bmp01

Yes please, could do with a few spare parts off that. ...

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And how do you imagine you'd deal with a service shop repair where the replacement piston comes from a batch that was significantly different to the original batch ?

Or how would you get over saws running on pi55 poor fuel (low octane) when all the saws come pre-tuned from the factory ?

Plus a million other exceptions to the saw being run in its correct operating window. 

The thing is the manufacturers have been at it for a little while,  they've done a few iterations by now and they know where they are in terms of tolerances,  performance vs risk etc. They've forgotten more than you or I imagine we know. 

And no doubt they'll  continue to hone the product with each new iteration for the end user to marvel at, not forgetting they are in the game of competing to sell better kit at each model change and at an economic price.

1 hour ago, Iwanp said:

Have you tried the sgs saw? Perhaps its the quality of the chain also, I clean it out everytime and sharpen the chain.

I need a lighter saw for logging tbh. 

No I haven't. 

Got the little top handle one though,  came secondhand broken and for cheap. Came with the original 4 chains. ... no doubt that means the chains are poor quality. If i was going to use it regularly I'd get a decent chain for it.  As it is, its good for giggles every once in a while - opposite end of the weight scale.

Its as cheap as chips but it cuts ok for the cc's. 

51 minutes ago, TuscanPhil said:

Might be a silly question but how sharp is your chain?  How are the rakers?  When did you last put a new chain on it?

My thoughts exactly.  Saws don't start struggling,  if it was ok to start then either the woods got bigger/harder or saw maintenance is lagging whats required. No 1 on the list will be "how sharps the chain ? ".

Pro saw will be lovely new and a good chain will last better than cheap one but you've still got to maintain it and sharpen chain,  might as well learn on the saw you have. 

Nice example there wyk, and that's a 65 cc saw. Presumably that was enough pulls for pressure to  reach a maximum. Where's the valve on the Procto, which end of hose ?

200t is half the capacity (near enough), gonna have bigger effect.

31 minutes ago, Paddy1000111 said:

....... I do wonder if the small stroke doesn't help with these bigger testers though.

You've hit the nail on the head there. 

Plus where the one way valve is in the tester - if your wee chainsaw engine has to pressurise a length of hose before the valve then you get the wrong answer. 

7 hours ago, Paddy1000111 said:

Well, I went to the stealership today. I'm going to stop calling them that now because they were very helpful and had a tech tune it with an EDT for free. It was all me being useless... I had the LA set too low and subsequently the idle set too low so the saw didn't have enough air on idle meaning that although the screws were in factory position it wasn't getting enough air hence it was flooding, giving the change in rpm when it was at an angle. The guy upped the LA and idle speed to where it should be and set the L jet then set the H screw which was too rich because I'm a wimp and didn't want to run it too lean. It now also doesn't bog when cold and starts faster too. 

 

He did say that the saw vibrated more than he liked on the handle which reminded me that the only non-genuine part on the whole saw was the AV rubbers as there weren't any in stock when I was re-assembling. I have now ordered some genuine ones. 

 

Hopefully this helps anyone with similar problems to me and stumbles across this thread! 

 

Glad it was as simple as that and you got it sorted.  Good result. 

Please do revisit your compression tester on a few other saws - for your own reference. 

If you have a question mark about the compression tester,  try it on some other good saws just to get a feel for where the 200T is in comparison.

150psi isn't outstanding, 200T's aren't high from factory either. I was trying to say if fueling is a bit wayward then high compression helps - in the context of fuel preparation. Plus it's a ball ache to pull it apart again to delete base gasket (did you check squish clearance when you reassembled ?)

Presumably your new carb is the latest and greatest version of original, Spud or someone with part number experience will know.

With the other running issues, ie different engine speeds depending on saw orientation I'd be looking at the metering arm setting in the carb, that can throw up some weird behaviour if it's a bit low. (I'm assuming you've checked there is some play in the throttle linkage and the engine mounts aren't shot etc).

Used to be known as fuel preparation (or lack there of). For decent combustion in a petrol engine the fuel needs to be spread evenly through out the fuel/air mixture in near vaporised form. Carburettors do an approximate job at best - you rely on a bit of the fuel preparation to happen as the gas is drawn into the cylinder, the turbulence and heat help vaporise the fuel.  If you think about the low speed or idle circuit in the carb the fuel is drawn through deliberately tiny jets into a turbulent flow of air as the air comes past the butterfly valve. As soon as you open the throttle the fuel comes from the bigger main jet into a  less turbulent air flow. I suspect without the engine temperature to help atomise the fuel, preparation is poor enough that combustion struggles.

150 psi isn't that high either,  higher compression is more tolerant of poor mixtures. Compression might go up a tad as the engine beds in.

If it's only from a cold start (ie doesn't happen after a hot start) I'd say that's what it is. Alternatively could be something to do with the dreaded accelerator jet but on a brand new carb should be OK. Does the new carb have exactly the same part number as the old ?

Lastly,  if your on old fuel you might have lost some of the more volatile elements of the fuel - just the feature of the fuel you need under cold conditions.

HTH.

Edit - big fat spark helps with poor combustion issues too.

9 hours ago, ChainsawAl said:

This forum is dead. Does anyone know a forum where people are actually active?

.... don't know the answer to your questions, didn't see much point commenting.... 

Think you're going to be very lucky if you find someone who has experience with that saw,  doubly lucky if said person knows answer to your question. Homework time ... 

Did you clean out the ring grooves with solvent or just check rings moved in grooves ? 

The fact that the saw ran at all tells us there wasn't a mega amount of friction. If it idles on std carb settings (ie carb idle speed screw not wound in), that says the small amount of combustion energy is enough to overcome the normal engine friction at idle. Any extra friction in the engine is most notable at idle where the combustion energy is tiny.

Does it pull over noticably easier now ?

Err ...chain pitch. ... 

Just because life is what it is and not simple or straight forward there are several pitches of chain. The common ones: 3/8 Low profile, 0.325 and 3/8 std. There are others: 1/4 and 0.404  The pitch is the distance between rivets, measured in inches.

 So you originally had 3/8" (probably low profile) and you've bought 0.325" bar and chain. The drive socket, bar sprocket (if there is one) and the chain all need to be the same pitch. 

Typically, one would buy the approprite bar and chain to suit the drive sprocket and save the hassle of swapping sprockets. 

Also worth considering,  a 0.325 chain will be bigger than a 3/8 low profile chain - taller, wider cutting teeth which require more torque and power from the engine. The length of bar is a consideration too but if you are milling you will not be using the full length of the bar so maybe ok in a hobby milling type application. ..but don't expect rapid progress.

2 hours ago, Dinosaw said:

How does that work? Those bottom nuts must raise the motor unit by 4mm or so and the same amount for the clutch and flywheel. Can't see that at all.

2 hours ago, spudulike said:

I think he is just using the bolts to hold the engine together whilst the liquid gasket dries thus holding the engine together when fitting in to the plastic cradle. You couldn't leave the nuts on the bottom unless you modify the cradle and reckon it would significantly reduce the strength!

Dinosaw - you're quite right that wouldn't work. Material removed from the housing and from the engine pan to get crank back on centreline.

Spud - that's how it goes into housing. The plastic bosses for the bolts are a good deal thicker than surrounding plastic. So far so good, done something like a dozen tanks of fuel clearing up a fallen oak. Engine has had a bit of work, could do with a tad more compression (i got that wrong, 24 thou squish) but its not bad for what it is.

3 hours ago, Dinosaw said:

That's what I do and then leave it for 24hours for the sealing material to go off. Pity they don't bolt up before you fit them though. Put manifold back on today, will let you know what happens when I've finished.

Ah-ha, my pictures weren't  clear then !

What you see in those pictures goes straight into the housing as is - compete with fasteners. Further set of nuts to clamp the engine into the housing rather than the std bolts. This was a solution I put together after those long bolts came undone in use - big air leak. 

Brake band is number 10 and lever to operate it no 11. Brake band would squeeze the clutch drum 12 to stop the drum spinning.

I know exactly the noise you're talking about when you refer to a skate board wheel, noise from my youth. Can't help but feel that would get downed out by the engine. Even the blades make a racket.

You could take the blades off and run it again - see if you learn something....

1 hour ago, B-rad said:

The crank seems fine yes and not exactly when the engine is at idle there is no noise but when I rev and the bearing starting spinning to move the blades I can hear the bearing spinning which is concerning as im starting to think it’s a dodgy/ damaged bearing or maybe it just needs to wear in? 

Sorry,  think I had my head up my backside back there. Clutch bearing is in the housing 1 below the clutch drum,  item 3 in picture below ?

Ball race bearings usually pretty quiet from new usually get louder with age but hardly, not much being in. I struggle to believe you'd hear a bearing above the engine. It's more likely to be gear whine ... 

If the old bearing was totally knackered, clutch won't have been running true, might have implications for the gear.

Or maybe the brake band rubbing on the outside of the drum ?

Assume the crank is still OK ?

The bearing is spinning at idle and up to point the clutch engages in drum. Once engine speed is high enough the bearing is stationary, is that consistent with the nose you hear ?

A word of warning,  don't run the engine above idle without the clutch drum fitted, otherwise theres nothing to stop the clutch weights from ever expanding. 

15 hours ago, Stubby said:

Does a 181 have one ?

For a short while,  yes. Then it becomes something else.  Just like all of them accelerator piston circuits. Aftermarket carbs although hit and miss on quality don't have this feature. 

15 hours ago, Dinosaw said:

Sorry Spud, not a trace of any old oil anywhere, not tight bits on crank, bearings excellent. Just started reassembling and forgot to put the manifold on. Idiot!

I'd like to see them put these engines into the housing in the factory. Seems to be a real puzzle wiggling it into place while the engine pan is sitting loosely on the upper clamshell. Prefer the older 170/180 in that respect - still a fiddle but at least the engine is assembled tight at that stage. 

Here's what I did to a 181.... makes life a lot easier but not exactly practical for a DIY. 

1 hour ago, spudulike said:

I would stick a new piston in it. I think you will be surprised with how well it will work. 

The damage under the port looks light and is much less likely to cause issues than the inlet side which would cause lots of blow back and leakage on crankcase primary compression.

If you haven't, lightly hone it with a rotary hone.....

It's had a real good chemical clean and a fair bit of abrasion to get to where it is now. Any other cylinder I've done would be as clean as a whistle by now.

Just rebuilding it with a new piston is an option, see if it survives,  then pull it apart for some tuning work. They come apart pretty quick.

On the other hand new OEM 385XP cylinders are available on eBay for reasonable money.  

Do both...

1 hour ago, Stubby said:

On that saw I would go OEM and fix the air leak as well !

That'll more than double the price of the saw. Husky cylinder& piston .....300 quid to you sir.

Should have resisted the temptation to rip it apart before leak checking. Ran fine cross cutting, short cuts though. Aftermarket 390 pistons (before Meteor brought one to the market) don't have a good rep, I'm gonna say it was that plus already knackered cylinder 

1 hour ago, AngrySquirrel said:

Failing that get it rebored and new piston/rings to match and Re nikasil'd

Friend had his 500cc single SuperMoto bike done

Feels like the right thing to do,  fixing the existing. Wonder if blind cylinders are within their experience band. ... 

1 hour ago, Toad said:

Before you get too far, check the crank isn't spinning inside the clutch side bearing. I thought I was onto an easy rebuild with my 385 before finding that. 

 

I have an aftermarket 390 cylinder of unknown origin that you would be welcome to if you want it, its probably a bit too crap though.. I was looking at getting a meteor piston and cylinder from the US until I had a very kind offer of a NOS one from a member on here.

Hi Toad,

I will check bearing spinning issue, good shout. I've been to see your thread on the subject, I'll check year of manufacture too. And thanks for kind offer of cylinder, looking for known brand I think. 

Don't know the history of this one but it looks like it has some previous. Bought the saw secondhand and I seized it (probably for the second time in its life) whilst doing a 12 inch milling cut after 2'ish metres. Bottom end is rock solid.  Top end less so, aftermarket piston was in there and its now trashed. Couple of piccys attached showing the cylinder condition after chemical and mechanical cleaning. White paper disk at the top of the bore - hopefully better picture. As well as the obvious scoring/discolouration in the bore, can you see the plating has been removed along bottom edge of the exhaust port ? One picture is taken looking down the inlet port just catching this detail. I'm guessing this plating removal was part of the previous clean up when the aftermarket piston was fitted. Just for good measure top cooling fin is busted too, which fits in with the plastics damage.

Saws not had an easy life,  but being what it is I think it's worth saving. Cylinder is a lost cause, certainly not a good place to start if I'm going to spend time porting etc. Replacement options; genuine (too expensive),  secondhand (like rocking horse poo), aftermarket (most likely) meteor, hyway. I've tried our Greek friend, he doesn't stock either. Plenty of Meteor in USA  on ebay but not here. Any one have experience with 390 cylinders? Other suggestions?  

9 hours ago, Dinosaw said:

How do you lot get the sealant off the clamshell joint? And thanks for all the input!

Nothing scientific, just scratchy tools. Flat surfaces - I use knife blade something line a Stanley blade,  the fake o ring groove - small screwdriver followed by drill bit (blunt end) with end ground square, groove doesn't need to be perfect. It's a PITA and a consumer of time.... Not found anything to dissolve the cack which I suppose can be seen as a good thing in service.

I like Stubby's suggestion, when it's back together. Similarly, taking the bar and chain off might help to locate the problem.