1993 Yamaha C-85 Hard to crank

[Les Robb]

I bought this engine 10 months ago on a project boat. Finally have boat finished but the motor is hard to crank. The previous owner had used starter fluid so I guess this has been a long term problem. Last time I tried to crank it the motor flooded but after cleaning plugs it fired up and this was about a month ago. I knew from the get go it had low compression with all 3 cyl reading 90 psi but had read that this was common on commercial engines. Anyway I'm curious if anyone has had the same problem or if they used sea foam or starter fluid to help on a cold engine. Once running in the tank, she smooths out real well when warm.
PS Never considered using fluid before .

 

[ondarvr]

So we are using the same terms, cranking is turning the key and the starter spinning the motor, the next step is starting.

​Hard cranking is typically from a bad starter, low battery, or bad connections.

​Not starting can be from incorrect method, poor state of tune, choke or enrichment circuit not working, low compression, etc.

 

[Les Robb]

Sorry about that and starting cold is the problem. Main question was about the use of starter fluid or sea foam.

 

[ondarvr]

If you need to spray starting fluid or fuel into the carb for the motor to start there's something wrong, this method just allows you to live with a typically easy to fix issue. Clean the carbs and make sure the choke/enrichment system is working, then work on a starting technique for that motor, this should eliminate the need for starting fluid. Low compression can cause hard starting too, and compression gauges can read very different from one another, so 90psi may or may not be OK for that motor.

​Starting fluid can be hard on a motor, it can lead to severe pinging (detonation) depending on how you use it, plus you need to buy the type that is designed for 2 strokes and has oil in it.

Sea Foam is not a starting fluid.

​

 

[Les Robb]

Agreed and thanks for the input. As an experiment I gave the engine a fast (very small) shot of fluid this morning and she fired right up. Once warm she starts up with no problem, and as soon as I can get my hands on a Yamaha service manual I will go through the entire system. It sat at least a month or more since I ran it last and I've never had it in anything other than a stock tank which limits me to low rpm's for running. I'm amazed at how similar this engine looks like the 3 cyl omc engines.

 

[ondarvr]

I'm amazed at how similar this engine looks like the 3 cyl omc engines.

OMC and their attorneys thought the same thing when Yamaha started making outboards.

 

[Les Robb]

That's a hoot, Wish my 70hp Johnson service manual would work on this engine. Thanks again.

 

[Les Robb]

One last question, found a 1996 C85U factory manual and wondering how you feel about using it for adjusting timing, link & sync etc on my 1993 C85STL?