignition behaves exactly as standard and provides a soft delivery with no advance, so there should be no noticeable difference, but I couldn't help feeling that pick up was also a little stronger and cleaner, not massively but maybe just enough to notice, but this could simply be due to the new CDI and HT coil providing a better spark than a tired Motoplat unit. One climb after yesterday's trial was a pretty steep and uneven climb with roots running horizontally across it at various intervals. It was on the expert route of one of the sections. The lads on the modern bikes were mainly using 3rd to get up it. I looked at it and thought bugger it, the bike's due a rebuild so if I trash it, it won't hurt too much... I nailed the throttle to the stop on the Ossa and it went up in 1st. It was singing a bit but it went up. Whether it has extra revs with this unit I couldn't say but it certainly felt like I could hang onto a gear for a bit longer, effectively making the gear a bit longer. The bike is a standard '75 310 MAR with no mods to the engine, well used and in dire need of a rebuild and TLC, but does it rev. The CDI and coil will fit under the tank but require the mounting bracket on the frame to be lengthened as there are now two components instead of one and the original bracket isn't long enough. This is easy enough to do and only took me about 15 minutes to sort something out, just a strip of metal bolted to the original mount. There are 2 types of coil, one of which needs the metal strip bent into an L shape at the end as its mounting bolt needs to point lengthways as opposed to sideways. Doesn't matter which coil is used as the advance is built into the CDI, not the coil. This is designed to work with the Motoplat electronic stator, not the points ignition. At the moment there is not a replacement unit available for the stator itself but this is being developed so hopefully there may be one soon which will mean that there could be a complete replacement electronic ignition for the Ossa models fitted with electronic ignition. Not sure if anything is planned for the points engined bikes but if so I'll post it. I've no idea on price or how many of these are available. If anyone would like any further info they will be available through TY Offroad. All I can say is that it works and is a viable replacement for the motoplat HT coil, particularly if you have a duff one. No need to go looking for a used replacement or trying to find another new one, this will do the job. At worst it is equally as good but in my experience it provides a noticeable improvement with the advance curve at higher revs which is genuinely useful on longer climbs or burning through mud. Quote Link to comment Share on other sites More sharing options...
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