1947 rigid with a 54 alloy engine

honda185 · Post by **honda185** » Sat Jul 28, 2001 7:20 pm

When its warm and I've been out anywhere, if I stop my bike is an absolute bugger to start. Its been ok till today but it just won't have it.
I've checked timing, points, tappets, plug but still no good.
There is a good spark from lead and plug, petrol is getting through but nothing at all. It doesn't cough, splutter or anything. I had to leave it at a mates ang get the bus - great!!!
Could it be possible that when the plug is in and tightened up the spark somehow dies - could it be anything to do with the magneto??
Help I'm totally lost

TommoT · Post by **TommoT** » Mon Jul 30, 2001 9:35 pm

Keith, two possibilities spring to mind:

1. If your carb is mounted directly on the manifold without an insulation spacer, the heat of the hot cylinder/head could be transferred to the carb, causing petrol vapourization and too lean a mixture for starting. Try using the air slide or cover the air intake somehow.
2. A partially broken down armature winding in your mag could give problems as described. When the mag gets warm, the air gaps between the ends of any broken wires get larger or the spark finds a shorter way to ground, i.e. short circuits. Also any weakness in the permanent magneto field strength gets worse as heat builds up. I recently gave up on a mag showing similar signs of weakness. After a longer trip abroad, with starting problems along the way, it finally gave up more or less permanently. I relented and send it CMES in Bristol.

Hope this helps

Tom M. (TM)

honda185 · Post by **honda185** » Fri Aug 03, 2001 8:43 pm

Hi.
Insulation to carb OK so I suspect its the mag - looks like a trip to the bike shop.
Thanks for the reply
Keith

clive · Post by **clive** » Mon Sep 17, 2001 10:26 pm

I have experienced this sort of problem and I reckon you have a problem with the seal between the carb and the engine. Do you get occasional popping on the overrun?