Hot Starting Problem Driving Me Nuts

Has your Voskhod broke again? Suffering dodgy Italian electrics? Post your tales of woe here. Or ask odd questions about the rear wheel spacer on a Vincent Black Widow, should it take your fancy.
moriniboy
Posts: 43
Joined: Wed Apr 03, 2013 7:59 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by moriniboy » Mon Jun 09, 2014 7:33 pm

Well Im using the same plug (BP6HS) as other Gilera owners are using with no problems so....

Coxy
Posts: 202
Joined: Sun Mar 29, 2009 11:05 am
Location: Sydney Australia

Re: Hot Starting Problem Driving Me Nuts

Unread post by Coxy » Thu Jun 26, 2014 10:49 pm

I would go back to the Mechanical aspect because when considering Compression one needs to remember the other important stroke that of the intake, A strong Vacuum is also needed to actually draw in the fuel and more importantly mix it through atomisation to a burnable mixture that wants to ignite, I think from reading the thread that will be the issue.
Not a strong enough Signal strength through the Carburettor in other words it needs More Suck through the carburettor when attempting to start, One way if available to check this aspect is a smaller carburettor and that is how a Plate type Choke mechanism like on CV Keihins works rather than the Bypass Mikuni type choke mechanism, In Both cases they rely on increasing the gas flow or speed to increase fuel mixture signal and draw in more fuel for starting when cold.

If however the Signal strength ie the Suck on the intake stroke is not strong enough you do not get enough Fuel being pulled into the Cyliner or not effective enough Vaporisation for consistent Ignition, That is where I think you need to investigate.

moriniboy
Posts: 43
Joined: Wed Apr 03, 2013 7:59 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by moriniboy » Sun Jun 29, 2014 1:32 pm

Coxy, given that the compression is down to 90psi (though a squirt of oil down the plug-hole only ups that to 92-93) and Ive tried nearly everything else (but not the cam-timing admittedly) I reckon you could be right. Even a blast of Easystart down the bore makes bugger-all difference to the hot-starting

DerryUK
Posts: 107
Joined: Fri Dec 03, 2010 11:24 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by DerryUK » Mon Jun 30, 2014 11:22 am

<Even a blast of Easystart down the bore makes bugger-all difference to the hot-starting>
That means you don't have a spark Moriniboy.

moriniboy
Posts: 43
Joined: Wed Apr 03, 2013 7:59 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by moriniboy » Mon Jun 30, 2014 2:49 pm

Im inclined to agree with you EXCEPT there is a good strong blue spark, at all times even when it's not starting (admittedly outside the cylinder)

But see the posting above from Coxy, I think, about 'not sucking mixture in', which would be symptomatic of a knackered bore and my comp. is only 90psi cold

DerryUK
Posts: 107
Joined: Fri Dec 03, 2010 11:24 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by DerryUK » Mon Jun 30, 2014 8:01 pm

<about 'not sucking mixture in>
If it was sparking the easy start would act as fuel, that was the reason for using it,it is extremely volatile. Remember to get something to burn we need oxygen, fuel and ignition. Compression helps but things will burn quite happily with no compression. Compression just improves efficiency by packing all the molecules closer together.

If it was lack of fuel alone then it should have burst into life with the easy start and then stopped. If nothing is happening you aint got a spark. Sadly I have no answers though.

If you want to prove the easy start how about the next time you run your bike turn the fuel tap off and use all the fuel in the carb until the engine stops. Then, with the engine cold give it a squirt of easy start and start your bike, fuel tap still off. It should burst into life and then stop.

Thinking about your nice blue spark but no ignition I wonder if some way the ignition timing could be completely wrong when hot? I have no idea why though. How did you set the ignition timing? Have you ever checked it?

moriniboy
Posts: 43
Joined: Wed Apr 03, 2013 7:59 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by moriniboy » Mon Jun 30, 2014 11:13 pm

Yes,well that all makes a great deal of sense, as do all the other not quite contradictory suggestions

The timing is by gears, and my mechanic Jim (ex-Rolls Royce engineer, runs Bikecare in Bristol and has all sorts of interesting bikes) timed it

Looper
Posts: 98
Joined: Fri Mar 20, 2009 11:04 am
Location: Ireland

Re: Hot Starting Problem Driving Me Nuts

Unread post by Looper » Tue Jul 01, 2014 10:01 am

Is it an alloy head and iron barrel?

moriniboy
Posts: 43
Joined: Wed Apr 03, 2013 7:59 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by moriniboy » Tue Jul 01, 2014 10:06 am

I wish! Iron head and barrel, which is why it has an insulating thick spacer

DerryUK
Posts: 107
Joined: Fri Dec 03, 2010 11:24 pm

Re: Hot Starting Problem Driving Me Nuts

Unread post by DerryUK » Tue Jul 01, 2014 10:31 am

I was going to have a look at a manual but I cannot find what bike it is other than a post war single. It might be a Honda with that description!

What is the bike?

<Jim timed it>
What does Jim think the problem is?

Derry.

Post Reply