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Post by quickscoot49 on Apr 10, 2017 16:24:03 GMT -5
I am upgrading my scoot to a 47mm BBK and I belive it has a EGR cylinder head on it. Would I need to get a non EGR head for it? What other parts might I need for the bbk?   |
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Post by AtariGuy on Apr 11, 2017 7:32:34 GMT -5
I am upgrading my scoot to a 47mm BBK and I belive it has a EGR cylinder head on it. Would I need to get a non EGR head for it? What other parts might I need for the bbk? It really depends upon the state you live in. If they're strict about emissions regulations, you need an egr head. Most of us do away with that system however. 90GTVert did a good writeup on how to remove it and block off the port on an egr head, but if you have the option (non-emissions state), get the one without |
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Post by AtariGuy on Apr 11, 2017 7:33:54 GMT -5
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Post by matt2015taotao on Apr 11, 2017 9:58:59 GMT -5
Isn't it good though to have the ventilation the EGR provides? I thought about deleting it but haven't. I'm not sure exactly of how it is acting or if there would be any real performance benefits.
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Post by 90GTVert on Apr 11, 2017 10:14:35 GMT -5
You can do it either way. To stay emissions legal, you'd need to get the emissions head if that's what you have to begin with and hook it up like it was with the old head. You can remove that stuff, but it may not be legal. If you stick with the stock muffler and it has a catalytic converter, you could risk clogging the converter section prematurely.
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Post by quickscoot49 on Apr 12, 2017 15:25:50 GMT -5
My question was if keeping the stock EGR head would cause lost compression or other problems?
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Post by badpumpkin on Apr 13, 2017 8:44:03 GMT -5
No,your compression is going to go up. A 49cc head is 5+-cc. To figure compression, 49cc÷ by 5cc=9.8 74cc÷5cc = 14.8 compression. Oh, and if you can, watch 90vert' how to port and polish a head. Its worth it if you can do it
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Post by quickscoot49 on Apr 13, 2017 8:48:04 GMT -5
So I should just leave the head stock?
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Post by knobby on Apr 13, 2017 12:41:14 GMT -5
I would leave the stock head and hook everything up the way it was. I don't see how a bigger bore would cause problems if everything was working correctly before.
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Post by greggkinney on Apr 16, 2017 6:57:19 GMT -5
if your only going with a 47mm big bore kit keep the stock head. if you do decide to change to a non emissions head get one for a stock size 50cc engine. the ones in the pics you posted are 50mm and 52mm, those WILL cause compression loss with a 47mm cylinder kit. for best compression (highest) keep the 39mm head or go no bigger than a 47mm head, emissions or not. if you decide on an a9 cam youll like the 39mm over the 47mm.
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Post by azzazzianjay89 on Apr 16, 2021 6:50:48 GMT -5
I bought a 80cc bbk and it came with a Non-RGR valve head with 69mm valves. I installed it on my little Chinese scooter and it ran just fine but I took it back off and installed it on a Tao Tao Peace Sport scooter and it sounds like it has no compression....Please help im going crazy trying to figure this one out.. I dont understand why it runs just fine on one scooter but it will not run at all on my other one
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Post by GrumpyUnk on Apr 16, 2021 8:57:24 GMT -5
Did you adjust the valve clearance after assembly? Did you use the same rocker arms as on the Chinese? The 69mm valve stems need correct rocker arms to function properly.
tom
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