Driftit Posted October 5, 2023 Share Posted October 5, 2023 Hey team, I have been slowly restoring an RD50 and poorly "restored" LB50 Chappy. Had the Chappy a while but ran into problem after problem and dodgy "fix" after dodgy "fix" which sapped a bit of motivation. That and nearly every part I have ordered via ebay has been wrong or they sent the wrong part. But they are both running now. Just took the Chappy for a good hour run around town and it didn't miss a beat. The RD just needs a tune and power to the headlight and she is good to go too. Just have to figure out the power issue to the headlight. Rear lights work and the switch seems good. But no voltage to the plugs behind the light at all. We have planned to head to the Scooter Pestival Sid's Run in Chch next month with these two and a 1950's Victoria Moped. Anyone else going? 7 Quote Link to comment Share on other sites More sharing options...
GregT Posted October 5, 2023 Share Posted October 5, 2023 i'll probably go along for a look. Go every few years to see who's still alive. 2 Quote Link to comment Share on other sites More sharing options...
Beaver Posted October 5, 2023 Share Posted October 5, 2023 Cool to see another RD50! I believe the headlight power feed is seperate to the rest of the lights, I think I have a wiring diagram somewhere I'll see what I can find. Here's my RD https://oldschool.co.nz/index.php?/topic/87461-beavers-yamaha-rd50/#comment-2559776 Quote Link to comment Share on other sites More sharing options...
Tumeke Posted October 5, 2023 Share Posted October 5, 2023 Yeah headlight should be AC and the other lights are generally thrown through a reg and are DC. 1 Quote Link to comment Share on other sites More sharing options...
Driftit Posted October 5, 2023 Author Share Posted October 5, 2023 58 minutes ago, Beaver said: Cool to see another RD50! I believe the headlight power feed is seperate to the rest of the lights, I think I have a wiring diagram somewhere I'll see what I can find. Here's my RD https://oldschool.co.nz/index.php?/topic/87461-beavers-yamaha-rd50/#comment-2559776 Nice. I saw that earlier when I was sculking around the forum. There are so few left now. Though I did spot a few in the Sids Run footage from last year. Mines an 81. Sold in NZ new but it is covered in Japanese stickers so must have been imported. 40 minutes ago, Tumeke said: Yeah headlight should be AC and the other lights are generally thrown through a reg and are DC. That makes it easier for me to track it down. I'm getting nothing at the plug end. The plugs have been replaced so someone has been in there before chasing this. Quote Link to comment Share on other sites More sharing options...
Tumeke Posted October 5, 2023 Share Posted October 5, 2023 not usual to have a break in the loom, or if you have a headlight switch check the put your multimeter to horse shoe mode over that. Check you have a good earth at the light too. A/C should be the yellow wire from memory. Go check you have some AC Pixies right down at your stator and go from there. 1 Quote Link to comment Share on other sites More sharing options...
Beaver Posted October 5, 2023 Share Posted October 5, 2023 Can confirm it should be yellow off the stator (looking at wiring diagram). Quote Link to comment Share on other sites More sharing options...
peteretep Posted October 5, 2023 Share Posted October 5, 2023 my yamaha had bad earths everywhere, thats probably where I would be looking Quote Link to comment Share on other sites More sharing options...
Driftit Posted October 6, 2023 Author Share Posted October 6, 2023 Awesome cheers guys. Will have a look after work tonight. Hopefully something simple. Found the clutch to be overly stiff on it today. I had a new cable made up as the old was frayed. However it looks like it was frayed as it was under far too much stress. Need to look into this also. Quote Link to comment Share on other sites More sharing options...
GregT Posted October 6, 2023 Share Posted October 6, 2023 On 05/10/2023 at 16:15, GregT said: i'll probably go along for a look. Go every few years to see who's still alive. Looks like I won't. Conflicts with CAMS Southern Classic. Quote Link to comment Share on other sites More sharing options...
Driftit Posted October 7, 2023 Author Share Posted October 7, 2023 I got into the RD yesterday. Usually fires first pop but it was not even trying. Pulled the plug and found zero spark. The ceramic has split right around the NGK print on the plug. Realized that it is a very old plug and not the correct one either. It's been thrown in by someone to get it running no doubt. Was a BR8HSA and should be a B8HS. The R being for resistor no doubt. Not sure what difference that would make. BR8HSA - 0.7mm gap with a 5k Ohm resistor https://www.ngk.com/ngk-5539-br8hsa-nickel-spark-plug B8HS - 0.6mm gap with no resistor https://www.ngk.com/ngk-5510-b8hs-nickel-spark-plug Could explain why I am missing any midrange. She idles perfectly but has nothing past about 3500rpm unless I back off the throttle a bit. Borrowed the Chappy's plug and she fired right up. The Chappy curiously is two levels colder using a B6HS plug. I found this recent youtube video of a guy tuning his Mikuni carb on an RD50. Was quite helpful. Will grab some new plugs tomorrow. Quote Link to comment Share on other sites More sharing options...
Driftit Posted January 8 Author Share Posted January 8 Still having issues with this RD50. It seems to eat plugs. We took it down for Syds Run last November. Was running before we transported it. But had no spark and needed to change the plug when we got there. Ran all run without any issues at all. Was a dream. Then when we got home to the Wairarapa it had no spark again. I left it for a while. Then chucked in my last spare plug. Started first pop and took her for a short 10min run. Left it for another two weeks. Now it has no spark again.... What on earth could be causing this? The old plugs some of which have done 10mins running seem to no longer have any spark or very very weak spark. They are NGK plugs from Repco and the recommended BH8S bar one BH7S which is also killed. Any recommendations for me to chase? Quote Link to comment Share on other sites More sharing options...
GregT Posted January 8 Share Posted January 8 Symptoms point to low spark voltage. I'd check the coil and ignition generating coils are within spec. Plug cap correct resistance. Pull all the wiring harness plugs and spray contact cleaner around. Fire it up in the dark and look for any spark leakage. Not unknown for the flywheel to lose magnetism too. Quote Link to comment Share on other sites More sharing options...
Beaver Posted January 9 Share Posted January 9 What do the plugs look like when they stop working? It's not something silly like they are foulling up with oil? Quote Link to comment Share on other sites More sharing options...
Driftit Posted January 18 Author Share Posted January 18 Sorry for the late reply to those with suggestions. I ended up with the spicy cough. I will get some photos of the plugs on the weekend and do some testing in the dark. Bike seems to be a bit of a parts bin bike from factory. From the many wiring guides I have found for the RD50's none quite match this bike. I have all the parts to rebuild the ignition system. Will look at that once I figure out the issue. Quote Link to comment Share on other sites More sharing options...
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