1948 Iron 4G Coil Ignition

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Re: 1948 Iron 4G Coil Ignition

Postby brenton.roy » Thu Oct 10, 2019 9:08 am

Yes, good luck with it. I'm glad you have made progress.
'51,'56 Squares, '48 VH, '27 Model C, R67/2, Mk IV Le Mans, '06 Super Duke and Ariel projects.

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Re: 1948 Iron 4G Coil Ignition

Postby Bob.Murphy » Thu Oct 10, 2019 10:15 am

Progress indeed. Congratulations on your victory over the Gremlins.

I look forward to reading your ride report ;) .

My avatar shows the late Len Rich in 1970 with the bike I now have - a 1958 Ariel VH

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Location: Tokyo, Japan

Re: 1948 Iron 4G Coil Ignition

Postby chris.matthews » Wed Oct 16, 2019 10:35 am

Hello Everyone,
In the aftermath of the Typhoon I have not had the chance to go for a run.
The bike has been standing in the workshop doorway where I can start it and let it run on the stand.
I'm hugely encouraged , it starts easily (like it always did) and runs well.
Suspicion of running rich, but that will be looked at with Real Runs - changing points cam is also on the menu.

No progress is possible for a few weeks as we are headed to UK (London) to see my daughter and celebrate my birthday
We will be able to follow World Cup Rugby in UK...…… but divided loyalties here between Japan and England.

With best regards

Posts: 37
Joined: Wed Oct 16, 2013 6:29 am
Location: Tokyo, Japan

Re: 1948 Iron 4G Coil Ignition

Postby chris.matthews » Tue Jan 21, 2020 11:28 pm

Hello Folks,
An update. I had it in mind to change the points, this was hastened when the teeny weeny wire broke.
Via this wonderful forum my points were correctly identified with a part number. These points were used on a variety of Mazdas and Mitsubishi Motors.
Given that I'm in Japan I thought getting the points would be very straightforward - how wrong I was. I got my Japanese buddies onto Japanese Internet and then resorted to 'bush beating' all to no avail.
The parts were estimated to be for cars over 10 years old and 'unobtainable'.
I then found the points via eBay - they were in Australia and ultra-cheap ($7) so I ordered two sets - the postage was about $40 ............…
The parts showed up around Christmas - they were perfect - I regarded them as a present to me and the 4G.
But it was too cold in the workshop to do much, but they have now been fitted and the bike starts and runs well - starting the bike in the doorway, but too cold for a Test Run.
Next up is a bigger challenge - 1938 MSS Velocette - low kickstart ratio, thick oil, cold weather and old legs have always made it a difficult starter.
The 1939 VB is much easier.
I'm waiting for a dose of Global Warming...………….

Best regards to everyone in Australia, I'm hoping you are all fit & well and not impacted by bushfires.

Best Regards

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Re: 1948 Iron 4G Coil Ignition

Postby tomwalker » Wed Mar 04, 2020 10:50 am

Hi Chris
Re starting your Velo....interesting in that I find my Mk 2 4G the easiest of bikes to start (those 250cc cylinders I suppose).
I have had a Venom for 2 years, and finally got the Half Nelson on the starting procedure, thanks to local club members.
The few old bikes Ive owned definitely dont need such a strict "routine".
Velos are almost impossible to start by just giving them a bloody good kick, but if you follow the procedure they start quite easily (assuming everything is working well, sparks and fuel). Also seem quite sensitive to the amount of spark retard you employ at the handlebar lever. That is particular to you and your bike.
Fuel on, and short tickle. They dont want to be flooded.
Full choke for cold start, no choke once warm at all. (Again may be particular to your bike).
"The Procedure"....
Find compression with kick lever.
Let kicker back up all the way.
***Decompress and steadily kick through all the way to the bottom, 6 oclock, not further.***
Kicker back all way to the top.
Tad of throttle.
Kick as hard as you can (no decompressor).

If you over flood the carb, my bike will start with the above procedure but with the throttle fully open.

I find the amount of retard is small, about an 1/8th in gap on the lever boss. But you will find the best for you. If it spits back, which is all mine will do if I dont get it right, I increase the retard by a fraction at a time. I actually have a tiny mark on my lever as a reminder of where it should be.

"The Procedure" is simply setting the piston in the right place so that it hits TDC on the firing stroke towards the bottom of the kick swing.

I bent my kick start shaft trying to fire it up when I first got it, because it would spit back with such force. Also hurt my foot!

But the amazing thing is, a local Velo club member has a fire-breathing Thruxton with high comp pistons and hairy cams etc, and it seemingly starts with no bother because he has the knack.

Good luck, shouldnt say this here, but Velos are lovely bikes too!!
Tom Walker
1955 4G.
1934 New Imperial 100
1934 Harley Davidson VL

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Re: 1948 Iron 4G Coil Ignition

Postby john.whiting » Wed Mar 04, 2020 11:26 am

Harley knuckleheads and panheads have 600cc cylinders,no lifter and no electric start,yet they kick start no problem.....cant flood the carb either ,just a butterfly choke. My old Panther has no valve lifter ,just the little lever on the cam case ,and starts no problem....Plenty of flywheel weight is the secret to easy starting.

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Re: 1948 Iron 4G Coil Ignition

Postby chris.matthews » Mon Jul 20, 2020 5:21 am

Hello Everyone,
This thread started almost exactly a year ago and earlier in 2020 we seemed to be 'nearly there', but needing some test runs.
Then we discovered Covid; Semi-lockdown and other such stuff. Periodically I strolled to the workshop and started the bikes, wishing for the end of semi-lockdown.
Then we got the all-clear and the 4G would not start - much disappointment as it was starting easily and I was due to take it to get the Shaken (local MOT).
After a huge amount of investigating I found that the Distributor Rotor was leaking through - the HT volts were not being distributed to the 4 cylinders. This distributor had a Mk I Mini Distributor Rotor - apparently these are notorious for such failures. The replacement rotor is the 'real thing' and its much better located - but the brass part is a bit smaller, long time back I included photos of the two rotors.
I'm thinking the ignition timing needs a small resetting. Hopefully over the coming days. We are in Rainy Season and have just had 20 consecutive days where we had a significant amount of rain.
At least the garden doesn't need watering.
Very best regards, please stay safe
Chris un Japan with '38 MSS; '39 VB; '48 Iron 4G and '52 B31.

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