This post is partly prompted by the recent magneto one referencing hard starting when warm, but I'm pretty certain it's fuel in my case. The bike will start first or second kick from cold (with choke) and runs fine but requires major flooding to start even between switching off and then immediate re-starting. Can't seem to get the plug wet even by what would normally be considered serious flooding from tickling. Has a nice old bronze Amal 89B/1AK which I'd like to keep using and has been stripped and every orifice cleaned on several occasions. Magneto is rebuilt and healthy. Float is NOS could it be sticking shut somehow?
Any thoughts appreciated as always.
Iron Head
Hard Starting When Warm '48 Rigid G80
- Iron Head
- Member
- Posts: 277
- Joined: Sun Jan 24, 2016 7:19 pm
- Location: BERKSHIRE UK
-
- Posts: 16
- Joined: Fri Sep 29, 2017 11:17 pm
- Location: Warwickshire England
Re: Hard Starting When Warm '48 Rigid G80
Something that slipped my aged mind in the magneto thread was that when warm my bike seems to have lost its compression. It pushes over past TDC too easily for my liking. Certainly don't need a valve lifter. I can stand on my tiger cub kickstart at TDC but not the Matchless. Strange, why only when warm. This of course means less 'suck' as well...? Just a thought.
-
- Posts: 2884
- Joined: Mon Mar 24, 2014 5:44 pm
- Location: Aberdeenshire
Re: Hard Starting When Warm '48 Rigid G80
Hi
I wonder if both these issues could be related to the exhaust valve clearance and differential expansion of components in the valve train. The significance of it only happening when warm could be down to the fact that certain parts will come 'up to temperature' quicker than others.
May be worth checking the exhaust valve clearance and opening it up a little if possible.
Regards Mick
I wonder if both these issues could be related to the exhaust valve clearance and differential expansion of components in the valve train. The significance of it only happening when warm could be down to the fact that certain parts will come 'up to temperature' quicker than others.
May be worth checking the exhaust valve clearance and opening it up a little if possible.
Regards Mick
- Iron Head
- Member
- Posts: 277
- Joined: Sun Jan 24, 2016 7:19 pm
- Location: BERKSHIRE UK
Re: Hard Starting When Warm '48 Rigid G80
Thanks for a good suggestion guys. Mick, I had wondered about valve clearances particularly as I haven't re-checked after the top end rebuild and a tight exhaust valve clearance might well be the culprit. I have plenty of compression and I do seem to get a sound each time like it is firing once but the 'firing' may be fuel in the exhaust?
Regards
Iron Head
Regards
Iron Head
- Iron Head
- Member
- Posts: 277
- Joined: Sun Jan 24, 2016 7:19 pm
- Location: BERKSHIRE UK
Re: Hard Starting When Warm '48 Rigid G80
Checked clearances last night and the exhaust was certainly tight using the ‘check exhaust with inlet just opening' and vice versa procedure in the manual for my year. Will run up tomorrow and report back.
Iron Head
Iron Head
- 1608
- Member
- Posts: 2496
- Joined: Mon Oct 05, 2009 1:00 am
- Location: ESSEX UK
Re: Hard Starting When Warm '48 Rigid G80
Difficult starting when warm can be caused by running too rich. Loss of compression can be caused by sticking exh valve due to valve/guide clearance closing up when warm due to burnt oil deposits. When engine cools the valve re-seats.
Just another thought, could it be fuel evaporation. Is there a Tufnol spacer fitted on the carb.
Just another thought, could it be fuel evaporation. Is there a Tufnol spacer fitted on the carb.
-
- Member
- Posts: 23
- Joined: Thu Jan 01, 1998 12:00 am
- Location: BADEN-WUERTTEMBERG GERMANY
Re: Hard Starting When Warm '48 Rigid G80
I had the same issue on my 1948 G80.
As far as I`m concerned,the spacer between the head and the carb was made of aluminium in these years
Swaped it for a more usual pertinax / plastik spacer and voila,
that took care of that, no more hot starting ploblems anymore.
Of what material is the spacer on your bike made of?
Regards,
Norman
As far as I`m concerned,the spacer between the head and the carb was made of aluminium in these years
Swaped it for a more usual pertinax / plastik spacer and voila,
that took care of that, no more hot starting ploblems anymore.
Of what material is the spacer on your bike made of?
Regards,
Norman
- Iron Head
- Member
- Posts: 277
- Joined: Sun Jan 24, 2016 7:19 pm
- Location: BERKSHIRE UK
Re: Hard Starting When Warm '48 Rigid G80
Thanks for the carb spacer tip Norman. Mine is aluminium so probably well worth a try! No change to hot starting with the tappet adjustment just more tappet noise?!
Iron Head
Iron Head