silentrob Posted June 9, 2008 Share Posted June 9, 2008 I just bought an '82 XS400J (Maxim) this week. It ran pretty well in the around the block test ride I took, but it was a little short in power. Of course there was nothing but flat ground in that neighborhood. After getting it home I took it around the block, which includes a good sized hill, and I noticed a huge loss of power. A little longer ride on a hilly road and it seems to do pretty well in the flat spots, but when I hit a hill I slow down to about 25 mph, even with wide open throttle (in 2nd gear). The tach is reading around 4000 rpm. As soon as I hit flat ground again the revs go back up, as does the speed. I plan to do an oil change and probably take the carb off for a cleaning tomorrow. Is there anything else I should be looking at? Link to comment Share on other sites More sharing options...
yoda Posted June 9, 2008 Share Posted June 9, 2008 I think it's old and tired. Clean the whole fuel system and fit a new fuel filter, put new spark plugs in and check the ignition timing is spot on. If all that fails it is an engine strip down. Link to comment Share on other sites More sharing options...
silentrob Posted June 10, 2008 Author Share Posted June 10, 2008 I forgot to mention I was putting new plugs in today too. Didn't get around to the carbs. I had already changed the fuel filter yesterday. There was some fuel in the oil when I drained it. My understanding was that this is usually a carb problem. The thing is I've usually heard of this on bikes where the petcock was left on when the bike wasn't running. With a vacuum petcock, I wouldn't think there should be much fuel getting in with the oil. Link to comment Share on other sites More sharing options...
bralkan Posted June 10, 2008 Share Posted June 10, 2008 I forgot to mention I was putting new plugs in today too. Didn't get around to the carbs. I had already changed the fuel filter yesterday. There was some fuel in the oil when I drained it. My understanding was that this is usually a carb problem. The thing is I've usually heard of this on bikes where the petcock was left on when the bike wasn't running. With a vacuum petcock, I wouldn't think there should be much fuel getting in with the oil. both cylinders having combustion? Both plugs look good? Link to comment Share on other sites More sharing options...
Recommended Posts