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Ya i imagine a non heated would fould up fast. My idea to get exhaust gases from the combustion chamber involves tapping into the little passage above the exhiast port and feeding it to a small chamber housing the O2 sensor. The outlet from the O2 chamber will be smaller than the inlet. My thinking is this will keep the pressure high enough in it so no intake charge can be pushed back into it. The combustion chamber pessure should be pretty low at that part of the stroke on its way back up.

Hey... weekend is almost here :)

I was looking into O2 sensors for two-strokes but the more i read the more it seemed like that are just regular heated O2 sensors... some two-stroke bungs are longer to keep the sensor out of direct exhaust flow, tho. I wont be drilling a massive hole into my stock pipes and welding anything to them... dont want to damage the chrome and it'll just look ugly. I have an idea on how to get exhaust gasses without having to do that... and if I dont go that route I will build an O2 sniffer and just stuff it in the end while I do my testing.

I think those O2 sensors in the E-Tecs last because those machines barely burn oil at all. Im guessing their oil injection systems send oil right the the cylinder walls and crank negating the need to use loads of oil because most of it will tumble out the exhaust. I think, anyway. I'll look that up sometime.

Did you see the price of those EGT's on ski-doo website?  ha! ha!   $100.94 - $182.64   effing crazy, what a scam.

I'm not even going to drill into my header pipes for the EGT's. I found a couple on fleabay that are rusted to hell. They will be used for testing. I wouldnt dream of ruining my stock ones.. the chrome is perfect. Once I get the Dyno working and sorted I will make loads of runs at each throttle % and rpm and log all the data. That will be enough for me to work with I imagine.

I was out in the garage... removed the rear wheel and fender to make room... sizing things up at this point. I think I have arrived at a good plan of action of how the dyno cradle will be built and sit back there. I found out these gear pumps use gears and chains with #40, #50 etc sizes and lucky me none of them fit a 520 chain. I ended up with a #50 because it has the same pitch but it's way too thick so Ive been trying to grind it narrower and evenly. pain in the rear :(

Been collecting parts...  just need to find an old propane tank to use as a reservoir.

I love how she looks like a stylish woman headed off to work in her jet shoes

quick question now that I see this thread... my rubber dampers came out easily and go in easily. Does that mean they are gone?

Thanks for the feedback, savOr :)

Thats pretty much my plan.. I'll be doing carbureted and stock ignition timing runs on the dyno and plotting EGT, CHT and O2 readings.. as well as torque produced. I ordered a 30kg load cell to plot that as well. It'll be invaluable data to have and compare against.

I just wish I had it as good as the 4-stroke guys with their O2 readings cause they get to know exactly what air/fuel ratio they are burning but I think with the outputs I have I should fair pretty good.

I have access to a 12x12 or 16x16 fuel and spark tables but I think since this bike can't reach 8000 rpm 16x16 tables is overkill. Plus 12x12 will be less of a headache to work with. I'm thinking about recording everything I do so everyone can follow along on youchoob and give me feedback and ideas on how I might do things differently. This is all a first for me so the more brains I have access to, the better.

I got rid of FB ages ago.. too much drama with my bonkers family.

I found this calculator for gear pump hp. I put 3000 psi and 17 gpm and it says 31 hp.

http://www.metaris.com/hp-calculator.php

Can I assume this means I can run a 31hp engine on it? If so I think it's a safe pump for 1 powered cylinder at a time like I was planning. I think the most I'll see is 20hp from 1 cylinder.

Wow that is a very cool bike and setup! I had no idea anyone had gone about it with an aircooled RD. I wonder if he is using the stock ignition. He's running a missing tooth setup so I'm assuming he's controlling spark unless the ECU he used isnt able to get ign pulse through coil with an opto isolator like I can with the Microsquirt but since Im doing ign curve as well I'll use the VR sensor of the Vape.

It said he tuned by the seat of his pants and logging during rides. Thats what I was planning on doing but I wouldnt even dare tune a ignition curve by the seat of my pants. Thankfully the dyno im building will be able to hold steady rpm and plot torque curve as I mess with spark and fuel.

Annoys me though... every time I see someone EFI'ing a two-stroke they always point out they are using O2 sensor but never acknowledge the unburnt oxygen that might be effing up the readings. I have an O2 that I will use but I wont trust it. Actually I have an idea on how to avoid the scavenging cycle unburnt fuel issue.. once I flesh it out I'll pass it by you guys. One thing at a time! Im finalizing in my head how exactly I will build frame to hold the pump between the swingarm and have the bike's stock chain drive it.

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

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

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

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.

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.

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

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