Might EFI my 1976 RD400 this winter

[sav0r]

The reason i asked is because you mentioned the two ways to adjust mixture.

With a dedicated cold startup map, things get so much easier. Most race cars don't run closed loop, they just load the right map for the conditions manually. Of course that seems like a lot of work (changing maps manually all the time), except that with cold startup the hot run maps might only need to be changed like three times a year. I assume fuel economy isn't a major concern... There are less map changes if you aren't running all winter long. Alpha N is the best option, but it introduces a lot of testing and messing around that I'm not sure you will really benefit from.

That said, it seems you are approaching this as a challenge and something you find to be fun, so in that sense I encourage you to push yourself as hard as your prefer.

[rd400canuck]

You are correct! Only doing this for the enjoyment and experience... need a project over the winter.

Im going to install everything in a way that allows me to put the carbs back on in a jiffy and be able to ride. I wish I had a damn dyno, that would make everything so much easier to tune. Id like to see just how good I can get a total stock bike to run with custom iggy map and fuel maps. I'm not too worried about tuning the fuel map but I do worry about the ign map. Id hate to destroy my motor trying to find the best advance for each rpm. My plan is program in the HPI ign curve because I already had that on my bike and it liked it and didnt melt on me. After than I'll carefully play with advance/retard and see what I can come up with.

Im also fairly certain I can get Speed density to work. The RD400 might have a little more vacuum signal to work with than the RZ I tried in the past (80 to 100), maybe.. and also there is no crossover tube that allowed the vacuum to draw from the other side... im guessing without this tube I'll see more of a vacuum.

Ordered a fuel pump from Aliexpress... 45lph and only draws 2.5 amps so 30 watts or so. Hopefully its not a piece of junk.

[rd400canuck]

Did a little test to see what kind of vacuum signal the RD gives me and it wasn't good. However, I used the oil injection nozzles for vacuum so when I use the actual throttle bodies with their proper vacuum ports it might be better but at this point it doesnt look good for Speed Denisty for the fuel table. The signal spiked between 100 and 80... completely unusable.

[rd400canuck]

Hi guys.... been reading about dwell time as there are settings in the Microsquirt in milliseconds to set...  From looking at the ignition coil I dont think this is a CDI and is an actual coil.

Can anyone shed light on dwell time for me in this case with a VAPE?

[klaird]

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[m in sc]

dwell in regard to what? ignition fire time, or trigger length, or injector pulse signal?  yes the vape is a cdi. the circuit is in the coil.

[rd400canuck]

Hey m in sc,

I was wondering about dwell time for coil I am guessing one would call it. I got some incorrect info on the microsquirt forum and was told VAPE is not a CDI type ignition. I have since figured out that it is and am told there is no dwell time for the coil... the cap just takes the juice that is sent to it until the ignitor circuit contained within the coil housing gets a signal from the VR sensor.

The microsquirt has a setting for this called 'Time after spark' and it was suggested I set the dwell time for the spark to 1 millisecond and that'd be long enough a signal to allow all the stored energy to make a spark. Im not certain why at this point but I couldnt select 1 so I put in 0.9ms

Originally I was only going to have the MS control the fuel but after my time with the HPI ignition I figured it made sense to use it to add in a spark curve. I needed the VAPE anyways for the 150 watts to run the fuel pump and the MS will fire the VAPE CDI/coil assy. My intention is to set it to static 10 degrees to mimic stock timing and then make sure the bike runs and feels similar and all is working as it should then program in the HPI curve.

[m in sc]

fyi stock isnt 10. its closer to 22 on a 400, 19.9 on a 350. just fyi.

[rd400canuck]

fyi stock isnt 10. its closer to 22 on a 400, 19.9 on a 350. just fyi.

Oh! I have no idea why but I was always under the assumption stock for rd400 was 10 btdc. Thanks for cluing me into that. I am planning on printing out a degree wheel and putting it on the vape flywheel to check for tdc and stock timing.. and afterwards the hpi curve i program in.

I'm now also looking into building a hydraulic pump dyno. For the cost of a couple dyno sessions I can build my own. Would be so great to hold the bike at a steady rpm and throttle % and adjust the fueling and spark while I keep an eye on EGT's, CLT and probably the O2 readings. If I go this route it wont be till summer. Just starting my research now.

[teazer]

The confusion may come from some of the old advance curves on line that show 10 degrees of advance in some CDI units back in the day, but that wasn't the static timing.  That 10 degrees was initial advance over stock static timing of 19 degrees on a TZ, so the "curve" was 19 at start, rising to 29 or so at low revs and dropping back to 19 degrees by 10,000 RPM.

Not sure if that's where 10 came from, but it's easy to be confused by the info online.

[m in sc]

just realized i never uploaded  this.  also added in the tech library under 'ignition'

[rd400canuck]

Thanks guys!

Ive been reading and researching the hydraulic pump dyno... so many guys start out to build them and then the threads just stop and they are never heard from again. I did find a few guys who completed their projects and am learning things not to do for a decent setup. I'm fairly certain I will set out to build my own, they seem pretty straight forward. A sufficient pump and needle valve aint cheap but if i do this right I'll be able to hold it at a certain rpm and throttle open and with a load cell I'll be able to add/remove fuel and spark and have it plotted out in real time so I can see where max torque is produced then back things off so advance and fuel are on a good safe setting. I'll be monitoring EGT and O2 so hopefully this should prevent me from melting anything.

I think it'll be worth it in the end if I can arrive at a good tune and the get the most from this motor in stock form. Better money into this dyno rather than rebuilding a melted motor.

Right now just waiting for EGT amplifier boards and fuel pump then I can slowly get started. Should be an interesting winter.

[rd400canuck]

Just want to pass this by everyone... for feedback...

The pump im planning on getting has a max of 36hp. The ones big enough to handle the RD400 are too much $$$$

My plan is to only do one side at a time. I will remove the rings from one piston and leave the head off. I will apply some bearing grease to the cylinder walls so that there is always lubrication. This side wont be getting fuel, either, obviously. I will then run the bike powered by the other cylinder and tune its spark and fuel tables. This way I wont have to buy and expensive pump and can get the $150 instead. I'll be dealing with less flow and pressures as well which I'm happy about. Then I can follow the same procedure on the other side.

Anyone see any issues with this? I'm assuming the un-powered piston will be fine revving for periods of time while I tune the other side but I want to make sure I'm not missing anything.

Here is the pump I'm currently considering.
https://www.amazon.ca/Hydraulic-1-4in3-4-15gpm-31-3HP-3000psi/dp/B091JR95PG/ref=sr_1_7?keywords=hydraulic%2Bgear%2Bpump&qid=1638385538&sr=8-7&th=1

[m in sc]

can you under drive it by, lets say 1:2 and then double reading for output numbers?

just spitballing.

[Striker1423]

The issue I see is the flow between cylinders that exists in the bottom end. The labyrinth seal isn't air tight. It allows flow between the two. Also the little end bearing and main bearings get fed lubricant through pressure dispersion in the bottom end. Without a spark plug sure, go to town for short runs, but  without the head, or supply to one side or the other... I wouldn't. just my 2 cents.