I bought a 1975 rd 350 it's really clean.Runs great at idle and low rpm's but at high rpms it runs flat. I'm thinking carbs timing ? points i need help i don't know much i just like to ride.
1975 yamaha rd 350 runs flat at high rpm
Started by
glaizinman
, Mar 25 2012 08:37 AM
8 replies to this topic
Posted 25 March 2012 - 02:16 PM
What do you consider high RPM? Be careful timing an air cooled two stroke if you're new at it. What do the plugs look like?
Posted 25 March 2012 - 02:54 PM
the plugs look good 5500 rpm it just don't pull I think it maybe in the carbs as well it won't idle down funny thing it will idle down when the head light is on it may not be charging either. I just got it the other day got a manuel i'm not real mechanical .All the help i can get would be great going to check the points soon
Posted 25 March 2012 - 05:35 PM
Yeah it should pull past 5500. Have you chargeed and checked the battery? Do that first and then check the charging system. Does it styart without the choke easy?
Posted 27 March 2012 - 07:38 PM
flat without popping is LEAN!!!!!
wore crank seals or to small main jet. fix it before you hole the piston
to confirm pull the choke as it gets flat
wore crank seals or to small main jet. fix it before you hole the piston
to confirm pull the choke as it gets flat
Edited by yellowsnow, 27 March 2012 - 07:40 PM.
Posted 28 March 2012 - 02:44 AM
Flat running at high rpm is typically due to carbon bulid up. Pull the silencers from the pipes and clean them. Depending on previous usage and mileage, sometimes they need port cleaning too.
Posted 28 March 2012 - 05:14 AM
It only took me about 3 years and 2 pistons to get my RD350 running right...no matter what you should pull and clean the carbs, check your timing, then see what you have. I would agree that flat on top sounds lean. Lots of info over at usa2strokers.com, good luck!
Posted 28 March 2012 - 05:23 AM
Thanks guys for the info. I cleaned the sileners did not clean the ports the silencers loked good the bike has 16 k on it. Is there an easy way to time the RD? And i will clean the carbs and check points when i get the chance just got back to work after not working for 3 months need the cash. When i start working on the bike i will get back to you guys thanks again
Posted 30 March 2012 - 03:44 AM
Only way to time it is with clean piston crowns, a dial indicator and an analog meter. The manual is very clear on the procedure.
As delivered from the factory, with stock pipes, the carb jetting was spot on (unless you are high in the mountains, in which case Yamaha offered a high alt. jet kit.
As delivered from the factory, with stock pipes, the carb jetting was spot on (unless you are high in the mountains, in which case Yamaha offered a high alt. jet kit.
