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Post by jmkjr72 on Apr 16, 2011 20:35:02 GMT -5
yeah the tornados seem to be odd this year we had 12 in last weeks storms
we were lucky no major ones
but the storm was bad engouh i was watching to see if we had to hit the closet
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Post by speedy1125 on Apr 19, 2011 18:43:58 GMT -5
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Post by speedy1125 on Apr 21, 2011 1:38:15 GMT -5
whats 47mm in fractional? 1 and 13/16"?
I have the motor out, head and piston off. As soon as I took the head off and saw the piston I knew it was the same size as the one in this box that says 47mm. Sure enough the "old" piston fits perfectly in the new bore and vice-versa.
So I either have a stock 47mm motor or a misboxed 47mm kit thats really stock bore. I am thinking the former since it seems to have so much power and also... Looking at pics of pistons, the top 12 o'clock edge of the intake valve cutout to the edge of the piston itself....its more distance as compared to a known stock piston (in photos anyway)
I measured both pistons and they are both exactly 1 and 13/16" so whats that in mm? all my micrometers got blown away by fire hoses when my shop burned.
Thanks to anyone who can help!
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Post by 190mech on Apr 21, 2011 4:53:29 GMT -5
1.812"=46.02mm
Formula is inches X 25.4=MM's
Or 47mm X .03937 = 1.850"(thats a touch smaller than 1 7/8")
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Post by 90GTVert on Apr 21, 2011 6:33:23 GMT -5
46.02mm would be about right for a 47mm kit's piston. It's easier just to measure the bore size. There are 44mm and 47mm stock engines out there. Sounds like you got lucky. That definitely explains the above average performance you've been seeing.
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Post by 2strokd on Apr 21, 2011 7:23:16 GMT -5
Yes, i remember Kliff getting some of those! Werent the called "Peace, or Bashin" some shit?
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Post by 90GTVert on Apr 21, 2011 7:29:49 GMT -5
I know a lot of people were finding 44mm in Peace scoots.
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Post by speedy1125 on Apr 21, 2011 21:05:58 GMT -5
Here they are, what was on the bike and what was in the 47mm box. They measure the same and the old piston will fit in the new bore/new piston in old bore. Just as 190mech said, they are a touch smaller than 1 7/8"  I didnt know this was possible and I am not used to being lucky but there it is^. I always found it odd that I was able to run a #88 with the needle all the way up and not foul plugs, now I know why. I wonder if the new scoot like mine I just sold is the same? hmm.. Seems like I saw somewhere that the "p" code motor is for "performance" lol..In my case I guess it was true ;D The gearhead in me just couldn't put it all back together the same so I put the 50mm that I had for sale on it...   Switched to a #95 main from the #88 and lowered the needle one notch, more grill paint on the exhaust, new belt... And of course a new valve cover gasket, timing chain tensioner gasket, intake and exhaust gaskets....  Anyone know where I can get this splash guard? when I went to take it off, it was about to remove itself...  Its back in and fired right up. When I plugged the charging system in it pushed a wire out the back of the plug and didn't make a connection. I let it warm up and let the oil circulate but when I went to take off the lights got way bright and popped the headlight bulb, oops. Fixed the wire but it was almost totally dark out so I just took it down the street and back. Pulls hard, Idles great, no crazy noises and no left over parts  2 new headlight bulbs on the way from PFS. Oh and magnetic drain plugs from enviromoto. The starter has always struggled to turn it over but it always cranks. Has anyone ever seen a high torque starter for these? |
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Post by speedy1125 on Apr 23, 2011 18:43:37 GMT -5
Rode about 25-30 miles today. Great power and top end speed. Id like some more bottom end so I guess I will play with clutch springs/contra spring. Sure hope it lasts but it really vibrates. Can certainly feel the big bore especially at idle. Shakes the mirrors and such lol, I like it but i'm not sure how the crank bearings are going to!
Modify:
Oh and as far as upgearing, I am glad I didnt do it. More power I have but its almost like it needs a HIGHER gear...it feels like its almost lugging at low speeds.
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Post by speedy1125 on Apr 23, 2011 20:45:00 GMT -5
I forgot to add..
I started out at a .004 valve lash. Too loose, making lots of noise. Went to .003, Same. Went to .002, Quiet but hard to start and crazy idle. .0025 seems good.
I hope this thread is helpful to someone who is planning to do this mod who is basically new to this engine like me.
MODIFY:
I would never do this mod using a stock head. Compression would be way too high. The head that came with this kit appears to be a stock head that has been milled to match the bore and has been worked to lower compression back down to about 10.5:1
I always use nothing but the highest octane gas I can find too.
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Post by speedy1125 on Apr 24, 2011 18:22:19 GMT -5
I used the "Big bore top end assembly" (50mm)from here: www.scrappydogscooters.com/139QMB_50cc_Performance.htmlCombined with the "GY6 Racing CDI" (blue) on the same page, 95 main jet, stock pilot jet and a Uni filter. Tried a 105 main today and that was too much for it. Ended up lowering the carb needle back to its original position too. (3rd notch from bottom). |
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Post by 90GTVert on Apr 24, 2011 18:27:05 GMT -5
Thanks for all the details. :thumb:
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Post by speedy1125 on May 1, 2011 7:36:21 GMT -5
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Post by speedy1125 on May 22, 2011 14:21:27 GMT -5
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Post by speedy1125 on Oct 5, 2011 10:07:11 GMT -5
i now have a total of 3000 miles on my double base gasketed 50mm engine. it passes true 50cc scoots like they are standing still and cruises at 50mph. so far so good  |
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