Honed 1 engine and put in new piston and rings, and yes, the rings required considerable filing for correct gapping. Now for the top end break in and seating of new rings. I understand that oil rich fuel is needed for the break in. Have 2 engines and no pre-mix, 1990 challenger 1800. Anyone have a suggestion on how far to adjust the pump cable, or an alignment (or misalignment) of marks to increase the oil to one engine by a suitable amount for the break in?
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Break in top end 787/800
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For break in I would just run the oil injection and pre mix 40 or 50 to 1. Use mineral oil for the break in, preferably xps so you can switch to xps full synthetic without all the hassle of cleaning out old oil, priming etc. Not sure if you want to talk about the need to file the ends of your rings considerably or not but this seems unusually to me. Did you put in a stock size piston? Or 1 size over?
STD, 82mm, piston and rings. Not gaping the rings is a common mistake as they come oversized. Mine came at .1 mm.
Ring end gap New 0.25 - 0.40 mm (.010 - .016 in)
Wear limit 1.00 mm (.039 in)
As far as oil, premix will send excessive oil to the other engine. In manual, it states that oil flow rate is doubled between tach of 1500 and 3000. Therefore, considering setting pump at 3000 mark for idle. This should about double the oil to that engine only.
Ring end gap New 0.25 - 0.40 mm (.010 - .016 in)
Wear limit 1.00 mm (.039 in)
As far as oil, premix will send excessive oil to the other engine. In manual, it states that oil flow rate is doubled between tach of 1500 and 3000. Therefore, considering setting pump at 3000 mark for idle. This should about double the oil to that engine only.
Hmmm, I’ve never had to file my rings. Rebuilt 2 snowmobiles and 1 Seadoo engine, always measured the ring end gap in the new rings and never had to file them, anyways good thing your checking that. Is your piston to cylinder wall in spec. ? With the ring being that tight I would be worried about that measurement, as mentioned 3 rebuild, 2 were nicasil plated on the snowmobiles and almost like new measurements, the Seadoo was just within spec for wear, taper, out of round, ring end gap was out of spec so I ordered new rings from OSD and they measured in spec right out of the packaging.
As for oiling, I’ve ran 50:1 many times besides the injection oil and never even fouled a plug so it’s no issue for that 2nd engine to be running extra oil. With the premixing besides injection at least you will be 100 percent sure you are getting the reguired oil for break in, but if you can set the pump to double up on oil, that works too.
No, you don't file the rings on a 2-stroke, especially on worn "honed" cylinders. They do not come oversized.
Adding oil to the fuel tank for a 50:1 mixture will not hurt the other engine or foul the plugs.
What were the cylinder wear specs of the engine?
Compression?
Honing and installing standard pistons and rings typically doesn't improve anything on these. If it is worn you need to bore next oversized and install new oversized pistons and rings.
Adding oil to the fuel tank for a 50:1 mixture will not hurt the other engine or foul the plugs.
What were the cylinder wear specs of the engine?
Compression?
Honing and installing standard pistons and rings typically doesn't improve anything on these. If it is worn you need to bore next oversized and install new oversized pistons and rings.
The problem was that one of the pistons was welded with its rings and scored that cylinder. Checked the ring end gaps on the good cyl and found that the they were at the low end for new. Not sure what the starting end gap was. I believe the piston ring mass and scored cyl wall in the other is due to not checking the end gap.
These new pistons and rings are Titan, and yes, they came oversized with a ring end gap of .1 mm after honing. Filed to about .3 as specs. call for a ring end gap of 0.25 - 0.40 mm. Piston clearance was toward the upper limit, but below. Who cares about compression, not looking to race the boat. I'll let you know how the break in goes and if was improved/fixed.
These new pistons and rings are Titan, and yes, they came oversized with a ring end gap of .1 mm after honing. Filed to about .3 as specs. call for a ring end gap of 0.25 - 0.40 mm. Piston clearance was toward the upper limit, but below. Who cares about compression, not looking to race the boat. I'll let you know how the break in goes and if was improved/fixed.
Sorry I had trouble following your last post, so the Titan pistons you ordered were for standard bore which is 82mm I think you said? The rings also from titan are called oversized and are supposed to come with a .1 mm ring end gap for a standard bore? Is this correct. What I see wrong here is that your bore obviously had some wear on it and that ring still measured .1mm ring end gap? So if you truly had a 82mm bore then the ring wouldn’t even have fit in the bore? I’m curious what your cylinder measurements were prior to honing and after honing? What the new piston measured? Any markings on it. Is Titan forged or cast. Sorry for all the questions, obviously you dont have to answer them, I’m just concerned that your piston to cylinder wall clearance is going to be to tight. I’m actually thinking that maybe you were past the wear limit, honed it and got a .25mm oversized piston in there.? Either way, hope that I’m overthinking this and that it goes well.
