I’ve been away for a work project for a couple of weeks, so no tangible work on Buzz during that time.

As is often the case, however, I’m always working on something, usually at least related.

I have borrowed a decent MIG welder and I am learning to use it. I have not yet done anything practical, but I have been practicing skills I will need to make my next manifold, whatever engine it goes on. It’s pretty easy to weld a nice bead so long as you don’t have to stop and restart. It gets ugly then. Welding a piece of pipe to a piece of flat, for example; I can only keep the wire feeding in at the proper angle for about 75 degrees around the pipe until I have to stop and reposition the piece. Then when I restart the weld, she’s not so pretty. I’m sure its just a matter of practice. I’m running out of practice pipe, though!

Assuming I can muster adequate skill to assemble a thin steel manifold, will I really need to? I have not yet spent the necessary time to see if connecting the vacuum line to the fuel pressure regulator will bring the fuel mixture into line. If so, I will instead need to make an adapter to let me put the twin throttle body on a Weber/Delorto manifold for the VW instead. That will essentially be a plate with adapter rings that will either fit around the outside of the TB and seal with an o-ring, or more likely, connect with a short length of hose and two clamps, kind of like on Buzz. The second also gives better physical support, so that’s probably how I’ll end up doing it.

Yesterday and today have been pretty riding days. At lunch yesterday, I got Buzz started with the intent of taking him to and from work, but he was idling funny. I checked and fuel pressure was a tad over 80 PSI. I’ve not seen that kind of pressure except when I had the regulator return line pinched off accidentally, which you may recall burst the pressure relief valve on the old pump. Hopefully, this one has not suffered the same fate. I verified that the return valve is open, but otherwise didn’t have much time for troubleshooting. Perhaps I can take another look tonight.

I knew that the purpose of a vacuum line on the fuel pressure regulator was to help vary fuel pressure according to manifold vacuum. I just didn’t realize that it’s actually pretty important to do that.

Quoted directly from the MegaManual:

The vacuum referenced fuel pressure regulator is essential. It provides constant pressure differential between fuel at injector nozzle and manifold air pressure [port EFI] or atmospheric pressure [TBI]. This makes the injected fuel quantity solely a function of the injector open time.

If you were to ‘cap off’ the manifold vacuum port on the fuel pressure regulator, you are reducing the dynamic range of the injectors. This means you will need lower pulse widths at [idle] (giving less control over idle mixtures) and lower flow under boost (restricting the maximum horsepower).

So, in general, for port injectors, have the fuel pressure regulator connected to the manifold vacuum is a good thing. There is very little reason not to do it (though some have argued against it for individual runner port EFI set-ups).

Ok, ok, hint taken, especially paragraph two. It will be very easy to hook up, assuming there is no pressing reason not to allow the vacuum from just one cylinder to operate the regulator. hmmmm Logistically, it would work really well to T off the MAP signal; perhaps the regulator would serve as an accidental vacuum accumulator and smooth out MAP repsonse… In any case, I hope to have some wrench time on Buzz this weekend. I also very much hope to have some *riding* time on Buzz this weekend.

Speaking of fuel, I forgot and left the fuel valves on again. I’ve been out in the driveway at least briefly most nights this week except last night and saw nothing out of place. Low and behold, tonight I go out and find a big puddle of gasoline under Buzz. Of course, it’s dark and I had no time to troubleshoot, so I just turned the valves off. Next time I go out there, there will be no leak and no evidence of a leak, thus nothing to fix.

In other light reading, I am trying to find specs on this twin TB. As sold, it was described as being for a Kawasaki KFX450R ATV, but everything I can find on the KFX450 indicates that it is a single. After looking around in the parts diagrams on Kawasaki’s website, I’m pretty sure these are from either a Ninja 650R or a Versys, both powered by a fuel injected 650cc parallel twin. I haven’t been able to match the part number on the box (16163-0078) but the illustration of 16163-0084 is identical. Furthermore, looking up parts for the KFX450R (as the box was marked in Sharpie and as the eBay auction described it) reveals a single throttle body, not a twin.

I suppose whatever the throttle body was intended to fit, it changes my conditions very little. I still need to find out what the injector ratings are. Googling for the part numbers on the injectors (ETA287 on one side, 2870581 on the other) doesn’t find them. I also will still need to build a manifold for it.

On that subject, the intakes on the heads are so nearly exactly 1″ ID that it will have to do. That end of the TB is 2.2″ and Buzz’s current TB assembly fits in 5.25 inches between the cylinder head and the base of the filters, , not including the filters. Since two TBs will fit between the frame pieces that currently limit the space available to four TBs, I may be able to stretch that distance a bit. Also, these TBs may be a a quarter inch or so shorter than the ones currently installed, but it’s hard to accurately measure with them installed.

But basically, I will be building two kinda short blocky Y (really more like a J with a crossbar; I need to draw it out and scan it), with a 2.2″ pipe on one end and two 1″ pipes on the other. The engine ends will have flanges and the TB ends will hopefully have an O-ring friendly pipe. The two J/Y things will be joined in the center for both rigidity and to facilitate a bracket to attach the TBs to. Because of TB and cylinder spacing, there will be an almost straight shot from the TB into #2 and a short horizontal runner to #1; likewise with #3 and #4. It’s pretty clear in my head, so hopefully my fabrication skills will keep up.

More ideally, there would be two equal length runners from each TB to it’s cylinders. I could probably accomplish this by feeding #1 and #3 from one TB and #2 and #4 from the other. Again, I’ll have to draw it out and see, and accurate drawings will be much easier the the arrival of the spare cylinder head.

Finally, the simplest manifold may be to simply take a 2″ or so pipe about 16 inches long, tap two 2.2″ TB connections on one side and 4 1″ engine intake connections on the other side and see what happens. No bends, a cap in each end of the big pipe, 4 flanges and 6 pretty much standard fishmouth pipe welds.

By the way, the sub-throttles can definitely be left in place on this unit. One kinda weird thing is that the fast idle cam arrangement on Buzz’s existing set of TBs is kind of done on these as well, but the cam is connected to the sub-throttles. When the are forced all the way open, the cam engages the main throttle, opening it about 1-2%. It would almost be funny if the IAC stepper function of MegaSquirt could be adapted to run this motor. [note: see this note in the VW Trike blog for the answer to that question – Sluggy] Perhaps someday someone will write some support for them into MegaSquirt. I don’t think I’ll ever had the time!

Woohoo! I won a really cheap auction for a cylinder head to use for fabbing the intake manifold for the smaller TB!

FedEx Ground tracking seems to indicate that it will not be delivered before next Monday. Phooey. I’ll be out of town all next week.

I’ve put some brain cycles into this intake manifold thing I’m considering. I’d still like to experiment with fiberglass fabrication at some some point, but I think I can make an effective steel manifold with less trouble overall. One of the biggest things is that a steel manifold will be relatively heat, vibration and fuel proof without resorting to exotic resins and generally speaking will just be a lot simpler.

I’m watching a couple of eBay auctions for cylinder heads, one of which has a broken exhaust flange bolt. That head would probably require repair for use on a bike, so maybe it will stay cheap. The intake side is just fine and I can thus use that head as a jig for building my intake. If that auction falls through for some reason, I suppose I can still use my own engine.

I see construction from relatively simple steel tubing. I could probably use EMT conduit if I had to, but I’d rather avoid burning zinc. I wouldn’t require a lot of material, anyway, so even hardware store quantities of 1″ or 1-1/4″ tubing would be affordable.

I can braze it together if needed. My torch will get hot enough to weld steel, but I have secured the relatively open-ended use of a decent gasless MIG welder, as opposed to the $120 Harbor Freight model that I might otherwise buy. I think this kind of construction might be easiest with an easy to use wire welder.

I also have a line on the short term use of a fairly decent metal cutting chop saw, which would make pretty short work of the cutting requirements for what I see in my mind.

When I get home tonight, I will do some basic layout and measuring to get started with a parts list.

It was a cool, but not unpleasant day today in the carport. I pulled the exhaust system and wirebrushed the area where the O2 sensor would go.

I decided that placing the sensor in the center of the collector was more important than the risk of getting the sensor oily. I marked and drilled the hole. I found, as was somewhat expected, baffles inside the collector. As luck would have it, however, my chosen location was not in the center of a baffle, but rather adjacent to one. I used a die grinder to relieve enough of the baffle to ensure that sensor would have access to exhaust from all four cylinders. The die grinder action went a little wild so the hole turned out a little oblong. At least it’s was smaller than the bung.

I suppose it goes without saying that I ran out of oxygen for the torch halfway through the brazing job, and it being Sunday, I should have just gone directly to Home Depot instead of trying closer places first. Even so, I think it came out very well.

I put the exhaust system back on the bike and mounted the LC-1 just below the steering head. That is probably not the greatest place, but I think it was the best place where the fixed cord length on the sensor could reach. I fished the wiring under the tank without removing it, an easy enough task. Solder on connectors, hooked it up, blew up an LED, another trip to AutoZone to get an almost but not entirely unsuitable replacement LED (I could have found a more suitable LED at Radio Shack, but they were closed by then) and finally fired up the ol’ LC-1.

Following the very simple directions for the LC-1, I calibrated it in open air then reinstalled the sensor permanently (I hope).

I hooked up MegaTune to the ECU and started Buzz up. Immediately, AFR was reading just over 12. I didn’t really need the gauge to tell me that the mixture was rich, but it was cool to see an actual figure attached to it.

I already knew that Buzz’s idle pulsewidth was just about at the minimum and it doesn’t look like I can affect idle AFR that way; the pulsewidth just can’t get much shorter. On the other hand, the pressure regulator seems to have drifted up to about 25 PSI. I need to connect the vacuum line to the regulator. That should let fuel pressure run low at high vacuum and higher at low/atmospheric levels. The lower pressure has also affected starting, so I need to tweak cranking pulsewidth as well.

I tried playing with the autotune feature of MegaTune. As expected, it had not room to adjust anything at idle, but I held the throttle at a few fairly low RPMs and was slightly giddy at seeing it automatically adjust the appropriate cells in the VE table. So, there are a couple of 30-something cells surrounded by 50 and 60-somethings.

That lead me to try again to generate a new VE table. It’s very frustrating that the obvious tool to use seems to think that my realworld parameters are erroneous. It want an idle MAP of <=60, but I’m sorry, it’s 72; that’s as low as it gets at idle. If it’s less that 72, Buzz is spinning down from high RPM with the throttle closed, not idling. Furthermore, I can’t seem to make the table generator happy with the horsepower and torque numbers. I entered the published horsepower spec for the stock bike, 50hp at 9000 RPM, but I tried the actual 9000 RPM (no load) MAP in my log of 79. Nope, sorry, the table generator prefers MAP to be =>90 at peak horsepower. I put in 90 like a good little sheep and it makes a table full of big values. So, I guess the table will be mine to generate manually.

Of course, all this MAP trauma is probably because my throttle bodies are too big, which I have suspected for a long time. I might have to build that intake manifold after all.

It’s still fun, in a kinda masochistic way