link and sync on a 1988 48 special

bob johnson

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Feb 25, 2009
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I dont have a manual for this motor or a similar 2 cylinder motor...

teh motor starts ok...then doesnt run great,...I havent had it on a boat yet so i do not know how it runs at higher rpms...it will rev in nuetral on the muffs...but runs poorly..150 lbs compression each hole, great spark..

went and rebuilt both carbs..runs exactly the same afterwards...

if I just throttle it with the carb linkage she moans and dies...if i rev it with the throttle arm that moves a plate under the flywheel as well...she revs ok...but..over all idles poorly and wants to die..

I am thinking of checkign the link and sync..

I have a 1988 70 hp factory manual...

can i use the proceedure in there....to do a link and sync ???

I know one more carb and cylinder....just a stab..

want to put the motor on my 16 foot boat and sell...so really dont want to go out and bouy a manual...

or if anyone knows where the proceedure is posted for a 48 special remote control motor ..let me know please

bob
 

Joe Reeves

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Feb 24, 2002
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13,262
Re: link and sync on a 1988 48 special

Bob..... To have your post returned to the top of the list, simply go back into it and reply to yourself with something like....... "Bump ^" without the quotation marks which seems to be the accepted standard.

Spark plugs should be Champion QL77JC4 plugs, gapped at .040 . You can try a revised gap of .030 later after you have the engine running properly.

Your quoted 150 psi per cylinder compression is ideal. Great spark?..... Should jump a 7/16" gap (with the spark plugs removed) with a strong blue lightning like flame.... a real SNAP! Does it?

The plate under the flywheel is the timer base (spark advance).

No, to my knowledge, you cannot use a 70hp manual on a 48hp engine.

Opening the throttle by hand without advancing the spark normally has the engine falling on its face so to speak.

If the compression and spark are as they should be, the problem you speak of is usually contributed to either fouled carburetors OR having the throttle butterflies opening too soon OR the throttle buterfly linkages between the carburetors being out of adjustment.

The linkage between the carburetors should be set so that the buterflies open and close at the same time..... by closed (at idle), you do not want one closed and one ever so slightly open.

The scribe mark on the cam....... the throttle cam roller should just make contact with that scribe mark when the roller is dead center with the scribe mark.

Hopefully you haven'y moved/adjusted the measurement between the metal cam and its connection at the other end. If you have, hopefully you remember where it was previously, and if not, someone else will need to guide you on that measurement as I don't have the book on it.
 

bob johnson

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Re: link and sync on a 1988 48 special

hello, my intent was not to shame you into answering my thread!!!!!!

really just matter of factly speaking...the nature of the beast...hope you undertsand my candidness..

as for my motor...used but new to me...a few years ago i was on a boat it was on and it ran ok..

thats it for history...now for me..

I have not adjusted anythign so far,,looked at a lot, I did removed and rebuild the carbs and reinstall...with no change...spark jumps blue 7/16th"..i have a spark tester!!

yes the test i did moving the throttle with out the timer base moving..does make the motor fall on its face!!!

there are lots of places for adjustment it appears....and i wanted to try and go step by step , so i asked about the 70 hp book, because the carbs and linkages look very similar and they are the same year!!

the plugs look to need to be replaced..i have brand new ones that i havent installed yet...the gap on the older ones actually looks bigger than ID THINK it should be..maybe .04"

I will look carefully at the throttle plate and see if they open the same in sync when the throttle is moved..

if you rev the motor is revs good...even though there appears to be a miss..

pulling a plug wire one at a time off each cylinder definately hurts the motor...

no leaks

just doesnt want to idle...very rough and will die if left on its own...I GUESS i could just screw the idle stop way in!!!!! but then I am sure the rpms would be close to 1100.

looks like ill have to chase down a book...

didnt want to wait a week or more for a $60 book( ken cook) and then sell the motor off a month later with the boat!!

If the plugs were bad the motor wouldnt rev like it does when given gas....would it???

seems like a timing thing...for some reason

thanks

bob
 

Joe Reeves

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Joined
Feb 24, 2002
Messages
13,262
Re: link and sync on a 1988 48 special

On a flushette OR in the water in neutral, the engine would rev high even if running on one cylinder. DO NOT rev the engine under these conditions any higher than 1800rpm, otherwise you chance a runaway engine..... BOOM!

Cleaning the carburetors (both of them), did you actually clean the high speed jets manually with a piece of single strand wire? If not, do so. If they're somewhat clogged, fuel to all other fuel passageways will be affected.

Change the spark plugs rather than guess whether the installed ones are okay or not.
 

bob johnson

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Feb 25, 2009
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4,304
Re: link and sync on a 1988 48 special

on muffs so far....

I never rev in nuetral more than maybe 1500 rpm ever!!!

I specifically looked at both jets in each carb...with a 5x loupe... they are superbly clean, and round!!!

I syringed all passages with solvent and compressed air..and ran small wires in all holes and re cleaned..and blew dry...floats are level when upside down...new needle and seat for the float valve...

check on the changing the plugs.

bob
 

bob johnson

Rear Admiral
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Feb 25, 2009
Messages
4,304
Re: link and sync on a 1988 48 special

I installed the new plugs yesterday, the mechanic sold me L77jc4, not
QL77jc4.

I gapped them at .04...that helped a little with the poor idle...the motor does not die now...but it sounds like a big block chevy with a huge cam!...if you know what that sounds like..I dont a way to check the rpms now, but it sounds a little fast...


the throttle arm moves a bit before the cam contacts the roller...so the timing is advancing...both plates inside the carb bore are close and open at the same time...

there is a primer device and I can hear it click when i push the key in...but i dont see a choke hooked up to the carbs!!

not like the 1980 I have sitting next to it that has a wire and spring runnign from that primer device to the choke plates.....


not that i needed choke yesterday!!

sounds like it misses just a tad when i try to rev it....

bob
 
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