laird387 Posted March 26, 2016 Report Share Posted March 26, 2016 (edited) Hi garyhib, The Johnny Burns 350/360 Villiers conversion he himself used in his trials sidecar, not scrambles bikes. I bought a bike from him which was a Cotton trialler with the 350cc conversion, as my first venture into two-stroke trials after years on Ariels and Ajays. It went well enough but then i organised the first Pre-65 trials and reverted to my favourite fourstrokes. I think the rider you are thinking of is Maurice Brayford, who still rides, indeed was in the Yorks Classic Captains Trial earlier this month on a 'different' DOT. On my Cotton I used a standard Villiers carburettor and also the same silencer/exhaust that had been on the 197 version - it all performed perfectly adequately in trials but it had a much wider spread of power delivery than the current standard Villiers of the day, that meant you could pull a higher set of gears, in my case a 52 tooth rear sprocket in place of the previous 58 tooth, and that really helped to get better grip on slithery sections. Hope this helps, but in any case - enjoy. PS, In our digital magazine there are many photographs, including several of Motocross Motors bikes from the Mumps in Oldham But for now, here is a photo by Jack Knoops of Maurice in the Captains Trial. Edited March 26, 2016 by laird387 2 Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted March 26, 2016 Report Share Posted March 26, 2016 Hi guys,i've now looked into the trailer load of bits and pieces i bought and i've now found a 932 concentric and what i believe is an old 'Jonny burns' Motox develoments barrel and two heads (350/360 c.c.?).So it looks like i have a bunch of pre '70 scrambling gear. Excuse my ignorance,but did i see in the press a fella trialing a big bore villiers? (was his first name Maurice?) I think i might try and stick it on top of a 32a in an old '62 dot frame i've got, and see what happens.(Any ideas about carbs and jetting and exhaust bore for that. Life's fun.many thanks. A few guys locally have tried these but not one of them has been a sucess sadly and they have all reverted to 250 barrels. Those big bore conversions were a nightmare to set up and get running right. No real world benifit. Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 26, 2016 Report Share Posted March 26, 2016 Hi Garyhib, I had a DOT Demon MX or scrambles bike which had a John Burns/MotoX Motors 360cc conversion fitted. The stroke is 72mm so same as the std Villiers,the bore is increased to obtain the extra capacity. This requires the crankcase mouth to be enlarged so really for those cases it is a one way conversion, if you have cases that fit the cylinder then these will have been enlarged to suit. My bike went rather well with great pulling power, noticeably more than a 250 though not quite up to CZ or Husqvarna speed. Engine was Villiers gearbox, Alpha crankcases and crank with Stefa electrics. The downside of the conversion is weight, there is a lot of alloy in the barrel making it much heavier than say a Greeves square barrel, also because the design is Villiers based the transfer ports remain the same size so this possibly limits the engines potential. If you have the parts though why not build it and enjoy something a little different Maurice goes well enough on his bike which uses a James or FB type frame. Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 27, 2016 Report Share Posted March 27, 2016 I thought this might be of interest, http://www.examiner.co.uk/news/west-yorkshire-news/outlane-engineer-paul-jacksons-million-to-one-4988697 Quote Link to comment Share on other sites More sharing options...
spen Posted March 27, 2016 Report Share Posted March 27, 2016 The old NCB wellies/Dunlop trials boots. Quote Link to comment Share on other sites More sharing options...
laird387 Posted March 27, 2016 Report Share Posted March 27, 2016 (edited) Hi trialsrfun, Nice to see Paul Jackson is still with us - how will he manage his bike with only one boot.................must be the right boot he burnt, but I have no photographic evidence of that! His left boot is still OK as can be seen from this partial image taken from ORRe -issue 40............ Only joking, honest! Edited March 27, 2016 by laird387 2 Quote Link to comment Share on other sites More sharing options...
spen Posted March 27, 2016 Report Share Posted March 27, 2016 Hi trialsrfun, Nice to see Paul Jackson is still with us - how will he manage his bike with only one boot................. Probably better than me with two boots.... 1 Quote Link to comment Share on other sites More sharing options...
christian Posted March 28, 2016 Report Share Posted March 28, 2016 Hi Gary and all reading this. I would like to see a photo from your engine with the Marcelle barrel. I believe that I have one on my Greeves. (will post a photo later) Thanks. Christian. Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 28, 2016 Report Share Posted March 28, 2016 Hi Christian, The MotoX cylinder & head are rectangular when viewed from above, wider left/right thanfront/rear. The fins at the upper part of the cylinder are wider than the lower ones exactly as on the picture above of Maurice riding his bike. Quote Link to comment Share on other sites More sharing options...
christian Posted March 28, 2016 Report Share Posted March 28, 2016 Here are some photos of my greeves. Quote Link to comment Share on other sites More sharing options...
garyhib Posted March 28, 2016 Author Report Share Posted March 28, 2016 Hi all,Christian,the picture of Maurices barrel/head is the same as what i've picked up.The angles,spaceing, shape and height are spot on. Could yours be a 'Parkinson' or a DMW? I'm sure someone can tell you.All the best. Quote Link to comment Share on other sites More sharing options...
laird387 Posted March 28, 2016 Report Share Posted March 28, 2016 Hi All, To complete the story, Here is another image from ORRe showing Maurice Brayford riding in the Exmoor Three-day in 2000, when his machine was entered as a James 360cc. The history is usually in the archive if you have the time to hunt.......... Cheers Deryk Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 28, 2016 Report Share Posted March 28, 2016 Hi Christian, Your Greeves is very nice but I cannot identify the cylinder other than to say it is not a MotoX conversion, how does the engine performance compare to other Villiers bikes you may have ridden. Quote Link to comment Share on other sites More sharing options...
christian Posted March 28, 2016 Report Share Posted March 28, 2016 (edited) Hi Christian, Your Greeves is very nice but I cannot identify the cylinder other than to say it is not a MotoX conversion, how does the engine performance compare to other Villiers bikes you may have ridden. The Greeves is my spare bike when the Norton is out and it is a completely different riding( is it a surprise? ) Once I get used to brutalise the throttle when I need power, it works quite well, it is very soft at low rev's and almost unstopable, about power, it is not my Norton but I really love to ride the greeves (not as much as the Norton thou). Compared to other Greeves I could test, there is a small lack of response at low revs. There is something strange on this engine, the conrod is the short one , I believe from the 190cc Villiers. Was it a modification they used to do?? I own this Greeves from 2005, and never saw one with the same barrel. Hello Deryk, on the photo you posted the barrel seems wider and head fins arrangement is not the same. Thanks for your replies. Christian. Edited March 28, 2016 by christian Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 28, 2016 Report Share Posted March 28, 2016 (edited) Hi Christian the first type of engine similar to the one you have in the Greeves was 9E 197cc with a 5 1/4" conrod, when this engine was enlarged to 246cc the barrel base flange was increased in thickness by 1/4" to add strength because of the greater power output, this required the rod to be lengthened by 1/4" to 5 1/2" these were the A series engines 32a 34a 37a. My knowledge of the alloy barrels is mostly Greeves, DOT, Ajax for the 197 to 225 conversion and late DMW. Parkinson, Marcelle and others also made cylinders but these I am unfamiliar with, possibly someone with engineering connections could have produced one or more as well. The last type of DMW cylinder was designed for use with the shorter 5 1/4" conrod, all Greeves and DOT barrels that I have come across use the longer rod as does the MotoX conversion that Garyhib has. Irrespective of rod length the stroke remains the same at 72mm. The porting in your cylinder appears to be very similar to the other Villiers fit barrels but without accurate measurements from known cylinders it is not possible to say. Often the greatest visible difference is the size/shape of the inlet port but maybe the biggest perfomance vaiation would be due to the type of head and compression ratio used. Hope this helps. Edited March 28, 2016 by trialsrfun Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.