SoCal Jet Boats

Tech Talk => Jet Pumps => Topic started by: HaulsBalls on April 24, 2011, 10:14:28 AM

Title: Berk issue in rev.!!!!!
Post by: HaulsBalls on April 24, 2011, 10:14:28 AM: I recently rebuilt my Berkely 12JC-A and had it out for the first time yesterday. It worked great in forward and neutral but when reversing the bucket there was a noticable RPM drop and it felt like the motor/pump was loading up pretty good. Is this normal when in rev. or is there something going on that needs attention?
Title: Re: Berk issue in rev.!!!!!
Post by: jet boat performance on April 24, 2011, 11:18:33 AM: Quote from: HaulsBalls on April 24, 2011, 10:14:28 AM
I recently rebuilt my Berkely 12JC-A and had it out for the first time yesterday. It worked great in forward and neutral but when reversing the bucket there was a noticable RPM drop and it felt like the motor/pump was loading up pretty good. Is this normal when in rev. or is there something going on that needs attention?

With the exception of a combination Hand throttle/Fwd Reverse controller , when your reversing the jet your simply redirecting the water flow the engine doesn't know the difference How is your jet and throttle controlled ?
Title: Re: Berk issue in rev.!!!!!
Post by: HaulsBalls on April 24, 2011, 12:57:59 PM: Foot throttle with hand control for the bucket control. I could have just passed it off as the pressure to redirect to flow and maybe the reverse outlet being smaller than the actual nozzle. Let me know
Title: Re: Berk issue in rev.!!!!!
Post by: HaulsBalls on April 25, 2011, 07:19:10 AM: Any opinions on this?
Title: Re: Berk issue in rev.!!!!!
Post by: jet boat performance on April 25, 2011, 10:05:27 AM: Typically theres Zero difference in engine load *(at idle) between FWD and Reverse
Title: Re: Berk issue in rev.!!!!!
Post by: HaulsBalls on April 25, 2011, 10:10:29 AM: Quote from: jet boat performance on April 25, 2011, 10:05:27 AM
Typically theres Zero difference in engine load *(at idle) between FWD and Reverse

That's what I had thought, but once the bucket is closed for reverse the engine rpm noticeably drops after about a second or two. I'm not sure if I did something wrong in the rebuild but the pump is pretty straight forward when assembling, would it need to break in the packing/bearing? I did use grease in the bowl bearings instead of gear oil but figured there were many other people running the same way.
Title: Re: Berk issue in rev.!!!!!
Post by: 77GT on April 25, 2011, 10:31:11 AM: How many RPM does it drop?
Title: Re: Berk issue in rev.!!!!!
Post by: HaulsBalls on April 25, 2011, 11:14:18 AM: Quote from: 77GT on April 25, 2011, 10:31:11 AM
How many RPM does it drop?

It would drop around 200-250 rpm (just an estimate but very noticeable when it happens), this is just from idle which is around 850 rpm.
Title: Re: Berk issue in rev.!!!!!
Post by: NORDIC454 on May 03, 2011, 01:38:04 PM: Over or through transom exhaust? If its through, It could be that when the boat is traveling in reverse, the tips are under water completely which seems to make it drop in rpms.