Husky 365xt to 372 conversion advice

[Ollie_M]

So just stripping the saw down ready to remove cylinder to do the transfer covers and am thinking I’ll do a base gasket delete and a ring replacement whilst I’m in there so just after a bit of advice as first time doing it.

 

firstly, I’m looking at replacing the rings whilst I’m in there as can’t be bad idea to do them, comp is 150psi cold, piston is absolutely immaculate on exhaust side with machine marks still visible zero scratches whatsoever. No ‘special ‘ tools needed to replace the rings is there?

 

Secondly I measured the squish currently at .95mm and I understand it wants to be just above .51mm - assuming gasket thickness from factory is consistent am I looking at needing no gasket just a sealant (recommendations please) or will I need some sort of gasket?

 

lastly, saw has limited coil and I’ve tuned it so that it cleans up instantly when put on load and goes straight back to four stroking when unloading mid cut (as I understand to be correct) - however I’m about 1/16 if a turn off the upper adjustment limiter so thinking I’ll need to remove limiters as more fuel will be needed after mods? Is that correct?

many thanks in advance for advice given

 

[spudulike]

Squish...0.5mm is what you aim for and the base gasket delete should be OK without any extra work. I use Carplan Gastite instant gasket as it has a decent temperature ceiling but any decent liquid gasket will do the job.

Not sure I would bother with the ring if the end gap isn't too large.

On tuning the carb, I usually take the revs down and then lean the carb up until it just starts making the tach bounce off the limiter and leave it at that. It is unlikely you will ever cut anywhere near where the rev limiter cuts in so no issues in doing this and gives a bit of safety margin.

When you increase the flow of the engine, it naturally pulls in more fuel as the flow through the carb increases so I have found the carb actually needs leaning down a bit .....I guess you will do a muffler mod as well.

[Ollie_M]

13 minutes ago, spudulike said:

Squish...0.5mm is what you aim for and the base gasket delete should be OK without any extra work. I use Carplan Gastite instant gasket as it has a decent temperature ceiling but any decent liquid gasket will do the job.

Not sure I would bother with the ring if the end gap isn't too large.

On tuning the carb, I usually take the revs down and then lean the carb up until it just starts making the tach bounce off the limiter and leave it at that. It is unlikely you will ever cut anywhere near where the rev limiter cuts in so no issues in doing this and gives a bit of safety margin.

When you increase the flow of the engine, it naturally pulls in more fuel as the flow through the carb increases so I have found the carb actually needs leaning down a bit .....I guess you will do a muffler mod as well.

cheers for that, had cylinder off today, base gasket was .45mm so will be nice a comfortable squish gap - got some hylomar blue of a mate which should be good as doesnt set so can take my time.
 

i think max allowable ring gap is 1mm? didnt get the feeler gauges out but was very small gap when ring put it bore so should be ok, def was less than half a mm

yeah that makes sense, baffle already drilled out but crocky's dual exit is very tempting

 

when i removed the carb i found the rubber partition was folded and trapped under carb on left side (flywheel side), replacated by my finger.

this may have been something to do with why this saw was being outran by a 038 super... as was very obvious that there was less fuel mixture entering through the left side of the cylinder/ tranfer port with it being almost clean compared to the golden brown colour of the right hand side. pictures of the removed fins from transfer cover below as i forgot to photograph the bore.

 

Edited May 1 by Ollie_M

[Dan Maynard]

Spud did this to my 365xt, definitely worth doing as it woke the saw up considerably.

[spudulike]

Those inlet manifolds are tricky for the uninitiated but always took great care when refitting when I did them. On ring gaps I am old school, 7 thou is nice, 20 thou is getting worn.....20 thousands of an inch = 0.5mm.

More critical on single ring machines. 

You should get 175 - 190 psi with the gasket deleted.....on a cold engine. 

It is a nice little mod and as Dan said, a relatively easy productive mod - you don't always need to get the timing wheel out to make BIG gains.

[Ollie_M]

23 minutes ago, spudulike said:

Those inlet manifolds are tricky for the uninitiated but always took great care when refitting when I did them. On ring gaps I am old school, 7 thou is nice, 20 thou is getting worn.....20 thousands of an inch = 0.5mm.

More critical on single ring machines. 

You should get 175 - 190 psi with the gasket deleted.....on a cold engine. 

It is a nice little mod and as Dan said, a relatively easy productive mod - you don't always need to get the timing wheel out to make BIG gains.

Just checked ring gap - came in snug at .25mm so just under 10 thou 👌

looking forward to getting it back together - was the most powerful saw id ran when I got it and I was impressed then but not difficult after running a Stihl ms250 as a ‘big saw’

i bought the last 2 oem rings for ls engineers when I made an order, will keep them in the parts bin possibly for a pop up piston one day

[Dan Maynard]

Mine spends most of its life with 8 tooth sprocket and 18" bar, cuts really fast so use that for ringing stuff up. It does ok on 7 tooth sprocket and 28" bar for chogging but don't need that so often.

[Ollie_M]

185psi compression cold, she runs pretty strong

 

Edited May 6 by Ollie_M

[spudulike]

Nice job, glad it worked out well.