Category Archives: 70-something Stires Trike


In no particular order, here is a checklist of things that must be accomplished to run this engine on MegaSquirt EFI.

1. Intake fabrication
a. mount intake boots to plate
b. mount intake manifold to engine
c. mount IAT to TB
d. mount TB to intake manifold
e. adapt throttle cable to TB

2. mount trigger wheel on crank pulley and install
a. clean, mark and drill stock crank pulley
b. bolt trigger wheel to pulley.

3. mount trigger wheel sensor on block
a. Bracket fabrication

4. mount fuel pump in tank
a. Sand bottom of tank clean
b. Cut interface ring and drill/tap it
c. Cut big hole in bottom of tank
d. Weld or braze ring to tank
e. Cut gasket and bolt in pump

5. Cylinder head temp sensor
a. May just use standard GM sensor

6. Mount controller

7. Lots of wiring

8. Tune

Intake Work

I finally got started on the throttle body adapter!

Using the gasket that came with the intake as a pattern, I cut a piece of 3/16″ plate to shape and cut the holes in it.

I struggled for a couple of hours trying to fit existing tubing and a couple different O-rings to the base of the throttle body. I tried using exhaust reducers. They came the closest to fitting and I guess it was worth trying, but the only combination that seems likely to work will be to gently stretch a 2″ fitting so that the smaller diameter end is very slightly larger than it is now. It will not be easy to do that and keep it round and O-ring-sealing smooth.

Luckily, I may not need to. After noticing that my hatless short sleeve work uniform was inadequately warm for the falling temperatures in the carport, I came inside and found that a best offer I’d submitted on a pair of actual EX650 intake boots was accepted.

There is a slim chance that I may have to remake the plate for these intakes, but it will be worth it to not have to deal with the precision required to seal and attach the throttle bodies to the intake manifold!

Since I’m waiting for parts now, I thought this might be a good time to apply some thinking out loud time to X-Tau acceleration enrichment.

In short, this is an enrichment that compensates for how much of the injected fuel sticks to the walls of the manifold. This is another one of those things that I’m so very glad that someone else had to figure out. As astonishingly brilliant as I am, I’m not sure it would have occurred to me. Anyway, the problem is that a percentage of the fuel going into the manifold sticks to the walls. This fuel eventually evaporates and makes it to the cylinder, only to be replaced by more injected fuel. In a steady state load, the sticking and evaporating fuel reach an equilibrium, but it can become a significant factor with changing loads, making the mixture unexpectedly lean during acceleration and unexpectedly rich during deceleration.

It would seem to me that intake tract length could be a large factor in this phenomenon, and in my configuration will in fact have a relatively long intake tract.

On Buzz, the intake tract was about 5 inches between the injector and the intake valve and there just isn’t much manifold wall to stick to. That doesn’t mean that it’s completely not a factor, only that its a small factor.

On the VW, in my configuration at least, there is a good couple of feet of intake tract between the injector and the intake valves. Additionally, the intake tends to be cooler near the injector and warmer near the valve. This temperature differential is why most VW manifolds have tubes to circulate hot exhaust gases through the manifold, so that the temperatures along the intake tract will be more consistent. A cold manifold will condense vaporized fuel, exacerbating the manifold wall wetting problem.

Honestly, getting the engine running will not require much attention to X-tau compensation, but tuning it for best performance will.

The Usual Delays and the IMS

Sometimes, it sucks to work.

I have spent most of what would otherwise have been a great week to work on the dragon trike in New Mexico working. I enjoy New Mexico and I like our people there, but I wanted to stay home.

Even after spending the week out of town, I wasn’t going to forsake the Dallas appearance of the International Motorcycle Show to work on the trike. Overall, the show was pretty good. Enjoyed seeing the Ducati stunt team. Nothing sounds quite like a Duck. Found that for all the hype, the Honda Fury is unridable for the same reason most other choppers are. Long bike, long seat, long pegs, short bars. Who want’s to ride when folded into a cramped “C”?

The bigger problem with the show was with what was missing. This is my third year attending. The first year it was held at the Fort Worth Convention Center. Besides being my home town and essentially walking distance from work, the Ft Worth show seemed much…. I don’t know, “fuller”. More vendors, more manufacturers, more.. stuff. Last year in Dallas, there were fewer bike vendors than the previous year in Fort Worth. Absent in Dallas last year were names such as Moto Guzzi and Vespa and Kymco that were prominent in Fort Worth the year before. Similarly, some notables were missing this year, like Victory, KTM, Triumph, and of course, Buell.

We still managed to have fun and shop a lot.

One thing that occurred to me suddenly whilst I was in the Kawasaki pod was that my plan to use the throttle bodies that were apparently from a Ninja 650 might be simplified by the acquisition of some stock parts.

One of the part fabs I will need to do is some kind of adapter between the TB and the manifold. The Ninja (or the Versys; they use the same engine) has to connect the TB to the engine, so maybe their connector can be adapted to my manifold easier than building something from scratch. According to Kawasaki Parts House, they are only about $20 apiece. Unless i can get RIGHT on fabricating something, I will probably order a couple of them.

Some parts arrive

Today, I received my manifold and my throttle cable parts from Flanders.

A lunch, I mocked up the TB and manifold and measured the combined height. I think I have 10 inches clearance under the fiberglass, as measured from the top of stock manifold cross tube.

Allowing for a little more than 0.25″ for the adapter plate and gasket, I only have about 2.25″ for an air filter. I think I can use a K&N RC-2380, which is a single filter with two flanges 75mm apart or RU-1822, which is a set of two filters identical to Buzz’s four. Obviously, I can rob two of these filters from Buzz for the time being. In fact, I’ve had one as a carb cover on this engine already.

To adapt the TB to the manifold, I will make a plate (or two joined plates) from 1/4″ stock, using the gasket as a guide. Atop that plate will be two cylindrical rings large enough for the base of the TB and an O-ring to slip into. It will have a bracket of some sort to secure the TB to.

The throttle cable is pretty normal throttle cable stuff. I had originally ordered parts for this trike, but used them on the Yellow Trike. These that arrived today are pretty much just replacements for those. Of course, now I need to connect it to the TB eccentric instead of the carburetor.

Finally, while this is not particularly EFI related, the guy at Mid Cities Cycle called, announcing the arrival of the switch pod. This will allow me to wire all switches except for the key switch to the left handlebar, just like the Yellow Trike, except that I won’t fry the start switch on this one. The solenoid on a VW starter pulls way more current than the little switch could handle. The simple addition of a relay addresses the issue nicely.

The body is on; so is the rush!

This blog is about the MegaSquirt conversion of the engine in my VW powered trike. There is another blog about other parts of the reconditioning of this trike and another at my trike blog. The trike referred to here is currently known only as either The Purple Trike or The Dragon Trike.

With the trike in place at the BTW clubhouse, I took the body off and set about trying to start the thing up. It hasn’t run since I took all the intake, ignition and charging components off to install motor bling.

Before and after:

Even before it came apart, it wasn’t running right and with the benefit of the experience troubleshooting the Yellow Trike, I now realize that I probably have some form of intake leak. On The Yellow Trike, it was around the throttle shaft of the carburetor. This one appears to have about as much play as that one did. If it turns out to be that, I will borrow the new carburetor off the Yellow Trike to get this one running enough to know that there are no other intake issues, then I will crank up the EFI project into overtime because I see no reason to spend $160 on a new carburetor to use temporarily.

Of course, in the attempt to test fire the engine, it appears that fuel is not getting *to* the carburetor and that even if it were, the battery is too low to crank it, so while the charger tops off the battery, I am here typing away. Which give me some time to organize my efforts.

I have elected to rob the MSII and Innovate O2 sensor off Buzz to get the trike running. That will save me about $500 in parts and shipping and waiting. I will need to get a DB37 connector for the wiring harness and find some kind of weatherproof box to put all the guts in, primarily the MSII controller, relays and fuse block. It should be big enough to put the trike’s other fuses and relays in as well.

A suitable intake manifold has been ordered and has in fact been shipped and is scheduled to be delivered this Thursday (11/05/09). Once I have it in hand, I can make the adapter plate to attach the motorcycle throttle bodies to it.

After that, comes lots of little bits that need to be done. In no particular order (and subject to change):

Attach trigger wheel to crank pulley and install (change belt)
Mount trigger wheel sensor
Mount EDIS module
Mount EDIS coil and wires
Wire EDIS system
Pull distributor and plug hole
Put fuel pump in tank
Put fuel gauge sender in tank (not really EFI, but should pull tank only once)
Plumb fuel to TB
Cylinder head temp sender for CLT?
IAT on/in TB
Lots of tuning.

70-something Stires Trike

I found and purchased my VW trike even while I was working on Buzz so perhaps needless to say, I am planning to ‘squirt it, too.

As is wise in such endeavors, I have been gathering some parts that will be needed for it.

I have the in-tank fuel pump from a Ninja 650 motorcycle. I think it will be easy to put it in the existing tank which is basically a welded up cube.

I am slightly concerned that the sump may hang down low enough to drag, but there is room to move the tank up on its mounts, too.

I have a set of thottle bodies that were supposedly from a KFX450, but appear instead to be from a Ninja 650 or maybe a Versys. The throats of this set of throttle bodies are set at 75mm between centers, which corresponds to the spacing on several Weber and Delorto carburetors that are popular on VW engines, so it should be pretty easy to adapt them to readily available manifolds.

The EDIS ignition I got for Buzz could not rev as high as Buzz’s engine, but will work perfectly for the relatively low reving aircooled VW engine. There is ample precedent for adapting trigger wheels from various Ford engines to the crank pulley on the VW.

I will probably borrow the WB O2 system off Buzz, probably temporarily, but maybe permanently.

After those items, the biggest thing left is the controller itself. I’d like to use a Microsquirt, but I will probably just get another kit from DIYAutotune.

More to follow….