1981 RD350LC running lean, need help.

I can get the bike about 6-7K before having to shift.


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Ryan Stecken,

Really nice work on your RD350. Appreciate all your help as well and everyone else that has commented.

Nice LC, sounds good, are you letting it warm up, they won't rev until they're warm, they cough and splutter when cold, it should rev nearly to the red line once warmed up.

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Thanks. I did warm it up and got it to about 8K but haven't pushed it really beyond that as it seems so high in the revs. Plug chop shows it being pretty rich so wondering if I should go down on the main jets or just leave it. There was a bit of oil when I checked the plugs, not sure if that is normal.

Let it rev. As someone said, it should rev to or close to the red line with throttle wide open. If you are riding at less than full throttle (normally sensible way to ride) and short shifting, you are not getting the most out of it. Don't worry about it hitting apowerband and having the thing take off. It's not like that at all on a stock bike. It should be smooth and rideable.

Its a 2 stroke man let it rev!

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I am getting a GoPro from a friend and will show how it sounds and runs through the gears for you guys. Not sure what to do about it running rich. If I should go down on the main one size.


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Might be worth checking that you are indeed getting wide open throttle. Just take the carbs loose and twist the throttle wide open and either look into the intakes or use a finger to feel if the slides are both in fact completely above the main bore.

You won't experience any down side to extra oil except the cost of the oil and in the main it is just a bit of a safety factor. It has to be a crazy excess to significantly depress power. Exhaust smoke isn't much of an indicator until the bike is running properly and you ride it a while to get a notion of what is normal. Often it will vary a lot depending on how much has accumulated in the pipes and when they are hot enough to start burning off the accumulation.

Getting good and correct info from looking at your plugs is a lot trickier than most people think. You have to get the engine hot, use brand new plugs, and have the engine at max power at WOT. On your bike that's 100 mph for 30 seconds, hitting the kill switch and coasting to a stop. Read this:https://www.strappe.com/plugs.html

Report back on the ride today, was able to get it to about 9K before redline and it ran great!


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So decided to take the bike on a long ride today only to find out that there was an oil leak on the engine crankcase cover. Also the bike doesn't seem to want to go over 7K in 4th gear and could only get it to run about 60 MPH on the freeway. Rode it back home and going to remove the crankcase cover and replace gasket. Checked compression and getting about 100 psi on each side.

Have you checked to see if you're getting full throttle

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julian.allard66 said:

Have you checked to see if you're getting full throttle

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Click to expand...

Just checked and getting full throttle. Both carbs when full throttle the slides are not visible through intake, they go beyond the bore.




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Here is a pic of the cover off. It is super clean. Not sure what to look for but I was getting a leak.


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Could be from the kicker shaft but just as likely that the cover has a ding in it or a gouge. Clean both mating faces and apply some engineers/bearing blue and lightly tighten the case. Remove it and see where the cases touched and where there are gaps. And make sure the locating dowel is not too long. Also check the gasket it it came off in one or two pieces to see if the compression is similar all the way around and look also for spots where it is not compressed at all.

Just a thought but did you gap your plugs properly? On the 2strokes that I have had, incorrect gaps hurt the top end performance. I have never ridden an LC but on my RZ and RG250 you can easily tell when the power exhaust valve opens, make no mistake. On my GT500 the power increase is more gradual.