Need a little help

rustybentwrench

New Member
Hello, new to the site.

I have a BACCIO scooter. Yup. Baccio. I can't find much on it, but do know it has a minarelli style 49cc horiz two stroke engine.

The main complaint is that it will not take full throttle. It is running lean and runs stronger after I drill the main jet out. Manual calls for a 76 main jet, I've drilled out to 98. It ran allot better but still goes flat at WOT. I bought a new carb, and the results were the same. Upon inspection, I found the compression was low -60psi. I rebuilt the top end (piston / rings) - everything went together tighter, piston fit and ring end gaps were at the min. as listed in the manual. Before stating it up, rechecked compression - 60psi. I don't get it. I've got about 20 minutes on the engine, and should check it again. But it runs the same. I could jet it up, but it is way more than the manual calls for.
ALSO - I noticed when I had it apart, the std spark plug BP6HS does not come down into the combustion chamber. It looks like a 3/4" reach plug is needed. All the books on this engine call for BP6HS.

enlighten me. THX
 
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rustybentwrench

New Member
posted a few days ago and no comments.

Thinkin about checkin the reed valves. I did a compression test after a good 40 mins of running and still 60 psi. Im thinkin something wrong there. I'm going to do again with another gauge.

Help?
 
Sorry for the late reply!
Yes, chekc the reed valves and replace with carbon ones. Also check if the intake seals are all well. If this doesn't help it's most likely the crank seals. There are ways to replace them without splitting the engine, but if you don't mind opening it, I'd replace the crank it with a 12mm gudgeon pin one (ideally a whole circle crank) and get some better bearings. You're save then for further tuning! Also, the fact that you need such a huge main jet tells that there is some air leak in the engine!

Best,
Daniel
 

rustybentwrench

New Member
Thanks for the response.
But you don't understand. Or I didn't explain thoroughly.

I'm not in this to spend money. Something is fundamentally wrong here.
After re- piston and ringing. it still has 60 psi compression.
Maybe need to check my gauge. --

It will take full throttle now and run hard, but after 10sec it boggs and will not take full throttle" till like" the float bowl fills back up.
That is what it seems to me. I'm going to check the float height on the carb, but it seems like a filling prob.
It all goes to hell when I put the air cleaner on it. Runs too rich or something. really runs like sh!t.
Reeds look good.

I can't work on this every day. I have a regular job (thank god) But it is a project in the corner of my garage.

I'm thinking about a new top end. Maybe 70cc since they are relatively cheap and easy to find. BUT, maybe i would be opening up to new problems.
 
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rustybentwrench

New Member
WOW.
have done some work on this and found out some stuff
Yea, I put a cheap 70cc big bore kit on it. - MORE problems - nothing un-solvable
but discovered some basic stuff if attention is paid to detail makes a big diff.


#1 - fuel flow is important. if you have a vacumn switched fuel system. make double sure it works as designed. I found mine was hanging up and after some cleaaning and lube, gas would flow with 3" of vac. No starvation probs after that.

#2 - LOOK at your intake manifold. Cracks may not be immediately visible. Flex it around. AIR LEAKS - big probs for 2 strokes.

sometimes 2 probs gang up on you when you are looking for 1 problem
 

rustybentwrench

New Member
oh yea-
check your compression w a gauge that doesn't have a 2' hose on it
use one that you have to hold to the head.

compression will be allot lower because you have essentially more head volume in the hose.
learn from my mistakes!
 

rustybentwrench

New Member
UPDATE

seems I was working against a couple problems.
mechanically all was fine. I got the cheap 70cc BB kit to work.
set it up w no base gasket, jus formagasket. Milled about .015 off the head w a belt sander.

the problem was;
the vacuum operated fuel valve.
an entire overhaul of the fuel delivery system did the trick.

Now I have a reliable smokin machine.
70cc kit
open aircleaner
poked out exhuast
runs about 45mph wide open w a tail wind
and takes off quick.
 
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