carb rebuild, 1966 650

[imported_miked]

1966 merc. 650, sn 2109652. My first try at rebuilding carbs. All three manuals say to remove welch plug. Is this really necessary? I see 3 ports that lead to the chamber behind the plug, and I'm sure that I can direct a blast of canned air into the larger one. Would this be sufficient? The carbs appear to be very clean while disassembling. Thanx, Mike

 

[nos1013]

Re: carb rebuild, 1966 650

I just rebuilt mine (66 650 also) and left the plugs in the carbs with no problems. I think you really only need to replace the plugs if they're leaking.

 

[Laddies]

Re: carb rebuild, 1966 650

mike spray some carb cleaner down the hole the needle screws into and it will come out the idle hole if they are clean

 

[imported_miked]

Re: carb rebuild, 1966 650

Thanx guys! nos, no sign of leakage. Laddies, I'm not sure what holes you're talking about. I'll take a close look tomorrow and it will probably be obvious. I have another question. The manuals say to remove the throttle plate and shaft, then to remove the throttle return spring from the throttle body. The spring on my carbs is outside of the carb. Is there any point in taking them apart? Thanx again, Mike

 

[nos1013]

Re: carb rebuild, 1966 650

the only reason for removing the throttle plates is to strip out the threads when you try to reinstall the screws. I didn't bother with that, either

 

[imported_miked]

Re: carb rebuild, 1966 650

Thanx nos. I have another question, concerning the main jets and altitude. The lakes I go to range from 4,000 to 10,000 ft. The main jets I have are .071". Does this seem right? If I need to change them, now is the time! Thanx again, Mike

 

[nos1013]

Re: carb rebuild, 1966 650

well mike, I'm a flatlander, so someone else needs to answer that question.

 

[Laddies]

Re: carb rebuild, 1966 650

Mike my manual lists 3 differant carbs for 650s around that serial a KC2A--std.jet .069//KC5A--std.jet .071//KC5B--std.jet .061 but the only listing for jet sizes for elevations are below 4000'=.061 //4000 to7000'=.059 // 7000 to 10000'=.057 even though I belive this is for the KC5B carb and you must have a KC5A I think the rule of thumb is the same. Newer carb recommendations call for .002 smaller per 4000 to 5000' of elevation. Hope this helps, USE CARE

 

[Mercr]

Re: carb rebuild, 1966 650

Hey Mike,<br /> <br />'Looks like we're neighbors. I'm now in Castle Rock, but spent most of my "formative years" in Colorado Springs. <br /> <br />I've been following "related threads" on things that I'll most likely end up doing to my "new- to me" 850. Where do you go, locally, for parts & stuff? Is Al West Boats still up on North Nevada? It's about the same trip to my "Denver" shop as it is to the 'Springs, so if you find ( or have found) a good shop, it would be good to know. <br /><br />My (45-225 HP, 1972-1989) Clymer manual states (650 - SN 4382056 & below, prior to '84) Carb jets for Elevations: <br /><br />2,500'-5,000': .072 Main, .084 Vent.<br /><br />5,000'-7,500': .070 Main, .082 Vent.<br /><br />7,500'& up : .068 Main, .080 Vent. <br /><br />Good luck!

 

[Laddies]

Re: carb rebuild, 1966 650

Those specs are for 1972 and newer carbs, not the older tillotson cards like carbs that are on Mikes 1965 65HP engine Mercr

 

[imported_miked]

Re: carb rebuild, 1966 650

Thanx guys! Laddies, the charts in my manuals (Merc., Seloc, & Clymer) don't seem to cover my motors year. It seems that the first 650 listed on the jet size page is several years newer than mine. I'll have to look closer. I agree, I must have the KC5A; again, I'll have to look a little closer. I talked to my local shop this afternoon, and was told .071 was standard, and that I might see some better performance at higher altitudes with .069. I fish mainly in the hills, so I think I'll make the change.<br />Mercr, the local shop I mention is indeed Al's. Great bunch of guys. <br />thanx to everyone for the help!