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73 RD 350 right cylinder runs hot

Started by lowandslow, April 02, 2025, 08:55:49 AM

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lowandslow

I started my 73 for the season and it idles well but the right cylinder gets very hot. Within 20 seconds of starting, you cannot touch the right exhaust down pipe. It is Scalding hot and I feel I will hole a piston or get the uncontrolled detonation if I let it run for long. The left is fine, can touch.
Any ideas why? Also I feel my motorcycle does not sound right. Do I need a rebore? or replace rings maybe?

RDDave

When I was an outboard motor mechanic, I often saw first start of the season problems. They were almost always carb/fuel related. Fuel drying in the bowls during storage reduced or stopped the proper flow of fuel. I would start by cleaning the carb on that cylinder.

1976RD400C

Don't you think the one that is getting hot is running properly and the cold one isn't? Exhaust gasses are over 1000 degrees and heat things up quickly.
'76 RD400 green  '76 RD400 red   '84 RZ350

m in sc

yeah too hot to touch is normal after 20 30 seconds of running

automan


lowandslow

What about the sound? IF I hear other RD 350s on youtube they sound so much sweeter?

Jspooner

My guess is the left side pilot and jet tube are plugged, so no fuel or very little fuel for that cylinder, also your carbs are probably out of sync and I'd also check the timing.
"Just quit brain fucking it and get it done"

SoCal250

#7
^^ what Joe said :agree:
and if it was parked on the kickstand that tends to make carb issues occur more frequently on the left
75 Yamaha RD125B   75 Yamaha RD125B (project)
75 Yamaha RD250B   75 Yamaha RD200B (project)
73 Yamaha RD350     77 Yamaha RD400D   79 Yamaha RD400F  
91 Yamaha TZR250R  89 Yamaha FZR400   05 Yamaha FZ6   
05 Yamaha XT225TC  82 Honda MB5  02 Aprilia RS250 Cup (sold)

lowandslow

Yes I will check the timing and the left carb. Also the sync. I was expecting this is how an RD350 sounds

https://www.youtube.com/watch?v=BWgb2Bb1_9A

Mine is nowhere near that  :sad:

m in sc

man that motors noisy,  but the tune sounds ok. yeah it sounds like you're dragging a cylinder.