05-14-2020, 02:55 PM | #46 | |
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I wanted to make sure those who are new to porting to know this so they don't go crazy and punch a hole through.
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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05-14-2020, 02:59 PM | #47 |
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I don't mean to Hijack your thread Jerry, but I figure these two pictures of my exhaust port might illustrate what I am saying better.
This is the exhaust side unported. After porting.
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05-14-2020, 03:03 PM | #48 |
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I've been hijacked! No problem Dan, That's what this forums for. Everybody has to start and learn from somewhere. The more information that gets out on here the more others will learn.
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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05-14-2020, 03:38 PM | #49 |
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So you take out the hump in the exhaust port wall where the valve stem hole goes into the wall of the port or am I seeing that wrong? Sorry if my terminology is incorrect or that doesn’t make sense.
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05-14-2020, 06:50 PM | #50 |
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I figured out the headlight issue. The connector to the rectifier unplugged. Something going my way for a change.
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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05-15-2020, 10:27 AM | #51 |
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You remove the material around the valve guide but not were the two valleys are on each side. That's where the head is thin. You can widen the port on each side.
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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05-15-2020, 11:01 AM | #52 |
Join Date: Apr 2020
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I see what you mean. That picture of the cross section does a good job showing where to not remove material. I am nervous about doing my own head work but I am pretty confident I can do it. I checked with Venom and a new head is only $110 plus shipping so if I do screw up it’s not that bad lol.
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05-15-2020, 11:09 AM | #53 | |
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Quote:
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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05-15-2020, 11:56 AM | #54 | |
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05-15-2020, 12:36 PM | #55 | |
Join Date: Apr 2017
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Quote:
His biggest complaint about the CRF port, and to some degree also true of both CG and CB clones, is the inability to raise the port floor with expoxy and then open up the port roof to match due to how thin the casting is at the valve seat, which would decrease the short side radius and increase port velocity. Since he has already removed as much material from the roof as he can he then widened the port floor at the radius going into the valve seat area to compensate. All three motors suffer from a fairly sharp short side radius angle and port angle in general. The straighter the angle of attack of the intake is to the valve and shallower the short side radius, the better port velocity and flow is. This has a lot to do with how "heavy" an air/fuel intake charge is. By widening the port where he did in conjunction with flattening out the short side radius it helps to reduce the chance of a low pressure spot right before the valve and thus maintaining or even increasing velocity. All of that work combined with the valve back cutting he shows there is actually better for lower and moderate lift cam profiles than it is for high lift/high duration race cams. It's actually a well thought out approach to match a large carburetor bore to a fairly mild cam profile to get the best throttle response possible and a nice wide torque curve. Don't take this to mean the exhaust port doesn't suck though, because it does lol. His post is mostly focused on maximizing the intake side with the upgrades in question given the limitations at hand.
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05-15-2020, 04:27 PM | #56 |
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Excellent explanation. Gets down to the issues of flow for sure.
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05-18-2020, 08:46 AM | #57 |
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Okay, so my bikes been parked for about a week due to all the rain we've been having. I go into my shed this morning and noticed a nice little puddle of oil under the bike. I've been cranking it up just about every other day and never noticed it. After closer inspection i see it was coming from the cylinder base gasket. I installed a new gasket. I knew i should of put some kind of gasket seal on it. Will this streak of bad luck ever end? I don't know when i'll have time to pull it apart now that i have a carport to deal with. So no problem, I'll take the Hawk t work. Dead battery. No problem. At least it will kick start. So i guess I'll have to show the Hawk some love for a while. lol
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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05-18-2020, 11:42 AM | #58 |
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Darn Jerry, that sucks. Well, lesson learned on using some gasket material when I take mine apart.
Do you plan on using some hi temp RTV?
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05-18-2020, 12:43 PM | #60 |
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I usually use the spray on Hi-temp Copper seal. I didn't have any at the time and the gasket had some type of sealant bead on both sides. I may have accidentally scraped some off when putting the cylinder back on.
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2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel |
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