Friday, August 26, 2011

Yesterday I got out of the shop and spent the day using my boat to haul supplies for a construction project.  A contractor is repairing a few of the roads in town and installing some culverts.  The contractor hauled their supplies by road from Nome to Teller, then they hired me to boat everything across from Teller to Brevig.

This photo shows two 24" diameter by 20' long plastic culverts in the boat.  I made several other trips with the boat and hauled more pipe, shovels, compactors, ATV's, etc.  There is a protected bay on the Teller end of the trip where we loaded the boat and a sheltered lagoon in the Brevig, but the 10 mile crossing in between was rather rough. 


Monday, August 22, 2011

Honda Foreman

I have a newer Honda Foreman in the shop today with a shifting problem.  It was hard to change gears, and impossible to get into neutral.  The transmission on this machine, like almost every ATV, is part of the engine.  In order to do any transmission work you need to remove the engine from the frame.  That takes 2 to 3 hours on this machine.

Once I had the engine on the workbench I pulled the side cover off and removed the clutches to expose the shift mechanism. 

 Part of the escapement mechanism that that turns the shift drum was broken.  This machine was sunk under water last winter.  I suspect that this piece broke when someone tried to shift the machine with the crankcase full of ice.  This second photo show the broken part and another used part that I had left over from a Honda 420 rebuild project.  It appears that Honda uses the same shift linkage on the 500 and 420.

This last photo shows the shift mechanism put back together. There are a lot of springs, spacers, and little parts to keep track of.  Now I need a few more hours to put the engine back in the frame and try it out.


Sunday, August 21, 2011

Polaris Sportsman 500

I recently had my own machine in the shop.  It is a 2008 Polaris Sportsman 500 with about 4000 miles on it.  It was not keeping the battery charged and the tachometer was not working.  The first thing to check in this type of situation is the output from the stator. 

The stator is a series of electrical windings around an iron core.  The flywheel on the engine has permanent magnets in it that surround the stator and  produces an electric current when the flywheel spins.  The power produced is an AC voltage that varies with RPM.  This AC current is converted into DC and regulated to a nominal 12 volts by the voltage regulator.  This is the same basic system that is in almost every small engine.

When I checked the output from my stator with the engine running I got an erratic reading that was very low (7-8 volts) at low RPM.  I then disconnected the plug coming from the stator and tested the resistance on each lead.  I found that one of the leads was shorted to ground. 

I pulled the side cover/recoil housing off the engine and pulled the flywheel to reveal the stator.  This photo shows what I found.  Several of the windings had burned insulation on them and one winding had a few broken wires.  Normally this would mean automatic replacement of this part.  I check around and found that a Polaris replacement part is around $500 and an aftermarket stator is about $250. 

Since this is my own machine and I am trying to be frugal I decided to fix the bad stator.  I cut and unwound the broken wire from the worst spot on the stator.  I then splice the remaining ends together and reassembled it.  When I fired the engine up it started charging fine.  The burned insulation on the other windings has me a little worried about the lifespan of this part, but I think it should be ok for a while.  I may look around for a good used one to replace it with.


Monday, August 15, 2011

Summer Vacation

I have been on summer vacation for a few months and have not had anything in the shop. We spent most of the summer in Minnesota and a few weeks in Guatemala.

While we were in Guatemala I had an opportunity to fix something.  We were walking to church on a Sunday morning and we noticed a very upset man trying to get the chain back on to the sprocket on his motorcycle.  Luckily I have a small crescent wrench that I carry around in my pocket (doesn't everyone).  With the wrench I was able to loosen the axle and get the chain back in place.  The motorcycle rider was very happy, I didn't understand what he said to me in Spanish, but he had a smile on his face.

I am now back in Alaska and getting back to my "regular" work.