Honda CB450DX - H plate (90) Lost a cylinder

[chrisio]

Hi All,
Picked up a Honda CB450DX cheap as a project and it was advertised as having engine issues! Anyway before I strip it all down to rebuild it I wanted to see if I could get it running to assess the engine. It starts fine but only on one cylinder, the dead cylinder occasionally barks and spits into life before dieing again.

Things I have checked
I have a spark from the coil
I seem to have compression as I can feel it out of that exhaust
I have fuel

I cant confirm YET if I have a spark at the plug due to no plug spanner in the correct size
I havent checked compressions yet due to the above!

Im going to have a go at it tomorrow but Im looking for other suggestions as to what I should be looking at.

Thanks
Chris

[stinkwheel]

Pretty sure you should easily be able to eliminate electrical problems quite quickly.

As I recall those are a 360 degree twin with a wasted spark yeah (like the 250 superdream)? As such, try swapping the whole electrical caboodle over to the opposite side (ie, swap the plugs round and swap the plug caps over).

One of three things will happen:
1) It will remain the same. Your problem is not electrical. I'd try the carb next.

2) The misfire will swap sides. You have isolated the fault to a very narrow area of the ignition circuit, buy new plugs, HT lead and plug caps.

3) It misfires on both. You have both electrical and other problems.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[chrisio]

Thanks for replying.
Since I dont have the correct size sparkplug socket today I pulled the HT lead earlier from the dead cylinder and earthed with a spare plug and I got a huge spark so i'm confident the HT side is ok. The only other thing it can be on that side of things is the spark plug its self and I will confirm that in the morning as well as doing a compression test on both cylinders.

Thanks
Chris

[chrisio]

Whoohoo. The problem was a closed up gap on the sparkplug. redid the gap and its away!

Cheers
Chris