Idle issues on a 75 115hp Rudy

[honald112]

I just want to start off by saying thanks for all the advice the seniors put out. I never really have to post due to finding most of my answers by looking at different threads.

Ok, main topic. I just installed an OMC tach for my 1975 115hp Evinrude. Model # is 115593. What is the proper idle rpms. Its currently at 1100 rpms at idle on muffs. When it warms up and I go to start it, I have to raise the warm up lever or it will stall almost instantly. It also stalls out when just trolling barely out of neutral. It turns right back over so then I just give it alittle more gas and its fine. I just dont like being rude making a little wake in a no wake zone if you know what I mean.

How can I adjust my idle in and out of gear?

Thanks for any advice gentlemen.

 

[Lone Duck]

Re: Idle issues on a 75 115hp Rudy

Try checking your throttle stop may be adjust it so the butterfly closes more . If that don't work , lynk and sync is next.

 

[emdsapmgr]

Re: Idle issues on a 75 115hp Rudy

1100 rpms on the muffs is probably normal. Don't plan on setting the idle when it's on the trailer. You must set the idle when the boat is at rest floating in the water. The idle is set by adjusting the idle timing, not the carb. There is an idle set screw on the throttle/advance lever on the starboard side of the powerhead. The engine should idle normally when adjusted to 650-750 rpm-in gear. If set properly and it still will not idle, the idle circuit passages in the carbs could be clogged with dried fuel, etc-requiring cleaning of the carbs.

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

Thanks for the advise. They want it raining for the next three days so after I do that and clean the carbs I'll let y'all know what happened. I'm sorta new to the 2 stroke world but I am mechanically inclined; what is a lync and sync?

 

[emdsapmgr]

Re: Idle issues on a 75 115hp Rudy

These engines must maintain a specific relationship between the carb butterly opening and the ignition spark advance. Called Sync and Link. The process is outlined in the factory service manual. It needs to be set properly for maximum performance and economy. In addition to doing this procedure, check the linkages and rollers for wear or missing parts. Many of the rollers deteriorate with age affecting sync and link adjustments.

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

All my linkages are in great working order and the butterflies are perfectly sync with one another. I cleaned out the carbs and adjusted he idle at he dock and she is sitting around 1000 rpms in nuetral and 750 in gear. I also adjusted the warm up bad per the factory man. You guys are incredible with the advice. One last question for now. I don't have a pee hole on mine and only way I can tell my water pump is working is thru the exhaust reliefs which starts to mist right at start up which makes me smile. How can I install one on my style Rudy. It's been in the family for 35 yrs ans want to keep her running perfect. Also what is the optimum water pressure thru the throttle range.

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

Sorry and I just rememebred to ask this. My prop is a 13x19 and is running at 5100 rpms at WOT at 38 mph on a 1975 reinell t-1900. Should I leave it be or try a 21 pitch to get a tad more top end and would that kill my whole shot for skiing? Thanks again for the replies! -Jake

 

[ezeke]

Re: Idle issues on a 75 115hp Rudy

Sorry and I just rememebred to ask this. My prop is a 13x19 and is running at 5100 rpms at WOT at 38 mph on a 1975 reinell t-1900. Should I leave it be or try a 21 pitch to get a tad more top end and would that kill my whole shot for skiing? Thanks again for the replies! -Jake

In my opinion, you are already over-propped and lugging your engine, which will shorten the life.

If your top end is 38 MPH at 5100 RPM you are already experiencing over 17% slip, which is too much, and it will just get worse if you increase the pitch of your prop.

I think that you should prop your rig to reach a maximum of 5800 RPM with your average load. You wll probably need to go to a 17 pitch at least to do that, and if you are pulling skiers, maybe 15 pitch.

Gear Ratio for the calculator is 2.00

http://go-fast.com/Prop_Slip_Calculator.htm

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

I hope I don't offend you by questioning your knowledge, but isn't it bad to push past my max rpm rating of 5500. I thought I was doing well with this 19 at 5100 lol. Guess I have a good reason to tell the misses I need to go shoping.

 

[kenmyfam]

Re: Idle issues on a 75 115hp Rudy

Sorry and I just rememebred to ask this. My prop is a 13x19 and is running at 5100 rpms at WOT at 38 mph on a 1975 reinell t-1900. Should I leave it be or try a 21 pitch to get a tad more top end and would that kill my whole shot for skiing? Thanks again for the replies! -Jake

As said 5,100 rpm at WOT is not enough for you. You need to drop down in pitch to make your motor run efficiently.

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

Will I get a higher top end and still have a decent hole shot along with more effiecnt fuel economy with the 17

 

[ezeke]

Re: Idle issues on a 75 115hp Rudy

I hope I don't offend you by questioning your knowledge, but isn't it bad to push past my max rpm rating of 5500. I thought I was doing well with this 19 at 5100 lol. Guess I have a good reason to tell the misses I need to go shoping.

You cannot offend me, but I do like outboards. I ran a 1976 115 from 1976 until 2007 when I gave the rig to my nephew who is still using it, and yes, he pulls skiers. The boat it is on weighs a little less than yours. I never used a prop higher than 17 pitch and I switched to the 15 pitch when I pulled skiers. The motor has never been rebuilt. I attribute the longevity to TLC and not being lugged. On a bad day that boat would do 40 MPH.

Here's what iboats has on your motor, and if it is correct, I'll stand by my recommendation: http://www.iboats.com/Reinell__V-1900__1975/bp/64b71265r0

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

Thank you very much for the advice. I will going to the local marina today.

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

I just check out your link and I have a t-1900. that's about 750lbs difference. Should I stick with you same advice or do u have any other suggestions?

 

[ezeke]

Re: Idle issues on a 75 115hp Rudy

I just check out your link and I have a t-1900. that's about 750lbs difference. Should I stick with you same advice or do u have any other suggestions?

The only T boat iboats lists for 1975 is I/O T 1901 weighing 750 lbs more because it includes the motor... http://www.iboats.com/Reinell__T_1901__1975/bp/64b71403r0

 

[emdsapmgr]

Re: Idle issues on a 75 115hp Rudy

You are lugging the engine at 5100 rpm. Not good. Follow the expert's advice and change your prop to a lower pitch. The engine will run easier and your fuel economy, holeshot should improve.

 

[honald112]

Re: Idle issues on a 75 115hp Rudy

Found out the motor was alittle low so now my anti cavitation plate is in line with the keel. Im getting 5700 out of it and 40mph at WOT. I still have the 13x19 omc prop on it. Do tyhe experts think i should leave it or should i try a 21 pitch. and if i am adviced to try it, will it still give me enough out of the hole to pull up and average sized adult on some skiies? Thankls again guys for the help

 

[emdsapmgr]

Re: Idle issues on a 75 115hp Rudy

5700 rpm is fine. The 19 sounds like a good prop for your setup. By the time you get 2 friends, a cooler, full tank of gas and their gear on board, you will be running under 5700 at WOT. Try your 19 for pulling skiers. It may work out ok. You will lose 10% of your torque by going to a 21 as well as losing top end rpm. You need more grunt to pull skiers-not less. When pulling skiers, you may even want to temporarily change to a 17 and gain 10% more torque than the 19.

 

[kenmyfam]

Re: Idle issues on a 75 115hp Rudy

Found out the motor was alittle low so now my anti cavitation plate is in line with the keel. Im getting 5700 out of it and 40mph at WOT. I still have the 13x19 omc prop on it. Do tyhe experts think i should leave it or should i try a 21 pitch. and if i am adviced to try it, will it still give me enough out of the hole to pull up and average sized adult on some skiies? Thankls again guys for the help

How much too low was it ??? I am guessing quite a bit to give you a 600 rpm increase. Make sure you are still cooling O.K. Moving up in pitch will only decrease the RPM's again. If you still need more hole shot for pulling up skiers then you may want to consider "porting" your current prop.

 

[ezeke]

Re: Idle issues on a 75 115hp Rudy

How much too low was it ??? I am guessing quite a bit to give you a 600 rpm increase. Make sure you are still cooling O.K. Moving up in pitch will only decrease the RPM's again. If you still need more hole shot for pulling up skiers then you may want to consider "porting" your current prop.

If you use the calculator, you will see that you still have way too much slip at 22%, using your numbers: 19 pitch at 5700 RPM and 40MPH.