oily muffler

[hecktwa]

I took my new cylinder, piston and ring set to a local machinist today and had everything miked and checked very closely. He said the clearances are fine an that I need to be looking elsewhere for the problem. When I mentioned I had already replaced the carb, he asked me about what kind of fuel pressure I had. When I said I hadn't checked it and the cart had been converted to an electric fuel pump, he just rolled his eyes and then said that was likely my problem. That is that the electric pump, unregulated, is likely pushing so much pressure on the carb, that its pushing against the needle and seat and causing the flooding which is filling the crankcase like it is. The PO had told me he just switched to an electric because the EZGO pumps where so expensive. Well, I have been looking around and they aren't that bad. I don't have a fuel pressure guage, but does that sound possible? I hate to keep throwing parts at this thing and coming up with goose egg after goose egg.

[cart around]

Yes, he is right.

My own personal opinion is that electric fuel pumps are nothing but trouble, and not worth the effort.

A couple of guys have had success by adding return lines to bleed off pressure, but again not worth the hassle.

[hecktwa]

Well, with that said it does seem to make sense to me and perhaps I actually had this problem before the top end kit was done and blamed it all on the worn rings and cylinder. So I may have had more than just a worn rings problem all along. I plan to go ahead and eliminate the electric pump without even bothering to test pressure, volume, etc and I've ordered a EZGO replacement fuel pump which appears for my year model will mount on the engine itself. That way, when I re-install the engine I'll start back with a clean fuel tank that has the proper break-in mix of 40:1 and new filter and lines to go along with the new pump. I'll check back in the event I have any troubles with the new pump and getting the fuel system set up correctly.

[hecktwa]

I have the new fuel pump so I'm starting back with the reassembly...very slowly and carefully this time! One thing that has cropped up is the reed valve block. There is clearly a difference in how it fits between the old cylinder and the new. I remember having a difficult time installing the four bolts that hold the intake manifold to the cylinder. I was afraid I was going to strip the bolts out while tightening them up. I got them all in and tight but it was slow go the whole way like the bolts were on the brink of stripping out. So with everything apart, I laid the reed valve block over the intake opening on the cylinder and noticed as it lays flat on the mounting surface, the four bolt holes do not line up. They are off about half of the hole. This apparently is why the bolts were so difficult to thread in during the first assembly. I dug out the old cylinder and just for comparison, I laid the reed valve block over the intake opening and it fit perfectly and all four bolt holes lined right up. I've enclosed pics of the difference between the new and old cylinders. It appears to me that the casting of the new cylinder inside the intake port is slightly different enough that the block isn't squaring up with the opening. If I hold the block directly over the 4 holes so they line up, then the block raises up about a 1/8 inch off the mating surface of the cylinder. Should I just declare this a bit of a imperfect cast cylinder and just take my old one and have it bored and fitted with an OS piston? That way I know the reed valve will fit properly. Does anyone have any ideas on this or run into something like this before?

[cart around]

Do some measuring between holes. I believe that block only fits one way.

I said this in an earlier thread, but I am not 100% sure.

[hecktwa]

OK, I checked the measurements between the holes and they are the same either way. Just to be sure I inverted the block 180 degrees and had same result...the holes still won't quite line up. Tried it on the old jug too and both ways the holes lined up perfectly. It appears the metal tabs that secure the reed valves are hitting the inside of the intake port on the new jug in a way that isn't happening on the old one. If I can determine that for sure, perhaps easier way would be to grind the area of contact removing only bare minimum to allow the block to sit flat against the mount surface?

[cart around]

Thanks for checking that. It has been 4 years since mine was removed. I just couldn't remember if the holes were offset. Good to know that they are all the same.

Now you need to measure the ports in each cylinder to determine how much material that you want to remove.

[Spicyunicorn]

This is the exact reason I choose to buy over sized piston and have my jugs bored out the quality of parts coming from China is less than ideal I would definitely get an over sized piston coming if it was me if that's messed who knows what else is on that jug

[hecktwa]

Yeah, Spicy, that was my first reaction when discovering this issue...just take my jug to a local guy I know personally and have him bore it out for an O/S piston. Like I've said before, I believe that when you do a repair and you end up with a problem you didn't have to begin with its either something wrong in the labor part or bad parts installed. I'm tending toward it being bad parts. I'm far from a genius on 2 cycles, but I have mechanical background and have been very careful on re-assembly to get everything right and to specs. So I'm guessing 0.30 would likely be the usual first oversize available for a 3pg? As sloppy as the original piston was in the jug, I figure it may 30 thousands to get it to clean up and I'm sure the machinist I know an determine that.

This is a lesson learned for me. Rather than getting lured in by a relatively inexpensive third world top end kit, I should have had my original stuff machined and likely I would have long ago been happily enjoying using my cart again around my property.

[Spicyunicorn]

I've always gone couple tho over the piston that's in there you'll have to wait until the piston shows up to take the cylinder in the machine shop goes off of the piston when machining to get the right tolerance so as long as your new piston doesn't fit down the cylinder you should be good to go also I would get ahold of the supplier you bought the kit from and show them your pictures and try to get your money back