Stihl MS260 Over-Fueling??

[hawthornheavyhorses]

Ok, so took the carb off again and took it home this evening with a view to changing the inlet needle. Looking at it, it does not appear to be moving very smoothly.

 

The carb kit I bought was an aftermarket one that advertised that it was suitable for all WT carbs, and unfortunately the inlet needle on mine is about half the size of the one supplied in the kit, so looks like I might have bought the wrong kit.

 

My carb has WTE 503 stamped on it, does anyone know which kit I should have bought?

 

Also on closer inspection the "nipple" on the metering diaphragm seems to be bigger, which could explain the over fueling, however the gasket seems slightly thicker, so could be compensating. The symptoms before/after fitting the new diaphragm were the same, so might not have made any difference.

 

Bit confused now! Spud, do you have carb kits for these? Will put it back in tomorrow but if it doesn't work it might be best to run it over to you after Christmas!

[felixthelogchopper]

Sorry to derail, but is that the same Dave Harris who works for Essex Wildlife Trust?

 

Alec

 

Yes mate

[GardenKit]

Ok, so took the carb off again and took it home this evening with a view to changing the inlet needle. Looking at it, it does not appear to be moving very smoothly.

 

The carb kit I bought was an aftermarket one that advertised that it was suitable for all WT carbs, and unfortunately the inlet needle on mine is about half the size of the one supplied in the kit, so looks like I might have bought the wrong kit.

 

My carb has WTE 503 stamped on it, does anyone know which kit I should have bought?

 

Also on closer inspection the "nipple" on the metering diaphragm seems to be bigger, which could explain the over fueling, however the gasket seems slightly thicker, so could be compensating. The symptoms before/after fitting the new diaphragm were the same, so might not have made any difference.

 

Bit confused now! Spud, do you have carb kits for these? Will put it back in tomorrow but if it doesn't work it might be best to run it over to you after Christmas!

The WTE is different to the normal WT. We are all so used to WT that we immediately think K20-WAT kits, which is what your supplier did. You need a K10-WTE kit.

hope this helps

[hawthornheavyhorses]

Thanks Garden Kit. Anyone know where I can source a K10 WTE kit? A google search only gives me US sellers.

[spudulike]

Garden Kit is spot on - all info can be found on Walbros site in the service section - http://wem.walbro.com/distributors/ServiceManuals/CarburetorGuide.PDF

 

Lots of good info in their other documents.

 

Sounds a little like an own goal with incorrect parts used - spares can be found on ebay or just search google - if time isnt an issue then I often pull them in from the States as they can be more cost effective.

 

Done a bit of a search and common carbs used are - WT-581/403/590/427 but strangely yours isn't listed but wouldn't worry about that.

 

The incorrect needle and diaphragm nipple being too large will all effect the metering of fuel

 

I would hope that once the correct kit is used, the carb will meter correctly and work fine - just make sure the limit caps are pulled off if fitted and would initially set the screws at 1 1/4 turn each, get a decent level idle speed (usually at around 1 turn out) and tweaking the idle speed accordingly, finish with the H screw. Don't turn the H screw in further than 3/4 turns - it will damage your saw, go for a very slightly flubby top end but one that revs up to about the right sound. If you take a deep cut and kill the engine, the plug electrode areas should be the colour of coffee - white is bad, grey is possibly overheating, black is rich!

 

Using a tach is the best method!

[GardenKit]

Thanks Garden Kit. Anyone know where I can source a K10 WTE kit? A google search only gives me US sellers.

I dont keep one but my supplier does. Problem is I close for christmas today, so am not going to be able get one until the new year. If you want me to get you one pm me with your details.

Have a happy christmas.

Barrie

[hawthornheavyhorses]

Hi Both,

 

Thanks for this, am a bit annoyed as I told the supplier the carb number and they said it would fit! Won't be using them again!

 

The Walbro site info is very useful, they list a WTE-5 for an MS260 which must be the closest, and as you say a K10 WTE kit.

 

I'll PM you Barrie, and we'll go from there. Cheers,

 

Matt

[hawthornheavyhorses]

Hi Barrie,

 

Carb kit arrived this morning! What service!

 

Many thanks for all your help, will let you know how it goes, fingers crossed!

 

Matt

[hawthornheavyhorses]

It lives!

 

Put the carb back in this evening and it started on the second pull!

 

However needs a serious tune up! Still seems to be running a bit rich but am a bit concerned about playing with the H screw too much.

 

I'd like to get a Tacho to do it properly,can anyone recommend a budget tacho that would do the job? I don't anticipate tuning 100's of saws, just checking my saws every so often, so just needs to be basic.

 

Also if I take the limit cap off the H, will I need to put i back in? Has it got a spring like the L screw to stop it from moving?

 

Cheers all.

[GardenKit]

Hi Matt,

Glad you got it going.

I use the Stihl tacho, but as I am home I cannot look up the price, if I go to the unit over the holiday I will look it up and PM you.

 

In the meantime I suggest initially leaving the H cap on. Set it in the mid range, you should be able to increase speed by weakening the mix (in) and slow it (out). hopefully you will be able to detect the speed by ear. You need to be able to to turn it out until the engine starts to 'fourstroke' (the note changes from a smooth sound to a very slight missfire as the revs drop.

 

Then do the stall as suggested by Spud earlier. If you cannot get it to sing, rather than fourstroke, then you are beyond the limits of the screw. You may be overfueling because the needle arm is a little high. I only say this because many people try to 'tune out' issues that should be fixed first. A saw in good order should run within the limit caps range

Good luck