Emmi Posted August 1, 2010 Posted August 1, 2010 Dear All, In an ongoing quest to get my bike on the road and to sit my CBT - I cannot seem to get my "Daisy" to tick-over properly. She often seems to have an erratic tick-over - even when warm. My Dad and I work on the bike - and I am asking the question. The Idle Screw is in good condition - but there are a few flat spots on the diameter after the point on the front. Would this lead to the problems I am having adjusting the idle speed. With the Idle screw wound in full the bike revs at about 2000 rpm when winding it out it just seems to suddenly drop down to stall. Sometimes just wiggling the screw causes it to alter the speed. I cant seem to find a replacement should I need one - though I may be able to get one made up. Any help would be appreciated. Thanks!
root Posted August 1, 2010 Posted August 1, 2010 Yes I can see this could be the cause,as the slide is stepping down the taper & not settling propperly , You could try Granbys http://granbymotors.co.uk/spares.php?lnk=Yamaha & here is a link its fo 1999 but I dont think the idle screw would be any different http://www.oemmotorparts.eu/oem5.asp?M=Yamaha&T=SR 125&Y=1999&L=YA-SR-125&O=CARBURETOR&F=YA-SR-125_ah&L2=YA-SR-125_ah ,
Emmi Posted August 5, 2010 Author Posted August 5, 2010 OK - things have progressed. Carb stripped down - turns out needle was bent - Jet barrel holes were blocked and some Petroleum Jelly was settling in the bowl despite Carb Cleaner through the Carb. Gave it all a really good clean - replaced the Needle. Calibrated the floats, re-assembled and fitted. Works like new - finally my bike idles beautifully! Thanks for your help... E
Emmi Posted August 26, 2010 Author Posted August 26, 2010 UPDATE: Since getting the Idling sorted when my bike runs there seems to be an erratic, inconsistent fade of power then backfiring VERY loudly! Now that she is sorted I can let you know what my Dad has done to sort out the problem; the problem being when going out on a ride from Cold. 1-2 minutes into the ride she fades and pops a bit. Then she rides cleanly at all revs/speeds for about 20-30 minutes then she starts to fade and backfire at higher revs. 10-20 minutes later she fades and backfires again - proper flames from exhaust about 6-10" out the back! This happens more and more with less time between backfiring. There is no set pattern as far as revs/speed but does it more at the higher end of the rev range doesn't matter on gear selection. But sometimes going from 55 to 10mph banging and farting like she does is a bit much... So after 3-4 weeks of time (when my Dad could) it is now finally resolved by: 1. Cleaned the Carb again - after totally dismantling it. Re-set floats, mixture and idle setting. 2. New Plug 3. New Plug Cap 4. New HT Lead 5. Checked HT Coil (primary and secondary) slightly high reading on Secondary side 12.7 Ohms instead of 7.9 Ohms - replaced 6. Checked timing 7. Re-checked and re-set Valve clearances. 8. Changed Fuel Filter 9. Proper greased all electrical connections. All of this made very little (apart from in my head) difference. 10. Changed Ignitor Unit - cannot be checked by anyone except Yamaha... FAULTY UNIT. She now runs perfectly right up to maximum revs and no more popping and farting or backfiring!!! FINALLY!!!
Moderator Airhead Posted August 27, 2010 Moderator Posted August 27, 2010 So after 3-4 weeks of time (when my Dad could) it is now finally resolved by: 1. Cleaned the Carb again - after totally dismantling it. Re-set floats, mixture and idle setting. 2. New Plug 3. New Plug Cap 4. New HT Lead 5. Checked HT Coil (primary and secondary) slightly high reading on Secondary side 12.7 Ohms instead of 7.9 Ohms - replaced 6. Checked timing 7. Re-checked and re-set Valve clearances. 8. Changed Fuel Filter 9. Proper greased all electrical connections. All of this made very little (apart from in my head) difference. 10. Changed Ignitor Unit - cannot be checked by anyone except Yamaha... FAULTY UNIT. She now runs perfectly right up to maximum revs and no more popping and farting or backfiring!!! FINALLY!!! Well done dad Emmi I was thinking doing the valve clearances might have helped with the flame throwing exhaust and fading so to me this would have been the cure. But you seem to say it wasnt and that changing the ignitor did it so was it still bad after the valves were done? If you were to swap back the ignitor CDI would the problem return?
Emmi Posted August 27, 2010 Author Posted August 27, 2010 Hi OGOAB, Doing the valves made no difference whatsoever apart from making the top end a little quieter. Inlet Valve was 0.002" out Exhaust was 0.014" out Once corrected the bike ran nicer and quiter, but the backfiring and "flamethrowing" were exactly the same. Apparently the Igniter advances the timing at higher revs, maybe it wasn't doing that on my old one so it seems to point to that. Been out tonight for 2 hours and never faulted once - deffo cured! will tootle along at 65mph. New Needle and main jet ordered to improve the flat spot. E
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