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problems starting

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jerryfudd
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problems starting

Post by jerryfudd on Thu 19 Mar 2015, 9:02 am

hi,

tried starting up the bike last night for the first time since I took it out the frame 6 months ago and naively thought it after a few attempt it would come back to life but as im asking for help that wasnt the case lol scratch 

so what did happen is after a few attempts a big what sounded like a backfire which isnt unthinkable to think that I flooded it aswell as some smoke/gas from the airbox, tried again and nothing so after a few attempts more another bang and this time popped a blue flame from the silencer tried some more and no flame but after the next pop/bang decided to call it a night.

other factors involved is that they are brand new OE carbs, also when I took the engine I was advised (and probably put too much) WD40 in the inlet and exhaust ports then seal them up and lastly I was attempting to run it off an auxiliary petrol tank like this....



I took the carbs back off and there was oil residue on the ports and checked the fuel screw - not precisely (will do that later - manual says all the way in and 2.5 turns back out) but there was movement both clock and anti clock so cant have been all the way in or out....

The only thing I can come up with is that maybe there is too much WD40 in the cylinder? as yet I havent taken the spark plug out to look but I did see something about removing oil from the cylinder by inserting a tube down the spark plug port and using a kitchen baster to provide suction - presumably sucking on it would be the same as thing because I don't own a baster?

Any ideas on causes or solutions?
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HomeBrew
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Re: problems starting

Post by HomeBrew on Thu 19 Mar 2015, 9:59 am

Is your battery flat after all this time? I would keep trying to start it for a while see if that oil clears out.
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jerryfudd
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Re: problems starting

Post by jerryfudd on Thu 19 Mar 2015, 11:30 am

it's a new MotoBatt battery plenty of charge
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Celt500
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Re: problems starting

Post by Celt500 on Thu 19 Mar 2015, 11:51 am

I'm hardly an expert but oily plugs maybe from the WD40?
Take 'em out and give them a quick clean with white spirit or similar.
I don't imagine that much oil would sit in the cylinder, wouldn't any excess slowly drain down past the piston ring gaps?

It took mine a good few cranks to get going after cleaning the carbs.
It's better to give it a go, rest it minute then give it another go rather than sit there cranking it - I've read the starter motors aren't that tough and can overheat.
Air filter in plus filter cover on? Airbox and carb rubbers on snugly?
Make sure you've lots of juice in the battery. She'll come right!

Also, there should be video of this historic start-up!  Smile
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eternally_troubled
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Re: problems starting

Post by eternally_troubled on Thu 19 Mar 2015, 12:47 pm

Have you got a can of 'easy start'?  Now might be the time to try it... ;) (except I'm not joking, it can sometimes be useful in diagnosing the problem)

If you disconnect the fuel from the carbs then drain them out you can use the starter to pull some air through the engine (holding the throttle open) - this might solve any oily/WD40 problem.  You can then try again as normal.

I doubt the auxiliary tank is is the problem unless you had the tap turned off!

Also, given these are new carbs, the idle screw setting may be very wrong, so it might be worth giving it a small bit of throttle just in case. As you mentioned it would also be worth setting the mixture screw to the standard setting.

If you have a car battery (and some suitable jump leads/wires) to hand then substitute this for the bike battery - it will give you much more cranking time (assuming that's what it needs!) and the voltage won't sag as much.  Just make sure that nothing shorts out on the frame....
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jerryfudd
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Re: problems starting

Post by jerryfudd on Thu 19 Mar 2015, 1:55 pm

just had a chat with a guy at work and he suggested that the problem could be (and seemed pretty confident) that I didnt have the vacuum pipe on the side of the inlet connected to anything - even guessed that was the case. as this would normally run to the fuel tap and because i was running the auxiliary tank which had no line for it i just left it hanging there.

he said i need to be blocking it off and that it would be sucking in air causing it to run lean and backfire..... does that seem like it could be the cause?
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ashcroc
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Re: problems starting

Post by ashcroc on Thu 19 Mar 2015, 6:19 pm

The disconnected vac pipe is a distinct possibility.  I've had problems before with them being hooked up wrong on a rebuilt engine & having one open to the air would just make things worse.
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badseeds
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Re: problems starting

Post by badseeds on Sat 21 Mar 2015, 6:50 pm

My first thought was vacuum hose. Have you fixed it?
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jerryfudd
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Re: problems starting

Post by jerryfudd on Sat 21 Mar 2015, 11:43 pm

@jchesshyre wrote:HT leads definitely the right way round? Apologies if these are stupid suggestions!



As the man said in another topic...... must have mislabelled them or something but the airleak also didn't help as once I sorted blocking the vacuum and swapping the coil feed (which was my actual problem sorting out Bl/Y from Y/Bl) it would start and then any tweak of the throttle would stall it. Then in installing the gauges for the balance it seems the blanking screw on the other inlet manifold was loose once I had resolved that with the gauge and finally refitting the screw with a bit of sealant it ran fine cheers

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