Cold Starting (or not starting)

[gilesorton]

I have been have trouble starting my 700S (138) since it went into the garage for the winter.
Over the summer she always started easily, usually second kick, though she always needed about half throttle despite the manual telling me to keep the throttle shut.

However, having sat in a dry but cold garage for a month she would not start in November. I have been trying further since mid December. Battery is fully charged and delivering a good spark at the plug. The petrol is only 3 months old so should not be too stale?

I thought of using Easy start, but see that the air filter is fairly crude foam plastic around the intake to the carb so I do not want to risk highly volatile Easy Start on it as if it does not dissolve the foam it might dissolve the glue holding the bits of foam together. Perhaps if I took the filter off first Easy Start would be worth a go?

Any thoughts/suggestions would be gratefully received?

[Smokey_Paul]

Drain the float bowl and freshen up the petrol three months on modern fuel is probably the only issue as it breaks down so quickly. I only use the high octane fuels especially Esso if it's available but I still drain when leaving standing.

[hendred]

Agree with Paul about fresh fuel and draining down the carb.  I also drain down the water system for the winter lay up.  Having to use a wide throttle opening to start the bike suggests a rich mixture.  I experienced a similar situation during the summer.  Have you checked the plugs - mine were quite wet when I tried to start the bike.  The problem turned out to be a passing fuel tap.  In my experience the Amal MKII float needle doesn't seal very well if the bike is left with petrol switched on.  Due to the angle of the inlet any petrol passing runs into the crankcase making the mixture very rich.  Kicking it over a with the plugs out to clear the crankcase and fitting dry plugs and the engine started.  Once started would then start with the throttle just cracked open.  Leave it for five days and back to the same problem.  Cleaning the carb and new float needle made no difference.  My petrol tap tapered plug was scored allowing a small amount of petrol to pass.  Lapped in the plug to make a tight seal on the tap and no further problems.  Bike starts as per the manual.  

[gilesorton]

Paul

Many thanks for the quick reply. I just need to work out how to do that, but it shouldn't be too hard.

Regards

Giles

On Sun, Jan 6, 2019, at 6:01 PM, Smokey_Paul [via Silk Motorcycles] wrote:

Drain the float bowl and freshen up the petrol three months on modern fuel is probably the only issue as it breaks down so quickly. I only use the high octane fuels especially Esso if it's available but I still drain when leaving standing.

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[gilesorton]

Many thanks indeed for your helpful reply.

[hendred]

My Amal carb has a plastic drain plug on the bottom of the float bowl.  I use the ring end of a combination spanner to remove it with the carb in situ.  I think it is 20mm from memory.

[Arthur Farrow]

Hmmm

Thursday out on bike ...all ok started easy. Adjusted tick over, 20 miles but it lost tick over whilst out. Stopped and restarted no issues a couple of times then when i got home it coughed then refused to restart

Friday cleaned carb. no issues all jets clean. Refitted and started fine but did not ride.

Saturday dead dead dead. Fat spark ( almost too fat) "easy start" in plug hole will not make it even a little pop .

Boyer with original Lucas coils. On switch on ammeter goes to about 6A then drops to 0 slowly. When you kick it over it shows discharge as I would expect

Bloody thing. Any ideas

[hendred]

Welcome to the joys of owning a Silk!  I guess you checked petrol was getting from the tank to the carb and the top hat filter in the carb banjo is clean.  Also you have compression.  I have had problems with petrol taps passing and partially flooding the engine.  Had to kick it over for quite a long time to clear with a wide open throttle, plugs were very wet. The inlet passage and transfer passages are sealed  from each other by silicone sealant under the inlet cover.  If the sealant breaks down for any reason air/fuel mix goes round in circles instead of to the combustion chamber.  I made a thin paper gasket sealed with Welseal and have had no starting problems from that source since.
 One last thought-has the timing slipped?
Hours of fun to come!!

[Arthur Farrow]

Plugs not wet at all. Just nice and fuel is getting in the carb, but I wish i could "tickle the carb, my 1928 Scott loves a good glug of juice. .......Its just odd. I really wanted another ride today (50 miles on the Silk so far on 2 rides and no running problems except lost tick over)

Bike has good voltage ( I know boyer will do odd stuff if V low) but the battery is on trickle for 3 hours and showing a minor charge. Ill try again in the morning then look at the pick up. I have ordered 2 new coils I know they can be a cause of non starting . Something is flakey, maybe the BIG spark should tell me something. Honestly when it goes it starts easily.

I cannot go back to Luminition as the springs are missing from the Adv/Ret unit and that looks buggered anyway. Pins all loose.and its a v early Luminition 

Loads of compression and if you put "easy start" through the plug hole it really should go bang this makes me think ignition despite the big spark

The Boyer wires are a disgrace very very short and stupid thin which means a connector just as it exits the casting. Ill check tomorrow that after a calming ride on my Vin

Arthur 

------ Original Message ------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

To: "Arthur Farrow" <[hidden email]>

Sent: 14/06/2020 22:49:38

Subject: Re: Cold Starting (or not starting)

Welcome to the joys of owning a Silk!  I guess you checked petrol was getting from the tank to the carb and the top hat filter in the carb banjo is clean.  Also you have compression.  I have had problems with petrol taps passing and partially flooding the engine.  Had to kick it over for quite a long time to clear with a wide open throttle, plugs were very wet. The inlet passage and transfer passages are sealed  from each other by silicone sealant under the inlet cover.  If the sealant breaks down for any reason air/fuel mix goes round in circles instead of to the combustion chamber.  I made a thin paper gasket sealed with Welseal and have had no starting problems from that source since.
 One last thought-has the timing slipped?
Hours of fun to come!!

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[hendred]

[hendred]

One other thought - have you tried new plugs.  I have found NGK plugs can spark ok outside the engine but not when fitted.  Something to do with the unglazed insulator fouling.  The fouling can happen quite quickly as it's a two stroke.  A hotter plug can help if you are not riding it hard.  I always fit new plugs at the start of the year (usually SORN the bike over winter) as it will start on the old plugs but not restart after the first run.  New plugs and problem resolved.

[Arthur Farrow]

I am using Champion N4G plugs, don't rate Champions never have, but I do have a pair spare. As a rule on old bikes I use new old stock plugs which have glazed ceramic tips (interesting item on Green Spark Plug website)

https://www.gsparkplug.com/shop/fouling-shortingout-problem-modern-plugs-champion-vs-ngk/

I once had a 750 Ducati from the 70's that destroyed modern plugs every other time it started (often just one plug) as it wanted flooding to start. Cured by fitting ancient KLG plugs which were NOS

BUT what plugs made ages ago would the Silk like ??

I don't like the really big fat yellow spark its doing now or the fact that on switch on the ammeter goes to 6A then slowly drops to zero until I kick it. This might indicate the Boyer is switching off the coils when static as they are draining too much current.


Lucas 6V coils (17M6) - 1.5 to 2.2 Ohms between the low-tension terminals.
                                   4 KOhms between either l-t terminal and the h-t terminal
                                   infinte Ohms between any terminal and the case.

I will test the resistance later today but have ordered a pair of new Lucas coils anyhow. These will be Indian made Green Box Lucas (they have had a Indian owned co there for ages I think) Fitting new coils transformed a Bonny I had a few years ago

Electrics ...yuk! cannot fix them with a hammer can you??

[hendred]

From what I have read, the Boyer does switch off if the engine is not running to protect the coils from overheating.  What you are seeing on the ammeter could be correct.  I have been considering spark plugs too.  I am goIng to try projected tip plugs.  There is plenty of clearance from the piston and it puts the spark further into the combustion chamber.  If that works I was then going to try Iridium fine wire versions of the plugs.  You are already using fine wire Champions I think.  A projected tip platinum plug works a treat in my Venom and a Champion L3G has improved the running of my MZ TS250/1 a lot.
Smokey Paul had problems with the enrichment system at one time, passing all the time.  You seem to have the opposite problem if the plugs are dry.  Might be worth unscrewing it and checking it isn't blocked for some reason.

[Arthur Farrow]

Heavens above what next !! One not for the forum I feel such an idiot.

The new coils arrived today so i decided to fit this afternoon to find a fuel leak...from the primary drive!! Friday when I could not get the bugger to start I left the fuel on by mistake. I guess its filled up the engine which has leaked into primary. Gearbox too? Very smart not having an engine drain plug eh ?.

Looks like it might be in the oil pump too.

Very depressed about it !!...especially as the house here has an annex attached to the house I use as my bike garage. Does the house stink?

New mk 2 carb needle ordered with float. Guess ill just empty everything in gearbox and turn the motor over a million times. I know you said this had happened to you. 

My next bike might be a Honda 50 Cub.

Arthur Farrow

Moorbarn House

School Lane

Stretton on Dunsmore

Warwickshire

CV23 9NB

Telephone : [phone]

Mobile      : [phone]

------ Original Message ------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

To: "Arthur Farrow" <[hidden email]>

Sent: 15/06/2020 13:32:27

Subject: Re: Cold Starting (or not starting)

From what I have read, the Boyer does switch off if the engine is not running to protect the coils from overheating.  What you are seeing on the ammeter could be correct.  I have been considering spark plugs too.  I am goIng to try projected tip plugs.  There is plenty of clearance from the piston and it puts the spark further into the combustion chamber.  If that works I was then going to try Iridium fine wire versions of the plugs.  You are already using fine wire Champions I think.  A projected tip platinum plug works a treat in my Venom and a Champion L3G has improved the running of my MZ TS250/1 a lot.
Smokey Paul had problems with the enrichment system at one time, passing all the time.  You seem to have the opposite problem if the plugs are dry.  Might be worth unscrewing it and checking it isn't blocked for some reason.

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[gilesorton]

Honda Cub ??

Going back to the spark plug issue thanks for your helpful post. I have had no problems with the plugs in the nearly two years I have had my Silk, so it occurs to me that at the very least I ought to buy in some spares so as to be ready when they are needed. Have you identified the optimum plug and more important still found a supplier of the new old stock you were after?

[hendred]

Back to float valve needles.  I fitted a new one after I flooded the engine after leaving the petrol tap on overnight.  Made no difference, still floods if left on the sidestand.  I think the angle when on the sidestand is too great for the float to close the valve properly.  You only leave the petrol tap on once!

[Arthur Farrow]

Lesson learnt ! No fuel in gearbox but drained oil anyhow. OIl pump side dry. Will have a look at alternator side tomorrow as the machine is stinking in an outhouse now in disgrace. New float and needle ordered.  The carb float bowl is a concentric therefore the theory is angles make no difference unlike say a monobloc, but they do not have the best reputation...I wonder if anybody has fitted a Japanese carb at any time???????. 

There are 2 allen grub screws left and right in the crankcase below the crank line. I guess they are oil drillings plugged not crankcase drains.

Being a Mk 1 Silk my petrol tap can only be accessed by taking off the LH side panel so my normal practice of switching off fuel 10 yards from home cannot be done unless i leave the LH side cover off but as that contains the tools I'd rather not do that. One of my other bikes a Morini has an Electric tap which is great but it means the carbs always have fuel in them, but at least when the ignition is off the fuel is cut.

------ Original Message ------

From: "hendred [via Silk Motorcycles]" <[hidden email]>

To: "Arthur Farrow" <[hidden email]>

Sent: 16/06/2020 18:29:33

Subject: Re: Re[2]: Cold Starting (or not starting)

Back to float valve needles.  I fitted a new one after I flooded the engine after leaving the petrol tap on overnight.  Made no difference, still floods if left on the sidestand.  I think the angle when on the sidestand is too great for the float to close the valve properly.  You only leave the petrol tap on once!

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[Arthur Farrow]

Having only done 50 miles on my bike I cannot give any experience of plugs. I suspect in a year i may be an expert!!!

------ Original Message ------

From: "gilesorton [via Silk Motorcycles]" <[hidden email]>

To: "Arthur Farrow" <[hidden email]>

Sent: 16/06/2020 18:05:39

Subject: Re: Re[2]: Cold Starting (or not starting)

Honda Cub ??

Going back to the spark plug issue thanks for your helpful post. I have had no problems with the plugs in the nearly two years I have had my Silk, so it occurs to me that at the very least I ought to buy in some spares so as to be ready when they are needed. Have you identified the optimum plug and more important still found a supplier of the new old stock you were after?

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[Smokey_Paul]

Always have a spare couple of plugs in your tool bag lol

[gilesorton]

Thanks . What would you recommend? I read the long post about New Old Stock .... but it did not offer a conclusion as to where to source the best option.