Saturday, November 8, 2014

Yamaha SR400 Review Update

The miles on the SR are slowly building.  Like many that own an SR, it is not my only bike, so it shares duties with others.  It has given us exactly what we had expected and it is a very good bike.

Some months back we did the 600 mile check on it and thought I'd pass on what we have learned.  Well, experienced maybe, I am slow to learn and it is too early to know if anything has stuck.

I have a copy of the Yamaha service manual and spent some time reading and studying.  The 600 mile check looked very straightforward and in fact it really was, after a fashion.  I thought the oil change would be a little messy and I had paper towels on hand and my oil catch pans in place.  There are a few more steps than I would have expected.  I warmed the engine but didn't get it hot.  I don't like hot oil running down my arms.  First the oil filter housing is drained, then you can remove and replace the filter.  The oil from the housing ran down the right side of the engine, dribbled on to the exhaust pipe and then dripped down to the floor not far from where the oil drain pan was placed.

Next I drained the engine sump.  The SR uses a dry sump, but there is still a bit of oil in the sump that must be drained.  The sump plug is on the bottom rear of the engine and it is easy to catch the oil.  The remote "oil tank" is actually the frame.  To drain the frame, a plug is removed from the from the front side of the down tube.  A catch pan had been placed under the down tube and the plug was easily removed.  It was at this point that my planning (or lack of it) let me down.  The front down tube is essentially a tall column and the plug is located at the bottom of the column.  There was more head pressure on the plug than I had planned.  (I had not planned on any)  So when I removed the plug, warm not quite hot, oil squirted forward onto the front tire.  In my rush to "plug the dike" I managed to get my hand against the hot exhaust pipe.  I still have a burn scar to help me remember to do it different next time.  So now I have a burned hand, an oiled tire, and a second oil puddle on the floor.  Once the head pressure dies to a dribble, the oil follows the front down tube and flows behind a small skidplate.  I cleaned and dried the area around the skidplate, but the oil managed to find its' way to the floor for a good day after the oil change. Of course I had removed the oil catch pan because I absolutely knew I had wiped up all the oil...   I replaced the oil with Mobile synthetic.  The shifts were always good, but now they are butter smooth.

A couple days later I checked, but did not need to adjust the cam chain.  I then set the valves.  Setting the valves is pretty easy. There is a little work to get down to the engine, although nothing like a full faired bike where you can lose half a day removing plastic.  First I removed the seat and the fuel tank.  I had run the tank nearly empty to make it as light as possible and followed the manual to empty the fuel lines.  By doing this, I did not have any fuel dribbles as the tank was removed.  There are a number of lines to remove as well as one electrical connection.  With these disconnected the tank lifts off easily.

Next I removed the spark plug so I could turn the engine over easily by hand.  The left engine side cover is removed so the TDC marks can be found.  I turned the engine over counter clockwise to TDC on the compression stroke.  I had expected the valves to be a little loose as I could hear some pecking.  Turned out the intake was spot on and the exhaust was a little tight.  Now there is a little more valve train noise than before, so that must be a normal noise for this engine.

Reassembly of the parts was easy except for one fuel hose that connects to the bottom of the tank.  A long 90 degree needle nose pliers are a big help for this chore.

After reassembling everything, the bike started right up and settled into a smooth idle.  As it has broken in, it is running freer and is noticeably quicker than when new.  It isn't quick, but it is quicker...

The fuel mileage has seen a low of 68 and the high tops 75, but I have noticed when we ride the SR and the TU250X (a well known standard of accuracy) together the SR manages to travel a little farther than the TU.  So the mileage could be a little optimistic.  I have measured the odometer using mile markers and in 10 miles the odometer will read 10.1, so that isn't really too far off.  The speedometer reads a couple miles per hour more than the TU at the same speeds.

The SR has been a blast to ride.  It is happy running down gravel roads and it is quick and lively on the curves.  We are having a great time with both the SR and the TU.  They attract attention where ever they are parked.  Both bikes will introduce you to people and new friends.  Both are great accomplices for exploring back roads.