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1995 pro150 carb rough idle seems to only be running on 4 cyl

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flats

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"1995 Pro150, will not idle ,

"1995 Pro150, will not idle , seems as if it is only runnig on 4cyl at idle, runs great once you open the throttle. Compression 110 per cyl., carbs were soaked,cleaned and rebuilt, rebuilt both fuel pumps. Fresh fuel. Still seems as if it is not firing properly at idle. Tested spark plug wires with a Leslie spark indicator and does have spark at all six cyl. but does appear to be weak? Any sugesstions??? Please Help."
 
I checked the spark by removin

I checked the spark by removing the spark plugs this evening and they are all firing. I started the motor and removed the spark plug cable one at a time from each of the cylinders and it seems as if the top number 1 & 2 cylinder are not firing or getting fuel. Could it be when the carbs were rebuilt the jets got reversed. the number (40) jets are mounted facing out from the carberator throat. Does any one know if this is correct. The two large hole jets are monted under the cover on the top of the carbs.
 
When the engine is running and

When the engine is running and I cover the top carb. with my hand there is no change on how the engine runs. When I cover the middle carb and lower carb. I see a big change as when the choke is applied. Why would there be less suction on the top carb. I guess the problem is it is not sucking in enough fuel. I looked at the reeds after removing the carbs and they appear to be fine. Any help would be greatly appriciated.
 
I sprayed seafoam into the top

I sprayed seafoam into the top carb today and it seem to run better as I was spraying it. Once I stopped it started running bad again. I acts like it is not sucking enough from the top carb.
 
"You were right (Just-in T

"You were right (Just-in Time). Sync it this morning and it's running like new.
As for the compression, it is 110 in all cylinders. Does antone know what it originally was when new? (95 yamaha pro 150 carb. motor). I have always used yamaha lube since it was new. Hopefully I can get a few more season out of it."
 
"as long as theres no big diff

"as long as theres no big difference between cyls, its hard to say what the compression should be, as all compression gauges will give different readings."
 
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