Project '71 ('73?) CL350... fuel injection and electronic spark control?

Wow, another year gone by? I really need to get in gear & get this done! Anyway, some renewed progress now that the project car is frozen shut, and a friend at work has introduced me to what is basically a crowd-sourced workshop with welding equipment, mills & lathes, electronics lab, all sorts of stuff - i3Detroit, but anyway, this comes at a great time, since the biggest part of the bike holding me back right now is some welding that I need to do on the fuel rails, tank, and a couple fittings. After a lot of consideration and some mock-up, the general layout I'm planning on going with is this:

So the pump draws from the tank at the location for the stock carb feed valve (through a filter, which isn't shown here), and pressurizes the fuel. Now, instead of sending the pressurized fuel through both rails, in one end & out the other, the rails are on their own spur coming off of the high-pressure side of the fuel pressure regulator (FPR), with only an inlet. Plumbing it this way means that I'll need to make sure that the fuel lines running from the rails need to be continuously getting higher so that any air bubbles that get trapped can make their way up to the regulator to get purged. This shouldn't be a problem with the orientation of the throttle bodies, and by capping the other end of the rail, I'll have less tubing running around out near my legs where it could possibly get snagged, and would need fewer other fittings to complete the fuel system. The FPR will be mounted right underneath the tank so that it's higher than the rails, and can drain right back into the tank.

To get the FPR to work properly, I'm going to need to drain into the top of the tank, so that the fuel pressure doesn't change with the amount of gas in the tank, so to do that I'll need to weld a new fitting onto the bottom of the tank with a tube that sticks up near the top so that the fuel will always be flowing out above the fuel level. For the moment I'm just going to weld an NPT bung to the tank, and plan on using a compression fitting with the tube sticking far through it to accomplish this. I also need to weld another fitting on the tank for the outlet, since the stock outlet is stripped and in poor shape. Then I can worry about re-sealing it where the POR15 coating was flaking off.

The fuel pump itself has proven to be a bit of a problem, since I can't use an in-tank pump (which would simplify life substantially - except there isn't room). The smallest external pump I could find was a Walbro GSL393, which is 155 lpm flow, and will be drawing 5-6 amps where I'll be using it. The problem is that the fittings on the ends are M10x1.0 straight thread, and I've had a really hard time finding much that fits that on one side and ends in a compression tube fitting on the other. I could go to NPT or -6 AN in the middle, but then it becomes really bulky. Instead, I'm going to take the M10x1.0 threaded hose barbs that came with it, chop off the hose barb, and weld on a 90* compression fitting for a nice, compact adapter.

All of the various fittings & whatnot for the next stage have been ordered, and hopefully I can try to get it done later this week or early next week. In the mean time, I took a spare fuel rail and pressure regulator from the project RX-7 and hacked it up and threaded it to give me a nice block to screw in some compression fittings.

I was considering the same idea, and had bought a CBR in-tank pump assembly to try to mock it up, but there just wasn't the cross-sectional area to fit the pump in the tank anywhere near the bottom. It would have required some major hacking & re-welding of the tank. Now, IIRC, the 550's tank is a bit wider, so you may be able to fit it, after adjusting where the pickup will sit and welding on a nice flange. This may be version 2 for me too, finding a larger tank that I can do that with, but for the moment I'm sticking with the external.

The triangle under the seat is already taken by a re-located battery box, relays, and the megasquirt itself, so the only empty real-estate I have is between and below the carbs over the transmission. Ive sat and stared at it for a number of nights trying to figure out where to put stuff so that it all fits, and trying to keep the high-current and high-voltage components away from sensitive electronics & fuel connections.

It's great to see you back at it. This is by far, the most interesting thing I've read on here. Keep up the good work man.

All right!

Most interesting thread on this board, to me. Sub'd. I have a bunch of cb/cl/sl stuff laying around if you decide you need something.

Thanks for all your kind words! What started out as a "hmm... it wouldnt be that hard to..." joking discussion with some friends over a couple beers has kinda taken on a life of its own.

Got some more time to stew over it last night & mock up where the fuel pump, filter, FPR, & fittings on the fuel tank will go. The best place for the pump seems to be laying flat on the back of the transmission, right next to the mount to the frame's spine so I can use that bolt for mounting. This also puts it as the lowest point, so it should have no problem priming/re-priming when I inevitably try to start the bike with the fuel valve off.



Speaking of the fuel valve, it will be in the same location as that picture, but I need to cut off the stock fitting since it's very stripped, and weld on a new NPT bung. The FPR can barely be seen in this next picture - it is way up under the tank (removed in the pic) near the top of the head, so that a continuous uphill run from the injector rails can be made. The little brass fitting in the middle, about 1/3 from the top is the inlet port from the fuel pump, and the high-pressure outlet to the rails is pointing backwards (out of view). The low-pressure outlet to the tank is pointing backwards too, a little higher up.



That position for the FPR should work out, and can be easily mounted to the two center studs at the back of the head holding the cam cover on. Since I'm welding on the tank already, I'll be adding another bung for the fuel return. Im considering putting it on the other side of the tank, but that would force all the fuel that gets returned to flow through the cross-over hose, which may be a restriction when the tank gets low. Plus, I couldn't get a tube inside up to the top of the tank, so it may have to go further forward, requiring tubing to be run forwards over the top of the head & next to the plug wires & coils. I'll need to puzzle on it a bit more before coming to a solution.


All tucked in for the night!

Got a little bit of welding done at i3Detroit last night - still needs a bit of finishing, and man am I rusty with the torch, especially on the thin walls of the tank! Anyhow, now for a couple pictures...


"custom" M10x1.0 to 1/4" tube compression fittings for the ends of the fuel pump


plugged the ends of the fuel rail with phillips-head screws, with most of the screw ground off


This will become the fuel return tube - basically its a section of tube inserted through a hole drilled in the tank so that it ends as close to the top of the tank as possible to keep the return pressure constant as the tank's fuel level decreases. I still need to cut off and grind down this side of it so that I can weld an NPT bung over it to thread the return elbow fitting into for ease of maintenance later on. Except...


Thats where the other end of the tube ended up. Right underneath the cap, which means that if the fuel pump is on when the cap is open or loose, you're getting a nice spray of gasoline IN THE FACE. In theory, this shouldn't happen if you shut off the bike, turn off the fuel feed to the pump, and wait 30 sec or so before opening the tank, but you can't guarantee that always happens, plus it really tests the seal of the tank lid, and the tank "breather" is in the lid, so you may end up flooding that and getting a leak anyway. Basically... I didn't plan this as well as I should have, so I'll be drilling out and grinding off this tube, bending the top around at least 135 deg so it points down into the tank, and re-welding it to remove this potential for disaster.

Anyway, a big thanks to my co-worker who introduced me to i3Detroit so I can get this stuff done and showed me the place last night!

I had a chance to go back to i3Detroit on weds night, and hopefully have the tank finished now! Still need to check for leaks (with water first - i've made that mistake before), and then re-seal the inside, but both fittings as well as a new return tube are welded on.

Return tube welded in & ground flat


Visible, but pointed towards the back of the tank where the pick-up is - much better than before


I thought this bit, welding a nice thick NPT bung onto the thin sheet steel with that much of a gap was going to be a big pain, but it actually went very smoothly


All done with that one! Right around the seam and cross-over tube was a little tricky to get the torch into, but it got done


And the other bung for the return, over the hole where the tube was welded into. I didn't remove the paint in a large enough space around this one, and it caught fire when I was welding. Took me a little bit by surprise, at which point I burned a hole in the tank which had to be filled, explaining that blob to the lower left of the bung.

So, the only welding that I can think of left is for the O2 sensor bungs in the exhaust, and possibly for a fuel pump/filter bracket

Got a little bit done this weekend - received the O2 bungs to weld onto the exhaust, got the new handlebars wired, connected & bolted on, and started putting things back together a little. Notably, the Megasquirt engine controller is installed & I got the firmware loaded onto it and began setting up the inputs. The battery I had for the bike was completely dead & wouldn't hold a charge, so I couldn't crank it over with the starter. However, kicking it over with the MS on and datalogging, it was reading about 600 RPM - this seems a little high for kick-starting, but at the very least I am getting signal from the cam position sensor. Picked up a new battery earlier today which I'll be charging to try again with the starter, and hopefully I'll have more of the sensors wired up to conduct a more thorough test.

At this point, the biggest mechanical tasks to be done are fixing a couple of tiny leaks around the new fittings on the tank that will need another weld bead drawn over them, re-sealing the tank, a little touch-up on the throttle cable mounts, and the O2 sensor bungs to be welded to the exhaust, plus a tiny bit of wiring and wrapping up the harness.

Electrically there's a bit more testing thats involved, and then of course the tuning, but for that to start, the bike needs to make its way out of hibernation in the basement

Don't stop now, this thing is looking fly!!

This weekend I was test-assembling things to make sure all the fuel tubing runs could be made and all the various connectors & wires were where they needed to be & providing signal. There was a small snag - without the injector connectors on, the throttle bodies fit fine, but the connectors hit the middle spine of the frame, keeping the whole throttle body from sitting on the mount correctly. Twisting the TB's around helped a little on one side, but the other would run into interference with the battery box or the TPS sensor. After disassembling & looking at the TBs closely, I realized that I could just rotate the injector so that the connector exited between the fuel rail and TB instead of on the far side of the TB.
to...

Now they could sit the way I had intended so any bubbles in the fuel could get bled out just through buoyancy. An added benefit is that the throttle cable doesn't need to bend as sharply around the engine to connect to each TB, making the routing a bit easier.


The downside to this is that the holes in the injector aren't pointing in the same orientation as stock, so I may be getting more wall-wetting than normal, but we'll see if that seems to be an issue once it fires up.

I also stole the battery from the project car, charged it a bit, and was using it to drive the starter so that I could get a much more consistent engine position/speed signal than kicking it could hope to provide. Anyhow, after adjusting the VR pickup in the cam end cover where the points used to be so that it was slightly closer to the toothed wheel, and fixing a couple settings in the code, the Megasquirt had no problems syncing up to the engine, showing a cranking speed of 250 - 300 RPM, as well as reading the coolant head temperature, air pressure, and throttle position.


Things are getting done slowly, but they are moving in the right direction!

Awesome. I'm still pumped.

Got a little bit of welding done on the exhaust and throttle cable mounts for the throttle bodies. I haven't had a chance to go back to i3Detroit, so this was done with a friend's flux-core mig-style welder; sure, its a Harbor Freight special, but it worked well enough. Not exactly pretty, but oh well

Oh, I forgot to ask, is there a source that anyone recommends for replacement or up-rated cam chain tensioner sprockets? Before assembling everything and filling up the area behind the engine & over the transmission, I'd like to take care of it. I've seen plastic ones pop up on ebay occasionally (although none seem to be there now), but was curious about what else was out there, especially if I could buy one from a site sponsor. Thanks!

Hey, you should talk to toplessFC3Sman over at hondatwins.net

He's doing a very similar project!

I'm so hoping this is a joke.

It's no joke. Seriously, check it out:

http://www.hondatwins.net/forum/viewtopic.php?f=5&t=2951&start=60

Dude... the OP of this thread is the same person.

But maybe the persona over there has info this one doesn't have.....

I'm not sure why I volunteered to argue with idjits... but..... the creator of the thread you are reading right now is the same damn person as that who created the thread over on HondaTwins. Unless two different people choose the same odd screenname... which isn't likely.