What's on your bench today?

[GardenKit]

Others may know better, but to my knowledge there is no tool for this.

 

What I have done on many engines, and it works for me, is to use a small cordless drill, with the chuck tightened onto the top of the valve. Smear the seat with a little fine paste and gently pull the drill upwards whilst rotating very slowly. Use a gentle 'pulsing' action i.e pressure on, pressure off.

 

Remember, the valves are machined, all you are doing is 'lapping' the valve to seal against the older seat. If the valve seat is damaged you need to replace the head.

[spudulike]

The 019 isn't running great on 60 psi Steve.... it's utterley gutless, you won't cut anything with it... unless very patient and using a technique similar to the bloke in that McDillen video.....

 

On completion I'm aiming for the 130 psi you suggested is needed for a saw engine to run properly.... not sure what these normally run at but it's some way off that at the moment!

 

Check the bore out to make sure the plating is in good order, sometimes saws ingest sawdust that wears the inlet side of the bore.

 

60psi really sounds like the saw has seized at some stage. The MS200Ts I have done run at between 145psi to 150psi on standard build up to 180psi on modified tuned build - low comp means low torque:thumbdown:

 

I would always thoroughly inspect anything running at lower than 140psi and expect wear.

 

Hopefully it is something simple!

 

What gauge are you using, some do read low - just depends on what sealing valve they have, the Gunson Hi gauge is what I use most of the time.

[AlvinD]

Hey all back again only this time it's with a husky 345 that I had bought years ago but never ran right and just sat in the garage. I've had a look inside the piston nowt really out of the ordinary there (to me anyway). I had lost the air filter so I chose to run it without to see if I could fiddle with the carb setting.

It idles no problem but whenever I hit the throttle it just won't go to full revs. There's no cutting out anywhere along the lines. It can be likened to a limiter in a car whenever I hit the full throttle, it's not reaching full revs. Halfway and then it sounds like its bouncing off a limiter. The exhaust is abit smokey almost tinge of grey/blue and I think some speckles of petrol coming out the carb.

[spudulike]

Hey all back again only this time it's with a husky 345 that I had bought years ago but never ran right and just sat in the garage. I've had a look inside the piston nowt really out of the ordinary there (to me anyway). I had lost the air filter so I chose to run it without to see if I could fiddle with the carb setting.

It idles no problem but whenever I hit the throttle it just won't go to full revs. There's no cutting out anywhere along the lines. It can be likened to a limiter in a car whenever I hit the full throttle, it's not reaching full revs. Halfway and then it sounds like its bouncing off a limiter. The exhaust is abit smokey almost tinge of grey/blue and I think some speckles of petrol coming out the carb.

 

Is the H screw set to one turn out? if not, set it to this and make sure the L screw is the same.

 

If this is as it should be then try pulling the pumping section of the carb apart and checking the internal gauze filter.

[AlvinD]

Hey spud L and H settings have been set to one turn out. Should I be looking at possible dirt in the gauze filter?

[AlvinD]

Rookie question. am i looking in the right area?

[AlvinD]

Cleaned whatever it was in those photos and lowered the L by a turn and abit, kept H at one screw out. With the L screwed in full the saw revs the tits off itself like it should. After putting L settin to previously said setting the saw does that limiting thing again. I cut up some hazel and the saw is lacking power maybe piston is just knakered? The saw is a 1998 model.

[WorcsWuss]

I'd throw away that metering diaphragm and get a new one, it looks a bit 'baggy', get a new gasket aswell.

Flip the carb over, take the screw out and replace the reed pump diaphragm and gasket as well....

 

Aerosol carb cleaner is essential for this job, an air compressor makes a big differece as well....

[GardenKit]

I,ve been trying to get my head round this one, so this is 'thinking outloud'

The L screw should only have a very marginal effect on the flat out speed. To have to lean it right out indicates that the mixture is much too rich, i.e too much fuel present (or too little air)

This does not tie in with failing to reach peak revs, that indicates too little fuel available, unless of course its 4 stroking. This would be too rich on the H screw, but I dont quite see how leaning out the L helps.

 

I think a carb overhaul is in order. Pay particular attention to the needle valve, it may not be seating.

 

This is of course assuming that compression and ignition are OK.

 

Others may disagree or indeed have more to add.

[spudulike]

I,ve been trying to get my head round this one, so this is 'thinking outloud'

The L screw should only have a very marginal effect on the flat out speed. To have to lean it right out indicates that the mixture is much too rich, i.e too much fuel present (or too little air)

This does not tie in with failing to reach peak revs, that indicates too little fuel available, unless of course its 4 stroking. This would be too rich on the H screw, but I dont quite see how leaning out the L helps.

 

I think a carb overhaul is in order. Pay particular attention to the needle valve, it may not be seating.

 

This is of course assuming that compression and ignition are OK.

 

Others may disagree or indeed have more to add.

 

 

Barrie, you are talking rolex again:lol:

 

Just joking - a bit strange this one as the saw may not reach high revs from being too lean or too rich as Gardenkit has just said.

 

The correct screw settings are one turn out on each - just for the record, the H screw is always the screw furthest from the cylinder - are you turning the correct one in and out???

 

The height of the metering arm - the bit that contacts the needle, should be level with the carb body where the diaphragm and spacer gasket contact. If it is out too much, the saw will run rich, if it is too low, the saw may not run or run badly.

 

The gauze filter is the one under the cast top cover that is held on with one big screw and usually bares the manufactures name.

 

You will need to remove the pumping membrane gasket and look for the round gauze that looks like the picture below (arrowed) and clear it of crap if there is any present. You have taken the diaphragm out and that meters the fuel.

 

If the needle is leaking, the saw will run rich and badly or not at all.

 

What colour is the plug??