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The 2-Stroke Garage => Turning Wrenches => Topic started by: lowandslow on April 02, 2025, 08:55:49 AM

Title: 73 RD 350 right cylinder runs hot
Post by: lowandslow on April 02, 2025, 08:55:49 AM
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?
Title: Re: 73 RD 350 right cylinder runs hot
Post by: RDDave on April 02, 2025, 09:05:38 AM
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.
Title: Re: 73 RD 350 right cylinder runs hot
Post by: 1976RD400C on April 02, 2025, 09:36:15 AM
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.
Title: Re: 73 RD 350 right cylinder runs hot
Post by: m in sc on April 02, 2025, 10:05:51 AM
yeah too hot to touch is normal after 20 30 seconds of running
Title: Re: 73 RD 350 right cylinder runs hot
Post by: automan on April 03, 2025, 01:05:22 PM
Coils or wires swapped.
Title: Re: 73 RD 350 right cylinder runs hot
Post by: lowandslow on April 03, 2025, 02:30:44 PM
What about the sound? IF I hear other RD 350s on youtube they sound so much sweeter?
Title: Re: 73 RD 350 right cylinder runs hot
Post by: Jspooner on April 03, 2025, 03:35:17 PM
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.
Title: Re: 73 RD 350 right cylinder runs hot
Post by: SoCal250 on April 03, 2025, 04:58:24 PM
^^ what Joe said :agree:
and if it was parked on the kickstand that tends to make carb issues occur more frequently on the left
Title: Re: 73 RD 350 right cylinder runs hot
Post by: lowandslow on April 04, 2025, 09:39:32 AM
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:
Title: Re: 73 RD 350 right cylinder runs hot
Post by: m in sc on April 04, 2025, 09:53:12 AM
man that motors noisy,  but the tune sounds ok. yeah it sounds like you're dragging a cylinder.