Thread: #6

**speedpro** · 7th November 2023, 21:18

Had a good session on the ESE dyno. I was only checking how the boost was building in certain scenarios.
Tried 3 setups
1 - Wastegate actuated as standard.
2 - Wastegate controlled by a solenoid, closed up to 160kPa, opening around 180kPa
3 - Wastegate held closed manually.
1 resulted in 140kPa boost with a gradual increase from 8,500-10,000rpm then ramping up to 140kPa at about 14,000rpm.
2 resulted in 180kPa boost with a gradual increase from about 7,000rpm, then from 10,000rpm ramping up to 180kPa at about 14,000rpm.
3 resulted in plenty of boost if I let it. It was making minor boost from about 9,000rpm and pulled through the 10,000rpm flat spot reasonably cleanly. By 13,000rpm it was making 130kPa and after that it was on a mission. I closed the throttle at 14,500rpm at which point it was making 190kPa and climbing.
3 resulted in 1-2hp more in the lower rpm which is worth having.
I'm going to add a spring to the wastegate actuator to hold the wastegate closed until about 180kPa or a bit less. This should make the boost ramp up quicker, the same as holding the wastegate closed manually. If it turns out that I can run lots more boost I'll add springs to achieve 90% of the boost and use the solenoid and ECU to limit/control the boost. It will remove control in lower revs and lower boost but that doesn't concern me.
1 = Green.
2 = Blue.
3 = Red.

**F5 Dave** · 8th November 2023, 10:42

My 50 would nail it from about 6000 to 11000rpm.

Lot of revs, but doing the business. Can you keep it above say 10 all the time out of the pits? Presumably pulls cleanly without loading up from there?

Must be low gearing.
.

**speedpro** · 8th November 2023, 16:53

It has a great gearbox. Once under way it's not difficult to keep it over 14,000rpm. The trick is changing down what seems like enough gears going into a corner only to find you need to drop another gear on the exit. With the boost control solenoid setup how it was it really liked being over 16,000rpm as it took until those revs for all the boost to be made. I changed it for these tests so that when it was connected, run 2 above, it was making 180kPa, max boost, by 14,000rpm. Nett result of doing just that was a 4,000rpm powerband where max boost was available. I limit max revs to 18,000rpm although I have been getting "noise" on the ignition recently which has made anything over 17,000rpm worth avoiding.

I measured the force needed to start opening the wastegate. I used a luggage scale, as suggested by Rob, to pull on the arm. It took about 4.5kg to move the actuator arm about 1mm. I've lockwired a spring between the actuator and the lever. Now it needs about 9+kg pull to open. The difference between the tests showed that the wastegate was creeping open even with no manifold pressure to the wastegate. The exhaust pressure alone was pushing the wastegate open. This will cause the boost to build slower than possible. Holding the wastegate closed proved this as it made more power from about 10,000rpm up.

**Grumph** · 9th November 2023, 06:30

That exhaust pressure opening the wastegate is something to be wary of. Some time back on probably another thread I mentioned being told of probs on a turbo'd Subaru where exhaust pressure spikes were opening the exhaust valves. With dire consequences. Blowing them open to where they were hit by pistons.
I know just how soft the valve springs are in the little FZR - so it may become a real possibility.
Even the 1200 Kawasaki turbo I rebuilt had witness marks on pistons where exhaust valves had touched. Putting the cams on wider lobe centers at least averted the worst.
The Subaru was eventually cured by redesigning the exhaust layout.

**speedpro** · 9th November 2023, 09:42

Originally Posted by F5 Dave

Must be low gearing..

As tested it was geared for 90-95mph. Previous dyno chart has x axis set to "mph".

**speedpro** · 9th November 2023, 18:08

Recent tests have recorded trigger errors and rpm noise. I racked my brain about the cause and the guy who tuned the Link suggested maybe some sort of backlash due to it happening if I backed off at high revs or after it hit the limiter. The thinking was that the crank and cam triggers were getting just that little bit too close for the ECU to process both signals at the same time. Yanked the alternator cover as part of the process of checking cam chain tension and found the wires had been rubbed by the alternator rotor. My little theory is that originally the wires were good as gold but tension has been applied and pulled the wires over a little boss making them stick up just enough to get rubbed. One of the 2 wires from the stator was disconnected where it rubbed. I've soldered it back together and put a bit of tape on it, reassembled it, making sure the wires were out of harm's way.
A good look at the logs after the dyno session showed the actual Lambda to be above the "desired lambda" across most revs. Both the old and new regulators looked to be set to the same pressure but obviously the new gauge reads different. I've wound it up .5BAR which will get more fuel into it and move the Lambda closer to the desired. I'll check it at the next dyno session. Either that or go for a ride and check the log, and adjust as required.
I've also adjusted the rev limit up 300rpm as the ECU limiting starts early and has a hard limit before or maybe just on 18,000rpm. I'd rather it revved to 18,000, and then started limiting. It'll be limiting at less revs than the standard redline. Standard of course it ran a bit less boost.

**speedpro** · 10th December 2023, 22:13

I rode the turbo twin on the Saturday of the 2hr meeting at Tokoroa. Apart from me being abysmally slow, the bike ran reasonably well. The engine pulled through the gears nicely and generally behaved. It was a touch lean in a few places but no real concern and easily rectified. The injector duty cycle was going over 90%, even close to 100%, so something needs to be done there. I've ordered bigger injectors. Once fitted it will be a simple matter to reduce the main fuel map values until the "desired" and "actual" Lambda match again. Very easy to do by highlighting the whole map and reducing values by, say, 25%. This would be done with the wastegate open so there is little chance of boost. Once that's sorted the wastegate is reconnected and a further test to confirm that the Lambda values match once on boost. Then I can start adding boost. I reckon it will be good right up until the head lifts and the coolant is blown out.
The front brake was absolute shit so I've taken the RS125 caliper off and fitted a big heavy standard front caliper. Piston size goes from 25mm to 32mm so the ratio of master cylinder to caliper should be much better.

**speedpro** · 10th December 2023, 22:18

I have other FZR250 chassis project bikes. I'm looking at possible plans and want to know what others have done to improve the handling. I already have emulators in my turbo twin forks but have received "feedback" about the front end. That bike has a stock rear shock which to me seems reasonable but I'm not a good judge. The chassis with the MB100 engine has a standard looking rear shock but it does have an adjuster on the base of the shock. I have not played with it so don't know the effect it has. My son seems to like how the bike handles. The front forks have a few washers each side on top of the springs. Apart from that I don't know what's been done. The turbo feels quite firm, the MB/FZR feels softer front and back, and Gregs twin is softer again. Greg's bike has a shock with a reservoir and adjustment. At a guess I think it might be off a 600 maybe but with a different spring. I'm considering emulators for the front of the MB/FZR from Sports Valve, https://sportsvalve.com/sports-valve. A friend has fitted them and is singing their praises. If someone knows of a good replacement shock I'll check them out.

**Grumph** · 11th December 2023, 05:20

Rob can probably confirm but I think my one was set up for/by Avalon. Hence the soft spring.

**F5 Dave** · 11th December 2023, 11:44

I ran 11mm master cylinders on my RS125 based bikes and they were pretty demonically vicious

on the picks. Which is how I like them. Check what mc size was?

That said my 100 was about 70kg and the 50 was 60kg. Both of which puts me to shame, but all helps trying to be nearer to stationary in the least possible time.

**husaberg** · 11th December 2023, 17:22

https://www.kiwibiker.co.nz/forums/s...post1130222905

the rear shock is from a 2007 GSXR600 with compression and rebound adjustment fitted with the original spring from my FZR 3LN frame.

**Grumph** · 11th December 2023, 19:15

Thanks for finding that link Husa. There you go Mike, I never touched the suspension so that should be what's still in it.

Emulators to copy even...

**speedpro** · 12th December 2023, 20:59

Sweet. I had already discovered where the shock came from by looking up numbers on it. Nice to know about the spring. I've moved the shock to the other bike(MB/FZR). The shock is 25mm longer which raises the rear by quite a bit and also messes with the link geometry. I used the standard dogbones at 140mm c-c rather than the slightly shorter, 137mm, original ones on the bike which would have raised the rear even more.

After a bit of feedback on another forum I've decided I need a 2006 or 2007 Yamaha YZF-R6 shock, maybe 2008. They are a straight bolt in and supposedly work OK with the adjustments backed off a bit. They are only a few mm shorter so may need slightly shorter dogbones to maintain ride height.

This is the shock. This earlier one has 2 separate compression adjustments while the slightly later has them combined.

If anybody has one or knows where to get one, let me know. I see them on ebay but holeeee shit, $$$$$. Maybe I'll talk Cricket into buying an Ohlins for it.

**speedpro** · 15th December 2023, 20:26

It's looking more and more likely that it's gonna get a pricey shock from ebay. No promises have been made yet.

I have put the standardish shock that it came with back in the chassis. I've played with the rebound damping adjustment and can detect no difference between either end of the adjustment. I left the standard dog bones in place.

I made an alloy strut to replace the shock in Greg's bike. Whatever happens I'll need a different shock for that bike as the Suzuki shock is too long to work.

I also drained the oil out of one fork and after pulling the spring and the many washers and spacer found there was an emulator in it. It looks a bit different to how I remember the Racetech gold valves I have in my twin but look to work in a similar manner. The oil needs to be changed as well as it's dirty. I'll probably dismantle the forks to check them out.

I weighed the bike as well using our bathroom scales. 39.9Kg on the front and between 46.3Kg and 44.4Kg on the rear. I made a number of measurements and for some reason got different numbers on the rear. Either way the bike weight with no fuel is between 86.2Kg and 84.3Kg so it isn't as bad as it looks. It still has the big steel tank and the rear disc could easily lose more weight, if I could be bothered.