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Good morning,

Check out this YouTube link and take a listen. Thanks up front for any thoughts. I don't want to start pulling things off until I have an idea of where to begin.

https://youtu.be/VVEdb2lLIJk

I've got an irritating clanking sound coming off the RD350. I hear it mostly at low rpm. At 5000 & 6000 rpm I do not notice the sound or the misfire. The bike was running perfect 1000 feet above sea level. I am now at 5000 feet above sea level and it was running rich. I changed the main jet to 135 and the plugs look great, it'll run up to red line no problem, but all this time, before and after jet change, it's been clanking and acts like it's hopping down the road a bit when decelerating. It'll stop running at a redlight sometimes? I think the problem may be on right side?

It's got new cylinder, pistons, rings, dyna ignition, oil pump is spot on. Plugs look perfect brown??

Have a nice week.

I appreciate all the good information. I'm hoping to pull these carbs today.

I always thought the drum brake was an early model before they swapped to disk. There's some signs of foul play as well. The right side tank has a ding and the blinkers on that side are a slightly different length than the ones on the left?? It's almost unnoticeable, but the handle bar seems slightly out of square. Maybe it was damaged and the front end swapped?? Bike really runs good, if it has oxygen, lol.

Thanks all,

Good morning,

I brought my 1974 Yamaha RD350 to Fort Collins, CO from Knoxville, TN and it does not like the thin air. HP is down and it's clearly running rich. The carbs on this RD350 are very difficult to get on and off the bike. Having said that, what would be my best one off adjustments to get the carbs tuned for this elevation? I'm probably going to sell or trade this bike, looking for a DT250 or something, but I want it running top notch for the next owner if I do get a buyer.

I've read some good suggestions in the forum, but still looking for a solid confirmation on this particular model and the changes I might need to make.  Does anyone live in the Fort Collins area? Any good mechanics if I needed one?

My RD has Dyna S ignition, rebuilt oil pump and top end, running new air boot with OEM type filter.

Thanks for the advice! LexPaul

Based on what I'm seeing in your photos and your explanation of the issue, I'd say your mechanic's advice was 100% wrong. It would be under-oiling not over-oiling! Not sure what logic he was using.

I would leave the pump in place and use it. No need to try some mickey mouse bypassing.

Get a new pump cable. Your DS7 should be the "old style" as used on the DS7 & R5: 278-26321-00-00 CABLE, PUMP
(Not the later cable version 521-26321-00 used with mid-75 model year and up pumps, assuming your pump is original. Refer to Tech Bulletin M8-015C).

Once you've replaced the cable and adjusted it properly then test your pump stroke again. Adding a shim will fix it if it's under the spec. Shims are readily available in several thicknesses and super easy to install. Just take the nut off the pulley, remove the pulley from the shaft, add your shim to the stack under the pulley, and reinstall the pulley.

In addition to the cable damage where the housing fits into the adjuster, it also looks like someone added a new end on it. At least that's what it looks like in your photo. As it rotates that blob (circled in red) will interfere with the roll pin preventing the pulley from rotating as it should.
Also it looks like someone has been messing with the pin (yellow circle). Make sure it's in there tight. But don't push it in too far. I think 4 mm is max, or about 6mm showing (from memory) or the plunger will bind.

How does one get that pin out, for the purpose of rebuilding the pump, which is what I am doing now? Does the pin fir back in easily during reassembly?

Got this Rd350 running like a top but the 2T oil pump is weeping just a drop or two per day. The oil appears on the cable and I believe it may be a shaft leak. When I take Q-Tips and look for leakage around the pump and oil lines there is no areas of concern.

Has anyone dealt with this? Should I look for a rebuild kit or a shaft seal? Thoughts are appreciated. Thanks

That looks correct to me, except, that I couldn't read the float measurement, which I'm going to assume you got correctly. The only think I would make sure of is that that channel from the air box nipple into the carb is clean, and I would, and I'm sure you have, checked to make sure the jets, needle, etc are the correct OEM part numbers.

Non Standard parts will kill what would otherwise be good performance from a carb. I had two bikes that the PO had used non standard carb kits on and neither bike had the right needles. When I changed the needle back to OEM, the bike ran just perfect.

Have fun. LP