Pressure sensor

[bro.betterley]

I have some questions about the part called a pressure sensor in the manual that conects to the vacuum port, I assumed it was a timing advance control ?


My concern is mine dosent hold vacuum, and the cylinder that it is conected to appears to be very lean (header is blue) could this be the cause of the lean condition?

 

[maleko89]

Yes, it has a strain filter and adds supplemental advance to the ignitor based on vacuum. If your header is blue I would take a look at that carb for excessive leaness. There is a test in the manual for the pressure sensor.

Disconnect connector. Hook 12V jumper wire to black/red sensor terminal. Ground jumper to black/yellow. Use VM and measure voltage between red/black and black/yellow wires. Should read about 2 volts.

 

[Rusty McNeil]

Even tho it is "connected" to one cylinder, it controls timing for all cylinders, if you have a header turning blue I'd look at the carbs first...

Are you talking about the stock pipes or do you have aftermarket single wall headers?, single wall are going to turn blue no matter what....the stock pipes might also with enough mileage....

 

[bazwell]

I haven't ever looked at that sensor on my bike, so this is just general advise.

If the sensor doesn't hold vacuum, it may be the source of a vacuum leak. That would make the cylinder nearest where it bolts up run lean.

 

[KJShover]

I'm willing to bet that the lean condition is in that cyl's carb.
I'd pop the plugs and have a look see to check out how they line up. Then if they all look good or all but the offending cyl, I'd start by adding more a/f screw on the lean cyl.

 

[Rusty McNeil]

If the sensor doesn't hold vacuum, it may be the source of a vacuum leak. That would make the cylinder nearest where it bolts up run lean.

Yes it could.
But these type of sensors almost never fail, at least not in the mechanical sense you refer to, they might stop transducing pressure to voltage but leaking is almost unheard of....

you could check it by spraying some ether on it while the engine is running to see what it does to make sure...

 

[one2dmax]

We've had a few fail and not seal internally causing the leak. It's not common normally but we have seen it.

 

[95spfldmax]

Isn't the little component half-way up the hose a check valve? I believe it is. I checked mine and a spare I had and niether one would hold vacuum in either direction.

Would this create a performance issue? Most likely not the blue-ing of pipes anyways.......

 

[Rusty McNeil]

Isn't the little component half-way up the hose a check valve? I believe it is. I checked mine and a spare I had and niether one would hold vacuum in either direction.

Would this create a performance issue? Most likely not the blue-ing of pipes anyways.......

I think that little thing your talkiing about is simply a reducer to slow down the pulsations and helpt stabilize the transducer output,,,,,,,,??:ummm:

 

[dingy]

Isn't the little component half-way up the hose a check valve? I believe it is. I checked mine and a spare I had and niether one would hold vacuum in either direction.

Would this create a performance issue? Most likely not the blue-ing of pipes anyways.......

I have one of the restrictor's laying on my desk, so picture is attached. It is not a check valve, there is a straight path through it.

It seems to serve two functions. 1st is to serve as a transition from the hose size on the intake to the boost sensor. 2nd it dose have a narrowing which will to some extent help smooth vacuum pulses. It is not as nearly restrictive as the dorman 3/16" restrictor though.

I just got a boost sensor Saturday that I bought on ebay and at first glance it appeared to not hold a vacuum. But it turned out to be the hose was damaged near this plastic restrictor.

The pulsations that were mentioned are viewable with the Ignitech TCI software. The pulses are somewhat high at idle, but smooth out quite a bit as RPM's increase.

Gary

 

[dman]

So not a one way valve just a valve that restricts the vacuum/pulse?