G12 Loss Of Power

TommoT · Post by **TommoT** » Sun Jul 15, 2007 11:56 pm

...yes, this is a Danegerous job, only for thoroughbred Vikings!

itma · Post by **itma** » Mon Jul 16, 2007 2:28 pm

now all we need is swedledee and swedledum....

snatchpiece · Post by **snatchpiece** » Wed Jul 18, 2007 12:21 pm

My magneto does not have a bakelite end cover so I can't try the car condensor trick.

The two main causes that have been suggested on here are ignition system and/or sticking exhaust valve.

I've noticed my plug leads go up from the magneto into the space between the inlet tracts on the manifold before going to their respective spark plugs, is this the usual route?
I intend to replace them anyway and do not want to route them through a hostile environment.

What could cause a valve to stick after 15/20 miles? bearing in mind that it appears my bike has done very little mileage over the last 10 years. Is there any visual check I can do under the rocker covers to determine if one is sticking?

Thanks again to all who are helping me negotiate this rather tight learning curve, or am I going round the bend?

GSAX1 · Post by **GSAX1** » Wed Jul 18, 2007 12:33 pm

Does your magneto have a cut-out button integrated in the end cover? There were several version of end covers, some with stop leads, some with stop button. If you have the button type then my trick is not easy to adapt without modifying the cover.

About the sticking valve: you would experience loud ticking noise from the top end if this occurs. Is there any audible difference?

Michael

lawrence · Post by **lawrence** » Wed Jul 18, 2007 8:32 pm

quote:
my plug leads go up from the magneto into the space between the inlet tracts on the manifold before going to their respective spark plugs, is this the usual route?

doesn't sound a good route

GSAX1 · Post by **GSAX1** » Wed Jul 18, 2007 9:30 pm

quote: doesn't sound a good route

No, but it's the route they went when bike left the factory according to old photographs...

Stephenwalls · Post by **Stephenwalls** » Sat Jul 24, 2010 11:21 pm

Stephenwalls · Post by **Stephenwalls** » Sat Jul 24, 2010 11:25 pm

Hi, I had exactly this problem...ran for 15 miles and then lost power. The problem was a blocked cylinder head oil way. I'd advise taking the rocker covers off and check if oil is reaching all the rockers

Stephenwalls · Post by **Stephenwalls** » Sat Aug 07, 2010 10:09 pm

Hi,
I had a similar problem with my G12 CSR. I could get about 15m and the had a sudden loss of power. Turned out to be a sticking valve because I had a blocked oil way in the cylinder head stopping the lube and causing the valvesto stick