Tillotson HR Carb Question

[tjmoening]

I did a search and didn't find anything specifically related to my question, so here goes.  Been battling a 1971 Arctic Cat Lynx 292 with a Tillotson HR70B carb.  Hard starting, high idle that won't come down from basically clutch engagement, when I try and adjust the low speed screw back, the sled sputters and dies, every time.  Hard to start back up, even when hot, needs the choke, then starts and has super high idle again.  Set both L and H screws 1 to 1.5 screws out to start.  If I rev the sled up to high speed, it runs great and revs nice, let off throttle, its dies.  I noticed the L screw is missing the washer and o-ring (packing) that goes in before the spring on the needle screw.  I think this may be my culprit ad I have an air leak.  Just verifying with the experts on here if this could be my problem?  Thanks for any and all help!

[Vintagesleds.com]

[apmoore]

After you put the washer and o-ring in, if still have the problem, don't rule out crank seals as a possibility.

[trashman36]

I would check for air leaks. Including crank seals

[tjmoening]

Ended up pulling the clutch off and the PTO crank seal was indeed bad on this Lynx.  Replaced the crank seal and she runs pretty good and idles down like it should.  BUT.....I have the high speed screw 3/4 out and its about right on the stand, the low speed screw I have out almost 3 turns to get it to idle down!  It seems to smoke heavily and has a bit of an oil drip out of the exhaust.  The Lynx does have a tuned pipe/stinger on it, so it may need for fuel to idle down since it doesn't have the same back pressure, but this seems excessive......and smoky.  Any further ideas to get her to continue to idle OK without needing the L screw so far out causing the dirty idle?  Thanks!

[motorman45]

the low speed screw shouldn't need to be out more than 1 1/2 turns. 1 turn is more typical. you may still have an air leak, did you do the Mag side seal too ? did you put the o-ring under the L speed washer / spring ? 

[snowracer]

Normal setting for high speed should be approx. turn and a half out and low speed three quarters. Sounds like an air leak. Crank seal, intake manifold, etc.

[tjmoening]

I tried to cheat and only changed out the PTO crank seal.  It improved a lot, but my guess is the MAG seal is still leaking some.  Will do that one too and see what happens.  Hope I don't mess up the timing taking it apart on that side!

[wankel303]

As long as you don't loosen the contact points up, you should be able to remove then reinstall the magneto without altering the timing.  In situations like this, use a flat blade screw and position the blade so that it's half on the stator plate and half on a part of the crankcase that is flush with the plate.  Give it a light rap and it'll make a hash mark on both pieces.  When you re-install the stator plate, align the marks and you're timing will be unaffected.  This is, of course, assuming that the timing is proper to begin with.