Stock 1974 Yamaha RD 350

[clutch]

I am having some lack of power issues with this stock 1974 Yamaha RD 350.

Does anyone here know how to fine tune one of these bikes, or a mechanic/shop that does.

Thanks for any help.

[stoinkythepig]

Assuming the carbs are clean and not messed with, the fuel and oil supplies are clean and fresh, and the spark plugs are new, the first thing I'd check is crank seals. They tend to dry out and fail with age and non-use and then the bike runs really lean and makes less power than it is supposed to.

[OreoGaborio]

Message TLRMan. Something tells me he could rebuild that entire thing in a medically induced coma.

If he pays you a visit, don't stand in front of him when he sees the bike. You might get wet.

[Expat]

Lack of power could be a lot of things, rings could be worn = low compresson. Carbs out of balance or dirty, crankcase oil seals as already mentioned, maybe even a slightly slipping clutch?? Without more of a description, it is hard to say.
I am just outside Worcester and could probably diagnose for you but I travel a lot for work so getting together could be tough!!

[landricscustoms]

LAndrics BOMO can take care of her. i personally have a specialty in vintage bikes.. and i just so happen to have a specialist on 2 strokes in my pocket... not literally but, you know what i mean.. seriously, i can get her runnin' right for you again.. pm me or call 774-200-6395

[VTRumble]

WWW.usa2strokers.com
WWW.2strokeworld.com
If you haven't been to either of these, the forums are good.

[gregp]

Somewhat related...check out this RD:
http://www.bikeexif.com/yamaha-rd400-custom

[Stromper]

Terrible ignitions
There is a place that has soild state upgrades... look at walnecks for add

My race tuned rd had to be warmed up then cold plugs put in

[VTRumble]

You can pick up a Dyna ignition from Vintage Smoke off one of the above forums. I bought one for my r5, nice to get rid of the points.

[Rambunctous]

Hmmmm....If after all the regular stuff has been checked like fuel, filter, sparkplugs clean have you done a crankcase leakdown test? A leakdown test consists of plugging the exhaust and using a adapter and fitting in the intake then pressurizing the engine.

[Rambunctous]

May wish to inspect the reed valves. All very easy stuff to do BTW. Just the first time is a little confusing.

[dipthat]

2 strokes is the shit, I used to own a yamaha RX-Z, and the big brother is of course RD. Add some castrol something to the 2t (if they have it here, which I doubt it), that thing will smell GOOD

[Stromper]

caster bean oil ... castrol

[jpallein223]

while the bike is at idle spray carb clean on the boots of the carbs, and where the boots connect to the reed cage(s). if you hear a spike in rpms (where it revs up after you spray) you have a leak somewhere in the boots and or reed cage gasket. On all the old bikes they seem to get cracks boots and or gaskets tend to go. i would start there if all regular checks have been done

[Sheppo]

lots of good ideas I would check the points first and then upgrade the ignition to points less

[clutch]

Here is what I have done so far:
Added in-line filters
Pulled carbs and cleaned them
Visual on the points, they look fine
Sync the carbs

Replaced the following:
Spark plugs
Petcock
Fuel lines
Air filter
Replaced oils

I think Rambunctous may be on too something?

As for jpallein223 suggestion, that tip seems easy enough to perform, thanks I’ll give it a shoot.

VTRumble, I have posted on 2SW, and will check what kind of feed back I get from there. As for USA2S, I’ll take a look at that one, Thanks.

Landricscustoms, I may just take you up on your offer to consider working on this RD. You being in Framingham is an easy target for me to get it to you, thanks.

I can do the spray test, but the pressurization, I got stuff, but not that kind of stuff.

The bike is close, real close. Its just one of those tuff itches that I can’t seem to scratch.

Thanks for all the feed back guys. I hope to have this bullet smoking the way it should be soon.

[Rambunctous]

YouTube - Pressure Testing a Minarelli Horizontal 2-Stroke Scooter Engine

[jpallein223]

if it dose rev up then you have a crack somewhere or a leaky gasket which should eb replaced. Get that thing going we need more 2 strokes out there!!!!!

[Expat]

May wish to inspect the reed valves. All very easy stuff to do BTW. Just the first time is a little confusing.

Did the 74 have reeds??

[clutch]

Hello landricscustoms

Back on 11/1/2011 I posted for some advise on one of my bikes, a 1974 Yamaha RD 350. I received some responses by others that were helpful. But I took from your reply that you would be interested in taking on the challenge to get this bike dialed in and running, as it should.

Quote: LAndrics BOMO can take care of her. I personally have a specialty in vintage bikes.. And I just so happen to have a specialist on 2 strokes in my pocket... not literally but, you know what I mean.. Seriously, I can get her runnin' right for you again.. pm me or call 774-200-6395

If you are still wiling to help me with this bike. That would be great!

So if you are interested, please let me know how and when it would be best to connect with you.

Thanks, Clutch

[landricscustoms]

yup! we're interested!! give me a call 774-200-6395 or 508-241-2666 (bomo)

[Stromper]

Stay with him but for both of you I have had good sucess bringing old rubber parts back to use by filling the cracks with black silicone.... and it makes them shiny too.

Also points may be fine but old condensor can't be viewed and ignition sucked brand new

[KB]

I would go with crank seals!

KB