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Post by bob123456789 on Mar 5, 2017 15:39:35 GMT -5
Once again I could use the good help of the folks here.
My Linhai 257 only fires when I spray starting fluid in the carb intake. This seems to be a fuel issue. How do I isolate it down to carb, fuel pump, fuel filter,...? I recently put a new fuel filter, some fuel hoses and a new vacuum line between the fuel pump and the intake. When put an old spark plug in the boot then ground it and turn it over I get spark.
Also I can't get the old exhaust header to seal tight in the new head It is loose even after I have tightened up both nuts. I will look around. Is there supposed to be an exhaust gasket on this engine?
As background for those who haven't been following my work recently here I am just finishing up a replacing the head, the piston and the rings. When I put it together the first time I had small leaks of both antifreeze and oil. I am just putting it together the second time. It is too early to say if the leak is now fixed.
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Post by rockynv on Mar 5, 2017 20:05:52 GMT -5
Then its a blessing that it won't run.
You can very quickly ruin that new head if the exhaust gasket is missing and the connection is loose. On a cast iron head its not as critical but on an aluminum one you can end up melting and deforming the exhaust port without the header pipe firmly in place to take the heat.
The lack of back pressure from the exhaust will impact intake vacuum and jetting of the carb too making the bike run lean and hot.
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Freshman Rider
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Joined: Sept 17, 2016 6:12:01 GMT -5
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Post by bob123456789 on Mar 6, 2017 14:04:18 GMT -5
I got a new exhaust gasket and put it in. Now when I turn it over it won't fire at all. Not when I have the air breather box connected or even when it is disconnected and I spray starting fluid into the card intake.
When put an old spark plug in the boot then ground it and turn it over I get spark.
This seems to be a fuel issue. How do I isolate it down to carb, fuel pump, fuel filter, ...? I recently put a new fuel filter, some fuel hoses and a new vacuum line between the fuel pump and the intake. When I hold my hand over the carb intake it feels like there is good suction.
Any ideas how to find the fuel issue?
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Freshman Rider
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Joined: Sept 17, 2016 6:12:01 GMT -5
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Post by bob123456789 on Mar 7, 2017 11:28:56 GMT -5
rockynv or anyone?
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Post by cyborg55 on Mar 8, 2017 9:31:03 GMT -5
Cam timing may be off,,,if it won't fire even with starting fluid introduced into the carb,,,
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Post by dollartwentyfive on Mar 8, 2017 23:39:31 GMT -5
i agree with the cam timing.
but you still should be getting something out of the engine, backfires, blowback through the carb.
but first check the timing.
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Post by rockynv on Mar 9, 2017 9:23:39 GMT -5
Bob says the new head gasket is leaking on the compression stroke now. I am almost leaning towards the new head being defective/not flat. This is one that I really wish was close enough to drive over to and take a look at.
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