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Post by alleyoop on Mar 30, 2013 1:15:55 GMT -5
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Post by triker on Mar 31, 2013 14:27:20 GMT -5
I got a little time to tear the new engine down and started to install a hoca 44 mm stroker crank. I just test fit the stock 39mm piston and jug. At top dead center the piston is flush with the deck of the cylinder.   I might just go with this set up for now and add the ncy 50mm bbk later. Just to see the difference. The stock crank has a 22 tooth oil pump drive gear and the oil pump has a 47 tooth driven gear. The hoca crank has a 16 tooth drive gear. Two options are available. 1) press the stock oil pump drive gear onto the hoca crank. 2) change the oil pump driven gear and oil pump. I cannot just change the 47 tooth driven gear to one with 33 teeth I must change the pump also. I knew this before hand and already have the correct driven gear and pump. Roy |
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Post by Deleted on Mar 31, 2013 16:33:05 GMT -5
Thanks for the info triker. I'm tempted to stroke my 139QMB in the future.
*With the same stock combustion chamber size, looks like you should be getting close to 11:1 CR with this setup.*
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Post by triker on Mar 31, 2013 18:47:24 GMT -5
I did some more test fitting. This time I used a 47mm piston and no base gasket. At top dead center the piston sticks out of the cylinder by .50mm. I will test fit a 50mm piston next. I do believe with a single base gasket the piston will not travel out of the cylinder. Note: The 39mm piston I have has a fairly high domed top. The 47mm piston has a concave top and the 50mm is slightly domed.
Roy
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Post by teddy554 on Mar 31, 2013 21:10:33 GMT -5
Very good info thanks and keep the info and pictures coming
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Post by triker on Apr 1, 2013 1:03:52 GMT -5
I ran into a problem with the oil pump swap. There is two dowel pins in the stock pump and only one in the new pump. The problem is it is not one of the holes bored in the case.  The stock pump is on the left. I could install the new pump without the dowel pin but with the slop in the bolt holes it will need to be adjusted properly so that the inlet and outlet holes line up. I tried to just change the gears in the pump, but that won't work either. the stock pump gears are thicker than the new pump gears.  I do like the stock pump better the backing plate is steel, and the gears are thicker. thicker gears in the pump should move more oil. other than the thickness of the gears they are the same size. I calculated the gear ratio's of the drive gears to the driven gears and the new pump will turn faster. But with thinner gears it will probably move the same amount of oil. Should I use the new pump, or pull the crank and press the old gear on?  Roy |
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Post by triker on Apr 1, 2013 11:01:10 GMT -5
I decided I'm Going to change the gears on the crank, and use the stock pump.
Roy
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Post by triker on Apr 1, 2013 12:04:07 GMT -5
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Post by triker on Apr 3, 2013 13:06:47 GMT -5
I got the oil pump gear pressed on the stroker crank and will use the stock pump. Also the two case halves are not perfectly flat where the cylinder fits into the case. I bolted down the cylinder and removed it and noticed that the base gasket had split where the seams of the case are. So I will have a machine shop plain the case so it is flat. I don't have a photo of this as my camera had died. I measured the lip between the case halves and it measured .29mm.
Roy
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..BAD TO THE BONE..
