My TS400 concrete saw rebuild

[alexcagle]

The spring on the stop swith lever needs to be bent a little to increase the spring tension. That's probably why is came off to begin with.
Just open the carb after you clean the outside a bit. I would just install a HS Tillotson kit.

 

[MattG]

The spring on the stop swith lever needs to be bent a little to increase the spring tension. That's probably why is came off to begin with.
Just open the carb after you clean the outside a bit. I would just install a HS Tillotson kit.

Thanks Alex,

I'll look at that spring in a bit. Yup, I've cleaned it up a lot more in the last coupla days. And got the filters off and eventually figured that tillotson means HS274 . I've stripped out the inside of carb as best I can now and cleaned it up. Will order some bits now I know what to get.

Is 160psi pretty good for compression for this saw then?

BTW One problem it used to have was that it would NEVER re-start without WOT. Any classic reasons for that on this saw?

 

[alexcagle]

160psi is really good.
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That restart problem sounds like you had an internal carb leak.
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Be careful blowing the carb out with compressed air or using caustic carb cleaners. They can kill the mylar nozzle check valve. WD-40 is good to clean a carb with. When I'm done building the carb, I spray lacquer thinner on the outside of the carb to dry it off. WD-40 is a magnet for concrete dust. If it's dry it will be less likely to stick to it.

 

[MattG]

160psi is really good.
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That restart problem sounds like you had an internal carb leak.
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Be careful blowing the carb out with compressed air or using caustic carb cleaners. They can kill the mylar nozzle check valve. WD-40 is good to clean a carb with. When I'm done building the carb, I spray lacquer thinner on the outside of the carb to dry it off. WD-40 is a magnet for concrete dust. If it's dry it will be less likely to stick to it.

Thanks for this last one Alex. I hope that I'm ok with the cleaning I've done so far. I did use WYNNs "Carb + intake cleaner" I'm afraid. My compressor is quite weak though, so hopefully it have survived.

Re the restart issue, yes there was evidence that the carb aint been looked at for ages, the gaskets were well embedded and there was very fine dust particles actually solidified in a lump under the internal needle spring! Also saw a weird lump in the metering chamber, I think it's a piece of lacquer that has broken away from summat - you may have a different idea though:

Also found that the filter closest the carb was incredibly clogged:

And the fuel hose is looking pretty sorry for itself:

It's just a testament to how good the stihl engineering was on these machines....I was using that saw just a couple of weeks previous clearing up more of the dumped concrete slabs we have around our property.

Well it's fair to say that I've got a lot of new parts on order for this saw now, Alex. This TS owes me nothing, has done some great work for me, and seeing as I'm not planning on stripping it down again for ages, I don't mind spending some time and money getting it tip-top again. I was even contemplating redoing the crank-seals just so that I know that they won't ever need looking it the future....but you'll probably think I'm crazy and that I shouldn't bother with them unless it fails in a big way.

 

[alexcagle]

The ring is exactly what I was talking about from the welch plug directly below the lifted glue ring.
The intermediate jet, the brass thing with a #48 on it, goes through to the venturi, and can be cleaned with a tiny wire. There is no check valve on that one to harm.
The threaded jet orafice should be removed to check underneath for the missing pieces of that ring of sealer.
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That inner filter is pretty bad.
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That carb leak can wet and oil the cylinder down, causing a falsely high reading until warmed up.
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Don't replace the seals unless the crank bearings are loose, and are being replaced. They arent that prone to leaking, unless the bearings are loose.
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You would be better off replacing the piston if you're that far in there.
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The condition of the intake skirt is as important as the ring gap on a piston ported engine. A new piston will make even a mildly worn saw run stronger, idle better, and start easier,( both cold and warm starts) .
It is an easy task to replace a piston on one those saws.

 

[MattG]

Thanks again pal,

Do I need to anything in particular cos of the glue ring? I.e. put new glue somewhere....apologies for sounding dim, but I don't know nothing about welch plugs

10-4 regarding the seals - I'll be sure to check the bearings (well shake the crank + conrod about some) well though.

And thx again re. tip on piston, I'll extend my current parts order....and yeah the piston should ok....I've done a MS200T before....now that was fiddly. I'm sure that this saw should be alright for me. This should be a pretty good work horse once I'm done with!

I'll keep you posted......

 

[alexcagle]

IMO your welch plug will be fine, with no sealer. A welch plug is merely an access cover over the 3 idle circuit bleed holes.
If you look in the inside of the carb under where the welch plug is you'll see the holes. It's designed so that as you open the throttle butterfly, you expose more holes to suck fuel from to keep the air to fuel ratio at the optimal 14 to 1 ratio.
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[MattG]

IMO your welch plug will be fine, with no sealer. A welch plug is merely an access cover over the 3 idle circuit bleed holes.
If you look in the inside of the carb under where the welch plug is you'll see the holes. It's designed so that as you open the throttle butterfly, you expose more holes to suck fuel from to keep the air to fuel ratio at the optimal 14 to 1 ratio.
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So what exactly is the deal with these welch plugs things? Do you pry them out and wreck them in the process, then get a new one to refit?



Just kinda curious really, I'm happy to leave mine where it is, less you reckon I should shift it.....

 

[alexcagle]

A welch plug is is a convex thin aluminum plug (disc) that drops in it's close tolerance corresponding precise hole with dome side up, then a flat ended driver tool that is about 2/3 the diameter of the plug is used to flatten it.
This both seals and retains it by exerting outward force against the walls of the hole.
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This is copied directly from a Tillotson HS instructional document:
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CAUTION: Under extreme conditions of clogged idle fuel supply channel and discharge ports, it may be necessary to remove the channel welch plug. If so, it must be very carefully done in following manner: 1. Drill a 1/8 " diameter hole through the 3/8” diameter welch plug. This hole should just break through the welch plug. Deeper drilling will seriously damage the body casting and its discharge ports located close behind the welch plug. On some models an additional smaller 1/4 " diameter channel welch plug is used. It is not necessary to remove this plug. 2. Carefully pry out welch plug, then clean discharge ports and cross channels. Now install new part 02531 (3/8" diameter, 1/32" thick) welch plug by placing it in casting shoulder, convexed side upward; then flatten to a tight fit with a 5/16" diameter flat end tool.

 

[MattG]

A welch plug is is a convex thin aluminum plug (disc) that drops in it's close tolerance corresponding precise hole with dome side up, then a flat ended driver tool that is about 2/3 the diameter of the plug is used to flatten it.
This both seals and retains it by exerting outward force against the walls of the hole.
*
This is copied directly from a Tillotson HS instructional document:
*
CAUTION: Under extreme conditions of clogged idle fuel supply channel and discharge ports, it may be necessary to remove the channel welch plug. If so, it must be very carefully done in following manner: 1. Drill a 1/8 " diameter hole through the 3/8” diameter welch plug. This hole should just break through the welch plug. Deeper drilling will seriously damage the body casting and its discharge ports located close behind the welch plug. On some models an additional smaller 1/4 " diameter channel welch plug is used. It is not necessary to remove this plug. 2. Carefully pry out welch plug, then clean discharge ports and cross channels. Now install new part 02531 (3/8" diameter, 1/32" thick) welch plug by placing it in casting shoulder, convexed side upward; then flatten to a tight fit with a 5/16" diameter flat end tool.

Thanks mate, well I'm definitely leaving it well alone if possible in that case!

 

[MattG]

Well it looks like xmas came early for the TS :

and my stihl supplier decided to send me an extra something too...Instead of getting 1 fuel strainer, they sent a bag of 6-7:

Very generous!!

 

[MattG]

So today finds me rebuilding the carby before getting down to some slightly more domestic chores

 

[MattG]

Wanted to do more on the TS400 today...but got stuck making kindling, then I realised that the garage was a complete dump...so had to tidy that

....then I decided that I could with cleaning around the TSs induction area better. Alex is probably chuckling I imagine but this is tough work when your compressor is a bit wimpy. So this is about all I got done today:

(Note how the saw is expertly balanced on my Stihl Tea cup, a recent Anniversary present from the missus)

Intake side of the piston seems nice:

 

[alexcagle]

Looks good.
Your saw looks to have been built within the first four years.
You have the earlier verion fuel tank. They updated the tank vent in 1999 after machine serial number 144576635.
If I were you I'd pressure test the tank (prior to fueling, obviously). Just spray soapy water on the rubber seals. If you use a pressure gauge, 5 psi is enough. Then pull vacuum to insure that the vent lets air in, and is not plugged up.

Those old tank vents always have evidence leakage when I get them, which is a large gook buildup. If you put an o-ring on each nipple before poking it in the grommet, it will tighten up the seal against the grommet.
If the grommet and the tank vent are much easier to install with either Stihl press fluid, or lacquer thinner. It makes it slick, and it'll pop right in there.

Is that the old piston in there?

 

[MattG]

Thanks Eric!

Your saw looks to have been built within the first four years.

Wow...so was it built pre-1999?

If I were you I'd pressure test the tank (prior to fueling, obviously)

Yay, I'm gonna change out the fuel line first though. The current one is well cracked, the cracks opening up as it bends around.

Just spray soapy water on the rubber seals.

I might get you to talk me thru this some more later on. But I guess that you are meaning soapy water where pipe goes in the casing, and the vent and cap etc.

If you put an o-ring on each nipple before poking it in the grommet, it will tighten up the seal against the grommet.
If the grommet and the tank vent are much easier to install with either Stihl press fluid, or lacquer thinner.

I'll come back to this with you if I get stuck

Is that the old piston in there?

Yes man. Dont look bad does it? I guess you'll be wanting me to pull off the muffler soon to take a look there as well

Well since this saw is a tad unfamiliar to me, and cos home life is very hectic right now (wife's had an operation, kids are 11 + 14, prepping firewood, car work etc.) I'm taking this rebuild very slow. I'm probably going to put what I have taken off back on now....give it a quick test fire...and then dismantle it again. I sometimes do this to get more familiar with an appliance - so hopefully soon I'll get more confident with changing out the piston for example....i.e. know that I can get things back together with out losing too many parts in my crazy garage

 

[alexcagle]

The intake side of that piston looks great.
How long did you say you've owned it?
That piston looks almost new.
Yeah, if the exhaust looks that good, and with 160psi compression, I'd almost say get your money back on the new piston.

 

[MattG]

The intake side of that piston looks great.
How long did you say you've owned it?
That piston looks almost new.
Yeah, if the exhaust looks that good, and with 160psi compression, I'd almost say get your money back on the new piston.

Well, I bought it 3 years back since I wanted to remove the concrete slab base of a domestic oil tank we'd de-commissioned. I didn't want to hire a pneumatic drill, and always needed a concrete saw for something every little while anyway...so it cut the base into 1 foot cubes for me to depose of.

Since then I've used once every couple months on small demolition (small outside walls + footings) projects round our property.

Guy I bought it from had been using it for much the same thing as me....and I guess it had been around the 2nd hand DIY and construction trade for a few years prior. Yeah it's real nice bit of kit......so you reckon it could been built pre-1999? If I find the serial number will we get more of a clue?

Anyway when get round to it I'll pull the muffler and we can see whether I need to change the piston or not.....otherwise I'll get the missus to sell the piston on ebay or summat.

 

[alexcagle]

Yep, they did a bulletin on tank redesign in 1999.
Not a big deal. They made that saw until 2006.

 

[MattG]

Yep, they did a bulletin on tank redesign in 1999.
Not a big deal. They made that saw until 2006.

Wow, they knew how to build them. That saw has been around for over 16 years. Pretty good going.

 

[MattG]

Minor annoyance now.....

I'm partially reassembling it to see how well it runs with my refurbished carb and new filters, lines etc. and discovered that (Alex will probably be rolling his eyes...since it's my own stupid fault for not querying this more when I made my parts order) since the fuel tank on mine is the earlier one, it seems that the fuel pipe is an earlier one part version, see below:

So I wondered if anyone knows the stihl p/n for the one part. I appreciate that I could (presumably) order the elbow connector (item 21 on schematic) plus some standard hose....but a 3-part hose seems to be a retrograde step to me.