Might EFI my 1976 RD400 this winter

[rd400canuck]

Hmmm... never thought about that seal... bugger.

As for the big and small end bearing on the none powered side I was planning on putting bearing grease on them as well through the intake port. Now that I think about it I'm going to have the cyl off to remove the rings so I'll just grease them up good then.

I dont think gearing the pump down will work.. the needle valve will still need to deal with pressure regardless of gpm and the pump can only take so much pressure. To keep the motor at a steady rpm and full throttle there would be less flow but the pressure would be too high for the pump rating. I am planning on gearing it down anyways... Id like to keep the rpms in a swath that will work for all engine rpms..  500 to 2500rpm... under 500 its not smooth running and the pump manufacturer recommends min 500 for best operation.

I think I'll trying my method and see what happens... as long as the proper mixture ratio is being sent into the crankcase I should see the combustion properties even if some of it escapes to the other side....   unless it sucks some clean air back in.

Perhaps I will have to just remove the rings... grease everything up. have the head on and have the injector operating but no spark. That way anything that goes between the two cylinders will have the same air/fuel ratio

[rd400canuck]

Anyone know how I can calculate the counter sprocket rpm in each gear vs engine rpm?

[m in sc]

math.

rpm x primary ratio x gear ratio of given gear = output shaft rpm. (primary and gear ratio in decimal format).

  that easy.

[rd400canuck]

ok perfect... I guess I could have figured that out if i had thought about it for a second  lol.

I have been looking into the gear pump dyno and there is a place called Princess Auto and the parts I need are pretty reasonable... except the needle valve... $80 cdn :(   There are loads on ebay etc for half the price but specs are skint. I need to make sure it's good for 3000psi and at least 20 gpm. more searching needed.

I've decided since im going to all this expense and effort (i love doing it, tho) I should just go ahead and start building the dyno. I'll have a 0-5v 20kg load cell with a 12inch arm and 1lb = 1 ft.lb torque. I can calculate hp with engine rpm If im interested in that. Not sure how accurate it will be but at least it will be repeatable. Since the load cell is 0-5v I can actually feed it into one of the sensor inputs on the Microsquirt and it will graph out in real time along with throttle %, rpm, spark advance, injector pulse, O2,EGT as well as CHT.

I should be able to hold it at a steady rpm and throttle and then add/remove fuel and spark and immediately see a torque curve and know where max is then back off and keep things in a good safe zone. I have no desire to tune this thing on the bleeding edge.

So now I will turn my attention to building the dyno and testing it with current carbs and static timing so I can see before and after.

Gonna be a fun winter.

[m in sc]

trying to regulate flow? consider a v port valve. (this is actually what i do for a living ;) )

[rd400canuck]

trying to regulate flow? consider a v port valve. (this is actually what i do for a living ;) )

Will that give me more linear control?

I notice on youtube some guys with needle valves hit a very narrow area of the knob that bogs the engine to the desired rpm and the littlest turn more will drop rpm significantly. This is one of my concerns actually... id like a valve that will get me a nice linear control over the motor without hitting a wall.

[rd400canuck]

math.

rpm x primary ratio x gear ratio of given gear = output shaft rpm. (primary and gear ratio in decimal format).

  that easy.

I seem to be doing something wrong...   for first gear;

7500 x 2.869 x 2.571 = 55,321 rpm

Should I be dividing it?  I get 1,017 rpm in that case

[m in sc]

yeah that looks wrong.

for example, rpm at 5000 rpm. if the primary is 34 teeth by 64. 34/64= 0.531 which would give the input shaft speed at 2656.25 rpm. and so forth.
then, for example, if 1st gear is .68..   2656.25 x .68 = 1806.25 rpm at output shaft.  and so on.

the primary is always there. also, those numbers I gave are NOT for the rd, i just listed it as an example. I'm -sure- somebody (socal250?) has the ratio info somewhere. I dont right now.

and yes, v ports are linear flow depending where they are and flow a lot better than a needle valve.  (volume that is).  you can get them in keyhole style, 15, 30, 60 and 90 degree v depending where you get them.  we sell them in packages with 4-20 mA positioners on a regular basis.  you can control them manually as well.



 

[rd400canuck]

Thanks for info on v ball valves,

I am getting primary and gear ratios for the RD400 from this site's archives. I'll have another look at the numbers. They also list a secondary.. should that be put into the calcs?

file:///C:/Users/johnh/Downloads/Yamaha%20RD400C%20RD400D%20Parts%20Catalog.pdf

[m in sc]

secondary usually refers to chain and sprocket.  .02


what pressures are you looking at on this line? that's going to be one of the biggest factors on valve choice. .if its going to be over 3000 psi then you're probably going to have to go with a parker style needle valve or the like.

[SoCal250]

As Mark pointed out, secondary ratio is referring to sprockets
Here's the ratio info for the trans and primary. From looking at your previous numbers it appears that you probably already have this
Primary: 66/23  2.869

[rd400canuck]

Hey guys,

The pump I think will be around max 3000psi and 3000rpm 20gpm (depends on which one, another has 3500rpm max) but I need to buy the correct toothed sprocket for the pump to be driven off the stock toothed sprocket on the bike so that in whatever gear I choose for the runs it is within the rpm limits of the pump while the bike is revving from 2000 to 8000rpm. I'm hoping there is a combo of counter sprocket and pump sprocket that will allow me to stay in one hear and do all my rpm holds on the bike. Most of the pumps I'm looking at suggest a min of 600rpms for smooth operation.

Was just at Princess auto and the place is like candy store. They have everything I will need to build this thing. They didnt have any v ball valves tho... just the $80 needle valve I see most guys using.  It's rated for 3000psi and the 4 ft hoses are rated for 3500psi.

I think this pump is good for what I need  https://www.princessauto.com/en/197-gpm-hydraulic-gear-pump/product/PA0008375446

[m in sc]

yeah, highest rated v port valve ive seen is 2000 psi, wont work.  that place looks fun. 

[m in sc]

hey, have you seen this? guys doing a 400 now on the FB rd group.

[Striker1423]

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