066 RPM's creep up at WOT, ? about fuel filter

[angelo c]

Mtngun,
if you want to try out a wj 69 I got one on a bench. I got a problem 066 I been chasin for a while too. Its got to be an air leak that just don't show up in a pressure test.

PM me if you want to spend some USPS money....

A

 

[Stihl-Pioneer]

Broke a clutch spring on the last outing, so it's down for parts, which is just as well till I get the ghost problem figured out.

As I predicted, the dealer did not have an OEM filter, but Grande Dog is sending me the supposedly good Bailey's filters.

I pulled the welch plug, and it was clean as a whistle.

Ultrasonic on order.

Throttle shaft seems to be a normal fit in the housing, no visible gap or play.

Will have to think about this some more as I'm out of brilliant ideas.

I have a new genuine stihl filter your welcome to, if it will help you. PM me your address and I will throw it in the mail.

 

[mtngun]

You guys are too kind. I'll take a rain check until I can come up with a plan.

 

[john taliaferro]

looks like i pull the carb on my 460 tommrow and change the filter thanks.

 

[NORMZILLA44]

Mtgun, sorry it's not ironed out for you yet. I can get the part number, when reading this i got concerned, because the replacment filter was smaller. Shop reassure'd me A ok! So I will run it. I trust them 100 percent, as with some good member's here!

 

[mtngun]

Received the replacement aftermarket fuel filters from Grande Dog. These look similar on the outside, but are completely different on the inside. Instead of soft open cell foam, the inner filter is a dense material -- possibly ceramic, I'm not sure. But it looks to be 100% more reliable than the soft foam.

 

[NORMZILLA44]

Look's identical to the one my shop just sold me. It is a Stihl replacement, and slihtly smaller than the stock youre's too?

 

[tdi-rick]

Interesting.

I asked for a replacement filter for the the Dolmak's at the dealer and he gave me some of the Husky solid (Poron ?) ones, reckons that's what they use.

The genuine filter for the 64/73/7900 is made by Tillotson and they use outer felts that are replaceable (rather than replacing the entire filter head) over a cast metal pickup so I had MCW order me a bag of those as the seems a touch heavier.
Just thought I should have weighed them both when i last did a filter change. Next time.

 

[mtngun]

Look's identical to the one my shop just sold me. It is a Stihl replacement, and slihtly smaller than the stock youre's too?

Yes, the outside diameter on this current aftermarket filter is slightly smaller than the old style.

 

[albert]

That filter looks better than the aftermarket ones I got from them. It looks to be the standard size filter, Stihl make a larger and a smaller filter also. You should be ok with that size. Have you made any progress with the 7900?

 

[shawn022]

Those filters look much better. Is the outer filter still stainless mesh or nylon?

 

[mtngun]

Shawn022, I'm not sure what material the outer mesh is made of.

Albert, I haven't got to the 'kita yet. Thinking it's a weak coil and this could be a good excuse to do Eric Copsey's unlimited coil mod. On the other hand, I'm not positive its the coil since it does have spark, and I'd feel silly if I spent money on a coil and that didn't fix it.

Today I did a complete teardown on the 066. Underwater pressure test did reveal a very tiny leak on the clutch side seal, not enough to cause problems, but the thought was that it might be leaking more when it heats up, so it got new seals and a new case gasket. Now it doesn't leak at all. Gage didn't budge for 2 hours.

Carb got a ultrasonic bath and new diaphragm even though the previous diaphragm only had a dozen or so tanks through it. Needle pops off at 18 psi and re-seats at 12 psi (spec is 10 - 12 psi).

For now it still has the same somewhat scuffed top end. I cleaned up the top end but didn't want to replace it until the ghost problem is fixed.

Didn't get it back together until dark so I haven't run it yet. If this doesn't fix it .......

 

[7hpjim]

How is the throttle shaft on your carb, I believe the shaft on the bad tilly is shot causing the throttle creep/ lean condition, when compared to the shaft on another good tillotson off a 288 the the 394 carb throttle shaft has axial and thrust play, checked on a new one and it will cost believe it or not 34 bucks to confirm my suspicions, I think Ill wait and try to find another carb to rob the parts from.

 

[mtngun]

How is the throttle shaft on your carb

Looks perfect to me.

 

[7hpjim]

Well hopefully the route your on will eradicate the gremlins

 

[mtngun]

Those filters look much better. Is the outer filter still stainless mesh or nylon?

Had another look at the new filter. The outer mesh appears to be a non-metallic synthetic material.

 

[mtngun]

Update on the 066 ghost problem. :msp_unsure:

As mentioned before, it got a complete tear down with new seals & case gasket. The carb got fresh parts, too, even though the old parts were barely used.

It ran fine at first, but midway through the first cut, it seemed to lose torque, and then it had trouble idling. Something wasn't right.

I immediately called it quits and proceeded to do a leak test. It had a big leak, at the cylinder base and at the head (this has the 2-piece head). Tried snugging up the head bolts and one was spinning -- threads stripped ! ! ! :mad2:

Apparently that bolt had popped the threads out while the saw was running. :mad2: Mr. Murphy hasn't been cutting me any slack, lately.

Tried a heli-coil. I accidentally screwed it in too far and was forced to fish it out. Tried another heli-coil, it went in kattywampus and had to be fished out, too. By that time the helicoil threads were too far gone so scratch the helicoil. Mr. Murphy strikes again ! ! ! :mad2:

No problem, I could tap the hole for 5/16-24 and make an homemade insert out of 5/16-24 rod. Except, the only 5/16-24 rod on hand was 18-8 stainless which is a bugger to tap. Broke my only 6 mm tap. Argh ! ! ! :mad2:

OK, ordered more taps and a chunk of carbon steel 5/16-24 rod. It showed up today. Made a purty insert and screwed it in with a couple of drops of red loctite so it shouldn't go anwhere.

Why did the threads strip out in the first place ? Thread engagement was 11mm, compared to 10mm on OEM bolts. But, to be safe, I made some studs out of 6mm all thread that provide about 20mm thread engagement.

New stud on top, old bolt on bottom.

It passed leak test with flying colors (0.72 inHg per hour) and seemed to run fine when I fired it up. Idled steady, and held steady RPM at WOT, though I did notice the H screw is very sensitive -- maybe a bigger main jet would reduce sensitivity ?

Will take it to the woods tomorrow and see if the ghost problem returns.

I did pick up a used WJ69, just in case, but will save it as a last resort, since I can't find anything wrong with the original carb.

 

[Eccentric]

Glad to see you makeing some hard earned progress. One thing to be careful of however.........................most all-thread is pretty low-grade stuff (at least what you find at the hardware store). Usually GR2 at most. Studs are usually GR5 or GR8. Probably won't be a problem at the torque levels you're opperating at. I suggest you keep an eye on it for stretch, and retorque from time to time...

 

[mtngun]

most all-thread is pretty low-grade stuff. I suggest you keep an eye on it for stretch, and retorque from time to time...

Yep, this 6mm all thread is low-carbon, and I was reluctant to use it for that reason. We'll see what happens. Can order 4140 all thread if these don't work out.

 

[Justsaws]

Yep, this 6mm all thread is low-carbon, and I was reluctant to use it for that reason. We'll see what happens. Can order 4140 all thread if these don't work out.

Since you are running it on a mill are you going to heat the allthread up to OT before installing?