XJ 650 TURBO BOOST GAUGE

My 1982 machine is running at last as it almost should, all tested etc but the screen Turbo Gauge does not move, really want that to work.
Turbo is working etc.
Does anyone know the best way to get this last bit sorted?

Any ideas please let me know.

Thanks

 

IIRC, the boost sensor on the turbo is actually above the swing arm. It takes the air pressure from one of the carb outlets via a rubber hose.

There is a spec for the voltage measurement at atmospheric pressure.

Have you confirmed that the hose is intact, connected, an that the boost sensor is working?

You can also add an aftermarket gauge. I have one plumbed behind the carbs at the air-box, tee-ed off to the hose on the fuel pressure regulator. Great for knowing what you boost pressure is directly out of the compressor, and especially useful if you install a manual boost controller (and higher pressure fuel pump).

 

Thanks manbot13, the machine has been rebuilt did have a aftermarket job with the hose running from a carb nipple, if that makes sense, have removed it as want to get the bike gauge unit working.
Been informed that turbo etc all works apart from the bike turbo guage, that information was from the guy who rebuilt engine etc.

 

Looking back at some of your past threads, being "informed" that it's working by a mechanic (it looks like you've had some issues in the past) may not actually mean that everything works.

If everything is hooked up correctly, then I would test the boost sensor, which is what that hose on the front of the rack connects to. I'll see if I can find the spec for it when I get home.

I was only suggesting the aftermarket boost gauge as an add on, since it will have actual numbers (red means something different if you increase the boost) and will tell you the actual pressure that the compressor built (in the air box). Yamaha installed on in front of the engine to determine how much boost the engine is seeing to retard ignition timing. You will be building more boost that this, the pressure decreases past the carbs due to losses from the constricted throttle opening, and venturi affect.

What kind of luggage to you have on that thing? Those side bags look impressive. Also, did you ever sort out your welded turbo exhaust situation?

 

Yes the welded turbo sorted, it has been with a guy who does custom turbos etc, cost me a good few grand to get it working, he had it for 21 months.
I know he had put 2 different spark plugs in, so the bike was having problems on 2 cylinders, (stone cold) so moved the good ones over and they worked so have now changed all 4 plugs for the best you can get and fires and runs great just the gauge problem, the turbo chap says all works everything turbo has been rebuilt as so as the engine, the panniers where really hard to find. they are HEPCO.

 

To test the boost sensor:

Connect 12V to red/white wire teriminal, and Black Yellow wire to ground. Measure the voltage between the black/red wire and ground. It should be 2.0 V at 1 atm.

You can also test it on the bike by pulling the TCI connector and measuring the voltage between the black/red wire and the Black/Yellow Wire with the keyed power on. But that assumes that all of the wiring between the units is functional.

 

Many thanks will give it a go, could always fix a after market gauge if not to difficult to do, old senzei no mechanic but will always try, many thanks for all the advice.

 

Actually, if the boost sensor is bad, and not just the gauge in the dash, then no, it's not enough to just install an aftermarket one. That sensor plugs into the TCI, not just the dash, because is changes timing with boost pressure to prevent detonation.

It needs to be working correctly or your bike won't perform correctly under boost.

 

Pity you don't live near by will do what I can and let you know. Thanks again