Topic: 1973 RD350

[Scott S]

 I just acquired this 1973 RD350. It's my first ever two stroke and I'm clueless.



 It's nice, but not so nice that I can't do some minor mods. It runs great (man...that kick in the pants when you get it past 5K RPM!), but will run even better when I get rid of the old gas and clean the carbs.
 I know you can get as wild as you want with mods on these things. I'm not going there....at least not yet. I'm kinda thinking about a somewhat period bike, like, what would it have been like in '74?
 I have some vintage Magura bars and want some cool pipes.
 
 I'll forgo the $700-1,000+ hydroformed chambers, but are the cheapo DG pipes any good at all? I don't plan on any porting or anything like that. It has a K&N filter in the stock air box and I know I'll probably have to rejet a little bit. That's it....that's fine by me.
 I would LOVE to keep the center stand (weight savings be damned), so that limits my choices. I would also prefer to NOT have to run rear sets at this time.

 Can you guys walk a total RD/2-stroke newbie through this?

[Stev-o]

Nice bike!   I have your twin and prefer to keep it stock.  It is a lot of fun to ride!
I used it as a pit bike at COTA....

[ekpent]

  May run better with the stock pipes. A major old two stroke guru and race tuner I know says expansion chambers are pretty much worthless on these without doing the port work.
   Welcome to two stroke world !!

[jas67]

Nice!    I had one just like it!

+1 on the chambers comment, you'll need port work to make it worth it.

I'd keep it stock!

[scottly]

  May run better with the stock pipes. A major old two stroke guru and race tuner I know says expansion chambers are pretty much worthless on these without doing the port work.

I don't agree with that. The first stage of hopping up a 2-stroke was chambers; it was the equivalent of a big-bore kit on a 750 as far as the increase in power.
Scott, got any pics of the DG pipes?

[MoMo]

Keep it stock, that looks like a beautiful survivor...Larry

[grcamna2]

Keep it stock, that looks like a beautiful survivor...Larry

+1
I had one just like it in 1975' when i was 17 and I put a Lot of miles on that bike.I was friends w/ the service manager Bill who owned an RD that he was always working-on/improving,etc. at the local Yam. dealer and had him do a simple performance improvement to the stock pistons(and came to his house a lot to visit & get lessons) which really woke-up the engine,powerband then pulled strongly past 9200 rpm w/ stock mufflers plus great midrange.The K&N filter in the box is also the hot set-up for great mid-high rpms;expansion chambers aren't what you want(unless you can find a pr. of 'Torque Engineering' chambers  )because they will limit you to just top rpms and the RD is peaky as it is plus the oil pump isn't too reliable when you keep it above 9500rpm steadily.

[Scott S]

 I'm probably going to leave it as-is. I ordered a set of mirrors for it and spent a little time detailing it. Also have replacement tires on the way - Avon M26 RoadRiders in the stock skinny sizes; 90/90-18 and 100/90-18.

 I contemplated pulling the carbs, only because the RH one will pee from the overflow sometime. It seems to be getting better the more I ride it, though. I drained out the smelly old gas and put in some fresh non-ethanol. I'll see if the float gets better with some heat cycles and good gas. If not, I'll do the carbs.

[grcamna2]

I'm probably going to leave it as-is. I ordered a set of mirrors for it and spent a little time detailing it. Also have replacement tires on the way - Avon M26 RoadRiders in the stock skinny sizes; 90/90-18 and 100/90-18.

 I contemplated pulling the carbs, only because the RH one will pee from the overflow sometime. It seems to be getting better the more I ride it, though. I drained out the smelly old gas and put in some fresh non-ethanol. I'll see if the float gets better with some heat cycles and good gas. If not, I'll do the carbs.

I think flushing the tank w/ some BB's inside will help,probably some sediment in the tank/petcock.

[Scott S]

 The tank is spotless and lined properly with a POR-15 kit.
 I did replace a couple of fuel lines between the tank and the carbs. This Yamaha now has genuine Honda 5.5mm fuel line on it now!

 The weepy carb is something recent  according to the guy I got it from. And like I said, it  doing it less and less. Some fresh non ethanol gas with a splash of Marvel Mystery Oil in it and some heat cycles and I'll see what happens.

 To be honest  I'm a little scared of pulling the injector  nozzles on the carbs. They're not available if I break one.

[bwaller]

The RD's were giant killers (and the best wheelie machines), great lightweight simple motorcycle. Your's looks great, have fun with it. There were 1000's roadraced since it was a cheap way to get started, myself included.

[grcamna2]

The tank is spotless and lined properly with a POR-15 kit.
 I did replace a couple of fuel lines between the tank and the carbs. This Yamaha now has genuine Honda 5.5mm fuel line on it now!

 The weepy carb is something recent  according to the guy I got it from. And like I said, it  doing it less and less. Some fresh non ethanol gas with a splash of Marvel Mystery Oil in it and some heat cycles and I'll see what happens.

 To be honest  I'm a little scared of pulling the injector  nozzles on the carbs. They're not available if I break one.

The oil injector nozzles on each carb. w/ the oil line attached are a tapered fit into the carb. and you can carefully & slowly twist them back and forth between the pair of locating tabs w/ a decent pr. of gentle pliers;you install them by pushing/twisting them in slowly side-side until they're tight and seated.

[becken]

Lots of good information here: http://www.2strokeworld.com/forum/index.php
Also a good source of parts is https://www.economycycle.com/
They are a great little bike. Weak coils was a problem causing a lot of plug fouling. The new coils available should be better. Hondaman's ignition will help a lot.

[ekpent]

  I 'found' this one some time ago, a low mile 1974, by sitting next to a stranger at a bar one night for a reasonable price. Pays to ride your motorcycle to places like that and carry in your helmet     I have only ridden it a couple times, felt like it needed carbs cleaned etc back then from sitting so long. Another project this year on the list if I can keep some motivation.  I like your color scheme much better.

[grcamna2]

  I 'found' this one some time ago, a low mile 1974, by sitting next to a stranger at a bar one night for a reasonable price. Pays to ride your motorcycle to places like that and carry in your helmet     I have only ridden it a couple times, felt like it needed carbs cleaned etc back then from sitting so long. Another project this year on the list if I can keep some motivation.  I like your color scheme much better.

You did 'Score' on that bike  , I've always liked the original Maroon factory paint on the 74' model.

[ken65]

Nice bike. Take your time , do your homework and get to know it. They're fairly simple machines and they can be a bit moody at times. 

Set it up and ride it like you stole it..  Modern oil now is very good with little smoke .
Make sure the oil pump is delivering enough oil. A little extra won't hurt.. Ps. Keep some extra plugs near by.

[grcamna2]

+1 on taking a spare pr. of B8HS plugs with you and keep them in your tool kit.I think the Yamaha repro coils sold by MikesXS(same style/size coils used on the XS650's) are a very good deal for a pr. w/ decent(china) 3 ohm quality,please change out those original coils 

[Scott S]

 It has new coils and plug caps on it, too. Done not long before I got it.

 Call me crazy, but I kinda want a luggage rack for it so I can ride it to work!
 I'm also in need of a tool kit if anyone has one.

[MoMo]

It has new coils and plug caps on it, too. Done not long before I got it.

 Call me crazy, but I kinda want a luggage rack for it so I can ride it to work!
 I'm also in need of a tool kit if anyone has one.

Not crazy at all on that thought-I had the earlier R5 with a luggage rach and rode it everywhere sans problems.  Carried a spare set of plugs but never fouled one.  The secret is a heavy throttle hand

[Powderman]

Why does your title say 1973 RD350 if it's a 74?

[Scott S]

Why does your title say 1973 RD350 if it's a 74?

 Because it's a '73??

[grcamna2]

That's a true 73',first year they made them;the maroon color one that ekpent posted is a 74'.

[Powderman]

Sorry, I mistook ekpents post about his 74 for yours.

[ken65]

this is the son of your 73.  my 81 LC

[grcamna2]

Nice RD350LC Ken;are you in Canada?

[Scott S]

 My Super at work has two RZ's that he bought new. One is a Kenny Roberts edition and the other has chambers, carbs , etc. I could probably buy one of them from him.

[grcamna2]

That 73' RD350A you have there is in such beautiful original condition that you could sell it and get enough $ to buy one of his RZ's 

[ken65]

Thanks Mr grgamma2. I'm in Australia and am seriously considering selling my bonneville

to buy an early air cooled 350 like Scott S's bike.

ken

[grcamna2]

That 73' RD350A you have there is in such beautiful original condition that you could sell it and get enough $ to buy one of his RZ's 

When I see the RZ350 and the LC they make me think of a more modern version of the later TZ350 race/track bike 

[Stev-o]

Thanks Mr grgamma2. I'm in Australia and am seriously considering selling my bonneville

to buy an early air cooled 350 like Scott S's bike.

ken

Hey Ken.....I suggest you ride one, if possible, before you buy one. 
As much as I like mine, I find myself only taking it for short rides around the 'hood for an hour max or so.  It's rather small and lightweight, not ideal for a highway cruiser. 
However, it is fast and nimble, a blast to ride!

[Retro Rocket]

Thanks Mr grgamma2. I'm in Australia and am seriously considering selling my bonneville

to buy an early air cooled 350 like Scott S's bike.

ken

Hey Ken.....I suggest you ride one, if possible, before you buy one. 
As much as I like mine, I find myself only taking it for short rides around the 'hood for an hour max or so.  It's rather small and lightweight, not ideal for a highway cruiser. 
However, it is fast and nimble, a blast to ride!

Steve, Look at Kens sig mate, I doubt he would buy a RD for a highway bike when he owns an FJ1200 and an R1 Yammy    Plenty of places to ride a nimble little "chook chaser" here mate......

[Scott S]

(WARNING: Long post ahead...)
  Getting familiar with the new to me '73 RD350. It's my first 2 stroke and the manual just showed up yesterday. When I first got the bike, the gas was OLD. After getting some fresh non-ethanol and running that through the carbs, the bike ran better.

 I would sometimes experience a bog at high RPM if I stayed in the throttle. What I mean by that is, it seems to bog sometimes around 6-7K RPM....but  only after I've wound it out in the gear before. In other words, if I roll onto it in 1st, 2nd or 3rd, it'll do OK, but when I grab the next gear and keep the RPM's high, there's a bog or a stumble before it recovers. Does OK in lower RPM's and does OK as long as I'm not wailing on it. The more I've ridden it, the less it does it.
 It has a stock air box with a K&N filter and no lid. Another oddity I noticed is that when I put a bag of tools in the holder (burlap bag about the size of a Crown Royal bag), that partially covered the air filter opening and I swear it's running better and doing it even less. Not sure if it's just fresh gas cleaning out the system or if maybe it was a tad too lean up top without the lid?

 Anyway, on to the points....
 I have a manual and a dial gauge now. I also watched a timing with a dial gauge video last night. I haven't done anything other than poke around and get familiar with the system. The points gaps both measured OK. A loose .011", snug at .012" and I kinda had to force the .013" feeler gauge in there.
 But I did notice that the front or LH points plate is maxed out. (Forgive me if I'm using the wrong terms. LH as I'm sitting there looking at them...which cylinder is this set for?)  I can also see witness marks where it used to be centered in the plate.



 RH or rear points are centered in the plate.



 And the pair.



 Only after seeing the timing video and taking some sandpaper to the rust was I able to find the timing marks. These are the two marks I'll be looking for, correct? The line on the housing and the notch on the rotor?



 Now....all that said....if I put the dial gauge on it and find that the LH points are off, is it as simple as loosening the two outer screws and moving the plate? And then loosening the third, smaller screw on the points themselves and adjusting to get the ~.012" again?

[grcamna2]

Scott,
I recommend that you remove that entire stator windings(I've never seen one look so rusty,they're usually nice and shiny factory zinc plated) that covers your brushes,etc. and get the outer part lightly sandblasted to remove all that corrosion(the points and brushes can't properly 'ground' and will give you a weak spark)and then polish the outer surface and coat it w/ a protective film.Replace your points,a Fresh pr. of condensers and finally clean your carbs.The points fiber blocks are wore down and they won't be able to advance much further.

[MoMo]

Left points are for the left cylinder...IIRC points should open 1.8mm BTDC. I never used the timing marks only a dial indicator and ohmmeter to determine when points open in relation to TDC.   Good suggestion in the previous post

[grcamna2]

Try to find oem Yamaha points if at all possible