Project: Cafe 2 Pump Chump (77 RD400)

[xjoey dubsx]

The RD, soon to be cafe..
1977 Yamaha RD400
2 Stroke
15k on the clock. Got it cheap, needed battery.

Video:

 

[xjoey dubsx]

Picked up a battery and took it out for it's maiden voyage yesterday...
Started up 2nd kick, took it to the gas station, then filled up the oil tank too.


1st thing that I have a question about... What would make it seem like it has no power in the RMPs? I can get it going, basically revving it, or it barely will make it without stalling, but on the top end of first gear, it hauls. Same thing in 2nd gear... Any idea why? Carbs? Spark plugs?
I got new spark plugs, so just gotta spark them and throw them in...


2nd thing... I was riding it no more then ten minutes then it kept stalling out, hard to kick over... The kick start even seemed stiffer.... I know the boots from the carb to the air box were barely on, so I put them on completely and it seemed to stop the stalling issue.. Not sure if that was it..


3rd thing.. Would it hurt putting on the dual cotton filters, like K and N on them and getting rid of the air box? Any problems? I know on quads, alot of people recommend not putting them on for what ever reason...


I'm sure I'll think of more..
Completely new to 2-strokes and restoration of bikes, so any help is appreciated!

 

[Spoonz]

Sounds like a jetting issue, carbs are more than likely plugged up. If you are gonna run pod filters you will need to rejet. Get it running correctly before you change filters then rejet accordingly.

 

[xjoey dubsx]

Sounds like a jetting issue, carbs are more than likely plugged up. If you are gonna run pod filters you will need to rejet. Get it running correctly before you change filters then rejet accordingly.

Think cleaning it and using a rebuild kit would fix it more then likely?
Any recommendation what to jet it to with pod filters?

 

[Spoonz]

Start with cleaning and rebuild kits. Replace jets with stock size, even if they look clean they may not be. When it comes to jetting when doing mods every bike is different wether they are 1 number apart or 1000 on the build line. Get a good assortment of main jets and idle jets, you will need them.

 

[Spoonz]

also make sure the exhaust is not plugged up. Pull the baffles fire it up rev it alittle and shut it off. When you do this see if anything comes out. When you rev it don't take it over 5000 and don't hold it cause you can fry a piston

 

[teazer]

Pods don't usually work well on an RD. Best filter is the so called Y boot with vertically mounted K&N. Spec2 sell them IIRC. Pods tend to run lean at the top end and rich off idle. With rods you will run way larger main jets and still have part throttle stumbles.

The carbs need to be spotless and it's always a good idea to start with fresh plugs and a thorough check out and service from stem to stern.

That "harder to kick over" comment worries me. Sounds like it stalled because it was seized and the reason it seized was probably the air boots hanging off making it run lean. Pull the plugs and let's see what they look like and pull the left head off and inspect the bore and if it's OK pull the right head off. No coolant or oil in there and the top comes off in seconds.

Before you run it again, I'd recommend that you clean those carbs and clean and set the points and timing.

 

[xjoey dubsx]

What symptoms would tell if it was? Some times it seems like it isn't getting best air flow out and suddenly frees up and runs better, part of that first gear problem.

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[honeybadger]

Clean those carbs, clean out the gas tank, make sure the floats aren't sunk (that was the problem with my bike, just shake 'em and listen for gas inside them) and make sure everything is SEALED (gaskets included) from the carbs to the head.


Cool bike though, I REEEEEEEALLY want a twosmoke

 

[xjoey dubsx]

Clean those carbs, clean out the gas tank, make sure the floats aren't sunk (that was the problem with my bike, just shake 'em and listen for gas inside them) and make sure everything is SEALED (gaskets included) from the carbs to the head.


Cool bike though, I REEEEEEEALLY want a twosmoke

okay okay i'll buy the rebuild kits! haha.

The gas tank was dead empty when i bought it, and just filled it up, so i'll run it dry again and then clean it.
How do you recommend I do that?

 

[darkhorse]

Good come up, get that thing running good and you'll be grinning ear to ear.

Rebuild those carbs. Sounds like your problems and it will also give you a better idea of how the bike works and make diagnosing problems and jetting for mods faster in the future.

You should also make sure the battery is charging. A new battery might mask an electrical problem (I had a grip on mine). Put a volt meter on the battery, should be around 12 volts at idle and then spike up to around 14 volts around 2-2.5rpms

 

[teazer]

Forget the rebuild kits. Just strip and clean the carbs. and pull the heads off to check for smearing on the cylinder walls

 

[xjoey dubsx]

Any how to's for rebuilding these carbs?

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[teazer]

Carefully remove the top cap and slide. Take out the needle. Remove the float bowl and float. Unscrew the jets and air screw. soak in a can of Beeryman's or use an ultrasonic cleaner. The dry and blow through all the passages with a can of carb cleaner to be sure that both carbs blow the same amount.

I'm sure the Haynes manual shows you how. And grab a parts diagram from an on-line store just to double check.

 

[bradj]

It was starting to lock up you probubly scored the skirt of a piston when that boot fell off (lean and mean)

 

[xjoey dubsx]

Well the 20th, I took my bike out again after I tighted those rubber hoses tighted up and it runs much better. No problems with stalling or anything! Still low power in the lower end of the RPMs but getting use to it and learning how to control it to get up and going with a little more ease.

Took it out again, and still running good! First around my neighbor hood, then to my buddy's condo. I've put 30 miles on it now, and can't wait to start getting more stuff!

I got new plugs for it still haven't put in like I noted before, but the ones in it seem to be good. I need to find out what the gap is supposed to be, before I put the new ones in.

First big purchase will be early next week consisting of:
Black Clubman Style Bars
Grips
Shocks and Springs


Was going to buy carb rebuild kits too, but going to wait until after I clean them up and see if it's needed. Hoping I can just clean them up and see how it goes.

 

[teazer]

Carb rebuild kits are a waste of cash IMHO. Just buy any parts you need from your dealer or any jetting on-line store and get genuine Mikuni parts that are the right sizes.

 

[Spoonz]

Carb rebuild kits are a waste of cash IMHO. Just buy any parts you need from your dealer or any jetting on-line store and get genuine Mikuni parts that are the right sizes.

Don't bother replacing the gaskets and seals in these thirty some yr old carbs, so when you take them apart and reassemble with the old crushed gaskets and dried out seals they leak like a siv getting gas on the nice hot engine, you, and create a fire hazard. Not to mention suck air in every seal above the fuel bowls.
Sorry, anytime I pull the bowls, I change the gaskets. And the first thing I did after getting my RD running was to replace all the seals and "O" rings in the carbs. Really made a difference. Try HVCcycles.com they have alot of parts for this bike and prices are reasonable.

 

[xjoey dubsx]

Rode the bike to work. Guy who knows all about rds said the carb cables are not synched hence why I have the hesitation in the low end. Its leaking oil too, so I'm not going to ride it until those are fixed. 15 mile ride home on main roads, and put a quart of oil in it on the way to work, so hopefully it'll be okay on way home.

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[xjoey dubsx]

Little work done today..

Most important thing I got done is figured out where the oil leak was. The cover for the oil injector was loose, and had oil dripping from it. I didn't know what was under it, then realized there was only one bolt actually on it. Took it out and noticed the one hose coming into it was cracked right at the barb fitting. I went and got a few feet of hose and replaced both the hoses to be safe. Then notices the other two threaded spots for bolts had bolt ends broken in them, so need someone to help me get them out being I don't have extractors myself.​

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Also, as silly as it sounds, thought it didn't have the regular kick stand because I didn't see it, but it did. The arm off of it is apparently nonexistant anymore, but kinda like it because it's hidden. Also took off grips. Nephew decided he wanted to ride since he just picked up a Ninja 500, so put about 15 mile on it putting around the neighborhood with no grips. I really need to get the carbs cleaned and adjusted... Anyone near Cleveland wanna help me? If not going to take it in soon, if I can't find help..​

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Ordered today from work (Well our affiliate company, JCWhitney):​

Hayne's Manual​

Drag Bars in Black​

Grips​

New Shocks(Black) and Springs (Chrome but will probably end up getting P/C'ed black)​

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