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Old 07 October 2006, 16:57   #1
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Boat name: Seawolf
Make: Osprey Vipermax 5.8
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Somebody's nicked me revs....

Out for a blast this morning and I have a little problem....

A couple of weeks ago I dismantled the throttle assembly because it has always been very stiff since I had the boat, and I wanted to see if I could find what was wrong. I eventually got it to bits after a bit of muttering, took one look inside at all the cables and slidy bits, and put it back together again in a hurry as 1. it all looked nice and greased and 2. I had no clue at all how it all worked so if it had gone "sproinggggg" I would never have got it back together in a million years.

Only problem I had was when I went to put the throttle lever back on the outside, it isn't "keyed" into one position on the splines in the unit, so I had to work it back and forth watching the cables and best-guess where it should be for the neutral detent to engage correctly.

I haven't used the boat since, but today when I was out I am about 400rpm short of the previous WOT revs, it was doing about 5200 and now is doing about 4800 which has lost about 3-4 knots at the top end. The gear selection also isn't quite right (sometimes doesn't come cleanly out of reverse unless you bang the lever forward against the stop preventing it going into forward gear). I've done nothing else to the engine and the load was identical to last time out.

Any thoughts please? If nobody has any ideas I think I'll try taking the unit off, moving the lever back towards reverse by 1 spline and see what happens (I guess that should cure the gear selection hiccup if nothing else), but I would have thought the full throttle stop would either be internal to the throttle assy or on the engine end? It will just be the standard Johnson throttle unit I expect, whatever was supplied with the engine.

Thanks

Stephen
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Old 08 October 2006, 10:08   #2
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stephen, did you shorten/lengthen the cables when you has it off and reassembled it? assuming they are similar to mine (AFAIK they are all pretty much the same idea) then you have a thread on both ends of the cables and a screw on fitting that clips on to engine/throttle. In addition there is a little locking nut. I set mine too tight at one point and had a problem similar to yours with the neutral/reverse not engaging properly. neil
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Old 08 October 2006, 10:55   #3
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As far as I know I didn't disturb any of the settings inside the unit because it looked fearsomely complicated. I didn't have the cables off it, I just unbolted it from the bracket on the side of the console, took the bolts out that hold it together and split it in two, thought "eek" and put it back together again! Is there anywhere you can download a PDF manual for stripping and adjusting the throttle unit? I have a workshop manual for the engine but as far as I remember there is nowt in there about the thottle unit.

It does feel "different" now though ... when you hit WOT it feels like there is a definite solid "stop" you are hitting in the mechanism, whereas before that WOT felt a bit rubbery and you just sort of shoved it hard forwards and that got WOT but it was very vague feeling. I really don't know why it is so stiff though, its fine around the neutral position and feels fine backing off the throttle, but to increase throttle needs a real shove.

It isn't the end of the world anyway but I'd like to restore normal service if I can, apart from anything else I haven't got to the big 40 yet

Its tipping with rain today but I'll have another look when it isn't and see if there is a locking nut on the outside, can't remember as it was a few weeks ago I took it to bits.
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