[Sergey]

As far as I know and see there are 2 valves (PC valve and suction valve) in GL1200's fuel line. I will highly appreciate if somebody can tell me in simple words how they operate and what are these valves in charge for? Also please explain the way the air and vacuum systems effect CDI and can some bugs in these systems cause problem with fuel, sparks and misbalance in engine? The matter is that me and my friends nearly go mad trying to find the reason of misfiring or gas cut off in my Wing.

Thanks in advance!

Sergey

 

[glhonda]

There no valves in the fuel line.
There is a petcock, a fuel filter and a fuel pump. That's it. If you have something else in the fuel line, it isn't stock.
There is no pcv "valve". The low pressure in the venturi pulls vapor into the air box. There is a moisture separator that is suppose to lead down to a reservoir on the left side of the bike.
There is, however, a vacuum cut or slow cut valve. It is normally open and is only suppose to close on deceleration to richen the mixture and prevent backfire. It shouldn't cause a high end miss.
On US 1200's, there is also a reed valve assy that allows fresh air into the exhaust to help "wash" it. (secondary air system) It is an emission design and may not be on your bike. It's not used on Canadian rigs.
It too closes on decel, so it shouldn't affect high end driveability either.
Have you considered the possibility of excessive blow by, since the problem only seems to occur at VERY high speeds.

 

[Sergey]

Thanks for reply! What do you exactly mean by saying "excessive blow by"? Detonation caused by wrong timing?

 

[dudeboy]

blow by

Thanks for reply! What do you exactly mean by saying "excessive blow by"? Detonation caused by wrong timing?

excessive blow by is when compression leaks around the rings. you can determin that by a compression test and using oil in the cylinders. if compression comes up with the addition of oil then you have bad rings and blow by.

 

[Sergey]

excessive blow by is when compression leaks around the rings. you can determin that by a compression test and using oil in the cylinders. if compression comes up with the addition of oil then you have bad rings and blow by.

Thanks dudeboy but compression is perfect in every cylinder (12)