Author Topic: Engine won't start!  (Read 1087 times)

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MrChris500

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Reply #15 on: April 02, 2024, 06:04:37 pm
The compression is higher than it should be. I was just glad it wasn't low! I'll need to get it right though. My engine has done 27,000 miles now.

It's weird how the oil is able to get to the air box, not sure how it does it. The airpipe to the throttle body is the only thing connected to the airbox now. Hopefully while cleaning I haven't damaged the sensors, I have some MAF/MAP sensor spray I used and it did run great afterward.

It's looking like some engine work will be needed to get to the route of these issues.



AzCal Retred

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Reply #16 on: April 02, 2024, 09:22:10 pm
" weirdly I found the old K&N air filter was entirely covered in mould. "

K&N Gauze filters need to be treated with K&N's "sticky" oil after cleaning. This oil is red. The filter (and any dirt coating it) should always be ATF red; your filter has no color at all. The only K&N oil I ever saw that was clear was from a lost can I recently found in my garage that had been baking in Arizona summer heat for the best part of 20 years. The color lets you know it has been properly treated.

A blast of starting fluid down the intake lets you know if there is enough spark & compression to achieve combustion. It's a go/nogo test.
« Last Edit: April 02, 2024, 09:25:31 pm by AzCal Retred »
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MrChris500

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Reply #17 on: April 03, 2024, 01:44:42 pm
I've still got the original K&N but have a free flow paper filter on the bike now. I may clean & oil the K&N and use it in the future once the bike is working reliably again.

While  the bike wasn't running at all I tried easy start into the air intake but even then the bike wouldn't catch - although since cleaning the MAP (and changing the CPS) it now does. Maybe more than one issue but I can get it running well now for a short period of time anyway. I will probably need to take it to a specialist to get to the bottom of it.

Note to self - Don't buy 2nd hand motorbikes off ebay before checking them out!


Haggis

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Reply #18 on: April 03, 2024, 02:51:23 pm
The bike should still start and run OK, even with the map sensor disconnected.
Off route, recalculate?


MrChris500

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Reply #19 on: April 03, 2024, 04:05:44 pm
Didn't know that 👍 I'll try the bike with it disconnected tonight - another thing ruled out then. Cheers!


MrChris500

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Reply #20 on: April 04, 2024, 10:22:20 pm
I uplugged my MAP and the bike ran but idled unevenly - and by the smell of it quite rich.

If the MAP is unplugged I suppose the ECU uses a default setting but maybe if it has a valid but inaccurate MAP signal, perhaps due to oil contamination, it may use that value to adjust the mixture so inappropriatly the bike won't run 🤷‍♂️ I need to test unplugging my MAP when the bike won't start again as the proper experiment!

Any recommendations in the Birmingham area for RE specialists?


Haggis

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Reply #21 on: April 04, 2024, 11:05:26 pm
It's a viscous circle with efi. With engine warm, if you have a misfire,  this leads to excess oxygen in the exhaust,  the O2 sensor reports back to the ecu that the mixtures too weak, give me more fuel please. You end up with rich running and a fouling plug which causes more misfiring  which causes more rich running.
If the engine is cold the the O2 sensor output is not used until things warm up.
« Last Edit: April 04, 2024, 11:08:09 pm by Haggis »
Off route, recalculate?


GlennF

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Reply #22 on: April 05, 2024, 05:38:17 am
I bypassed the O2 sensor but my B5 still runs too rich and fouls after a few short trips.  I am at 4000' which may not be helping.


SteveThackery

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Reply #23 on: April 05, 2024, 09:26:26 am
It's a viscous circle with efi. With engine warm, if you have a misfire,  this leads to excess oxygen in the exhaust,  the O2 sensor reports back to the ecu that the mixtures too weak, give me more fuel please. You end up with rich running and a fouling plug which causes more misfiring  which causes more rich running.
If the engine is cold the the O2 sensor output is not used until things warm up.

Yep, and you also end up with an overheated catalyser because the combustion happens in there rather than in the cylinder. 
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Freddy1

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Reply #24 on: April 06, 2024, 08:39:49 am
This intervention of mine won't help anything but I'll do it anyway.

When I used my Bullet EFI to commute to work, I took short trips around town every day, 7 kilometers in 20 minutes, and the engine never reached high temperatures.
It often happened that the motorbike didn't start or, if it did, it misfired and jerked.
The spark from the spark plug appeared perfect, like that of friend MrChris500, but by changing the spark plug (with the original BOSCH) the bike started working well again for about 10 days, then the problem recurred.
I tried with the spark pluga little warmer (NGK BPR5ES) and the problem had improved but not disappeared. Every 30 days or so I still had to dismantle and clean the spark plug because the engine misfired.
So I fitted a hotter spark plug (NGK BPR4ES) and the problem no longer occurred.
5 years have already passed and I have driven 15,000 km and since then I have never had to remove the spark plug, not even to clean it (I was afraid of getting damage to the engine, self-ignition, melting of the piston crown etc. but I have also done long trips even in summer with very hot weather but everything is ok... for now).



MrChris500

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Reply #25 on: April 06, 2024, 09:20:22 am
Thanks Freddy1,  it could well boil down to something like that on my bike too. This is something else I can try 👌