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engine rebuild

Old 12-09-2006, 06:01 PM
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Shockwaver
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Default engine rebuild

Hello all I have a kb 3.5 outboard engine that i just rebuilt but cant get it to start. my question is should the sleeve once its installed line up where the port openings are exact or do they overlap which is the way it looks to me a little, I think i have the connecting rod and piston in ok the oil hole for the rod is facing up and the piston pin is also up toward the carb? I have a mc9 plug and am running 25% odonnell fuel i've tried the needle setting any where from 4 to 2 1/2 turns out and she wont even fart . It pulls fuel up to the carb I know to connect the starter backwards clockwise and know the plug and glow starter are ok meter shows good and have tried os8 plug also when i got the piston and sleeve (from ebay) they looked good and the piston goes in about 7/8 to the top when out of the crankcase is this ok? seems to hit maybe where sleeve is worn and when installed has slight bind on top of the stroke, but turns over and then will lock up Must be bad parts
Old 12-09-2006, 06:18 PM
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w8ye
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Default RE: engine rebuild

Sounds as though you have the wrong piston, rod, or maybe even the sleeve. Piston should come up higher than that?
Old 12-09-2006, 06:27 PM
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Default RE: engine rebuild

Maybe try the MECOA forums? The guy who is now manuf. K&B's should be able to help ya out?
www.mecoa.com
You'll have to register to get into the forums, but there is a specific forum just for K&B questions...
Old 12-12-2006, 12:13 PM
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Default RE: engine rebuild

Did you compare the new parts to the old ones to make sure they was the correct parts to start with?
Theres no way a piston can only go up 3/4ths of the way and get enough compression to fire.A 2 stroke engine has to have good compression to be able to run.
As far as the ports go I line them up, so if the hole in the sleeve is smaller I split the diff on both sides of the exhaust port and so far I have not had a problem.
I agree a trip to Mecoa may be your best bet here.
Old 12-13-2006, 08:56 AM
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Default RE: engine rebuild

try locking up factory settings when you have it all done
Old 12-13-2006, 03:43 PM
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Default RE: engine rebuild

proptop thanks for website cyberwolf piston does come up more but has a spot where it feels like its hitting something looking at the sleeve once apart again looks like sleeve might be worn , Parts i bought might be bad !!! Thanks guys
Old 12-13-2006, 04:27 PM
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Default RE: engine rebuild

He said 7/8 of the way to the top when out of the engine. I think he is talking about the pinch which would be normal. It may of course go up higher with the extra leverage of the crank. Sounds good to go to me, but not really enough info.
Old 12-13-2006, 05:33 PM
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Default RE: engine rebuild

My mistake I miss read your post ,After looking at the breakdown of the engine it appears to be a ABC design so Sport is correct what your feeling is the pinch just before TDC .But here again if theres not enough compression the engine will not run .
Was these parts new or used that you bought? After reading what you said about wear it appears they was used,as a rule not such a good idea.

Mecoaengines.com has the complete line of parts for that engine new and in stock .
Good luck .
Old 12-14-2006, 12:30 AM
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Default RE: engine rebuild

I think it is locking up because it has a lot of pinch from the tapered bore and it is cold. You can heat it up with a monocote gun or a hairdryer, it will be easier to turn over then and should start with fuel and hot glow plug.
Old 12-14-2006, 09:48 AM
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Default RE: engine rebuild

It pulls fuel up to the carb I know to connect the starter backwards clockwise
Most of these engines run counter clockwise when facing them.

Since Sport brought it up is the engine turning over or just going up to the tight spot and slipping the starter cone ,I find it very hard to think that a little engine of this size could do that,but stranger things have happened.

A little more info would be very helpful
Old 01-05-2007, 07:35 PM
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Default RE: engine rebuild

Found Problem Old kb 3.5 outboard had shorter head Mc9 is a long plug it was flooding tried os 8 shorter plug She's alive
Old 01-05-2007, 10:54 PM
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Default RE: engine rebuild

HUH was the plug hitting the piston head?
Anyway Im glad ya got it going,Happy boating.

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