SL 1050 Performance

[awolverton42]

Anyone??

[K447]

... I know there's a port chamfering specs that are special to the 1050 engines ... what the spec is ... how important it is?

And will it need to be redone if the cylinder is bored to match .25 over pistons? ...

Is the chamfer spec found in the service manual?

[awolverton42]

Is the chamfer spec found in the service manual?

Yes it is in my paper Clymer shop manual. It specifically points out the chamfering of bottom edge of the exhaust port only for 1050 engines.

[K447]

... paper Clymer shop manual. ...

I surmise you did not click the link I provided (Tip: use a computer, not a smartphone).

[awolverton42]

I don't see anything about it in the link. It has a section about re-assembling a three cylinder engine but the one they use is a fuji engine an doesn't mention hardly anything about the domestics.

[casey67]

Chamfering is simply removing any sharp edge at openings so that the rings will not get snagged.
Look at the angles at the openings of the cylinders BEFORE it gets bored.
Anybody that bores cylinders will know what needs to be done.

There is no "spec".
Nothing special about a 1050- it's just a steel sleeved 2 stroke

[sdlvx]

I don't see anything about it in the link. It has a section about re-assembling a three cylinder engine but the one they use is a fuji engine an doesn't mention hardly anything about the domestics.

If you do not chamfer the ports and round them out, the rings will get stuck and break. You have to very carefully round them out without lowering or raising them. I use a long, small file. I have one that's bent all the way in a big radius, very helpful. There is no spec, you should drag your finger across and not feel anything catch, it should be smooth when you drag your finger over it, no edges, bumps, anything that doesn't feel smooth.

Imagine a piston ring going up and down there a few thousand times a minute, and the ring is pressing against the cylinder wall. Do you want that sliding up and down a nice smooth port opening or a sharp one?

[savageman69]

Nothing special about a 1050- it's just a steel sleeved 2 stroke

i wouldnt say nothing lol....the sl1050 was a purpose built grudge racer, very under estimated...so much so i sold 2 slx instead of it

[casey67]

i wouldnt say nothing lol....the sl1050 was a purpose built grudge racer, very under estimated...so much so i sold 2 slx instead of it

Yeah, I realized I was really focused on the chamfering for the 1050.

Like most models, the different years 1050/700 used different cylinders. 96-97 used the added port that later models/parts seemed to prove was not needed. But there was nothing special about chamfering for a 1050.

[wmazz]

If you have the right Keihin carbs, you can add some real arm jerking acceleration
with a simple carb mod.

A few yrs of the 1050 came with CDK2 carbs with a mid-range circuit. If you drill
out the 2 mid-range circuit holes to .040" it will make a big difference in acceleration.

If they (the carbs) need a rebuild, spend the extra money get oem carb kits. As far
as I know, very few shops actually sell the Japanese kits. Sudco is the distributor.
They should cost $65 to $85 ea.

Have you assembled the top end yet?


Bill M.

Why such a large squish on Polaris? Normal is .040" and it allows you to run more compression,
safer because it decreases the possibility of detonation and increases acceleration.