Merc 650 starting issues

[djcanuck]

Hi there
I am having troubles starting my 74 merc 650. It will turn over with the cold start lever up but then shuts off. I checked the fuel filter it seemed to be clean. Plugs are clean. That leaves me to think that it is the carb. Whats your take? If I have to take the carb out does anyone have pictures or a step by step how to do it? My manual doesn't show me. I have a spare 79 (i think) 70hp could i use the carb out of that?
Thanks
Dan

 

[Starppy]

Re: Merc 650 starting issues

All things being equal, it sounds like a carb cleaning is in order. It's not as bad as it sounds. 2-cycle carbs aren't nearly as bad as 4-cycle carbs that you would find in older cars. If you have mechanical experience a lot of times a manual isn't needed. You just have to make sure that you take note how they were assembled so you can reassemble it the same way.

The main things you need to do are clean the screen filters at the inlets, check the floats and needle valves and clean all orifaces. While you have it apart, you may want to put a kit in it which will consist of new gaskets, needle valves and seals.

While the 650 was replaced in 1977 with the 3cyl 70hp and they were basically the same engine (block and LU wise at least) the carbs may or may not fit. There were certainly changes to the design. Even the 1976 650 veried from the 72-75 version. The only way to tell for sure would be to cross reference the part numbers.

In my opinion, if you are going to go through the trouble of swapping out the carbs, you may as well just clean the ones that are on there now. It will definately be less work and a whole lot less trouble.

 

[djcanuck]

Re: Merc 650 starting issues

Yeah I'm just going to take the carb apart and clean it. Thanks for the tips
Dan

 

[djcanuck]

Re: Merc 650 starting issues

Ok
I cleaned the carbs
However when I was taking the distributor cap off I noticed a crack in it, which then broke as I took it off.now there's a hole on the rim of the cap and the engine won't start up at all. Was this the issue all along?
Dan

 

[Starppy]

Re: Merc 650 starting issues

Could be and deffinately an issue, but you are better off having cleaned the carbs and certainly not wasted effort. Most would consider that "standard maintenence".

Before you replace the cap, check the distributor assembly and see if you can figure out why the cap cracked. Caps rarely just break. Look to see if it was a seating issue or if there is a problem with the rotor. Look for signs of scraping or rubbing inside the cap. You don't want to put on a new cap only to have it bust again.

The reason that is important is because those caps aren't cheap. Last time I looked they were NLA from Merc and there weren't any 3rd party equivilent. Whatever is out in the dealer channel is all that's left and they aren't cheap. I believe www.oldmercs.com has new ones available but they are $273. If you check the salvage sites you might be able to find a used one for $100.