brt650 Posted September 10, 2009 Report Share Posted September 10, 2009 Hello again, The only crankshaft I can find so far is out of a mark 9 250 pursang.It is the same. I say that with tongue in cheek. The balancing will not be correct for sure. I have been reading some articles on balancing the crank. But has anyone actually done this sucessfully? If so would you care to let me in on any secrets that might make this task easier. I'll keep reading my articles untill I'm confident to start drilling. Thanks Again Quote Link to comment Share on other sites More sharing options...
fsb Posted September 10, 2009 Report Share Posted September 10, 2009 (edited) Hi. I've done this a few times and I can tell you it's a ****ty work, due to the hardened material of the crankwebs. First you have to figure out what balancing the crankshaft has at the moment and what balancing you need. The balancing is declared in %, so have to find out how much % the original crank mechanism from your 350t has and what you have to change at the Pursang crank. Obviously you already know sth. about balancing, so you understand how to calculate the percentages, right? And then you need two prism to messeaure your actual balancing percentage. If you need to increase the balancing percentage, you have to remove material around the lower conrod-end. Otherwise you have to fill the holes with some material, e.g. aluminium or steel, depending on how much weight you need to get your correct balance. In my case I had to remove material around the lower conrod-end and so I used a drill and a chamfer with 1/4" shaft (like these ones: http://img-europe.electrocomponents.com/im.../W690877-05.jpg. I calculated who much steel I have to remove and fortunately it was only one percent away from my wanted balance. If you have questions about measuring the balance I could translate a german article for you in which it is described very good. I hope I could help a little bit. bye, Felix Edited September 10, 2009 by FSB Quote Link to comment Share on other sites More sharing options...
swooshdave Posted September 10, 2009 Report Share Posted September 10, 2009 Didn't you say you had a 64mm stroke crank now? What was wrong with it? I thought you were going to put a Pursang top end on it and try that. Will that not work? Also it might help if you keep just one thread going on your engine adventures. People will know when you update the thread, so there isn't much reason to create a new one each time. Quote Link to comment Share on other sites More sharing options...
brt650 Posted September 11, 2009 Author Report Share Posted September 11, 2009 Hello Dave, Noted Yes I did have a 64mm crank in the engine, but was joking about the pursang cylinder.I'm not man enough. Trying to get a Alpina cylinder would appear just as difficult as getting a 350T crank. I am going to look at some more cranks in 2 weeks.I'm hoping to find the correct crank if possible. That way I won't have to bodge up the pursang crank. Would anyone have a side on picture of the 159 crank I need ? That way I could identify the crank I need easier. I still haven't ruled out stripping my spare italjet engine to check out the crank in it. It's just the benches are cluttered with a multitude of other bike engine's. Thanks again Brian P.S. There is still the reason that this bike was fitted with this crank. It has a Honda 34mm CR carby fitted and different tail end exhaust section. Was this a rare special developmental model secretly being tested in the rugged outback of Australia? Or simply a stuff up by some dislexic outback bushy? I believe the second statement to be the truth. You need to meet some of my mates if you have any doubt's. Not you (Greg) Quote Link to comment Share on other sites More sharing options...
swooshdave Posted September 12, 2009 Report Share Posted September 12, 2009 Hello Dave, Noted Yes I did have a 64mm crank in the engine, but was joking about the pursang cylinder.I'm not man enough. Eh, it's not that bad. Considering what you want to do it should work just fine. Quote Link to comment Share on other sites More sharing options...
brt650 Posted September 12, 2009 Author Report Share Posted September 12, 2009 Hello Felix, Thankyou for the offer of translating that balancing article.I might take you up on it later. The Italjet crank is my next option.I have a photo of the engine dismantled out of a 1980's magazine.The crank looks the same. But I'll dismantle my spare engine and measure it up. The italjet had a 83.7mm bore standard. That's quite close to my 84.2mm bore I have now. Thanks again Brian Quote Link to comment Share on other sites More sharing options...
brt650 Posted December 4, 2009 Author Report Share Posted December 4, 2009 Hello Again, Well I have balanced the 250 Pursang crank and assembled it in the engine.Fitted into my 159 cases.I just started it up today and it sounds great, Or should that be ,feels great.I haven't ridden it yet as I have the wrong carb fitted and no tank or seat.The carb fitted at the moment was the one I bought with the bike.It's a Keihin 36mm of a CR125 honda early model.Oddly enough it runs really sweet. Idles nice too. But I'll replace it with a smaller carb when I find one.A Amal mark2. I have had a new tank made,that should read(a friend of mine had a 3 tanks made and one of them is mine) 199 tank,fiberglass.It looks great. The tank and air box are being painted blue.Why , because I like blue.I know it's supposed to be red .but hey. Well if I could list a photo I would. Well that's it for now.I'll keep you posted. Brian Quote Link to comment Share on other sites More sharing options...
gomey68 Posted December 4, 2009 Report Share Posted December 4, 2009 Sounds great! Would love to see some pics and more details on the glass tank.. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted December 4, 2009 Report Share Posted December 4, 2009 Well if I could list a photo I would.Well that's it for now.I'll keep you posted. Brian Brian I would love to see it too. You should be able to post photos on Trials Australia www.trials.com.au Alternatively you could email me photos and I will post them up David Quote Link to comment Share on other sites More sharing options...
brt650 Posted December 5, 2009 Author Report Share Posted December 5, 2009 Hello Dave, Thanks for that offer. Please try this photo bucket link and tell me if it works http://i818.photobucket.com/albums/zz110/b...n1/100_2197.jpg http://i818.photobucket.com/albums/zz110/b...n1/100_2244.jpg http://i818.photobucket.com/albums/zz110/b...n1/100_2225.jpg Well maybe one photo may be wrong. Thanks Quote Link to comment Share on other sites More sharing options...
brt650 Posted December 5, 2009 Author Report Share Posted December 5, 2009 Here is a photo , all be it ugly of the bike in running condition.Just in case there are non believers. http://i818.photobucket.com/albums/zz110/b...n1/100_2248.jpg I've had an update on the tank and air box.They will be finished by Friday next week. I'll post some pic's when I get them And one for the Italjet fans http://i818.photobucket.com/albums/zz110/b...n1/100_2155.jpg Cheers for now. Brian Quote Link to comment Share on other sites More sharing options...
brt650 Posted December 12, 2009 Author Report Share Posted December 12, 2009 (edited) Well I bought the correct crank off ebay in the UK. That only took 4 months. But all good things come to those that wait. So I'll still try my modified crank and see how it goes. But fitting the correct crank will at least make me feel better inside. Happy Riding Brian Edited December 12, 2009 by brt650 Quote Link to comment Share on other sites More sharing options...
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