Navigation

You are here: Home / Messages / Singles / Hot Starting Help

Hot Starting Help

Up to Singles

Hot Starting Help

Posted by andrew_how at May 13. 2017

As a novice Norton owner (3 days from rebuild after being a non-runner) and after 3 days and two massive backfires I think I need to seek advice from wiser owners.

My bike a 1957 Model 30 Inter with a tt carb, and she starts 1st kick from cold with the advance lever approx a 1/3 retarded from full advance.

The first backfire was experienced with the advance/retard lever in the same position as when I started from cold.   The second backfire was today and after advice from another (BSA) rider I had the lever fully closed (maximum advance?).

Please could someone advise where I should have the advance/retard lever for easier starting as I'm not finding nursing a massively swollen ankle much fun :(

many thanks in advance for any assistance given.

Re: Hot Starting Help

Posted by David Cooper at May 13. 2017

You need to be totally sure which way is advanced if you don't want to break your Achilees tendon.

The prewar inters were usually slack wire advance  so if the cable snapped you did not lose the race. I imagine yours is the same.    Lesser bikes more often have tight wire advance. Kick starting on full advance will result in a kick back and possible serious pain or worse.

It depends on the magneto you now have 60 years after the bike was built. If it was a proper engine backfire it might well have upset the ignition timing anyway. You should have timed it with the magneto on full advance and retard it to start. How did you set the timing?

Have fun!

Re: Hot Starting Help

Posted by andrew_how at May 14. 2017

Previously David Cooper wrote:

You need to be totally sure which way is advanced if you don't want to break your Achilees tendon.

The prewar inters were usually slack wire advance  so if the cable snapped you did not lose the race. I imagine yours is the same.    Lesser bikes more often have tight wire advance. Kick starting on full advance will result in a kick back and possible serious pain or worse.

It depends on the magneto you now have 60 years after the bike was built. If it was a proper engine backfire it might well have upset the ignition timing anyway. You should have timed it with the magneto on full advance and retard it to start. How did you set the timing?

Have fun!

 

 

Hi David,

I'm thinking it wasn't a full back fire as I'm only bruised and swollen.

i had the engine rebuilt and commissioned by Ness Restorations as it had sat for 3.1/2 years with R40 as engine oil.

I was shown how to start it from cold with about 1/3 retard then once going full advance (slack cable) but nothing was said about starting hot...

I should have asked before venturing out but never thought.... all my other machines are modern era.

Even with a swollen ankle, I still returned home grinning!!

Thanks

Re: Hot Starting Help

Posted by john_holmes at May 14. 2017

The more advance the faster the tickover, so with a warm engine you can get away with less advance than on a cold engine. I have an advance curve that is fully programmable with inputs from crank position, crank speed and oil temp on a B44 single. For cold starting I have more advance than for warm starting, as soon as the revs go over 400 rpm I change the curve used to one with idle stabilisation, as the revs drops the advance is increased which brings the revs back up. If I used this curve for starting it would kickback.

Re: Hot Starting Help

Posted by George Phillips at May 14. 2017
I had a similar thread, Andrew, and I was asked to define backfire. In my case it was the piston firing backwards and the kickstart flying back up rapidly. If this is your scenario then the ignition is too far advanced - or possibly a weak mixture. Do you have an air control lever? When my ES2 is warm/hot it generally starts without the air lever being closed but with the ignition still retarded (for safety!) George

Re: Hot Starting Help

Posted by andrew_how at May 14. 2017
Previously George Phillips wrote:
I had a similar thread, Andrew, and I was asked to define backfire. In my case it was the piston firing backwards and the kickstart flying back up rapidly. If this is your scenario then the ignition is too far advanced - or possibly a weak mixture. Do you have an air control lever? When my ES2 is warm/hot it generally starts without the air lever being closed but with the ignition still retarded (for safety!) George
Hi George, Yes I have the same scenario, although I'm told the the lever on the right hand side of my bars is for the fuel mixture on the TT carb not air as in a choke, coming from a Japanese bike background and currently also running a new model speed triple I find I have so much to learn!! When I'm feeling brave enough and my ankle is back to normal I will try a hot start with full retard. Thanks Andy

Re: Hot Starting Help

Posted by robert_tuck at May 15. 2017

Hi Andrew, Yes the TT carb is different and what looks like a choke is not. Getting the mixture right and a little flooding with the tickler is all you can do.  The fuel level is critical ,too high and it floods ,too low and starting and pick up suffer. For safe starting you want the spark to occur a fraction after top dead center, once position is found I mark the advance lever with two blobs of red nail varnish . I think its better to set the static timing a few degrees retarded from the book as todays fuel seems to need that.Also with a points gap a couple of thou less than book I find the Mag flux position not too compromised.(which it usually is as its designed to favour the advanced position).

Re: Hot Starting Help

Posted by David Cooper at May 15. 2017

If it is hot and stopped there might well be a bit of fuel evaporation and a bit of 'tickle'  might well help.  You will need to retard the ignition just as you did when it was cold or it will kick back - as you've found out.

I'm sure we can discuss static timing for ever - I'd prefer to set it at least as far advanced as the book figures because modern fuel (no matter how much we hear it criticised) has much better octane that the stuff that the Inters were designed to expect not long after WW2. Octane had improved by 1957 but had the engine been changed?  And you can always retard it a bit on the lever - or mark the lever with dots at the book figure.  Has anyone ever needed the full retard lever setting?

I don't know about what others agree but, to me, a back fire is an explosion in the exhaust due to a late spark, which is different from the kick back due to engine firing off in the wrong direction due to over advance.  We had that problem with a difficult prewar Inter - and the mag sprocket moved and that made it impossible to start.

They are all different it seems.  We found it helpful to choke it slightly on kicking over with decompressor just a bid disengaged using a couple of fingers over the bell mouth.

Re: Hot Starting Help

Posted by jonathan_newton at May 15. 2017

Andrew; couple of things.  The enrichment device on the TT carb is exactly  that, it allows more fuel to come into the mix for starting; I never use it....  as  above, they are a bit prone to flooding but work well. 

You seem to have cold start in control so for warm/ hot my regime is:

  • Always kick it with the expectation of it starting, do not prod it, kick it.
  • Make sure you follow all the way through, no half kicks...
  • Do not touch the throttle when starting warm; the restriction of the slide will give you better draw on your fuel and she will just fire and then you  can control it.
  • When I stop I tend to back off the advance first so it settles to a  reasonable idle;  that is the setting I then restart at.  ( If its gone cold, I  will increase a little).
  • Shut the fuel off a little early just to stop any over fueling, (I am on a side stand only and the angle can cause a bit of flooding).
  • No tickling initially, only if she shows no sign of firing/backfiring...

 

All machines are different, these tips may work, but what is key is that you get to know what the bike likes for each situation and keep to it.

 To prove your settings bump start it and see how she reacts; if they are  right she will lope off down the road a you get your leg over!! and remember   Duke, Surtees, Hailwood  et al never needed a kickstart...

 Enjoy it;  F/bed inters are pretty rare, they are no slouch and handle like a dream...  the pain will soon wear off 

J

Re: Hot Starting Help

Posted by andrew_how at May 18. 2017

Thanks to everyone for your help and advice, which I will put into practice when my ankle has healed.

Today I relented and went to my doctor, after an x-ray it appears that I've torn m yligaments and muscles...... but was then told that it would have healed quicker if I'd actually broken my leg!!

Re: Hot Starting Help

Posted by robert_tuck at May 19. 2017

There is a definate  learning curve with starting big tuned singles, and much pleasure when you get it right.  My comment on fuel suitability was not in relation to octane but to speed of burning  which is faster than of yore and so needs less advance for complete combustion,less advance gives less stress on old components and tends to make starting easier.  With respect to the TT carb , the clue is in the name, It is a racing carb  and well suited to a Mountain course. The "choke" is an air correction device and when fully closed affects the depression on the  mainjet  and changes it by approx 3 sizes ,its function is an aid to fine tuning at large throttle openings particularly at varying altitudes. Close it for starting if you wish,but its effect at kickstart speed is an illusion unless you are bump/roller starting at large throttle opennings.

Re: Hot Starting Help

Posted by ken_campbell at May 19. 2017

 

I'll stop referring to it as a choke tube now.

I hadn't heard of using the air valve on a TT to adjust the mixture for altitude. It inspired me to do some reading. I get the impression that  the system was originally designed to aid cold starting, but folks subsequently figured out it could be used to correct mixture for altitude as you mention. Your comment about it being basically useless at kickstart speeds is interesting. Took me a minute to figure out the translation for depression.

Thanks for posting that Robert.

 

 

Re: Hot Starting Help

Posted by robert_tuck at May 19. 2017

I spent years closing the "choke" on a TT  for starting. The Amal literature does not clearly explain the device either. It wasn't till I used the Dellorto ssi carb which is the same design (don't know who copied who!) and read the Italian explanation that the penny dropped. It was never intended to be a cold start device, which is an encumberance on a racer and just one more thing to cause a problem.

Re: Hot Starting Help

Posted by jim_hill at May 19. 2017

Previously john_holmes wrote:

The more advance the faster the tickover, so with a warm engine you can get away with less advance than on a cold engine. I have an advance curve that is fully programmable with inputs from crank position, crank speed and oil temp on a B44 single. For cold starting I have more advance than for warm starting, as soon as the revs go over 400 rpm I change the curve used to one with idle stabilisation, as the revs drops the advance is increased which brings the revs back up. If I used this curve for starting it would kickback.

Re: Hot Starting Help

Posted by jim_hill at May 19. 2017

W.T.F.

Re: Hot Starting Help

Posted by ken_campbell at May 20. 2017

Found some Amal reading material here.

http://victorylibrary.com/brit/TT-c.htm

It does mention that it can be used to richen the mixture for starting. It doesn't say anything, but it does seem that the way it is designed, it wouldn't have much effect if any at small throttle openings.

Powered by Ploneboard
This is Brio Diazo Plone Theme