550XP, seize issues

[GardenKit]

A very clear and concise post Johnny.

I apologies if my musings were in any way taken as a slur on your integrity.

Let us hope that Husqvarna can provide you with a satisfactory solution.

[Mark_Skyland]

Thanks for all the ideas much appreciated:thumbup1:

 

I think Jonny explained the fuel situation but I was going to mention before I saw his post is that he had a demo saw while we were waiting for the parts to come in from Sweden for a few weeks which was running the same fuel by the same lads with no issues.

 

I understand where the suggestions are coming from as quite often it is the fuel that causes these problems.

 

In regards to a few other questions, no blockage on cooling system, plug condition sorry cant remember, it was a brand new carb and ran well so dont think it was that and checked the exhaust and screen for blockages but all very clean.

 

All I can pin it down to is an ignition fault ie possibly advancing the timing too much but ive never had to check the ignition timing on a two stroke so if anyone wants to point me in the right direction....

[Jonny Burch]

No need for apologies, just wanted to add to the discussion. Plus I've been away for flippin' ages and fancied a chat!

[spudulike]

Thanks for all the ideas much appreciated:thumbup1:

 

I think Jonny explained the fuel situation but I was going to mention before I saw his post is that he had a demo saw while we were waiting for the parts to come in from Sweden for a few weeks which was running the same fuel by the same lads with no issues.

 

I understand where the suggestions are coming from as quite often it is the fuel that causes these problems.

 

In regards to a few other questions, no blockage on cooling system, plug condition sorry cant remember, it was a brand new carb and ran well so dont think it was that and checked the exhaust and screen for blockages but all very clean.

 

All I can pin it down to is an ignition fault ie possibly advancing the timing too much but ive never had to check the ignition timing on a two stroke so if anyone wants to point me in the right direction....

 

You did ask, firstly you need to find a suitable area where it is possible to mark one of the fin tips on the flywheel and see around and inch either side of the mark from the top side. You need to fabricate a plate that will fit above the flywheel and allow the flywheel to spin freely.

 

You then get a timing wheel, put a stop in the plug hole and rotate the timing wheel clockwise and anti clockwise so the readings are the same so you can get TDC. Once the readings are the same both clockwise and anticlockwise with "0" in the middle, the stop can be taken out, TDC set and a flywheel fin can be marked as well as a mark adjacent on the plate, you then move the flywheel clockwise in 5 degree increments marking the plate. do this for 35 degrees.

 

You can then stick a strobe on the sparkplug and see what the machine ignition is doing. These modern machines will generally have a big retardation at low starting revs, building to around 15-20 degrees at 3000-5000rpm, at around 10000rpm you will be at circa 27 degrees and this will then fall to 15-20 degrees flat out and peak revs.

 

Probably simpler to mark a flywheel fin you can see at TDC and then make sure the mark advances as you rev the machine and compare to another machine...........I have done the above to set the ignition on a machine I fitted a non standard coil to and had to take the flywheel key out to set the timing - I don't advise playing like this unless you really have to and know your onions!

[Mark_Skyland]

Thanks for the thorough explanation!

I didn't think it would be easy, so yes I think I will give it a miss unless there is absolutely nothing else it could be.

 

Although I'm hoping husky will sort something out I do want to know what the issue is though. After all, it is just a lump of metal and plastic.

[Sveriges]

I'm sure Husqvarna would be very interested to have a look especially with a failure on a new cylinder. The carb values would also be of interest

[njm]

Thanks for the thorough explanation!

I didn't think it would be easy, so yes I think I will give it a miss unless there is absolutely nothing else it could be.

 

Although I'm hoping husky will sort something out I do want to know what the issue is though. After all, it is just a lump of metal and plastic.

 

Husky 560xp and 550xp saws have a nasty habit of drawing from the chain oil tank , done a vac test on one the other week all looked good but it was burning chain oil when running hard , I think this could be your your carbon problem . guess what happens when they run out of chain oil ? Bang ,

Edited January 28, 2016 by njm
more info

[Stubby]

Husky 560xp and 550xp saws have a nasty habit of drawing from the chain oil tank , done a vac test on one the other week all looked good but it was burning chain oil when running hard , I think this could be your your carbon problem . guess what happens when they run out of chain oil ? Bang ,

 

In interesting . How does it get by and into the crank case ? and from the way you say it it sounds like a known fault .

[Sveriges]

Husky 560xp and 550xp saws have a nasty habit of drawing from the chain oil tank , done a vac test on one the other week all looked good but it was burning chain oil when running hard , I think this could be your your carbon problem . guess what happens when they run out of chain oil ? Bang ,

 

This isn't a common issue however I to have seen it before but only twice. On both occasions the operator has reported the saw not running clean, a slight misting of exhaust smoke. They should run clean when on good fuel and oil especially on aspen. The saw would also not perform to its maximum but this is also why the carb values are important as you can see how the saw has been running.

[Mark_Skyland]

Husky 560xp and 550xp saws have a nasty habit of drawing from the chain oil tank , done a vac test on one the other week all looked good but it was burning chain oil when running hard , I think this could be your your carbon problem . guess what happens when they run out of chain oil ? Bang ,

 

Interesting thanks.

 

When someone mentioned chain oil in the fuel I did think of a possible leak on the gasket(I know some off the earlier 560xp has this problem but have now been fixed) but dismissed it with good pressure test and clean running but I wonder if the aspen could be masking a smoky saw? Definitely something to check.