My TS400 concrete saw rebuild

[MattG]

Ok... at long last I decided to rebuild my TS400. I've posted to the chainsaw forum...if that's wrong, then redirect me to the correct forum...anyway it's nearly a chainsaw...I mean it's got a belt instead...and a diamond tipped wheel attached, so I'm not far off the mark

I bought this about 3 years ago for a demolition project....it looked pretty battered up then...but it still performed pretty well. Anyway now I think that now has come the time to give it some love.

The things that I definitely want to look at:

1. the stop switch no longer works (I switch off currently using the choke)
2. the rewind spring seems weak
3. could probably do with a vac + pressure test
4. could probably do with a carb service
5. imagine the piston could be a bit worn out...from all the brick dust etc.

Anyway this is what it currently looks like:
I'm gonna just quickly mention @Dan Forsh since he's got a few TS400s in his signature, and if he's still about he might be able to give me a couple of tips.

I'm not planning on doing the work particularly fast, but thought I'd create this thread, in case I feel like sharing some of stuff I end up doing on this piece of kit.

 

[HarleyT]

First thing is to determine the engine's condition. Take off the muffler and take a peek. Also pull the rope fast with the plug out and listen to the engine bearings.

 

[alexcagle]

The TS400 is an excellent saw.
My favorite to run.
The Cylinder design reminds me of an 036 cylinder, but 49mm.
*
The stop switch problem is very common on that saw, and is usually either because the wire is broken off at the connector contact on the bulkhead mounted switch, the short yellow jumper wire has lost it's ground, or the stop switch actuator rod is bent and is not pushing the contact spring at the switch.
*
There are two different kill wires, to correspond to either the early 3 bolt coil, or the later 2 bolt coil. The wire for the 2 bolt coil from Stihl is supplied as an ignition conversion kit for about $11 - $15
and includes a new spark plug wire, and kill wire in a sheathed covering to keep it from rubbing a bare spot in the kill wire , and a new air guide with wire retainers.

If you don't want to buy the kit, and you are going to solder it on, make sure you triple cover it, and the lower wire section that is close to the metal crankcase with heat shrink.
They rub through quickly If allowed to vibrate.
Then here comes a gremlin...

The 3 bolt coils are notorious for the kill function failing at the terminal.

This failure can be tested by using a self powered and lighted continuity tester like this one. It's good, as it's at half brightness.

If you ground one end to the iron frame of the coil, then touch the other end to the kill switch leg on the coil, it should light up, but about 50% dimmer than when you touch the two ends of the tester together. If it doesn't light up at all, then the kill function is bad. Viola.
* Does anyone knowledgeable know whats awry with that coil part number?
*
On the rewind spring;
make sure the pull rope is #4.5 or #5, and no more than 40 or 42" long.

Unload the spring tension and unclip the rope rotor pulley.
Then after you've pulled the rope rotor pulley out, pry out the spring carrier carefully, and check the condition of the spring. If someone put a rope in that was too long it will break the spring.
If concrete is built up on the rewind spring, from somebody oiling it, ( this makes dust stick to it), you should unwind it and use a knife, or paper towel and clean it off. Then use something like brake cleaner to end up with a dry spring.
* Skip the next mundane paragraph if you already know how to wind a starter correctly. LOL....
*
Then wind it back up, reinstall it, then install the rope on the rope rotor pulley.
Then drop it into place while lightly pushing down and rotating counterclockwise until it drops in and engages the spring. Then install the washer, pawl and clip.
Next, pull the rope all the way inward through the eyelet. The rope is already tied to the rope rotor pulley, so rotate the rotor counterclockwise until the rope slot it is at it's closest point by the eyelet. Then engage the rope in the slot, pull it upward, and wind it 6 times, or until the spring binds.
Then carefully rotate the rotor pulley clockwise until the slot is back at the eyelet. Then hold the rope rotor and pull the handle to feed the rope back out though the eyelet.
The rope should now retract correctly. Give the rope some super hard yanks all the way to its end to see if the knot slips. The rope cannot stick up from it's slot in the rope rotor pulley, or it will interfere with the pawl clip, causing the pawl not to fly out when the rope is pulled.
*
A pressure & vacuum test is jumping the gun, IMO.
*
I recommend you pull the fan cover, and starter off.
See if there is any up/ down play in the crankshaft (this is aka radial play).

There should be zero. Period.

If there is, then crank bearings are needed. I can offer advice if needed after you check them... This is already a Novel.
*
To check the piston, remove the starter, then back the 3/4" white plastic nut of the belt tensioner (on the cut arm) counterclockwise 90 degrees until the cam holds it there. Next, remove the three 3/4" belt cover bolts. From there you can remove the guard assembly, then the muffler.
*Note* If the T27 screws are rusted and you strip them, you'll need to use a cobalt 3/8" drill bit to drill the head completely off the screw. WD40 helps. You'll be left with a long enough stub to use vice grips to unscrew it easily.

Another thing notorious to cause problems on this saw is a metal baffle flap that vibrates and breaks off inside the muffler after a few thousand hours.
It can get back inside the exhaust port if the saw gets rolled around when transporting. Which is bad.
If you look in the muffler inlet and you can see if the flap is still on yours.
I recommend bending it back and forth to force it to break off and fish it out as a preventative measure.

The exhaust spark arrestor needs cleaned every 100 or so hours. It pulls out after you remove the clip, then break it loose from the muffler rust with pliers by rotating it. They also keep sand, debris, and mud daubers out. They are a good thing on these saws.
*
Inspect the piston next. Grab the starter hub and rotate the crank until the rings are visible.
Then, very slightly wiggle the crank back and forth.
If there is a noticeable play in the ring groove up and down, or the machining manufacturing texture marks are completely gone, then at least a new piston kit is needed.

If you pull the cylinder off and there is chrome loss under the intake port, above the exhaust, or at the very top of the cylinder.
*
The crank lower rod can be a bit loose side to side, but zero up/down movement.
*
They quit making that saw about 2006, so those carbs had that old welch plug glue that lifts, and starts floating around causing problems. Usually ends up under the needle lever.
*
The fuel hoses were updated to a two piece hose and an elbow connector. if yours has a ribbed one I'd replace it.
*
Next the 180° bend "U" shaped hose left of the fuel hose should be pulled and the metal grub screw cleaned out so it leaks slowly for the tank vent. They get plugged up over time.

If this hose is loose, fuel will seap out. I use a viton o-ring next to the shoulder of the hose that is outside of the tank. This will tighten it up. A trick I use on the hard to install vent hose is to squirt a bit of laquer thinner on it just prior to installing. It makes rubber slick for a few seconds until it evaporates. This works for intake boots, and AV buffer plugs too!

Also put an O-ring on the tank vent check valve to the right of the fuel hose if it is loose.
The tank vent should hold 4psi, then bypass if it's working correctly.

I think that about covers the most common issues.
Hope this helps.
By the way, the Osha stickers are free from your local Stihl dealer.
Alex

 

[alexcagle]

Also, if you want it to have more power, omit the base gasket. They have about .050 clearance when stock with the gasket.
I recommend 518 loctite anaerobic sealer with #37509 "activator" to make it cure quicker, or 3 bond brand #1184 . Hondabond, Yamabond 4.
I do NOT recommend permatex motoseal. For some reason, cutoff saws don't like it.

 

[MattG]

First thing is to determine the engine's condition. Take off the muffler and take a peek. Also pull the rope fast with the plug out and listen to the engine bearings.

Thanks HarleyT, I'm actually gonna look at doing the stop switch first, just to get that job out the way. As alexcagle mentions I'm suspicious of the rod coming from the handle actuator downwards to the innards where the electrical contact is supposed to happen.http://www.arboristsite.com/community/members/alexcagle.59529/

 

[MattG]

The TS400 is an excellent saw.
My favorite to run.
The Cylinder design reminds me of an 036 cylinder, but 49mm.
*
The stop switch problem is very common on that saw, and is usually either because the wire is broken off at the connector contact on the bulkhead mounted switch, the short yellow jumper wire has lost it's ground, or the stop switch actuator rod is bent and is not pushing the contact spring at the switch.
*
There are two different kill wires, to correspond to either the early 3 bolt coil, or the later 2 bolt coil. The wire for the 2 bolt coil from Stihl is supplied as an ignition conversion kit for about $11 - $15
and includes a new spark plug wire, and kill wire in a sheathed covering to keep it from rubbing a bare spot in the kill wire , and a new air guide with wire retainers.

If you don't want to buy the kit, and you are going to solder it on, make sure you triple cover it, and the lower wire section that is close to the metal crankcase with heat shrink.
They rub through quickly If allowed to vibrate.
Then here comes a gremlin...

The 3 bolt coils are notorious for the kill function failing at the terminal.

This failure can be tested by using a self powered and lighted continuity tester.

If you ground one end to the iron frame of the coil, then touch the other end to the kill switch leg on the coil, it should light up, but about 50% dimmer than when you touch the two ends of the tester together. If it doesn't light up at all, then the kill function is bad. Viola.
*
On the rewind spring;
make sure the pull rope is #4.5 or #5, and no more than 40 or 42" long.

Unload the spring tension and unclip the rope rotor pulley.
Then after you've pulled the rope rotor pulley out, pry out the spring carrier carefully, and check the condition of the spring. If someone put a rope in that was too long it will break the spring.
If concrete is built up on the rewind spring, from somebody oiling it, ( this makes dust stick to it), you should unwind it and use a knife, or paper towel and clean it off. Then use something like brake cleaner to end up with a dry spring.
* Skip the next mundane paragraph if you already know how to wind a starter correctly. LOL....
*
Then wind it back up, reinstall it, then install the rope on the rope rotor pulley.
Then drop it into place while lightly pushing down and rotating counterclockwise until it drops in and engages the spring. Then install the washer, pawl and clip.
Next, pull the rope all the way inward through the eyelet. The rope is already tied to the rope rotor pulley, so rotate the rotor counterclockwise until the rope slot it is at it's closest point by the eyelet. Then engage the rope in the slot, pull it upward, and wind it 6 times, or until the spring binds.
Then carefully rotate the rotor pulley clockwise until the slot is back at the eyelet. Then hold the rope rotor and pull the handle to feed the rope back out though the eyelet.
The rope should now retract correctly. Give the rope some super hard yanks all the way to its end to see if the knot slips. The rope cannot stick up from it's slot in the rope rotor pulley, or it will interfere with the pawl clip, causing the pawl not to fly out when the rope is pulled.
*
A pressure & vacuum test is jumping the gun, IMO.
*
I recommend you pull the fan cover, and starter off.
See if there is any up/ down play in the crankshaft (this is aka radial play).

There should be zero. Period.

If there is, then crank bearings are needed. I can offer advice if needed after you check them... This is already a Novel.
*
To check the piston, remove the starter, then back the 3/4" white plastic nut of the belt tensioner (on the cut arm) counterclockwise 90 degrees until the cam holds it there. Next, remove the three 3/4" belt cover bolts. From there you can remove the guard assembly, then the muffler.
*Note* If the T27 screws are rusted and you strip them, you'll need to use a cobalt 3/8" drill bit to drill the head completely off the screw. WD40 helps. You'll be left with a long enough stub to use vice grips to unscrew it easily.

Another thing notorious to cause problems on this saw is a metal baffle flap that vibrates and breaks off inside the muffler after a few thousand hours.
It can get back inside the exhaust port if the saw gets rolled around when transporting. Which is bad.
If you look in the muffler inlet and you can see if the flap is still on yours.
I recommend bending it back and forth to force it to break off and fish it out as a preventative measure.

The exhaust spark arrestor needs cleaned every 100 or so hours. It pulls out after you remove the clip, then break it loose from the muffler rust with pliers by rotating it. They also keep sand, debris, and mud daubers out. They are a good thing on these saws.
*
Inspect the piston next. Grab the starter hub and rotate the crank until the rings are visible.
Then, very slightly wiggle the crank back and forth.
If there is a noticeable play in the ring groove up and down, or the machining manufacturing texture marks are completely gone, then at least a new piston kit is needed.

If you pull the cylinder off and there is chrome loss under the intake port, above the exhaust, or at the very top of the cylinder.
*
The crank lower rod can be a bit loose side to side, but zero up/down movement.
*
They quit making that saw about 2006, so those carbs had that old welch plug glue that lifts, and starts floating around causing problems. Usually ends up under the needle lever.
*
The fuel hoses were updated to a two piece hose and an elbow connector. if yours has a ribbed one I'd replace it.
*
Next the 180° bend "U" shaped hose left of the fuel hose should be pulled and the metal grub screw cleaned out so it leaks slowly for the tank vent. They get plugged up over time.

If this hose is loose, fuel will seap out. I use a viton o-ring next to the shoulder of the hose that is outside of the tank. This will tighten it up. A trick I use on the hard to install vent hose is to squirt a bit of laquer thinner on it just prior to installing. It makes rubber slick for a few seconds until it evaporates. This works for intake boots, and AV buffer plugs too!

Also put an O-ring on the tank vent check valve to the right of the fuel hose if it is loose.
The tank vent should hold 4psi, then bypass if it's working correctly.

I think that about covers the most common issues.
Hope this helps.
By the way, the Osha stickers are free from your local Stihl dealer.
Alex

Wow Alex! That little lot was awesome....you've already covered one of my theories re. the stopping problem. As for the rest of this post, it looks like I have a bit of work to do This post of yours is definitely worth a double like. Like I said I'm gonna do the work quite slowly probably over a few months....day job, family life etc. permitting. But I'll probably post some more piccies in the next week....and definitely scream for help for any tips that you've not already covered!

thanks again!
Matt

 

[alexcagle]

You're welcome!
I'm actually completely rebuilding a TS400 right now.
The kill switch design is archaic and overly complex with too many ways to fail. IMO
They never stay working without something failing for an extended amount of time.
This saw Im fixing has been dead, sitting about 10 years on a shelf in a guys shop. It's really roached out, which is normal. "Rode hard, and put up wet". lol
To go through every system, and bring everything up to reliable condition takes a couple hours. I stock every single part for the common saws of all brands.
That way there is no waiting on parts.

Gosh, actually writing in understandable detail about a starter repair takes about four times longer than me doing it! Lol

It makes me understand a tip of the iceburge of just what's involved in writing a repair manual.

 

[MattG]

The 3 bolt coils are notorious for the kill function failing at the terminal.

Is the kill function on the coil really that complex? With lot of ignition circuits I'd naively assumed that it's just a case of shorting the LT side and preventing the coil on that side ever creating an electric field.....

If my simple assumption is correct then presumably a shiny clean terminal on the coil assembly seems a worthwhile prerequisite.....but anyway I might be being a little naive on this one....if so, apologies in advance

 

[alexcagle]

No, it's not complex. It's how I can tell if a kill function works while I'm slapping it together. 5 seconds saves 5 minutes later if it is crapped out. Helps estimates too, because most saws I get, won't start to test it anyway.

 

[MattG]

Hi @alexcagle I wanted to ask a question. I was having a quick play with the TS last night before tea and it became apparent that things would be a lot easier to work on on my restricted work bench if I took the guard (obviously the cutting wheel first!) off. I started looking at the manual about this. I was a bit surprised since the sequence of pictures in the manual would imply that the first thing to do would be to back off the belt adjuster, i.e. the arrow marked hexagon "Relax V belt" and then remove the bearing screws. This just seemed odd to me as I am used to working on car belts where you often have a locking nut etc. to back off first before you loosen the adjustment.

Could you confirm that the first thing to do is indeed to back off that arrow marked hexagon? I just don't want to strip anything, as I imagine that this part of the machine has not been touched for a long while.



Thanks in advance, Matt

 

[alexcagle]

When you loosen the belt adjusting nut 90 degrees counterclockwise, you will feel that it has a breakover point that will hold the spring on it's own, and indefinitely, and will not move.
Then you can remove the blade guard assembly, (even without removing the blade). lol
When you reassemble it, you put the belt around the pulley then put the belt guard on, then thread in the three bolts, and tighten them up lightly, then back them off 1 turn.
Then, on the belt adjuster nut, apply sufficient force in a clockwise direction to release the spring pressure on the belt. It should "pop" the belt to the correct tension automatically. Then just tighten the three bolts up until "gutentight".

Note; that, if the belt tensioner doesn't "pop" it tight when turned back over to tighten the belt, then squirt a little WD-40 on the gap of the nuts' cover with the saw on its side to allow it to flow to the back of the nut , where the concrete dust has built up, inhibiting its function.
Then excercise it back and forth until it pops the belt tight.
cheerio

 

[MattG]

When you loosen the belt adjusting nut 90 degrees counterclockwise, you will feel that it has a breakover point that will hold the spring on it's own, and indefinitely, and will not move.
Then you can remove the blade guard assembly, (even without removing the blade). lol
When you reassemble it, you put the belt around the pulley then put the belt guard on, then thread in the three bolts, and tighten them up lightly, then back them off 1 turn.
Then, on the belt adjuster nut, apply sufficient force in a clockwise direction to release the spring pressure on the belt. It should "pop" the belt to the correct tension automatically. Then just tighten the three bolts up until "gutentight".

Note; that, if the belt tensioner doesn't "pop" it tight when turned back over to tighten the belt, then squirt a little WD-40 on the gap of the nuts' cover with the saw on its side to allow it to flow to the back of the nut , where the concrete dust has built up, inhibiting its function.
Then excercise it back and forth until it pops the belt tight.
cheerio

Thanks for now, Alex - I'll keep you posted!

 

[alexcagle]

Here's the one I was working on yesterday. Most people don't know that a TS420 deflector will work on a TS400.
All you have to do is switch out the TS420 cut arm for a TS400 deflector hub,and use the TS420 rubber arbor adapters.

 

[MattG]

Got a bit enthusiastic tonight... So yeah the guard is easy to come off (thanks again Alex)


and took off the shroud....


the shroud itself....with it's, umm...under-engineered attempt at a kill switch...I'm pretty sure that the refusal-to-stop using the switch problem emanates from this gremlin. Sorry the photo is a little unclear...crappy camera and operator


Busy day at day job tomorrow probably have to wait till sunday for resumption of any more serious TS work.

 

[alexcagle]

The little spring needs to clip behind the upper part of the actuator rod. This will make the actuator rod spring back.
I can't tell from the picture, but if the other end of the spring is broken, then you'll need to buy one.
It looks to be just unhooked to me.

In this picture, the yellow and green jumper ground wire should be under the white cylinder cover against the metal underneath, then the bolt through it.

It's a good idea to file the flat contact surface and the wire eyelet free of corrosion.

I'd bet your main problem is the brass contact spring and the kill wires' end connector both need the dirt and corrosion scraped off their contact points.

 

[MattG]

The little spring needs to clip behind the upper part of the actuator rod. This will make the actuator rod spring back.
I can't tell from the picture, but if the other end of the spring is broken, then you'll need to buy one.
It looks to be just unhooked to me.

In this picture, the yellow and green jumper ground wire should be under the white cylinder cover against the metal underneath, then the bolt through it.

It's a good idea to file the flat contact surface and the wire eyelet free of corrosion.

I'd bet your main problem is the brass contact spring and the kill wires' end connector both need the dirt and corrosion scraped off their contact points

Thanks for this Alex, I'm at work now and busy with the day job, and busy with other things probably til sunday....but then I'll take another look at the TS...with your thoughts in mind and have a play. Probably send up a few closer detail pics of the spring etc.

thanks again for your time,

Matt

 

[MattG]

Hello again @alexcagle - thanks for your tip re. the spring. I found a bit of time after work today....and yes the spring was unclipped it seems...though of course I have no experience in how it is supposed to look. Another closer shot of how it was, when I first took the shroud off:

Based on what you said in your last post...I've clipped where I guess it must go. And yes the actuator rod seems to be more controlled now...this is how is it now....this must be the right situation...?

Apologies in advance (but I'm back inside now in the warmth ) for my lack of focus in this next shot:

I marked a component with 2 white dots.... I guess this thing is just there to act as a pivot point for the actuator rod...but it looked a bit overdone just for that. At first, before I blew the dust off, I thought that it was something to do with the kill function...but now I see that it is not. Finally I can see that the end loop of the actuator that I point to with a white arrow must bear against the contact thing....I'm pointing to that in this next shot:

I can remember a time when I using the saw 2 years back...the last time when the kill switch worked...and I think that one time I forgot which way you moved the switch to shut it down..and fumbled with it excessively....I believe it must have been around then the spring must have gotten dislodged...and it was from then on that it stopped stopping properly.

Anyway, sometime in the weekend I'll clean the metal bits a little and reassemble and give it a test.

Since I've already got the guard and disc off and I'd like to keep them off for now...but it still has the belt on...which I need to remove if I'm gonna test start it I guess. So is it easy to take off the cover near the drive+rewind, get the belt off, and then get the cover (with the recoil still in it) back on?

thanks again, for your help and time, with my questions Alex.

 

[MattG]

I cleaned up the spring contact and the contact sleeve and chucked a few bits back on....and hey presto the continuity tester reveals the stop switch is working again (i.e. it shorts the LT side to ground).

 

[MattG]

Quick update on matters with this saw. I did a compression test on the saw last night, and got to 160 PSI (this was with the choke valve closed). IDK what it should be but it seems quite reasonable.

The next thing on my TODO list is to service the carb. I can't upload images from where I am now...so will just describe what I saw last night.... the carb says Tillotson on it's top cover and stamped on it's side is 274B634.

Now the IPL I've got for the saw, does not seem to list a carb kit for this saw, indeed my IPL lists the following as carb choice

HS-274E carb kit p/n 1124 007 1060
WJ-108A carb kit p/n 1122 007 1060
HS-279D carb kit p/n 1124 007 1060

The carb kits just contain the gasket/diaphragm pairs, and I'm also thinking of changing the inlet needle, the spring that controls the needle, and possibly the fuel strainer.

Does anyone if the parts from carbs listed above can be interchanged with those from my fitted Tillotson (I'll try to send in a piccy in a day or so). The reason for my curiosity, is that it will be a lot easier to get parts from the small engine spares people I use, if I can just quote p/n.s straight from my IPL.

 

[MattG]

@alexcagle

Hey Alex, Have you any ideas on whether the IPL-listed carbs I mentioned above have parts which I can interchange on my Tillotson carb?

EDIT:
I've just found (on the small engine spares site that I regularly use for Stihl)

http://www.lsengineers.co.uk/tillotson-carb-diapragm-kit-for-makita-dpc6200-dpc6400-dpc6410.html

But changing the spring + needle would probably to be good to do too at this point, I think. Do you think that the parts for IPL carbs will swap over? I'm asking you because I imagine that you know far more about them than the ladies who answer the phone when I call there!

thanks Matt