Still Looking for Ideas - 1979 Intruder Won't Make Speed

[mswyka]

First, a hearty Happy Thanksgiving.

Next, we live in hope for new snow and in preparation for what we believe will be a great season, I want to solve a problem that we have with one of  our 79 Intruders.  Everything works, it runs well, but just won't make speed.  It gets up to 25 or 30 and just won't go any further.  We had some brake disk issues, that I now think have been resolved, I may have even changed the primary clutch, I am not remembering at the moment. 

We just ran it this past week to move it out of the way so that the boat could be backed into the machine shed.  So it ran and drove on grass just fine for the little bit we moved it.

I think the sled is too good to work this bad.  so I am interested in thoughts for what I should look at this season.

[Dandb7]

Compression..?

[mswyka]

150 both sides.

[DougKauer]

fuel pump or carbs???

[rminier]

  mswyka, I'm sure you have considered most of these things....just throwing ideas out there.
 One of the 1st things that comes to mind is a partially restricted exhaust pipe or airbox...
      Does the engine seem to rev up to its normal 7000 RPM range? Does there appear to be normal exhaust flow coming out of the exit hole at the back of the pipe when you rev it up on a stand to 5-6000 RPM?
 I'm sure you have checked track alignment and tension.....have a bunch of the wheels in the skidframe suddenly decided to lock up?.....probably not.
 I would remove the drive belt and, with the track jacked up off the floor, try turning the secondary clutch by hand.....does the clutch, chain, drive shaft, and track all turn fairly easily?
 With the drive belt still removed, I would use a crayon or marker to mark a line on the sheaves of both the drive and driven clutches. Try riding the sled....if the clutches are trying to shift at all, the belt will erase the marks on the sheaves..starting to move upward on the drive clutch, and down from the outer perimeter of the secondary clutch...it could be one of the clutches is locked in place?
 This is a long shot, but I managed to dislodge the little flywheel key when installing the flywheel on my Blizzard 9500....that certainly throws the timing off....    If your engine seems to start and rev up fine, I doubt that the flywheel key is the problem.
 Hope you find the solution.

[Interceptor398]

Mouse nest in the muffle can do that.

[mswyka]

Excellent thoughts. Thank you.  I appreciate the insights and will give these each a check.

[kawhead]

carb o rings,power jets reversed[pto is richer]spark  plugs black?

[mswyka]

carb o rings,power jets reversed[pto is richer]spark  plugs black?

Tom, thanks.  As near as I can tell I have no issues with the engine.  Plugs look good, compression is good.  Checked the carbs, even swapped in a new set of carbs just to be sure.   We need a little snow so that we can do some more checking.

[kawhead]

rubber track without the correct wheels really drags....turn driven clutch by hand,checktrack and chaincase resistance

[mswyka]

rubber track without the correct wheels really drags....turn driven clutch by hand,checktrack and chaincase resistance

Now you are making me wonder.  This problem started a few years ago - possibly coincident with our studding the track.  I am going to check back through my records to see if this is really the case.

[mswyka]

We have been picking up little storms every couple of  days and today had a nice covering so it was time to take out the Intruder and do a little trouble shooting.  I don't know if I should  be pleased  or upset, but we ran that sled for more than an hour and didn't have any problems.  It was a little more sluggish than the 78 and wouldn't idle for an extended period, but put the juice to it and  she flew.  Hopefully it stays this way all season.

[Lloyd (ljm)]

  Oh the joys of issues that fix themselves.   I'm glad it is working better for you Mark.  I know I would have trust issues with it for a while.