bmp01

Its a weird setup on these... the link is made to twist when you pull the trigger, the link is bent into a shape so that it acts as a cam which pushes on the carb lever. Twisting the link can take out play.... The wire link wears, the nylon block on the carburettor arm wears and the throttle rod can become dislodged from its location in the handle, then you only get half throttle movement. My favourite hate is the cover for the throttle trigger with its protruding piece of plastic that keeps the linkage located in the handle - it's often broken off during reassembled. Result is notchy, half throttle movement. There have been several threads on here about this, new cover fixes the problem until the next time its taken apart and subsequently broken.....

Chain will start to run dependant on engine speed (so not directly related to throttle position). Presumably you are comparing with the newer saw ? Are you saying there is more movement in throttle trigger before the saw responds (wear in the throttle linkage)? Or you need more engine speed before the chain moves (possible clutch issue) ? Either get agreement or wait until your brother is not watching then borrow the complete carb off his saw and try it on yours ! Taking known good parts and swapping them onto your saw is a sound way to diagnose issues. Complete clutch assy ought to be right up there to try as well. Hope that video makes an appearance soon, Feburary is looming...

I can't see any pictures, just minture no entry symbols ??? If all the parts look ok, could it be the inside of the drum is oil or grease coated ? Too much grease on the clutch bearing ? Oil pump leaking? How long have you been sharpening chains, have you got the raker depth correct (not too deep)? Picture of the saw chips ? (But this type of problem would cause the drum to over heat. ... and drum isn't blue (hot) so...)

Those 2 grooves are in the OD of each tooth. The chain is driven on the face of the tooth, you will see a singIe wear mark on each tooth face - or with extreme wear a slot cut through each tooth (cuts the tooth more or less in half).... One in the attached picture is worn but would still drive the chain.

Bog std Walbro or Zama carb I'd expect. Assuming you start the saw from cold there is unlikely to be much pressure in the fuel tank, you reply on the pump in the carb to deliver fuel to the metered side of the carb. This is controlled by the metering diaphragm in conjunction with the Needle Valve, ok call it a metering valve if you like. That's all pretty low pressure. With running (think vibration) and heat you often get a build up of pressure in the tank (depending on breather type). If the needle valve were a bit suspect it mght not seal adequately. Breather types - modern breathers are one way valves, allow air in, don't allow fuel vapour out and cause pressure build up in tank. Old breathers like 023 were a hose at the top of the tank with a grub screw (or pair of) in the pipe with a tiny drilling through - allow air flow in either direction. Not sure what version the 230 is. But anyway, fuel starvation is most likely, breather or otherwise.

As you say - an engine spluttering to a stop is likely to be fuel issue, after 5 mins tank vent strong possibility. When it stops, have you removed the tank filler cap and tried to restart it? You might even loosen the filter cap before then as it starts to cough and splutter, does it recover? The 5 minute time would vary dependent on amount of fuel in the tank. Does the 230 still have that vent pipe with 2 grub screws in it ? Easy fix if so. But it could also be the other way around, building up pressure in the tank, flooding the carb/engine if the needle valve in the carb isn't closing at pressure, less likely but possible. Let us know how you get on.

I'd be interested in the bar/chain and winch? Might take the lot if you don't want to split. Whats on offer? Have to got pictures or details ? New thread time? Thanks.

John - regarding compression test, in your previous thread you confirmed - the crude hang it from the starter cord test ....the saw dropped and nearly stopped at each compression stroke. Ok, its not precise but it confirmed compression isn't too bad. I think Spud was offering multiple choice type questions, but nevertheless you're one step further on. Got any pictures of the clutch drum?

Sounds like it or the sprocket is so completely trashed the chain is slipping over (or through) the teeth. Either way it doesnt sound like an engine problem.

Open fires win on appearance. Stoves win as a means of heating a room because they only need to draw the right amount of air for the fire to burn. Compare that to the open fire that has a chimney that is also open to the room. The point here - once the chimney is hot it can move (draw) huge amounts of air from the room and that air has to be replaced from somewhere, usually from outside. By opening the fire door (or not having the glass in the door) you are converting your stove to something like an open fire because you've allowed as much air up the chimney as it can suck through the big opening. Ceramic glass is used in stove doors. It's a special high temperature glass, available as cut to shape glass for common stoves but can also be cut to a template shape if need be. Quite expensive unfortunately. Edit - I used the term 'Mica glass' which was wrong, Mica sheets are a different thing. Looks very thin and weak compared to the stove glass.

It would be different for an engine that has 20 thou squish compared to a saw that has 40 thou of squish. Squish being the distance from top of piston to underside of chamber at TDC. You'd have to know what the squish was in ech case and then move the piston down a further equal amount on both set ups. Halfway down the stroke the squish gets less signifcant but its still there in the detail.

Ok, I want that to be the case (just wires, no electroncs). I like simples. I was looking for an explanation for why the strobe timing and the tacho went beserk when the saw started misfiring. ... which I now think was fueling induced not coil induced. Understanding the tacho is easy - its looking at the time between sparks to determine engine speed, if engine speed is changing dramaticlly due to musfire then the tacho can't follow it sensibly. But the strobe, if it flashes in response to a spark and the coil isn't limited type, then the spark and strobe should keep happening at the ssme point in the engine cycle. Maybe the strobe can't operate at high 2 stoke engine speeds, it's a plain and pretty old strobe I'm using. I'll pull the covers off it and hope to find just wires.

Nope, I'm screwed as soon as the flywheel is off as well. All my numbers will be wrong by the amount I move the flywheel on the crank. It wasn't very clever really, I wasn't thinking more than the one step when I did it, just wanted to know the existing timing. Piston stop, yep, much better than my approach, doesn't move about. Just so long as you're a decent distance away from TDC. Making a bespoke one is on my todo list for tomorrow. What do you kniw about strobes ? Must be some timing circuit inside them? Can't believe they flash as soon as the sensor detects the spark. ... nothing can be that quick, surely?

Thanks. Did you get to see part number as well ? No worries if not.

I should make it quite clear - the chain is OFF the saw for all this messing..... Bar and clutch cover on for stability and to shield the other moving parts. My 11 year old son was in charge of camera, that was scary enough for me.

Less good picture, engine being cranked with battery drill. You have to use the geometry of the flywheel to establish timing. Second picture is with the engine stationary as I interpretted it...

Idle speed, strobe above camera to minimise refection. You can see the 10 and 30 marks quite clearly 20 is right where the fin is.

Fek, I've jumped to the wrong conclusion then. In my defense its not black it's navy blue (compare to the ht lead in picture). Certainly not bright blue though, Google educated me on the shade of blue for a 'blue' coil. So remember I have a 3mm dowl pin in the flywheel where the original key used to be, I'm checking what I have; not starting from a complete unknown. Finding TDC, degree wheel fitted loosely to f/wheel, exhaust off, piston crown below top edge of exhaust port. Drill blank in the gap, rotate crank to cause contact - note angle on timing wheel. Rotate engine through BDC, cause contact in other direction - note angle. Hold crank still, rotate degree wheel to get equal angle before and after TDC. Repeat umpteen times to check, recheck blar, blar. I picked the top edge of the top lamination on the coil for the above. I just marked the flwheel with TDC, 5,10,15,20,25,30 DEGS BTDC. Degree wheel off, engine rebuilt, engine started, starter cover removed while running and strobed the result. Pictures on next post.

That looks like the right coil Spud. It's done all of its advancing between 0 and 3000 rpm, just 9 degrees, flat timing there after. Don't know why I saw 30 degrees difference between 1000rpm and 3000rpm. Also no limiter acording to the data.... I wonder if I've been caught out by shades of blue and the saw needing a retune now the airleak is fixed ??? Tomorrow... Googling SEM and AM44 also throws up a hit on acresinternet.com for the 394xp which they say uses the SEM AF44 coil. Date code on my coil is 2007 W47 (a bit late for a 394 part?) My 395 is an 2008 model - those 2 dates fit together quite nicely. htb - thanks for the offer, not sure if you'll be able to see the part number without removing the coil though . See picture, the part number info is below the coil laminates when fitted.

Thanks for the that Spud, next time you have one in then. .... Checked the coil and rechecked it's behaviour this morning. First thing, it's blue, so that's a limited coil. Part no on the coil 810 204 16 also has SEM and AM44. The Americans think it should be a black unlimited coil. L&S Engineering list part number as 503 63 98-01 Second thing, (with this coil) from idle (2800rpm) upwards it's fixed timing. Retarded at cranking speeds (think battery drill cranking, spark plug out, ~1000rpm) by 30 degs or there abouts. And yes the tach and timing light go beserk as it starts misfiring. ... Edit - I've had no luck identifying the coil 810 204 16 online, no idea what its from.

Love it ! Absolute classic ! ?? Yeah, wasnt really expecting exact degrees, it was more of a summary statement (coming back to timing question) having resolved in my mind the way forward. Up till you mentioned the piston stop thing I hadn't really seen how to change the timing by an accurate amount (or keep it the same). In my mind I'd lost all reference once the flywheel was off, so thanks for that. I think I'm shooting for around 24-26. As you say 19 is too low, I was a little disappointed when I measured that's what it was. 30 has me twitching a bit and well y'know, I'd like to think I've gained turbulence and flame speed with the combustion chamber I have (wide squish band, 0.50mm clearance). But I will, without a doubt, be listening for those 'don't fxxk with me' noises. Too much time into this saw to nuke it.

Chap said JB Weld flexible gasket. Looks like JB Weld are putting their name to a few other products these days, flexible gasket should be ok providing its compatible with fuel.

Thanks for the detailed reply Spud. I don't think there is much chance of a comparison with a standard 395...I've only ever seen one, that 'one' came home with me ? ? It's a thought though - comparing to std. I think I only need a standard flywheel - if the comparison is done statically I can get my saw locked up against an accurate piston stop swap in a standard flywheel, marking position, swap to my flywheel on and see how it lines up. Don't even need to torque the standard flywheel up. But let's say I'm happy with what I know about the timing as it is, let's say it's 19 degs BTDC. If I do a similar thing, accurate piston stop and mark the relative position of flywheel to housing before disturbing the taper. Then even after I've disturbed tbe flywheel I can get the piston stopped in the same place and I can rotate the flywheel to align the marks. Even better, I can also retime it (say) 5 degrees by moving it 5 mm (such a happy conversion). Soooo, back to the timing question......

With the coil I have on the saw it's fixed timing at idle and above. No idea if it's the original coil, saw was secondhand when i got it, I should go and check part number on coil though - I'll do that... Testing was done the same as the video, find tdc, mark flywheel and casing. I then marked 10, 20, 30 degrees of advance on the flywheel so I could read advance directly. Removing flywheel cover while engine was running was surprising easy, but you need to be precise and deliberate with removal. ...

Yes, cast in key. It left a witness in the flywheel taper after it departed. I used a ball nose cutter in a Dremel to very carefully add a round groove into the flywheel. A 3mm pin is then used as the alignment feature. Accuracy was in the order of 0.25mm (magnifier deployed etc) but even then it's at a very small radius so that could be several degrees. I've also lapped the flywheel onto the shaft for maximum torque capability (spoken about quite a lot on the American site's and copied from 2 stroke racing bike engines), should be better than the original engagement. Not blowing the engine up with too much advance is at the forefront of my thinking but equally running retarded from optimum will leave a lot of heat in the exhaust gases (and presumably piston, cylinder )...