spudulike

Personally I work from the outside in, there are limitations on what can be done, there is a known SAFE maximum size a port can be widened - too wide and it can cause excessive wear or a snagged ring. You also have limitations caused by where the rings end and by the type and size of piston skirt. There are again known distances a piston MUST cover a port by and distance a ring end must be away from a cylinder opening including the upper transfers. The only work I do from the inside is re modeling the rear transfer and ensuring a smooth bevel on the inside of all modified ports - failure to do this will snag a ring pretty quick as some have found out:thumbdown: There are many ways of looking at this type of work, I get 80% of the gains with the work I do and don't spend all my life trying to get the further 20% with port timing changes, my porting ethic is to increase flow within the cylinder and to improve blowdown and scavanging plus a hike in compression and generally get between 20 & 25% faster cutting speed with the work I do. A recent MS200 came back to me with 190psi with the owner saying it hurt pulling it over - he had busted his wrist earlier though but still nice to see a modded saw having so much compression with a relaively simple mod. Standard MS200 of that age are generally 150psi and a real good one in standard trim - 170psi! Hope that gives you a little insight - don't think it is easy, don't just attack the ports with nothing but hope, look at how wide your piston skirt is, look at where the rings end on the piston and personally would start by widening the exhaust and inlet followed by a muffler mod and then tune the carb based on what the engine is now doing - VERY generally, this will be turning the H screw IN by between 1/8 and 1/4 turn - this is down to the extra venturi effect on the carb caused by the extra flow you have created. And they said it was easy:lol: Oh - and use diamond burrs forr the nikasil plating and HSS ones on large aluminium excavations - HSS or files are bad news on hardend plating! Good luck:thumbup:

Martin has a 372 nearing completion that he will want to part with, yours would make a few bucks on ebay or can repair the damage and use as a backup - that 395XP is a bit big compared to the 372:lol:

Ah... Think I am ahead on you as I have put together quite a few PCs and went through a period of severe overclocking and cooling on a rather hot desktop PC I used for gaming - got a bit obsessive....now where have I heard that before:001_rolleyes:

Online photo manipulator mate - thought you young uns know it all:thumbup:

Been porting a 371XP tonight, the top image is before, the lower - after. The exhaust port has been widened as has the inlet though less so. The lower transfers have been modified heavily and the rear transfer has been re-modeled to improve scavanging.

Well the black chicken looked pretty worried, not sure what more I can say Matty - sheer muppetry is probably the best way to describe that attempt! Do you want to borrow a proper saw horse:lol:

Well he is better than that Damien Hurst bloke but suspect your kids are getting bored on school holiday:001_rolleyes:

That doesn't sound too pleasant, hope the op works for you!

Yeah - bloodie groundies, can't they do something useful for a change:001_rolleyes::lol:

A "senile" member:lol: think you need a Parker Knowl chair, a stannah chair lift, zimmer, tartan slippers and matching rug and a liking for hanking baskets:lol: Try turning your predictive text off:thumbup: By the way, a few of us on here are senior despite the number of posts:blushing:....just call us grumpy old farts!

If a carb freely lets out fuel then it is the needle valve that is either being held open or simply leaking allowing fuel to flow in to the metering part of the carb and flood in to the carb throat through the low speed injectors. If you mean the engine becomes flooded because it won't fire and pulling over the engine on full choke fills the thing with fuel then that is different. Assuming the latter if it has had a new carb on it - if it won't fire on say five pulls on full choke, have you tried holding the throttle fully open with the choke off and pulling the engine over - your problem may be that the fast idle mechanism that holds the throttle open isn't holding the throttle valve open as it should. A blocked exhaust/spark arrestor will cause problems and worth pulling the exhaust off for a closer look. It could be that the carb needs a better tune or that the engine is lacking compression enough to cause issues. The other thing I have found with these four mix engines is that the valve clearence needs to be set 100% otherwise it causes all sorts of issues and this is also worth a look at. I do specialise on two strokes and try to avoid the four mix engines - funny as I spent my youth on four stroke bikes and never had a two stroker:lol: Someone else may have greater experience on your long reach. Oh - it may have an auto decompressor mechanism that has jammed on... or off!

Muffler mod on a 371XP.....to be followed by porting and final tune. The saw should fly once done - tried and tested procedure now:thumbup:

Possible blocked high speed check valve or low speed injectors but could also be a leaking Welch plug!

The pullers work better on larger seals, I cut through the rubber part and then select the jaws with the largest lip that can be pushed in. I also crank up the screws to make them really tight on the seal. They can work really well or be a bit of a PITA on smaller seals!

It's gone the same way as your 084 Ben, glad you survived and no one was hurt - think you need a bit more than a tube of JB weld on that one:lol: Good luck in getting it repaired!

I recently warned a local guy off a four mix long reach, all is fine if they are running perfectly but IMO, the two stroke is so simple, no moving parts in the port timing so are generally very reliable and very simple to work on. Good luck with it:thumbdown:

Second on that, they are very helpful:thumbup:

Just haven't got round to doing the timed cuts, got the rim, the chain and bar but no time...story of my life:001_rolleyes: Good to see some of the US guys showing an interest in what we are up to:thumbup:

It sounds like your gauge is manufactured for car engines and not small bore kit. It should have a light sprung schrader valve in the end of the gauge - the Gunson one is very good! It is Muriatic acid and it is the old school name for Hydrochloric acid - this works fine and a strong alkalie will have the same effect!

Got a red cover off a Jonnie 2165 - any good?

Blimey, not this one again....if you are using Oregon power rim then just change the rim drive. If you are using OEM clutch drum then you may need to change the drum, rim and oiler! I have considered 3/8 but would need to do timed cuts to see how 3/8 performs!

Normal compression for one of these saws is 150 - 170psi, mine pulls 200psi but is lightly tuned:blushing: Wear gloves and eye protection when messing with acid:thumbup:

Personally I would get a can of carb cleaner, remove both top and bottom carb covers, blast a bit of carb cleaner on to both sides of the carb, remove the L & H screw, blast some cleaner down both holes and make sure you get a healthy stream out of the jets in the diaphragm section of the carb and also make sure you get a good spurt out of the high speed check valve and low speed injector holes when spraying the cleaner in to the respective H and L screw holes, reassemble and use L screw one turn out and H screw 1 & 1/2 turns out and see how that goes. Worth checking the impulse hole is clear by sticking some carb cleaner down it as well!

105psi????? This is too low to start - is this with 5-6 pulls until the needle doesn't rise any further and with the decomp out? Is this the EPA version with automatic decomp? A new ring is not a silver bullet, it won't make a difference if your existing ring is new. The "Scores" is this aluminium transfer or thin straight lines scored in to the plating - cleaning the bore up isn't too difficult, making sure the reason for the saw failing is repaired is usually more difficult!

Firstly - for God sake - do NOT remove that tab, it makes sure the rings don't snag in the inlet port, removing it will cause bad bad damage to the rings and bore:blushing: The openings of the rings can face forwards, backwards or both, on a saw of this age they generally run down both sides of the inlet port. The circlips can be a pig to get back in, I generally push them in with decent quality long nose pliers - someone did say to push the circlip in to a thin tube and then push it out in to the piston - not tried this one out. The lug, I think I would make a thicker lug and then pin it to the casing with steel pins and JB weld and then spray it - or just get a second hand cover:thumbup: