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05-13-2015, 12:08 AM | #1 |
Join Date: May 2015
Location: Canada
Posts: 41
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250cc OHC Air Cooled rebuild Issues!
Hey hows it going. well to start it off, i have a 166fmm zongshen 250cc OHC Air Cooled engine im working on, it ran alright before winter but just before i noticed it started smoking a bit. so i decided to replace a bunch of things...
- 65.5mm Honda xr200 Piston with Rings - Honda xr200 Head & Base Gaskets -Valves & Springs -Muffler Gasket - Carburetor Rebuild Kit everything went perfectly fine up until after the rebuild. now this is where it gets interesting, i can get the bike started BUT it will only let me kick it maybe twice and on the 3rd or 4th kick it stops dead in its tracks like theres compression buildup, so i have to wait a minute or two and try again (never happend before rebuild) . now problem 2, when i do eventually get the bike running, it Idles really high, like half throttle reving. if i turn the idle screw it turns down but almost falls out before it actually makes a difference. if anyone can give me some insight on this i would be VERY greatful! you guys rock |
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05-13-2015, 01:45 AM | #2 |
Join Date: Apr 2015
Location: Sudbury ,Ontario
Posts: 855
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Have you checked to see if the carb slide is in correctly ?
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05-13-2015, 07:41 AM | #3 |
Join Date: May 2015
Location: Canada
Posts: 41
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Carb slide is seated correctly, that was the first thing i checked, throttle cable is working smoothly i had even installed a friends brand new makuni carb with the stock jetting to see if it was just mine and his did the same thing. Im stumped im thinking a possible vacuum leak?
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05-13-2015, 03:05 PM | #4 | |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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No disrespect intended when I ask, are you certain that the slider is in the right way? You seem to be very experienced, but it is an easy mistake to make. The slider has a small ramp at the bottom that lines up with the idle screw, and I suspect it's above the screw or 180 degrees out.
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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05-13-2015, 03:17 PM | #5 | |
Join Date: May 2015
Location: Canada
Posts: 41
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05-13-2015, 03:28 PM | #6 |
Join Date: May 2015
Location: Canada
Posts: 41
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i also never thought of switching the transmission to an xr200. thats actually a good idea, i may have to look further into that. might just be my next project
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05-14-2015, 01:09 AM | #7 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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So glad to hear that! I love CG engines, and very few around here share my disorder.
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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05-13-2015, 11:53 AM | #8 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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It certainly could be a vacuum leak.
I'm stuck on how you got XR stuff to fit. I have a CB250, and the frame of architecture is larger in almost every way. That said, I'm working with a 69mm bore, so the mouth in the bottom end is larger, and will not accept an XR200 base gasket. I'm intrigued that you got a Honda 65.5 piston to fit; that's good news for another build I'm considering. Is it a genuine Honda piston, or a Wiseco? Perhaps the compression is too much for a stock China setup that does not have a compression release (like the XR does).
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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05-13-2015, 01:39 PM | #9 | |
Join Date: May 2015
Location: Canada
Posts: 41
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05-13-2015, 03:00 PM | #10 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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That's all really good information; I hadn't considered the '93-'02 XR200, since all of my junk is older.
Is it possible that the cam chain is off by one tooth? If the ignition was advanced, I could see starting difficulties.
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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05-13-2015, 03:01 PM | #11 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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It just occurred to me that the stud spacing on the CB200 I'm working with is wider than an XR200, but again, that's due to the 69mm piston. It's good to know that newer XR200 stuff fits the 65.5mm bore size.
I've also considered putting an XR200 transmission into a CB motor to get six gears.
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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05-13-2015, 04:32 PM | #12 | |
Join Date: Mar 2008
Posts: 2,436
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Rings spec: http://www.dongya.cn/prodlist.asp?page=8&tp=4 http://item.taobao.com/item.htm?id=36744024764 | http://item.taobao.com/item.htm?id=41515872521
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05-13-2015, 04:37 PM | #13 |
Join Date: Mar 2008
Posts: 2,436
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To whom needs OHC 223 parts ,the alternative (ie. needs agent)
As stock http://item.taobao.com/item.htm?id=35517374143 Higher grade: http://item.taobao.com/item.htm?id=17587251271
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Last edited by humanbeing; 05-13-2015 at 05:50 PM. |
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05-13-2015, 07:36 PM | #14 | |
Join Date: May 2015
Location: Canada
Posts: 41
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Update* I got my bike running good today, cleaned the carb and blew through all the passages with a air compressor, still idles a little high but way better none the less. now one last problem, my bike while running sounds like its making pop corn out of the exhaust, not loud, but loud enough to notice is. now is this normal? i wouldn't call it "back firing" because it happens almost the whole time the bike is idling even while riding it, i have my fuel screw set to 1-1/8 turns out and my throttle needle on the 4th clip with great throttle response and doesn't bog out. Starts first kick almost every time accept for when its cold. What do you guys think could be causing this weird "popping" noise? i took a video of it running but you cant really hear it |
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05-14-2015, 01:24 AM | #15 | |
Join Date: Mar 2009
Location: Sardis, BC, Canada
Posts: 25,977
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Quote:
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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