#6

[speedpro]

Change of plans. I am not going to Tokoroa. I was looking forward to riding the bike, it's only been 20 years in the making, and I have the spare bike ready to go as well which anybody could have ridden. My plan now is to carry on and join the EBP Kart club and go to Edgecombe for a play on my own or preferably with a couple of mates, somebody else's mates. I haven't got any of my own. Hopefully the grippy track will compensate for the tyres though given how old I'm feeling lately I'm not expecting to doing much more than puttering around, albeit hopefully at up to 18,000rpm. Hopefully it will be a good turnout and the weather will be good for racing.

[F5 Dave]

Probably wise. Towards has at least 3 corners which are thoroughly 'front endy' as well as broken corner near start unless they've fixed it

[speedpro]

The sensible twin has a new home.

[husaberg]

found the missing rocker cover here if you want one
funny how that chassis made it back to Auckland
One of Robs NSR ones came from me.
now that one which was ex Rob goes to CHCH and back

[Grumph]

The sensible twin has a new home.

Did you find the spare ignition box tucked in beside the motor ?

[speedpro]

I got it. I'm taking #6 to Edgecumbe tomorrow for a bit of a ride. Nervous isn't even close to describe how I feel. I'll give the MB100 powered bike a ride as well.

[speedpro]

The MB100 one wasn't taken off the trailer. It was too hot and I couldn't be bothered after riding the twin.

The twin went reasonably well. It started with the first pull on the back wheel and ran OK. There are definitely improvements to be made to the tuning but it's rideable. It was revving clean right out to the rev limit which is currently at 18,000rpm and was sweet from about 13,000 up with full throttle.

The only little problem was a leaky oil seal on the end of the cam behind the cam trigger disc. It's easy to replace. There was a bit of oil sprayed around on that side of the engine after about the 3rd session.

There's a little video which is a bit wobbly due to being unable to see the screen in the bright sunshine and the camera wanting to focus on the mesh in front of the verandah. The sound is OK.

I have to check it out, do an oil change, and fit a new seal. Hopefully that's it and I'll be able to have a ride at HD.

Link to video: https://www.youtube.com/watch?v=cqPq20fi43o

[husaberg]

Golly it sounds like it only revving to 11k on video?
much deeper note than i would have expected.

[speedpro]

Spent the day at Hampton Downs yesterday. It was the first time on a track for 9 years or so, apart from Edgecumbe a few weeks back. The bike seemed to run OK but still has a slight oil leak somewhere around the head. It's not much but is enough to coat everything on the left.

The bike ran OK but unfortunately with the short notice for at least one race and the time it takes to warm up I was taking it a bit easy at the start of a few races. Only the last one was it warmed up when I went out.

The fuel pressure regulation is still a problem. Most times I turn it on the pressure needs to be adjusted, sometimes up and sometimes down. Despite having run it on the dyno and got the fuel map in the ballpark, at 100% throttle it was still lean around 13-15,000rpm. It was REALLY lean according to the log so a bit surprising it ran as well as it did. Definitely not quick but it ran OK. I did check the fuel pressure at one point and found it a bit low so adjusted it. The data log for the next race shows the AFR not as lean so the leanness may simply be a fuel pressure problem.

Interestingly, Ellie to whom I sold Cricket's CB125, was on track in the same class. There was very little difference between the 2 bikes. I was glad to see the CB going well. I'd fitted a 150cc kit and done a bunch of machining to get things just right and i always had a nagging worry that it might go "boom" but it was going really well, even the gearing was more or less spot on for HD.

Anyway, it was a good day. There was a good crowd of various bikes and a few new and newish bucket racers. I think Ellie has only been to one other meeting, I was back, and the 2 guys sharing an FXR, the old club bike, were parked next to Rob and I. The weather was near perfect and as far as I could tell everyone had a good time, with maybe one exception, being the person taken away in the ambo.

[speedpro]

I've been looking at the fuel supply system due to the variation in pressure I've been seeing. I've tested the system by setting the pressure regulator to 3bar and then applying compressed air through an air regulator to the fuel regulator. With about 8lbs boost pressure the fuel pressure rose to about 3.5bar which is about right. It turns out that the pump will only push about 4 bar max which means the fuel pressure will only be compensated for about 1bar of boost. That might be enough or it might not. I can of course run it over 1 bar boost without fuel pressure compensation as long as the injector duty cycle doesn't top out. I set up a test rig with a spare fuel pump I had which I thought was only supplying about 1.5 bar fuel pressure. It turns out the pump supplied 4 bar when asked so it seems OK. The problem was probably the regulator. The original regulators have a plastic body with a metal capsule clipped in. There are a couple of o-rings that seal things and I know that the little one had a habit of leaking. If I get bored I might look at machining an alloy housing for the capsule with the "open-to-air" end of the capsule sealed in and supplied manifold pressure. There are holes in the capsule so it is another possibility for a rising rate regulator. One disappointing thing is how the pump speeds up when the battery voltage is boosted and how the pressure rises with it. The good thing is that the data log shows the battery pretty consistent when the engine is running so hopefully the fuel pressure regulator can be adjusted with the battery voltage at 14v and it will be consistent while the motor is running. If anyone knows of a small EFI fuel pump that is capable of pumping say 50hp worth of fuel I'd be interested in having a look.

[speedpro]

Dyno time was interesting yesterday. Right at the start there was a little problem with water not circulating. I figured it was the water pump. Although it is mounted near the bottom of the water circuit it is still possible for air to be trapped inside the pump housing as the feed hose rises up to the pump and the outlet is at the bottom of the housing. Rob and i rolled it back out of the front clamp and leaned it each side until the air was pumped out. After that it seemed to be fine.
The fuel pressure regulator is definitely not very stable. Initially it was more or less 3BAR but as the session went on I had to screw the adjuster in to maintain pressure. This morning when I ran the pump here at home the pressure was 4BAR. It's hard to determine what is causing this but I suspect it is related to fuel temperature and possibly the regulator diaphragm. I ended up adjusting the fuel pressure 4-5 times through the session for some sort of consistency.
There is a table in the Link ECU where you are able to enter desired Lambda values at different throttle positions and RPM. I've simply entered values that will see the engine running a bit rich and hopefully safe. What I did on the dyno was hold the throttle at 10%, 20%, 30% and so on and let the engine revs rise at each setting. The ECU logged the actual Lambda and a report can be displayed showing the difference between desired and actual Lambda at each RPM and TPS position. A simple double click sees the required adjustment made to the value at each position in the fuel table. I was doing each cell one at a time as I didn't want to adjust the whole table in one go as there weren't enough samples in some locations for reliable outcomes. I ran through this a few times and the Lambda was looking reasonably steady. The main thing was that it wasn't going lean, which it had been. Although the engine seems to run sweet and the logs show a reasonable Lambda, the fuel map, when you change from a chart type display to graphic looks very peaky as there are values in a few locations that need further adjustment. Some may need to be adjusted without a logged Lambda as the engine is never operated with that particular combination of RPM and TPS. I really need to have a better fuel map as it is the basis for the fuelling when the turbo is fitted.
When boosted the fuel is dependent on the value from the fuel table and a multiplier which comes from another table. The multiplier values are determined by boost and RPM. With the turbo there will be areas of the main fuel map that are used which when unboosted might not be.
So many things to adjust. I'm going to run ECU controlled boost as well so something else to sort out, and I've cut the intake plenum so also need to machine a piece to go on the front to connect the turbo outlet.
I'm gonna need to talk sweetly to Rob & Cully about a bit more dyno time, after I fix the exhaust pipe that broke right at the flange. The other pipe has already been welded by someone else at some stage. Rob did mention that the bike was a bit rowdy so maybe a little bit of work there as well if the turbo gets delayed for some reason. I like the sound of it. For a 125cc twin it sounds reasonably serious. The 100cc(cough) turbo version will sound quite different with the turbo but the last one had a nice sound.

[pete376403]

If anyone knows of a small EFI fuel pump that is capable of pumping say 50hp worth of fuel I'd be interested in having a look.

Probably doesnt meet your requirements of "small" but for a turbo project I built years ago (speedway 1440 mini) I used a Triumph 2.5 PI pump. LOTS of pressure and volume. Most of the fuel it pumps went straight back to the tank via the boost modulated regulator

[speedpro]

I have sat looking over the fuel system and in particular my surge tank setup. The theory of it seems fine with the idea that an uninterrupted supply of fuel is important going to the pump. However, I have the return line also going to the surge tank and this return line seems to return fuel along with a reasonable stream of bubbles. These bubbles build up in the tank over a bit of time. On the dyno it may not be a problem as typically there is a fuel supply on a pole and the fuel line is directly down and into the surge tank. Fuel gets in easily and the bubbles are able to exit given the reasonably straight path up and out. With the setup on the bike the bubbles aren't able to exit so easily.

There seems to be a few options. The first one I thought of is to fit a nipple to top of the surge tank which attaches to the top of the main fuel tank via a tube. This would allow the bubbles to exit out to the main tank. The 2nd thought was to have the fuel return line go to the main fuel tank. There would still be a possibility of bubbles getting into the surge tank but only through the fuel line from the main tank which wouldn't normally be too much of an issue except that any fuel the pump pulls out of the surge tank has to be replaced by fuel from the main tank in a continuous cycle. If the pickup in the main tank is exposed for any reason it will simply suck air and fill the surge tank. whether that is actually a problem or not I don't know.

I've never seen an actual in-tank EFI pump setup but that is the obvious 3rd option.

I'm leaning toward the 1st option but if anyone has an idea . . . . .

[Vannik]

Returning fuel is often aerated and warm, in a well designed FI tank the return flow is on the bottom of the tank to stop the fuel from forming a jet into the fuel which can add more air. The return is also separated from the suction point by one or more baffle plates. On an FI system the fuel is used to cool the injectors and then there is often a cooler added to the return line. Fuel temperature is quite critical as both FI and carburetors are volume control instruments while AFR is a mass ratio. Controlling the temperature and thus the density of the fuel is critical.

[Flettner]

I have sat looking over the fuel system and in particular my surge tank setup. The theory of it seems fine with the idea that an uninterrupted supply of fuel is important going to the pump. However, I have the return line also going to the surge tank and this return line seems to return fuel along with a reasonable stream of bubbles. These bubbles build up in the tank over a bit of time. On the dyno it may not be a problem as typically there is a fuel supply on a pole and the fuel line is directly down and into the surge tank. Fuel gets in easily and the bubbles are able to exit given the reasonably straight path up and out. With the setup on the bike the bubbles aren't able to exit so easily.

There seems to be a few options. The first one I thought of is to fit a nipple to top of the surge tank which attaches to the top of the main fuel tank via a tube. This would allow the bubbles to exit out to the main tank. The 2nd thought was to have the fuel return line go to the main fuel tank. There would still be a possibility of bubbles getting into the surge tank but only through the fuel line from the main tank which wouldn't normally be too much of an issue except that any fuel the pump pulls out of the surge tank has to be replaced by fuel from the main tank in a continuous cycle. If the pickup in the main tank is exposed for any reason it will simply suck air and fill the surge tank. whether that is actually a problem or not I don't know.

I've never seen an actual in-tank EFI pump setup but that is the obvious 3rd option.

I'm leaning toward the 1st option but if anyone has an idea . . . . .

With my autogyro's, I have a collector / surge / working tank, call it what you will. Originally it was of sealed design. Gas bubbles would build up after a short flight and cause the engine to lean out, or even stop. The fix in my case was to vent this tank. Fitting a clear line saw gas bubbles continuously rising out of this tank, no matter how long the engine ran. After this vent was fitted, no more in flight engine issues.

My 360 has an in tank pump, circuit return is well away from the pump intake, pointing down, near the bottom of the tank.