Join Date: May 2009
Location: Central coast of California
Help! Vstar 250 problem
On a comfortable (60 degrees) morning ride not long ago, I came into town to the first stoplight and found that my bike would not idle. It worked on one cylinder only unless I kept the revs up. I nursed it to my destination, ran an errand of approx. 10 minutes, came out and started it up to find that now it idled. I've never had any problems with it prior to this.
The next morning, I checked the valves, they were spot on in the middle of their adjustment range just where they had been for the last 11,000 miles. I changed the sparkplugs and went riding. Ran on both cylinders, but I found that the mileage had dropped by about 11-12 miles per gallon. It has stayed that way since that day. For no apparent reason, the mpg has sunk and it will not idle with any vigor although now it does idle. And the power is down needing a bit more throttle than before for the same speed.
It has never been over-heated. It doesn't burn oil. The valves have never been out of adjustment. It has spark, but I cannot tell by looking if it is proper. At idle, if I pull the rear sparkplug wire, it will continue idling at a lower rpm. If I put it back on and then pull the front cylinder plug wire, it will die so it seems that there is some problem with the rear cylinder.
Both cylinders have 160psi pressure when tested cold. I am allergic to messing about with hot engines. If there was a compression problem, there would be a difference hot or cold.
Is it possible for the timing to slip? Individually by cylinder?
Any ideas are appreciated.
I accidentally posted this in general bike forum. Maybe better here?