My perkins genarator is overspeeding what could be causing this???

It sounds like there is a air leak at air intake. Take normal underarm spray and when the bike is running spray around intake ,revs should stay the same, if it increase , there is a air leak at intake manifould/rubbers.

http://www.trawlerforum.com/forums/s6/adjusting-governor-perkins-t6-354-a-28180.html

Check out this thread on adjusting the governors on the perkins.

We are Perkins diesel generator OEM and can provide 22KW to 1800KW Perkins diesel generator including open type,silent type and container type genset. Each genset has its user's manual.

Normal starting procedure of Perkins Generator set

1. As far as possible do not start the generator set under load conditions.

2. Transfer the key switch to the starting (STAR) position. The engine should start immediately.

3. After the engine starts, return the key switch to the running (RUN) position. If the engine has not started after 10 seconds, turn the key switch back into operation and (RUN) for 10 seconds. Then repeat steps 2 and 3. If the engine is still unable to start after three attempts, please find out why.

4. After engine starts, follow steps 4.a and 4.b.

A. Check the oil pressure.
B. Check the machine for leaks.
C. Make sure the battery is charged.
D. After running the engine for five minutes, check the generator monitoring system. Make sure the engine works properly before loading.

Note: do not use ether-like spray starting aids in cold weather. Otherwise, it could lead to explosion and personal injury.

The use of water jacket heaters or extra battery capacity improves the machine's start-ability below 10 ?.

Methods for checking and cleaning the core of the rear cooler of Perkins generator set

Check for damage, corrosion, dirt, grease, insect stains, leaves, oil and other debris on the cooler. Clean the cooler if necessary.

https://www.dieselgeneratortech.com/generator-sets/Instruction-for-Perkins-Generator-Set-Maintenance.html

the question is ---is the tacho faulty at those rpms causing a short to the ignition module
or
is the ignition module faulty causing the tacho to react accordingly
tachos get a power supply and an impulse signal from the ignition system and that impulse is registered as a rpm reading
try disconnecting the tacho and see if the problem occurs and if it makes no difference then look for the problem else where
the problem may be in the carby/s ( assuming that the engine is carby run) or if efi then run the fault codes for problem s in the maf/vaf sensors

Any engine runs better doing what its built for, but it should not be very noticeable. If you are familiar with this engine, then I would tend to go with your instincts. The injector timing is a likely cause and could be supplying more fuel than you need creating a laboured combustion which evens out under load.
Perkins parts were found everyware around western Australia 20 years ago and were cheap, I'm a bit out of touch on that aspect these days, but they are worth the effort, you should try to find some old school farmers around to speak with, they often have golden and unique solutions.

I have a similar problem with mine, but the drop from three to two cylinders only happens when moisture gets into the tach -- the tach itself has been jumping around for years and I pretty much ignored it until now that I'm having the problem. The Tach is connected to a coil, and the moisture appears to short the circuit, preventing the cylinder from firing properly. Perhaps other problems with your tach are causing similar problems with the coil, even in dry weather? I just ordered a new Tach from 2wheelpros.com after shopping around for a while. There may be some aftermarket alternatives for less, but I'm in a hurry to get my bike running again for a charity event, and don't have enough time to look into aftermarket parts and hope they work. I hope this helps -- good luck with yours.

We have this same issue with a Perkins model mp 400E here in Afghanistan. It will start up and run for about 30 seconds at its normal 50HZ 1500 rpm operating speed, then it will gradually start to slow down and shut itself off around 1350 rpm. There are 4 vertical fault lights on the control panel, and the bottom one stays red and refuses to reset. We can't figure out what is causing this fault light or the stalling engine. Any help would be greatly appreciated!

purchase some chemtool B-12carb spray around your throttle body. may have manifold hose leaks. when you spary it and the idle increases then thats where the problem is. can i get some feed back thanks.

I take it it's diesel. Have you renewed filters? Bleed fuel system Make sure there is plenty of diesel flowing out of tank (pipe not blocked) Check lift pump working

Is the generator a disel engine.

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