MoTeC Global Forum

I would like some help if possible, I have a Turbo Suzuki Hayabusa running M400, the bike has had the same turbo kit for 3 years and I have been running MOTEC M400 on the bike for the past 18 month’s. I am part of a race team, we run 3 bikes of similar spec, the 3 bikes are running Bosch 044 fuel pumps, Bosch 750cc injectors and the same ignition modules

The 3 bikes over winter were stripped and rebuilt, 2 of the 3 bikes have run like clock work but my bike has been burning the barrel between cylinders 2 and 3 at low levels of boost, less than 1 bar. The piston’s and cylinder head show no signs of detonation.

I have just had this bike on a dyno, with some strange results, because of the problems I have been having we started running the bike at low rpm with no wastegate, time after time the bike would start to show very lean stutter and stop running, restart, run for a couple of minutes, show very lean and stop running. Fuel pressure remains constant at 50psi, injector duty is fine, so is the pulse width.

Attached is a log file that shows a very strange BTDC ignition timing, this showed only once on the logs, 55 seconds in you can see the ignition advance BTDC advance which caused the motor to stop running, there is nothing in the map to explain why this happened. But, the engine failed the same way at least a dozen times.

I had a feeling that if the ignition module I was using was at fault, could the ignition advance the motor receives be different to what is shown on the log?

I changed the ignition module and re ran the bike, all now appears to be correct, the bike has ran on the dyno for over 1 hour with 10psi boost with no problems.

Has anyone else come across a similar problem?

Hello Harold,

You need to fix your Ignition ET Comp table! At 100 degrees you have values of -50, when your engine is reaching 90 degrees and above this trim is interpolating to a -50 trim at 100 degrees. You can see this happen quite clearly if you overlay the "Ignition Advance" and "Ignition Base Advance" channels in your log file. You are going to have a problem every time your temperature goes above 90 degrees. You also should take a look at the Ignition Comp1 table, I am not quite sure what that is intended to do. If the timing error was related to a module fault you would not see these values in the log file.

I would recommend that you use a better quality sensor to measure the fuel pressure, a TI sensor would be better and will allow you to see fluctuations in fuel pressure. The sensor you are using is really not suitable in my opinion.

Thank you for the reply; I will take your advice on the fuel pressure sensor.

I completely over looked the Ignition Comp table, I removed the figure in the table prior to changing the ignition module, only once did the motor run that hot which explains why it can be seen in the log, thank you for spotting it.

The bike ran very well after the ignition module was replaced, is it possible for the module to retard the ignition when failing, or maybe scatter the ignition which may give reason to the heat build up in the barrels, unfortunately I am not running any egt’s

Thanks again

The ignition module is unlikely to fail in this way. I would say that it is more likely to be the ignition trim that would cause a problem. If the engine ever reached 95 degrees, for example, the timing would have been retarded by 25 degrees! Even at 92 degrees there would have been 10 degrees retard.

Could you take a look at the 2 attached logs, the engine failed in both, I have failed to spot anything that would of caused the mentioned damage.

Many thanks

Do you have any pictures of the damage, I am not sure what you mean by "burning the barrels'? Are you sure that there are no signs of detonation? WHat type of fuel are you using?
FYI it would be a good ideal to log oil temp, assuming that you have the configured sensor fitted.

Please see the attached, the motor has a 2mm spacer plate under the barrel, the piston's are wiseco, each time the motor has been built the barrels were honed with new rings, the scrapper ring gapped at 22 thou, compression at 20 thou, cometic head gasket, 12mm studs at 75ftlb. The fuel I use is VP Racing C16.

Cheers

Harold

This damage is caused by a head gasket failure, once the gasket has failed the hot gasses have eroded the top of the block (and possibly the head) away. I couldn't really say what has caused the gasket to fail, it could be caused by detonation or it could be that there is poor clamping pressure on the gasket.

I agree with what you are saying, after the first failure I thought that maybe I made a mistake on the engine build so the second build the head and barrels were skimed to make sure they were flat and that engine lasted 4 runs with less than half the boost I was running last year. It has even been sugested that maybe the head gaskets themselves were faulty. The bike is being used for 2 days 6-7 September, I will post what I find

I would suggest doing a cylinder leakage test before you run it in anger to check that the gasket has sealed properly in the first place. Then test again between runsso that if the gasket fails you can strip it down before it does so much damage.