028S Tillotson carb ?

[Mad Professor]

Had this saw for many years then had an issue with starting and lack of power. Traced to a lack of fuel, popped with some gas added to carb, so went into the HU-40D Tillotson carb, new OEM carb kit RK-15HU. Replaced gaskets and diaphragms although they looked O.K. (35 years old). Needle/seat were fine, left them in. Screen was very clogged with fine debris, replaced that. That's besides general cleaning. Clogged screen seemed to be the issue.

When working on it the plastic fuel inlet nipple came loose, I pushed it back in and seemed O.K. there.

Saw ran great again after rebuild. Then stored for a while. Next time starting there was a lean condition at idle with saw racing, shut it down/never put in wood.

I may have an air leak, it's 35 years old. But I'm wondering about the fuel inlet nipple being the leak? If so an easy fix to check first. I'll check and see if pushing it in, temporarily solves problem.

What do you suggest for a sealant for fuel inlet nipple?

If it's not that inlet nipple I'll check the carb again and look for vac leaks.

 

[stihl86]

I'd just pressure test the inlet to try and find it, if there is one. While the tester is out, test the power head.
As for the sealer, I'd try Loctite Retaining Compound. 609
Because, have you ever found anything that is completely gasoline proof?

 

[Mad Professor]

I'd just pressure test the inlet to try and find it, if there is one. While the tester is out, test the power head.
As for the sealer, I'd try Loctite Retaining Compound. 609
Because, have you ever found anything that is completely gasoline proof?

Tester is not handy right now. At my other place, next state, covid travel restrictions............my spare fuel/impulse lines are there too. Well that could be "essential travel".......bring a load of wood along

I bought up a set of spares for all my saws: carb kits, impulse/fuel lines, gasket sets, filters. All my stihls are 1980s-90s, nice and simple to work on

I don't have spare seals but will be buying a br400 gasket set as the 028 run same seals, and I have a br400 blower too (set cheaper than seals).

Mainly wondering about sealant for the elbow, # 609 is "super glue".

Meanwhile I'll be using the 036 for firewood, the 028S is my 2nd small saw I bring in the woods. Usually it's 038M and 036, or 036 and 028S depending on the trees. Two saws are always good if one craps out, or you pinch a bar in a cut and have to cut it out

 

[stihl86]

609 is a green retaining compound. Its like 620 but not as heat resistant.
It will take up .005 or there about. I use it often.
It smells like Locite thread locker. Probably the same stuff with a reduced viscosity.
The red "High Temp" thread locker use to be "Bearing and Stud" mount 20 years ago.
Might be all marketing horsechit.
I disagree with the "SuperGlue" comparison.

 

[Mad Professor]

609 is a green retaining compound. Its like 620 but not as heat resistant.
It will take up .005 or there about. I use it often.
It smells like Locite thread locker. Probably the same stuff with a reduced viscosity.
The red "High Temp" thread locker use to be "Bearing and Stud" mount 20 years ago.
Might be all marketing horsechit.
I disagree with the "SuperGlue" comparison.

They are both acrylate glues, polymerize in presence of moisture (very weak bases/water). Can't get enough info on their website as to fuel resistance. Both should be good with hydrocarbons but not compatible with solvents like acetone. I'm wondering about ethanol/E-10.

 

[Maintenance supervisor]

I've replaced them with metal elbows.

 

[SteveSr]

When working on it the plastic fuel inlet nipple came loose, I pushed it back in and seemed O.K. there.

These were the bane of Walbro as well. They would crack and leak. Best thing is to just replace them with a new part or metal elbow stolen from another bad carb.

Cyanoacrylates (a.k.a. Super Glues) are supposed to be fuel resistant.

 

[Mad Professor]

One more thought. If the nipple is not cracked just JB weld it in place.

I've got another 028S parts saw, I could take a cover off, but that's at my other place too......

 

[SteveSr]

One more thought. If the nipple is not cracked just JB weld it in place.

JB Weld is just an epoxy and as such is not particularly fuel resistant but it could last for a while in an emergency.