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Flaming engine
voucht - 15/4/20 at 09:31 PM

Hi,

First I hope everyone is safe and healthy, and that you don’t get too bored despite the lock-down. Here in France we are in the same situation, and we just learnt yesterday that the lock-down is extended for 4 more weeks, until May 11th...

Could you please watch this short video I made today, and if you have a good experience with engines, tell me if I should worry about the flames going out from the exhaust ports.

Is it supposed to be like that because there is no exhaust manifold installed to hide the flames, or are these flames totally abnormal and should I worry?

https://youtu.be/wRnzQc0-u3U

The engine is a bike engine from a Kawasaki GPZ550 (ZX550) Unitrack for 1984. It is 100 % stock, and running the OEM constant depression carburettors. Ignition is electronic managed by a small ECU.

I completely renovated the engine, dismantled it completely, change every part that needed to be changed (oil seals, bearing, pistons, piston rings, valves, o-rings, gaskets, completely refurbished the carbs, adjust the valve clearance, and so on...) I reassembled it following scrupulously the instructions of the Haynes service and repair manual, and adjusted the cam timing accordingly.

I was very glad that the engine started straightly, from the first try (the video doesn't show the first start, but the third or fourth, so it was already warm. For a more complete video from the first start, please watch this one: https://youtu.be/PtSWGLxIivg).

I think the engine seems to run very well, take the revs correctly, no lean cylinder for what I can sea, feel and hear.

But this is my first engine rebuilt. As it started straightly, and seems to run correctly, I think I haven’t done a complete mess of it, so I’m pretty happy, but I just want to make sure that everything looks and sounds OK to the eyes of more experienced engine rebuilders on here, and that small flames going out of the exhaust ports are totally normal.

Thank you.

Stay safe.


gremlin1234 - 15/4/20 at 10:07 PM

I have not watched it -yet, but what fuel are you using? I guess in france it's e10?


Simon - 15/4/20 at 10:23 PM

Looks perfectly normal - did the same thing when I had my Fiat 500 in 1983


ReMan - 15/4/20 at 11:39 PM

Perfectly normal..
Well done rebuilding it, though it sounds expensive, was it worn out?


Mr Whippy - 16/4/20 at 01:54 AM

I watched the vid and then read are the flames normal.. That did make me laugh

Those flames are small... I miss the old days when flames poured out the side pipes and burnt all the wadding from the silencer. You need more unburnt fuel!


steve m - 16/4/20 at 07:47 AM

I do believe ALL petrol engines produce some form of flame at the ports, as the fuel is still burning as it gets ejected out

My best memory of this was a friends e-type 4.2 that I helped (spanner monkey) rebuild when I was about 15
once the engine was in and ready, but no headers or exhaust at this point, he fired it up, the sound was amazing, and even
on tickover, the flames were about a foot long

And did I mention the sound !! it was like an aircraft engine

steve


voucht - 16/4/20 at 08:45 AM

Hi,

Thank you very much for all your answers, very helpful. I'm totally reassured now, and I can put the engine aside for now and start renovate the rest of the motorbike.

quote:
Originally posted by gremlin1234
I have not watched it -yet, but what fuel are you using? I guess in france it's e10?


Yes, spot on that is exactly what it is

quote:
Originally posted by ReMan
Perfectly normal..
Well done rebuilding it, though it sounds expensive, was it worn out?


The gearbox part was in perfect shape, I changed some bearings by security but some were still in good condition. The problem is I don't know the history of the motorbike, I don't even know how many km it has run, so better to be safe. Same for the clutch, good conditions and discs thicknesses within the tolerances.

The engine part was not in a good shape. Valves were damaged (I made a post here about that the some months ago) and needed to be replaced, pistons had small cracks between the piston rings slots, and needed to be replaced too, as well as all the piston rings. Alternator rotor was completely corroded, and went into an electrolyse bath, and is fine now. I needed to repair a few threads with helicoils here and there. The electric loom was looking very old and crappy, but it turned out that everything is working fine (relays, converters, IC ignitor, coils, etc.)

Appart from that, all engine casings have been cleaned, sandblasted and repainted (both DIY). Motor has been reassembled with stainless steel screws and bolts. So yes, it was a bit expensive, because motorbike parts are insanely expensive, when you find them! But it is part of a bigger project, to make a Café Racer of the old GPZ550, and hopefully a good looking one . For more details, here is a link yo my build blog (it has a google translate widget): https://cafrazx550.blogspot.com/

Again, thank you all for having put my mind at ease

Stay safe.


Mr Whippy - 16/4/20 at 09:05 AM

I suppose if you have never run an engine without headers on it looks a bit wild but as the exhaust valve opens before the piston has reached tdc it's still burning. On some engines you can actually see a bit into the engine as a ring of light round the valve. Just watch your eyebrows

Mostly a nice blue flame so the mixture looks to be good

[Edited on 16/4/20 by Mr Whippy]


Slater - 16/4/20 at 09:50 AM

Yep, I agree with above, blue flames are normal.

Here is my version of 1st engine start up with no headers, blue flames can be seen......but with a 1.8 Zetec.

Youtube Linker

As you will see, I was soooo excited and my wife was totally un-impressed.


jps - 16/4/20 at 11:20 AM

Sylvain - this has just given me a massive boost in motivation to get my Pinto to the same point. Can't wait to see flames spitting out the side. I'm imagining it will be like a scaled down version of this (skip to 1:58 for the action)....


scudderfish - 16/4/20 at 11:29 AM

quote:
Originally posted by Slater
Yep, I agree with above, blue flames are normal.

Here is my version of 1st engine start up with no headers, blue flames can be seen......but with a 1.8 Zetec.

Youtube Linker

As you will see, I was soooo excited and my wife was totally un-impressed.


That brought a genuine smile to my face


nick205 - 16/4/20 at 12:04 PM

Petrol engines certainly emit flames from the exhaust ports. Obviously with a manifold and exhaust system fitted you don't see them. Starting an engine without manifold and exhaust mean you'll see them. People can get caught out / burnt as can bits of vehicle if you start the engine fitted in the vehicle.

Take care, stay safe and stay the right side of the engine


Mr Whippy - 16/4/20 at 12:08 PM

quote:
Originally posted by Slater

As you will see, I was soooo excited and my wife was totally un-impressed.


Lol


nick205 - 16/4/20 at 04:41 PM

quote:
Originally posted by Mr Whippy
quote:
Originally posted by Slater

As you will see, I was soooo excited and my wife was totally un-impressed.


Lol



LOL again, reminds me of my moments of kit building excitement and SWMBOs borderline disinterest