038 Build

[sherlock349]

I am rebuilding an 038, ( I have rebuilt several 028,s and 038’s in the past) the crankcase I am using is in good condition and cleaned up well, I have fitted a new Stihl cylinder and piston kit Number 11190201202, I tested for leaks and all is okay. I have then fitted the coil and flywheel and pull start. The saw is extremely difficult to pull over with a plug fitted. No plug and it’s fine. I have used an aftermarket base gasket, is it possible that this has raised the compression causing the problem. It pulls over fine with out a spark plug. If a fully assemble I am confident I wont be able to pull it enough to start it. Any thoughts appreciated.

 

[Maintenance Chief]

You can get electric solder and poke it through the spark plug hole till it just touches the cylinder wall , then rotate the cylinder over by hand using the flywheel. The piston should crush the solder , measure the solder and calculate the squish.
Should be shooting for .017-.040 anything in that range. Half a mil is .050 I think?

 

[Canadian farm boy]

How much oil is in the cylinder?

What’s the squish clearance?

To much oil above the ring can essentially cause hydro lock especially with a tight squish clearance.

 

[sherlock349]

Okay, I will check the squish and flush the assembly oil this morning with gas 2 stroke mix. Will let you know my findings.

 

[Al Smith]

If memory serves with a stock cylinder with a gasket the head deck clearance is around .043-.046 .With a shaved base you can get around .022 and still pull it over but unless to have arms of a gorrilla it about takes a D-handle .With the set up it will eventually once the rings are seated be around 180 PSI
They usually start fairly easy but if you manage to flood it it either has to sit for 15 minutes or cleared out by pulling the spark plug .

 

[Al Smith]

Chainsaws are kind of like women .They are all sisters but they are not identical twins .How they start or run you have to figure out plus remember .

 

[sherlock349]

So I have checked the squish and it is 1.mm (40thou) I gave it a flush through with carb cleaner and it is marginally better but it will still be difficult if not impossible to pull start. I am now thinking there may be a problem with the crank

 

[Maintenance Chief]

So I have checked the squish and it is 1.mm (40thou) I gave it a flush through with carb cleaner and it is marginally better but it will still be difficult if not impossible to pull start. I am now thinking there may be a problem with the crank

Are the clutch springs broke? Maybe your trying to pull the chain around at the same time as the motor?

 

[sherlock349]

There is no clutch fitted. What I have done is run it for about 20 mins using a battery drill and a 13 mm socket on the flywheel nut. I kept it oiled with a very light oil. After washing out the oil it is definitely looser on the pull over now. I am probably running it at 300 - 400 revs and In cant see that it will do any damage. Going to do it some more tomorrow and see if it gets any better.

 

[sherlock349]

I had no spark plug fitted when doing this.

 

[Al Smith]

You have to watch rolling it over with a drill . I spun a nut loose on a 95 cc old as the hills gear drive once .That flywheel orbited my garage about three times and just missed my wifes Cadillac ,

 

[sherlock349]

The saga of this cylinder and piston continues. I purchased OEM parts new so I am a little puzzled by what is happening. After not being able to lower the compression I decided to change bottom ends. I had another 038 bottom end that is in good shape. I swapped the piston and cylinder and had exactly the same problem, too much compression and not able to pull motor over. The gasket I have been using is 0.5mm. I have now reverted everything back to the original bottom end but have fitted 4 x 0.5mm gaskets, I am now able to pull the motor over without too much trouble and I think it will start and run. I am thinking I will get some 2mm thick gasket material and make a new solid gasket and thats my best route to prevent any leaks rather than sticking with 4 separate gaskets. If anyone has any other thoughts or suggestions I would really like to hear them. Never had this problem in the past.
TIA

 

[Maintenance Chief]

I

The saga of this cylinder and piston continues. I purchased OEM parts new so I am a little puzzled by what is happening. After not being able to lower the compression I decided to change bottom ends. I had another 038 bottom end that is in good shape. I swapped the piston and cylinder and had exactly the same problem, too much compression and not able to pull motor over. The gasket I have been using is 0.5mm. I have now reverted everything back to the original bottom end but have fitted 4 x 0.5mm gaskets, I am now able to pull the motor over without too much trouble and I think it will start and run. I am thinking I will get some 2mm thick gasket material and make a new solid gasket and thats my best route to prevent any leaks rather than sticking with 4 separate gaskets. If anyone has any other thoughts or suggestions I would really like to hear them. Never had this problem in the past.
TIA

Made my own .080 gasket for a 288xp with an 066 piston because of clearance.
Thing is if you've got oem every thing ,compression shouldn't be too much?

 

[Al Smith]

Something is not right with this .My modified 038 mag has 180-185 PSI compression with 22 thou piston /head deck clearance .I've got a d-handle start .It pulls over fairly hard but always starts . If I recall the stock clearance with a 20 thou gasket is around 46 thou
You might look at the recoil because often the pulley gets worn to the point it runs excentric which will bind it up .
Now if something is wrong with the carb and you manage to flood it and cause a hydro lock it will be almost impossible to roll over .

 

[Al Smith]

I think the 038's might have had a metal starter pulley ,single or two pawl but some could have a single pawl plastic pulley .If I recall the metal had a brass bushing that should last forever .Plastic I don't recall if it had a bushing or not .If the pulley tilts on the axle very much that would pretty much tell the tale IMO .However saying all that all I can do is suggest a thing or two .I can't see that far from half way in the middle of the USA and 2500 miles across the great Atlantic ocean .

 

[sherlock349]

Something is not right with this .My modified 038 mag has 180-185 PSI compression with 22 thou piston /head deck clearance .I've got a d-handle start .It pulls over fairly hard but always starts . If I recall the stock clearance with a 20 thou gasket is around 46 thou
You might look at the recoil because often the pulley gets worn to the point it runs excentric which will bind it up .
Now if something is wrong with the carb and you manage to flood it and cause a hydro lock it will be almost impossible to roll over .

Good thought on the recoil, I will check it, no carb fitted at the moment just flywheel, coil, and pull start.. Thanks

 

[Al Smith]

A story from a few years ago .I landed a Husqvarna 2100CD from a forum from some island off Washington state ,cheap . I could not hardly pull that thing over but they pull hard anyway being 99 cc's and no compression relief .The starter drum on that thing had a nylon bushing that was worn out .I could not find another so I turned a brass bushing . It still pulled hard but at least I could roll it .That thing needs a kick starter .