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  1. J

    Yamaha 250 OX66 Loss of Power

    I have twin 1999 Yamaha OX66's. The starboard engine has been acting up lately. The engine will stall at low idle and at high RPM (above 4,500 RPM). At fast idle and through the mid-range, the engine performs fine. Shifting into reverse stalls the motor as well. The engine will work under...
  2. J

    Yamaha 250 OX66 Sluggish

    The weekend befor last, I took a long cruise down the Chesapeake Bay about 50 miles to Solomon?s Island. In looking at my oil reservoirs, I figured I would be a bit short on oil based on the 100 miles I expected to travel. After going to 8 different stores/docks, I was unable to locate Yamalube...
  3. J

    Yamaha 1999 250 OX66 running hot

    I have a pair fo these motors on my rig. A couple months back, both were rinning hot only at low (below 1500) RPM's. Changed out Poppit Valves and 1 engine corrected. Of the remaining possibilities (water pump or T-stats) which is more likley to be the culprit, or is there something else to...
  4. J

    1994 Yamaha 225

    I have a 1994 Yamaha 225txrs sitting on a fixed rack in the full down position. The tilt/trim has a seal leak. I am trying to tilt the engine up so I can (i) get to the trim unit itself and (ii) remove the lower gearcase. Apparently there is not enough fluid in the resovior to engage the trim...
  5. J

    Twin Yamaha 250's out of sync

    I have twin Yamaha 250 OX66 EFI's. I recently switched out props from 23P SWS II's to some 22P Bravo I's. The engines both run fine, but are now out of sync about 300 RPM's-Port motor is lagging. No outward signs of poor performance, just lagging behind the starboard motor 300 RPM or so. I...
  6. J

    Ignition key panel compatability

    I have a 1995 dual station prime start key panel. Is this compatable with a 2003 set of 4 strokes?
  7. J

    Prop Binding

    I have just installed a pair of Bravo I's on my 1999 Yamaha OX66's witht he Flo-Torq II Hub assembly kit per instructions; Thrust washer, Drive Sleeve, Prop, Drive Sleeve Adapter, Tab Washer, Lock Nut. As I begin to torque down the lock nut, the prop starts to bind with hardly any torque...
  8. J

    Poppot gromet

    While changing the Poppit valve in my Yamaha 250 ox66, I managed to push the old rubber gromet into the cavity beneath the poppit. Any suggestions on how to retrieve it without taking apart the whole back side of the engine? WIll this cause problems if left. I did start the engine and run it...
  9. J

    1999 Yammi 250 EFI coughing

    I recently re-powered my rig with twin 1999 Yammi 250 ox66 EFI's. Splashed them in the water for the 1st time yesterday. While motoring out in no wake zone (4 mph), Starboard engine sounded temp alarm after about only 5-10 minutes. I shut it down and continued out w/ port motor. Ran the...
  10. J

    Installing new water pressure gauges

    I'm installing new water pressure gauges on my 250 Yammy's. Instructions were vague. Need to know if I'm suppost to cut the hose to lenght. Both ends are pre-terminated (one end with the brass fitting into the engine, the other has a small brass insert in the hose). Which end should be...
  11. J

    Priming the oil line necessary.

    I just completed an engine swap (1999 Yammi 250's) and was wondering it I need to somehow prime the oil injection system. The oil resevoir on the engines are full, but the supply lines to remote tank were replaced during the swap. Do these lines need to be primed? Thanks
  12. J

    What constitutes "over-propped"

    I'm wondering what level of decrease in WOT rpm would constitute my motors being over-propped. Got a pair of Yamaha 250's (replacing last years225's) on a 25' BW Temptation. Yami specs say 4,500 - 5,500 rpm range. I'm swinging a 23 pitch prop (up from a 21 pitch on the 225's) but have not had...
  13. J

    Yamaha 250 OX66 Fuel Rail

    I am replacing the fuel rail in one of by Yami's and need to know about the clamps that hold the hose on, both at the top and bottom of the rail. Rodbolt, you suggested in a previous thread not to use hose clamps on this type of connection. Do you or anyone else have an opinion about using...
  14. J

    Yamaha Fuel Management Gauges

    There has been a couple of recent threads regarding these guages. I am re-powering with 1999 Yami 250's that came with 2 Tachs, Speedo and Fuel Management. My old set-up also had these gauges (1994/5 era). My replacement gauges seem a little different on te rear. First, the older gauges have...
  15. J

    1999 Yamaha EFI Fuel Rail connections

    I'm hoping someone could point me in the right direction regarding a break in my fuel supply leading into the fuel rail (and on to the injectors). There is a small brass fitting at the top and bottom of the steel fuel rail, both having a nipple to accept fuel hose and a clamp. On the top brass...
  16. J

    Re-powering Yamaha's

    I am getting set to retire a set of 1994 yamaha 225's and replace w/1999 EFI 250's. Although I am pretty handi, I am not a yahama technician nor do I pretend to be and don't want to get half way through the project and have to call for help. Can someone offer suggestions as to what elements of...
  17. J

    1999 Yamaha OX66 Propellers

    Thanks again for the quick responses on my previous compression thread. Another issue I need to tackle is what size props to outfit a C/R pair of 1999 Yamaha OX66's. I have owned 3 previous sets of Yahama's and never had reason to change out of the stock stainless. However, I would like to...
  18. J

    Yamaha 250 Compression

    I am considering pulling the trigger on a pair of 1999 Yamaha 250's. I've read a lot about compression and gathered that consistency throughout cylinders is most important. The motors are reported to have 110# throughout all 12 cylinders. I have seen other motors with higher compression...
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