Redcap19 Posted June 7, 2021 Share Posted June 7, 2021 Hi guy finally got my boat out and got the digital rev gauge on and had it tunning great butt still cant get more than 10 knots out of her it ticks over at 840 and revs up to 4300 flat out and the compression is 125 in each chamber and i have checked all the back and front boxs Quote Link to comment Share on other sites More sharing options...
Saintly Fish Posted June 7, 2021 Share Posted June 7, 2021 Hope you don’t mind, but I’ve moved this topic to the relevant area. Quote Link to comment Share on other sites More sharing options...
Andy135 Posted June 7, 2021 Share Posted June 7, 2021 Hi Redcap, Remind me, what's your engine make & model? 4300rpm max seems a bit low. Quote Link to comment Share on other sites More sharing options...
GPSguru Posted June 7, 2021 Share Posted June 7, 2021 3 hours ago, Redcap19 said: Hi guy finally got my boat out and got the digital rev gauge on and had it tunning great butt still cant get more than 10 knots out of her it ticks over at 840 and revs up to 4300 flat out and the compression is 125 in each chamber and i have checked all the back and front boxs As a semi displacement hull, with 25hp they will do about 14 knts, some people fit 30hp, but I think the hull is only rated to 25hp The reasons for not getting the revs, could be wrong engine size, or incorrectly propped ........... Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 7, 2021 Author Share Posted June 7, 2021 Hi its a 25hp johnson Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 7, 2021 Author Share Posted June 7, 2021 The boat is rated off 22knots woth a 25hp on the back iv tryed to different props and im friend has the same boat and he is running a 25hp yamaha and he gets 19 knots at 3/4 of a throttle Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 7, 2021 Author Share Posted June 7, 2021 On my m8 25hp yamaha he has the same size prop there both 91/2 x 13 pitch Quote Link to comment Share on other sites More sharing options...
Maverick Posted June 7, 2021 Share Posted June 7, 2021 Your revs are way under the recommended which is min 4700-5300rpm Johnson operators guide I would suggest as a start you ensure you are getting full movement in your throttle cables. I had that once on a Hardy 17 with a 25hp outboard Quote Link to comment Share on other sites More sharing options...
GPSguru Posted June 7, 2021 Share Posted June 7, 2021 1 minute ago, Redcap19 said: The boat is rated off 22knots woth a 25hp on the back iv tryed to different props and im friend has the same boat and he is running a 25hp yamaha and he gets 19 knots at 3/4 of a throttle The boat is rated by Orkney at 14knts with an absolute max of 22knts. There are a lot of Strikeliners here locally and not many guys get more than 16 - 18 knts even with a 30 on the back and only single crewed ! If your boat is propped correctly and the hull is clean, then you have an engine issue, which usually means it is running way too lean at high rpm. Take it for a run at max rpm, stop the boat and pull the plugs, if they are white, then it is too lean. Also remember that with a displacement boat, your speed will influenced buy whether you are running with the tide or against the tide. Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 7, 2021 Author Share Posted June 7, 2021 1 minute ago, GPSguru said: The boat is rated by Orkney at 14knts with an absolute max of 22knts. There are a lot of Strikeliners here locally and not many guys get more than 16 - 18 knts even with a 30 on the back and only single crewed ! If your boat is propped correctly and the hull is clean, then you have an engine issue, which usually means it is running way too lean at high rpm. Take it for a run at max rpm, stop the boat and pull the plugs, if they are white, then it is too lean. Also remember that with a displacement boat, your speed will influenced buy whether you are running with the tide or against the tide. I when yesterday so ill check the plug iv all ways been told to run my outboards 50:1 mixs so i had 24l of fuel and 480ml of oil as that what quicksliver says ?? When i go the boat it had a 10 1/2 x 11 pitch and it was doing 16 knots and it was a bit choppey and i was full throttle and couldn't keep up with my m8 Quote Link to comment Share on other sites More sharing options...
Andy135 Posted June 7, 2021 Share Posted June 7, 2021 Yep, @GPSguru beat me to it... you're both right. Below taken from the Orkney site in respect of a Longliner, which superceded the Strikeliner I believe. Bottom line though is that whilst 22 knots may technically be achievable, the factory will have recorded this with the lightest crew they could find, and with no gear on board, with a following wind and with the tide. I'd argue these probably aren't real world conditions. Regardless of this, your revs are still low. As @Maverick has suggested, check your throttle opens fully at the engine, and if it does, then check your fuel lines and filter are allowing full flow of fuel. When you get to 4300 rpm, does the engine struggle to get there, or does it zip round but not go any higher? Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 7, 2021 Author Share Posted June 7, 2021 It rev up to the 4300 revs no problem and just says there iv had the hood of and checked it be for that it is out fully Quote Link to comment Share on other sites More sharing options...
GPSguru Posted June 7, 2021 Share Posted June 7, 2021 56 minutes ago, Redcap19 said: I when yesterday so ill check the plug iv all ways been told to run my outboards 50:1 mixs so i had 24l of fuel and 480ml of oil as that what quicksliver says ?? When i go the boat it had a 10 1/2 x 11 pitch and it was doing 16 knots and it was a bit choppey and i was full throttle and couldn't keep up with my m8 Ok, it is not the fuel / oil mixture that is questionable, it is whether the engine is running lean at high revs (fuel/air mix on the carbs). If the plug colour is white, then it is lean, if the plug is black the it is too rich. You need to be hitting 5000 rpm at full throttle. Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 7, 2021 Author Share Posted June 7, 2021 Ok ill check then thanks for your help Quote Link to comment Share on other sites More sharing options...
suzook12 Posted June 7, 2021 Share Posted June 7, 2021 Have you put new plugs in? I would put new plugs in as well, we had this with the lads mx bike, just wouldn't rev out, no missing, spluttering or anything, tried jetting to no avail. Put another plug in and bingo. To check the mixture you need to kill the motor on a flat out run, pop the plugs out and check the colouration around the centre electrode and sheath. Other things to consider..... Is the hull carrying a lot of water under the floor? Have you weighed it? Quote Link to comment Share on other sites More sharing options...
GPSguru Posted June 7, 2021 Share Posted June 7, 2021 2 hours ago, suzook12 said: Other things to consider..... Is the hull carrying a lot of water under the floor? Have you weighed it? I did give that a thought, but even with several gallons of water in the bilges the engine should still reach almost max rpm but the prop would slip against the weight. Quote Link to comment Share on other sites More sharing options...
Odyssey Posted June 7, 2021 Share Posted June 7, 2021 How are you measuring the revs? Is this a digital output from an ECU or via a tachometer that needs to be configured? I speak from experience of someone who tried to reprop their boat and the revs didn’t go up as the tachometer frequency was interpreted incorrectly... Quote Link to comment Share on other sites More sharing options...
suzook12 Posted June 7, 2021 Share Posted June 7, 2021 he says electronic rev counter so probably one of those x turns round an ht lead jobs.... Good enough for trying to figure out what's occurring. 870rpm at idle is right ball park GPSguru 1 Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 30, 2021 Author Share Posted June 30, 2021 I have finally got to boat back out and was running a new prop on her and i was getting 5200 and am now get 16 knot so a lot better than before just need to fine tune abit more 👍👍 Quote Link to comment Share on other sites More sharing options...
Saintly Fish Posted June 30, 2021 Share Posted June 30, 2021 4 minutes ago, Redcap19 said: I have finally got to boat back out and was running a new prop on her and i was getting 5200 and am now get 16 knot so a lot better than before just need to fine tune abit more 👍👍 Good result , now we need to hear some fishing reports 👍🏻 Quote Link to comment Share on other sites More sharing options...
Redcap19 Posted June 30, 2021 Author Share Posted June 30, 2021 Lol we have had sum bass tope and turbot showing the last couple of weeks so not bad down here at mo Andy135 1 Quote Link to comment Share on other sites More sharing options...
Andy135 Posted June 30, 2021 Share Posted June 30, 2021 1 hour ago, Redcap19 said: I have finally got to boat back out and was running a new prop on her and i was getting 5200 and am now get 16 knot so a lot better than before just need to fine tune abit more 👍👍 That's a good result. Well done. As @Saintly Fish says, get some reports up 👍👍 Quote Link to comment Share on other sites More sharing options...
JDP Posted July 1, 2021 Share Posted July 1, 2021 (edited) What prop is on now? Edited July 1, 2021 by JDP Quote Link to comment Share on other sites More sharing options...
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