spudulike

It most probably will have a splined round H & L screws - you can sometimes use the plastic end of a crimp connector to move the screw and I have taken them out before and slotted them. Most carbs are set to one turn out each, there are exceptions but this setting generally gets the saw going well enough to adjust the L screw first and then set maximum revs with the H screw.

Thoughts - yeah, buy a two stroke:thumbup: These sort of projects can take days of work and still not work so don't go too mad, it may well be not worth it!

Once had a MS880 in with the H screw set to 1/2 turn, needles to say, the piston had expired!

Look at the amount of moving parts in a four stroke engine compared to a two stroke - all the timing on a two stroke is done by a solid cast aluminium cylinder - the only thing that moves is the piston and bottom end. Compared to the 4T engine, you have valves, tappets, cam followers, cam, timing chain, timing chain tensioners, advance and retard mechanism, gears, valve springs, collets etc etc. Now tell me that this is an improvement over a simple cast cylinder with no moving parts:confused1: I worked on Wolfies KM100s, got it working fine, a week later, it was back - I had to kep adjusting the tappets and we gave up in the end as the next thing was to start stripping the engine -under 30 mins on a two stroke, much longer and more complex on the four stroke:thumbdown:

The piston looks OK, the valve seat may be able to be ground in, look for a nice grey seat around the full circumference when done - do the other and compare. If it isn't good, you will lose compression and burn the valve out in time - if you have time, try it. I admit to hating these Stihl 4T engines and not having had many on my bench, two strokes are far simpler and have never seen valve issues with them:sneaky2:

Sounds like fuel restriction - under load , the saw needs more fuel and lack of it is stopping the engine making full power. Before diving in to the carb, it is worth removing the muffler and looking at the piston through the exhaust port. If there are any vertical scores (not small scuffs) then you have real problems. If the piston is wet and grey silver with no marks, then you need to remove the carb and it is worth removing the cover tht is held on with one screw - there is a wire gauze strainer in there the diameter of a pencil and it is common to get fine wood chip catchng in there. Other than that, you may have a holed fuel line - it is possible to remove both ends plug one end and then suck and stick your tongue over one end to see if it holds vacuum, I prefer a pressure gauge:thumbup: It may be worth opening the H screw up 1/4 turn (anticlockwise) but be careful as if you turn it too far clockwise, you may melt/seize the piston!

If you rev the saw flat out with the bar pointed at a log etc, you should see a line appear within a second or two. The oil tank shouldn't empty before the fuel tank if both are full before you start - as Steve said!

I also believe that in a fight, a grizzly bear will see off a wolf:thumbup:

I think we can conclude that the MS261 is like Marmite - perhaps that is what we should call it from now Marmite261:lol:

The saw not idling - try making the coil to flywheel gap smaller, had twom"non runners"that leaped in to life after a quick tweak:thumbup:

I have never seen or heard of a tuning kit for the MS200, you can buy aftermarket big bore kits and dual prt mufflers for the big stihls but nothing for the MS200. The muffler mod is the simplest mod but I do far more than that inside my engines and have developed my techniques over the last few years to make the saws stronger in the cut! It is all about compromise, time and skill - if you have 10 minutes, a big hole is a simple mod and I also always pressure and vac test engines as many saws that owners have sent in have had leaking crank seals so have repaired before returning the saw. The porting will generally protect the saw as it will run a little richer and faster but tuning is not just about quick easy mods - the base machine has to be sound before tuning is done. The MS150 and MS201 ARE saws that a hole in the muffler is a decent easy option, the MS200 has further gains that can be made!

The one thing that is baffling in all this is the dry plug you mention because the rest sounds like a leaking carb needle valve which will make the engine not run well if at all and will flood the engine at standstill. A new full carb kit would be good but it is worth checking the carb metering arm height and make sure the spring under it is correctly in place. I would normally pressure check the carb but lacking that equipment you may struggle. If the engine is suspected to flood, pull the plug, turn the engine so the plug hole is downwards, turn the ignition off and pull it over fast a few times. My money is on fuel - worth checking the fuel filter and line and if it plays up again, see if loosening the fuel cap helps. Also make sure the compression is good, if you have a bright small LED torch, shine it down the plug hole and try to look at the exhaust port side of the cylinder wall to inspect for scores. All these engines are similar and operate on the same principles.

It is always easier to start rich and work down than to start lean and seize the engine although that probably won't happen!

You can only see the damage if a needle is missing. You generally feel too much play on the clutch drum and change the bearing when it happens.

Glad you are enjoying it Patrick, I dd warn you it will be a bit of an animal:thumbup:

I recently had two on and one had no rollers in its clutch bearing, never seen one that bad before! I was being factual and pointing out what I had seen rather than slagging the saw off!

Looks like you will have to work it out the hard way then:001_rolleyes: Lots of general info on this site and Arboristsite.com - all you need to do is put it all together in to something that works and doesn't kill the saw:thumbdown: Reliability is sometimes last in someone's mind when porting where it should be in the forefront!

The issue is with the fibre glass in the clutch needle roller bearing breaking down, making the clutch drum loose which then wears through the oiler arm. I don't know what the ultimate route cause is but would try to find a steel caged needle roller bearing of the same size which I believe will last longer especially if it is lubricated regularly. If the clutch drum is still loose with a new bearing, the drum may need replacement as well.

Compression is a funny old thing - we are talking secondary compression and not primary (crankcase) compression! I have had a few engines that have made good compression (150psi+) and severely lacked power, on inspection I have generally found worn piston skirts causing the problem. I have had other low compression saws I have tried to up the compression on by dumping the base gasket and had a good increase in compression but still low on power output. The summary to all this is that if your saw is down on compression and/or power then a "quick bodge" isn't possible on a worn piston. The piston needs more than a decent ring to give good power and the skirts being a good fit do more than stop piston slap and aid low down torque and ultimate power!

Probably worth pulling the carb, checking the impulse line, the fuel line and filter then checking the pumping section of the carb for the "shyte in the gauze strainer" issue and then take the H&L screws out, bit of carb cleaner down them and set at 1&1 turns out then check the diaphragm and metering arm height. I usually pressure check carbs to ensure the needle is sealing but in absence of this, put it all back together and try - 40 mins work and should get it singing:thumbup:

You are checking the crank seals, inlet manifold if rubber, impulse line if rubber and all gasket joints - usually cylinder to crank and the crankcase vertical joint....and decomp valve if fitted. You do this by sealing the inlet and exhaust port, sealing the impulse if separate and then attaching a holed spark plug hole adaptor so a pressure/vacuum gauge and pump can be connected - this can be a purpose manufactured bit of kit or home grown like mine - the pressure you need is 10psi and the vacuum is -15 inches of Mercury.this There is no real alternative to doing this correctly - it is best to get zero leakage on the engine even when rotating the crank slowly. A water and detergent mix can be painted over suspect leaking parts to see if it bubbles. I would have thought that the airvane would have stopped the saw over revving but may need checking again. Seals tend to last for 5-10 years + but you may have an issue somewhere.

Yes but it sounds like you are using fluid under pressure rather than air under pressure and then vacuum. Different leaks behave differently under vacuum and pressure. Holding on to revs is a classic sign of a seal leaking under vacuum FYI. You should check that the throttle valve is fully closing and the closing spring is still working well, also make sure the throttle linkage is free moving and loose when the throttle is closed. Also try manually shutting the throttle valve with your fingers to see if the engine revs drop if you push it closed. I am not familiar with the 090 but doesn't it have a aerovane rev limiter on it - the Contra I worked on recently did! the plug going white will be down to a lean mix and over-revving!

From what I have seen in my workshop, some of the sharpening is laughable - mostly on home owner saws though. Everyone knows you get the best edge with a grinder:lol: ...that's for Treequip to comment on - got to keep the old boy busy:001_rolleyes: The angle of the cutters usually become more acute and pointed as it is easy to file the edge rather than the hook! A favourite of mine is a sharp chain and the raker depth gauges being to high so the chain polishes the wood! If you are getting good chip out of the saw, all is good, personally I do it by eye and use a Stihl depth gauge for the rakers. The grinder comes out for the mullered chains where filing would take forever...even with a new file and good technique! The cutters can always be lightly dressed after with a file as required! People also forget that the bar is a supporting element to the chain, too much roll in the rails and it will allow only one set of cutters to work or even none of them in bad cases. I have seen many with one rail 0.5 - 1.0mm below the other:thumbdown:

Just purchased one for general cleaning, drilling and porting where space isn't a constraint - already got a Silverline dremmel type rotary tool with the flexible drive so should be useful - £25 is nothing and if it lasts a year or two, it will have paid for itself many times over!

I tend to buy any thin jaw pullers I can lay my hands on, the few quid they cost is pulled back damn fast when pulling a flywheel takes minutes instead of hours. It is worth looking on the bay for Sykes or any other older manufactured kit that was produced when kit was made to last. One tip is to not just keep turning the screw but to get torsion in it and belt the end with a hammer - the jolt frees things up generally last time I fell ass over tit when doing a 395 as it seperated and went from lifting the weight of the saw to just the flywheel:blushing: