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Workshop => Engine and Bottom End => Topic started by: Bowtie316 on October 07, 2013, 06:05:58 PM
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I just checked this new motor I bought, it's an ESR 330, with a +4 crank. I wanted to check the port timing just to know what it is, I came up with 197 on the exhaust ports and 134 on the transfer/boost ports.
Also, it has a race gas dome, haven't checked yet but it is supposed to be setup at 14.5:1 UCCR.
It was supposed to be a mid-top dune port. This is more than I was expecting, is this normal for a 330 with extra 4 mm stroke?
Thanks for any feedback.
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drag engine bud.
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drag engine bud.
That's what I'm afraid of, I have no use for a drag engine. I guess I'll try it out but will probably be looking for a different cylinder. I wanted a good dune port, and planned on using a trx5 pipe and 38A/S carb.
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Wow, I'm surprised, Maybe call k&t and see if they remember the specs or have documents on what the timings are on the motor I specifically had that motor set up for a dune motor, 40.5 carb, and Trx-5 cm pipe. Those seem kinda high.
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I just checked this new motor I bought, it's an ESR 330, with a +4 crank. I wanted to check the port timing just to know what it is, I came up with 197 on the exhaust ports and 134 on the transfer/boost ports.
Also, it has a race gas dome, haven't checked yet but it is supposed to be setup at 14.5:1 UCCR.
It was supposed to be a mid-top dune port. This is more than I was expecting, is this normal for a 330 with extra 4 mm stroke?
Thanks for any feedback.
Whats the squish? How thick is the base gasket?
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sounds high expeciallyin the transfers it was probably a stoke ported cylinder then someone added stroked crank and increased port timing even more.
are you very sure of your port timing numbers, I see many people not use a piston stop or a dial indicator to find TDC and their port timing number are inaccurate.
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Rsss, I had k&t set the motor up from scratch with a unbored and unported cylinder.
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ok maybe double check the port timing numbers, that does not sound like typical k&t work to me. unless the wrong spacer was stuck on the motor accidentally by them or someone else.
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134 sounds odd . do you plan to ride it soon ? if so report back how it works
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Whats the squish? How thick is the base gasket?
Squish was at .049. Spacer is .197" and the gaskets are .020" x 2 of them.
Hopefully I am measuring the port timing wrong. But basically, what I posted is the amount of degrees of crankshaft rotation the ports are open before the top of the piston closes them off.
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Just ran it again, tried to be a little more exact with the point the piston crosses the plane of the port roof. Came up with 194 and 130 this time. I used a piston stop to find tdc and found the exhaust port open at 83 degrees ATDC and the transfer/boost port at 115 degrees ATDC. And came up with the same degrees BTDC. That gives me 32 degrees of blow down time. Better than what I got last time but still more than I expected. I guess it's time to put it together and see how it does.
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Just ran it again, tried to be a little more exact with the point the piston crosses the plane of the port roof. Came up with 194 and 130 this time. I used a piston stop to find tdc and found the exhaust port open at 83 degrees ATDC and the transfer/boost port at 115 degrees ATDC. And came up with the same degrees BTDC. That gives me 32 degrees of blow down time. Better than what I got last time but still more than I expected. I guess it's time to put it together and see how it does.
Damn I wish I knew how to measure port timings.. Put that thing together and ride. Let us know how it does, K&T assured me it was going to me a beast in the sand. I hope so!
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Damn I wish I knew how to measure port timings.. Put that thing together and ride. Let us know how it does, K&T assured me it was going to me a beast in the sand. I hope so!
Yeah, I'm going to try to get it on and running this afternoon. Still got to do a leakdown check then it should be good to go. UCCR came out at 14.89.
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Try just degreeing from TDC down to just before the ports crack open, the exhaust & then the transfers & jot those numbers down.
Neil
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Try just degreeing from TDC down to just before the ports crack open, the exhaust & then the transfers & jot those numbers down.
Neil
That's basically what I did the last time Neil when I got 194 and 130. I'm just going to run it and see. Its back together now, base gaskets leaked, had to replace those and add some ultra blue because the spacer was milled rough on one side. Also had a leak on the coolant side, into the top exhaust flange bolt. It's all sealed up tight now, both passed 30 minute leak down. Engine is on bike, got a couple more things to button up then it's ready for some heat cycles.
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That is the problem with using a cylinder designed for a 72mm stroke and then putting a 76mm stroke crank. I hate it when people ask me to do that. You either have to much port timing (especially transfer timing) or you have to lower the cylinder which put the piston out the top of the cylinder. This gives you a crappy combustion chamber shape. Before We had 76mm stroke Sphinx and Puma cylinders I would build a longer sleeve which would come put of the top on the block. We then used a spacer plate on top of the cylinder. We did this up to 80 mm strokes on the Niks Cylinders. I am glad that we not have cylinders designed for the stroke. It is much easier now.
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That is the problem with using a cylinder designed for a 72mm stroke and then putting a 76mm stroke crank. I hate it when people ask me to do that. You either have to much port timing (especially transfer timing) or you have to lower the cylinder which put the piston out the top of the cylinder. This gives you a crappy combustion chamber shape. Before We had 76mm stroke Sphinx and Puma cylinders I would build a longer sleeve which would come put of the top on the block. We then used a spacer plate on top of the cylinder. We did this up to 80 mm strokes on the Niks Cylinders. I am glad that we not have cylinders designed for the stroke. It is much easier now.
What cylinders are designed for or can be adapted easily to a 76mm stroke and have lower port timing? I suppose the sphinx and puma, any others?
Just got back from the dunes and honestly this bike wore me out, it's just too peaky for me.
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i have same port timing on my 344 and run very very hard with less compresion 12.5:1.
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i have same port timing on my 344 and run very very hard with less compresion 12.5:1.
What do you mean ran very very hard? How is the midrange? I have always heard that on a 2-stroke the extra compression will help the low end and midrange.
I leaned the needle out and got it a little better, went a little further then I could hear some pinging so I put it back. I just doesn't have the power curve that I am looking for.
I am going to try to figure out my options and get something going.
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I can have both Sphinx and Puma cylinders made for 76 mm stroke.