TPS mount & plumbing

A little more work on the project over the weekend. I have fabricated a mounting plate on which to mount the TPS to the end of carb #1. This is simply a 3mm aluminium plate shaped to incorporate the TPS mounting holes and fixed to the carb through the top clamping rod and by way of a threaded hole into the side of the float bowl chamber. The clamping rod end needed an additional 3mm spacer in order to bring it level with the float bowl chamber.
The movement of the throttle will be transferred to the TPS through an M3 bolt whose head has been ground flat to fit in the TPS. The end of the throttle rod will been drilled and tapped to take the bolt. To fix the position of the bolt in place, both a locking nut and thread locker will be used.

TPS mount plate

TPS in approximate position.

The fuel pump mount has been cut out of the ZX6R tank ready for transfer onto the spare mc22 tank. It seemed a pity to cut up a perfectly good tank but all for the better!

ZX6R fuel pump flange

A mock mounting of the throttle bodies and fuel rail revealed that there was interference between the fuel rail and thermostat housing. Fortunately, I was able to overcome that pretty easily by adding an 18mm spacer underneath the thermostat housing mounting bracket. That pushed the thermostat housing down low enough to provide clearance for the fuel rail.

Fuel rail mock fitting (very approximate)

Ideas to deal with plumbing to the fuel rail have been run through also. The first option was to use standard threaded -6 motorsport hose fittings on one end of the fuel rail. That would involve a threaded adapter to sit into the fuel rail end. A 90 degree swivel fitting would then be threaded onto the adapter and lead onto the hose. The issue with this setup was side clearance on the fuel rail. The adapter and 90 degree fitting would need c.50mm end clearance to fit between the fuel rail and frame, which was not available.

The second idea was to run the same type of setup but with a 180 degree swivel fitting threaded into the bottom of the fuel rail and back on itself up towards the fuel pump. A quick CAD mockup of the carb bodies with blanking plates, injectors and fuel rail installed showed there wasn't the clearance available for this either.

CAD mockup of injector and fuel rail position relative to carb body

The final (hopefully) solution is to run a banjo bolt into the end of the fuel rail and clamp the fuel hose onto a barbed fitting. This would achieve something similar to the first  option but with less end clearance required. The other end of the fuel hose will be clamped to the original ZX10R fuel hose fitting to allow it to clip onto the fuel pump.

Throttle bodies & wiring

A new year brings with it a new approach again and some good progress. First the throttle bodies.

The plan to fully modify the existing carburetors to become permanent throttle bodies has been changed again and simplified. While putting the exact modifications required down on paper, I discovered that there is not enough wall clearance in the carbs to fully bore out the step in the casting that forms a small part of the venturi. That realisation then snowballed to simplifying all aspects of the modification.

• Instead of interference fitting a block of aluminium into the slide orifice and machining out with the rest of the bore, I will now bond the original slides in place, fill them with high temperature epoxy resin and take them out to match the carb bore by hand. 
• The main jet protrusion will be drilled out and smoothed out using epoxy.
• The protruding float bowl pieces will be cut down to the level of the float bowl mating surface
• New blanking caps will be made up to fit where the float bowls once fitted and an additional piece fixed towards the front of the carbs to allow for good injector seats. This will become clearer in photos.
• Any imperfections and gaps between the carb body and the new blanking plates will be filled with temperature resistant JB Weld.
• The only professional machining required will be to drill and bore the injector seats in the throttle bodies and the fuel rail.

The major advantage to the new (again) approach is that the majority of the work can be done using basic tools and so can be done quickly. Even better is the fact I am already pretty much ready to send off the carbs and fuel rail to machine the injector seats. Photo's of progress so far below.

Float bowl cut down to seat face

Mock up of float bowl blanking plates

Detail showing infill of gaps with JB Weld for injector seat

Slide filled with JB Weld

Rough filling of drilled out needle jet

I have also been tidying up the wiring somewhat to make it the entire setup more permanent. More to go and there's not a whole lot to see anyway but some idea of what the old CDI area currently looks like is below. Including resistors hard-wired inline into the VRIN wires.

Slow progress

Since getting ignition control sorted, progress on the project has been very slow. Mainly due to work commitments, holidays and spending time on other projects.

The main restriction to major progress has been the throttle body modification. I have switched my tactic again and decided to modify an existing bank of mc22 carburetors to act as throttle bodies rather than to modify the GSR throttle bodies to fit the mc22 engine. This would consist of machining out the carb venturi to create a smooth, unobstructed passage from carb inlet to butterfly valve, also blanking off the slide passage and float bowl and machining injector seats into the bodies after the butterfly valves. The advantages here being that the machining involved is within the scope of my own abilities on a manual machine simply because I don't trust other people's QC!
Since last posting I have procured a spare set of carbs to be modified and am currently trying to find a workshop I can use in my spare time to do the work.

As well as carbs, I've procured a spare fuel tank that can be modified to take an in-tank fuel pump and also procured the fuel pump from a Kawasaki ZX636R.

In the meantime, I have begun to tidy up the wiring loom to a more permanent standard using proper wiring connectors. A lambda sensor has been connected to provide input to the ECU.

I have also wired in the Koso dash into the existing loom and now have a fully functioning rev counter which takes it's input from the ECU. Installation on the bike was pretty straight-forward and consisted of some minor modification to the mounting bracket supplied with the clocks and bolted onto the old clock stay bracket. Wiring was also straight-forward with the majority of inputs being supplied through the stock 9-pin connector for the old clocks. This tidied up the wiring a nice bit as the additional inputs consist of

• Constant 12V
• Switched 12V
• Fuel sensor
• Coolant temp
• Oil temp
• Speed signal

Koso mounting bracket installed

Koso dash installed

Main wiring connected. It is still a mess to be tidied up closer to completion

I'm also trying to get the CBR600RR stick coils to fit but having issues with cylinder #2 clearance with the fan motor. The coil itself is just too long and sticks up too far. Anyone know of stick coils that are just 15-20mm shorter than those on a 2007 CBR600RR?

First ride on ignition control

Delayed a bit getting this up so apologies but things have been slow anyway and haven't been getting a lot of time to work on the bike.

First impressions of riding the bike after sorting out the RPM synch loss errors are all positive! The bike revs cleanly and pulls strong all the way to the limiter. I cannot say for certain if that is all due to the new ignition advance curve as I have been running open carbs for testing purposes. (Couldn't be arsed removing the airbox every time I had to go at anything near the carbs basically)

The ride has confirmed that the ignition control is now working perfectly so its ready to progress with the fuelling side of things. Thats a side that needs the most physical work done in terms of pump installation, throttle body manufacture/modification and full wiring so that may take some time yet. I neglected the fuelling side also as I didn't want to use money and time on it only to find the ignition wasn't feasable.

Data log extract from ride showing rev limiter

Ignition Issues Sorted

I am delighted to say that after a much longer time than I had planned on, I have found all 17,800rpm within the microsquirt!!

As it turns out the internal noise filter settings that were the issue. They were causing more problems than they solved. I started with running the bike with higher than standard noise filter settings but immediately became clear that was the wrong way to go as the engine hit a limiter at only about 5-6k rpm. I then started reducing each noise filter a little at a time which gave slightly better results every time. Eventually turning them all off altogether got me very close to where I needed to be (16,800rpm) but it still wasn't enough. I was still getting synch loss errors at high rpm.

Further research suggested that simply soldering in a 10-20k resistor into each of the wires coming from the VR sensor should fix the problem. I tried a 10k resistor first and straight away the issue disappeared! Now the engine revs cleanly and smoothly all the way to the preset limiter every time with no synch loss errors recorded on the data logs.


Log below and a ride log and video will follow.

Log of static engine run to limiter showing no synch loss errors through the range

Almost there

Before progressing any further with the injection side of things I wanted to make sure that the ignition control was working as expected throughout the range. That meant actually going out and riding the thing with the laptop plugged into the ECU datalogging while riding.

The first time I took the bike out I noticed straight away that it didn't seem to be revving as high or as freely as before. As I had no dash connected, I wasn't able to tell what the issue was until I pulled the datalog. The bike seemed to refuse to rev above 12,500rpm. After riding and logging some more times I was getting a clearer idea of what was happening. The power appeared to flatten out more as the revs grew higher and eventually there was just not enough power to pull anymore after 12,500rpm. At first I thought it was spark timing retard as the revs grew (hardware latency) but a quick test with the timing light debunked that theory. The small amount of retard I was seeing as the revs grew could easily be put down to lag in the timing light itself.

I left the problem simmer with me for about a week and while doing some research on dwell duration on the CBR coils and typical spark durations, I figured I had the root of the problem. The MS documentation suggested a typical max dwell duration of 3ms for most coils, so unable to measure the dwell on my coils I went with that number. Additionally, as I had not investigated the spark duration, I left it at its default value of 0.2ms. I discovered that the actual max dwell on the CBR coils was 6ms instead of 3ms. And I also found that typical "normal" spark durations run between 1ms and 2ms. MS works by trying to fit the max dwell duration int a revolution and if the period of a revolution reduces to below the sum of the max spark and dwell durations, it will reduce each duration proportionally to fit in the period. I plotted what was happening with the original numbers and the spark duration was quickly being squeezed down to numbers which would barely allow a spark to occur.

So I reset the dwell and spark durations and went for another ride. The difference was apparent straight away. The engine pulled as hard as it should to higher revs. Although I did stumble into another issue then. The RPM signal dropped at about 14,800rpm which cut spark. The signal was gone for 4 seconds before it reappeared and ignition kicked back in rather suddenly. This is likely to be just a noise filter setting in the microsquirts software but I have not had a chance to play with it since.

Datalog showing 4s period of RPM dropout and also a momentary signal dropout that happened just before the main one. That small downward spike just felt like a misfire at the time

I have not installed the CBR600RR COP just yet as I need to make sure ignition is working properly before ditching the HT leads that the timing light works off of. 

Ignition!

A bit late updating this but I am delighted to announce I have ignition!!!

I got my transistors in the post a while back so I built the coil driver module and had a crack at starting the bike. At first I was getting a whole pile of nothing, then a few backfires and then a dead battery. I figured I must have had the wrong cylinders at TDC when I calculated the base advance angle so I went back 180 degrees and tried again the next day. It seemed to be making an attempt at starting but couldnt quite get there.

Coil driver module temporarily plugged into the old CDI plug.

So I went back to the drawing board and discovered that a bit of ambiguity around the language for calculating base advance in the manual had made me measure the angle the wrong way around. I took a stab at an estimated angle and it fired up first time! I had set the advance to be fixed at 20 degrees BTDC so I checked with the timing light and found it was actually firing at 1 degree BTDC. It just took a moment to redefine the base advance less 19 degrees within the ECU and everything lined up perfectly after checking again with the timing light.

Testing in progress

I had purchased a Bluefox race ignition unit for the mc22 a while back and had one of the guys on the cb250.com forum map the ignition advance from it. Thanks to him, I was able to load in the Bluefox ignition map straight into the microsquirt table. The map is only 2D but it serves as a good base point until I get the fuelling sorted and then I can play with modifying it into a 3D map. The bluefox map is running with no issues now. I intend to ride the bike to test it out, make sure there are no signal dropouts or misfires at higher rpm and do some preliminary data logging but there are a few wires to tidy up first! Unfortunately, I have been travelling quite a bit lately so I've been behind on this project.

Screenshot of the ECU running the Bluefox map. The only gauges working correctly here are RPM, Ign advance & MAP

While running the bike on the Microsquirt ECU, I tried plugging the TachOut wire into the stock tachometer but the signal is clearly different. So rather than messing with the signal to get it to work, I used it as an excuse to pick up a Koso RX2N digital gauge! The installation of that will come at a later date.

Also, while browsing eBay one day, I happened across a set of CBR600RR ignition coils and harness for nice and cheap so I purchased. These are coil-on-plug so should tidy the engine area up quite nicely. Another advantage of the COPs is the lack of HT leads should minimise ignition "noise" in other signals going to the ECU. The wiring harness for the coils needed to be modified to allow for wasted spark firing. The coils should be installed shortly and I will update how they go.