Jcarteradams Posted September 24, 2019 Report Share Posted September 24, 2019 (edited) Hi guys l have been having some great fun on my Sherpa 350 183 recently however I did a silly thing and left it outside for a few days and it got wet and stood there for a bit and so she didn’t start for a while. I re-cleaned the carb and renewed spark plug and it fired up BUT, the throttle cable was stuck on full whack and as I don’t have a kill switch on it yet it ran, full throttle for around 20-30 seconds before cutting out. I adjusted the throttle cable, and It re started moments later but then it came to a spluttering stop with a small backfire. Now it doesn’t start! I’ve tried a couple of new plugs, but nothing as of yet. Still plenty of compression too. Just wondering if it is a coincidence it’s not starting as I’ve recently refilled with new fuel, so I hope I’ve got the ratios right, I hope it is this rather than damage to something internally. Many thanks in advance James Edited September 24, 2019 by Jcarteradams Missing info Quote Link to comment Share on other sites More sharing options...
b40rt Posted September 24, 2019 Report Share Posted September 24, 2019 Are you getting a spark ? Is the plug wet ? Sheared woodruff key if your lucky. 1 Quote Link to comment Share on other sites More sharing options...
Jcarteradams Posted September 24, 2019 Author Report Share Posted September 24, 2019 Spark must be really faint as I can hardly see it if anything. It’s a new spark plug and dry. Woodruff key is a good shout as I remember the guy who helped with resetting the points said it looked worn a few weeks back. It’s had a new condenser and Ht coils and was working perfectly though. And when it does fire up the kick start always shoots back and rattles around until I get hold of it when turning the kick start pedal inwards, then it’s able to sit there without the rattling. I will have a look tomorrow at the woodruff key and let you know. I hope it’s just that. It not could it be anything else inside - damage to piston or anything like that? many thanks James Quote Link to comment Share on other sites More sharing options...
b40rt Posted September 24, 2019 Report Share Posted September 24, 2019 (edited) Good habit to get into, before starting the bike twist and release the throttle, you should hear it closing with a clunk from the carb. You should be able to see the spark, even faintly. (not advised, but I have held the plug to feel if something is happening ) Plug should also show some petrol, if completely dry check tank / tap / carb. A small amount of two stroke mix down the plug hole might be all it takes to get it going. Good luck. Edited September 24, 2019 by b40rt 1 Quote Link to comment Share on other sites More sharing options...
tony27 Posted September 25, 2019 Report Share Posted September 25, 2019 The backfire as it died would suggest timing has moved to me, pull the flywheel & check the woodruff key 2 1 Quote Link to comment Share on other sites More sharing options...
pschrauber Posted September 25, 2019 Report Share Posted September 25, 2019 On Bultaco ignitions, the spark should be a super bright flash! Try to locate the timing with a multimeter with inbuild "beep" for connection and disconnection of wires, then use a mm gauge for finding OT and measuring distance of spark before OT. That is IMHO the easiest way to check the right triming. You want to check too the distance of the points which should be precisely 0,4mm, more then 0,1mm off and the ignition can fail to deliver spark. 2 Quote Link to comment Share on other sites More sharing options...
lorenzo Posted September 26, 2019 Report Share Posted September 26, 2019 (edited) On 9/24/2019 at 10:36 PM, Jcarteradams said: And when it does fire up the kick start always shoots back and rattles around until I get hold of it when turning the kick start pedal inwards, then it’s able to sit there without the rattling. It needs a k/start return spring https://www.inmotiontrials.com/product/bultaco-kick-start-spring Edited September 26, 2019 by lorenzo 1 Quote Link to comment Share on other sites More sharing options...
Jcarteradams Posted September 27, 2019 Author Report Share Posted September 27, 2019 Thank you everyone. I did remove the flywheel to find a sheered-off woodruff key. So that’s now been replaced along with new spark plug. However still not producing the spark. Time to re-set the timings and points as suggested. The vibrations from the throttle being fully open probably effected things. The nut for the magneto was lose too. Thanks everyone James 1 Quote Link to comment Share on other sites More sharing options...
b40rt Posted September 27, 2019 Report Share Posted September 27, 2019 Try another / old plug first. Disconnect an kill switches, check h t lead is secure at both ends. 1 Quote Link to comment Share on other sites More sharing options...
Jcarteradams Posted September 27, 2019 Author Report Share Posted September 27, 2019 12 hours ago, b40rt said: Try another / old plug first. Disconnect an kill switches, check h t lead is secure at both ends. Would the HT coil burn out at all? Will double check the lead is secure. No kill switch on, that’s waiting to be fitted. Thanks again james Quote Link to comment Share on other sites More sharing options...
Jcarteradams Posted October 9, 2019 Author Report Share Posted October 9, 2019 Hi gents, so I reset the timing and all looked good. I got a good spark and so screwed everything back on and she started up, which was music to my ears. However as soon as I opened the throttle she spluttered and cut out. Which could be the carb settings, but it didn’t start back up again, and it was late so I left it for the morning. I’ve since tried again this morning and still no spark. I’ve tried the multimeter on the HT lead, and it’s not reading anything (hence no spark) - Is this a timing problem? Thanks James Quote Link to comment Share on other sites More sharing options...
bullylover Posted October 9, 2019 Report Share Posted October 9, 2019 I`d check the wiring all through the system. Make sure it has continuity through the wiring. After that just check the top coil earth. Pull the coil off and resand the contacts onto the frame. Bad coil earths can cause what you are describing. How is the end of the high tension lead where it joins the spark plug cap. Chop the end off the lead and rejoin the plug cap. Good luck. Graham. Quote Link to comment Share on other sites More sharing options...
Jcarteradams Posted October 12, 2019 Author Report Share Posted October 12, 2019 Thanks for the replies. So Ive just spent a bit of time going through the ignition parts, and found that the woodruff key had sheared off yet again!! It turns out the crank case was pushing on to the crank nut, which was not the correct size and looks much deeper than the standard issue size, and has actually marked the inside of the case and was simply loosening off the nut, magneto wheel and therefore sheering the woodruff key. Correct nut and bolt ordered and new woodruff. Hope it will sit in the crank shaft and magneto wheel now ok though!! 1 Quote Link to comment Share on other sites More sharing options...
lorenzo Posted October 13, 2019 Report Share Posted October 13, 2019 Mag. outer cover cannot loosen the flywheel nut - the cover is marked as a result of the nut having loosened when the key sheared. (Crank rotation suggests that the nut would actually be tightened, not loosened). The reason the key sheared is the the poor condition of the shaft taper - it's this and its fit within the flywheel boss that determines the security of the flywheel - the key is there in the main to locate the flywheel/points cam in the correct place. You need to address the issue of the damaged taper(s). 1 Quote Link to comment Share on other sites More sharing options...
bullylover Posted October 13, 2019 Report Share Posted October 13, 2019 (edited) A good way to do this is to put some valve grinding paste onto the crank where the taper is then lightly put the flywheel on with no key. Then just turn the flywheel and lap the flywheel to the crank. You might need to do this a few times until you have a smooth surface on both the crankshaft and the flywheel. Good luck. Edited October 13, 2019 by bullylover 1 Quote Link to comment Share on other sites More sharing options...
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