• 4 Stroke Husqvarna Motorcycles Made In Italy - About 1989 to 2014
     TE = 4st Enduro & TC = 4st Cross

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'12 310 ring end gap spec?

R

R_Little

Husqvarna
Pro Class
I only have the manual for my 2010 TE250.

I'm reassembling a 310 motor and just checked the ring end gap.

Top Ring .015"
Middle ring .026"

My 250 manual says:

Ring A .018
Ring B .033

I suppose the bigger 310 has a higher spec.
Is it normal to have two different specs for each of the compression rings or is ring "B" the oil scraper? I come from a 2 stroke world.

Anyone have the spec?

Also, any one have the headspace spec for the 3 different sizes of head gaskets.....5mm .6mm and 7.mm?

Thanks!
 
Usually .002-.003" of ring end gap per inch of bore as a rule of thumb.
Attached is a 2013 manual to compair Screenshot_2016-05-20-19-16-02.png
 
I found the manual for 2012. it is the same spec as the 250. Go figure.

Still don't know why top ring is supposed to be tighter than the middle ring.
 
Top ring is the "compression ring"
Second ring is the "scraper" ring. It is designed to "wipe" the oil off the cylinder so it doesnt need to be as tight. While you may get better compression with it tighter, you would increase friction exponentially as you decrease the ring end gap.
 
Matthew525 said:
Top ring is the "compression ring"
Second ring is the "scraper" ring. It is designed to "wipe" the oil off the cylinder so it doesnt need to be as tight. While you may get better compression with it tighter, you would increase friction exponentially as you decrease the ring end gap.
Click to expand...

There are 3 rings on the piston...two compression rings and one oil scraper.

Middle one has more end gap than the top.....designed that way. I don't know why.
 
The middle ring is not just a compression ring. It is the "scraper ring" the bottom ring is the "oiling ring"

The oiling ring oils the cylinder, the scraper ring "un-oils" the cylinder.

sometimes the middle ring is called a "second compression ring" but it is still the "scraper ring"

Again,
goes back to friction and the happy meduim between good sealing and low friction.

11.png
 
okay!

Gotcha.

Explains the lighter tension.

I would think the bigger bore 310 would have a larger end gap spec but the manual shows the same for both.
 
The differences in bore on a red head 310 vs 250 are 3mm. 79mm for the 250, 82mm for the 310.

At .002-.003" of end gap per inch of bore that would make the difference .0003" in ring end gap between the 79mm and 81mm bores.
So according to the rule of thumb they should be 3 ten thousands difference, this is less than your measurment error and is negledgeable, if you could be that accurate, i would buy you many beers.

Hence why there is only one spec for the 310 and 250 in the 2013 manual.
 
Matthew525 said:
The differences in bore on a red head 310 vs 250 are 3mm. 79mm for the 250, 82mm for the 310.

At .002-.003" of end gap per inch of bore that would make the difference .0003" in ring end gap between the 79mm and 81mm bores.
So according to the rule of thumb they should be 3 ten thousands difference, this is less than your measurment error and is negledgeable, if you could be that accurate, i would buy you many beers.

Hence why there is only one spec for the 310 and 250 in the 2013 manual.
Click to expand...


Thanks, I guess most of the increase in displacement is stroke.
 
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