Question For Wisco Piston Kit Users

[TopCatGr58]

Rob,

It's quoted from their sale catalog:

XS1100
Kit includes: (4) Pistons, Ring Sets, Piston pins, Retainer Clips and (1) CFM20 Head Gasket
1179cc
2.913” or 74.00mm
2.5mm oversize
Stroke - 68.55mm
K1179
$523.77
(D62413)
10.25:1

1196cc
2.933” or 74.50mm
3mm oversize
Stroke - 68.55mm
K1196
$523.77
(D62413)
10.25:1

I put premium in mine cause I didn't want to take a chance with my new pistons experiencing "PINGING" or detonation which can and will damage them if allowed to go on for too long! Our bikes don't have the fancy ignition systems to automatically vary the timing like AUTO's do, so that's why several of us prefer to use "Hi Test" in our big bore machines! YMMV!
T.C.

[79XS11F]

Thanks TC
The DIA numbers there make sense. I measured my bore with a analog caliper and came up with 2.9 inches on the nose. So I will be doing some ring filing I guess.
I will likely get back to this engine soon after I return from a 5 day camping trip that starts tomorrow :-) I would like to break it in in the cooler fall weather.
If I am lucky my new used headers will be here when I get back to put on my current engine.

Questions.
I have not even considered any mods to the timing or valve timing as yet. Any suggestions for best performance on this 1179 Wisco engine?

Also I will guess that I do not reinstall the cam tunnel seal with this head gasket?

Rob

[TopCatGr58]

Rob,

You'll need to talk to MAXIMAN with regards to valve timing changes!! His changes are more for low rpm grunt, but at a sacrifice of higher rpm power/range!

I didn't change anything, have stock cams, just increased my main jets due to pipes and intakes. I like to rev mine, and it easily revs to redline!

You're right, no cam chain channel seal, just the head gasket!
Enjoy your trip!
T.C.

[79XS11F]

Is there a particular type of or special file I need in order to do the ring gap work.
Rob

[mainlylinux]

79XS11F, did you put the rings down in the bore and measure them that way?

I've always compressed the rings and sent them down the bore with one of the pisons, and then measured the end gap with a feeler guage. Is that how you are measuring the gap?

I typically do this for each ring that goes in a particular bore, and then if that ring needs adjustment I make sure that it goes back into the same bore.

Also, your ring gap should measure the same towards the top of the bore and towards the bottom as well. If there is a taper in the area of the piston's stroke, your rings might fatigue quickly.

Dan

[79XS11F]

Originally posted by mainlylinux
79XS11F, did you put the rings down in the bore and measure them that way?

I've always compressed the rings and sent them down the bore with one of the pisons, and then measured the end gap with a feeler guage. Is that how you are measuring the gap?

I typically do this for each ring that goes in a particular bore, and then if that ring needs adjustment I make sure that it goes back into the same bore.

Also, your ring gap should measure the same towards the top of the bore and towards the bottom as well. If there is a taper in the area of the piston's stroke, your rings might fatigue quickly.

Dan

Yes I am checking them in the bores using a piston to square them up and checking them at the top and the bottom. I have labeled the box for each set as to where they will be used to avoid mixing them up during final assembly.
I do need to do some very minor adjustments to the end gaps on a few of them. I am guessing there is a special file for this job given the size of the gap even when the rings are not compressed.

[TopCatGr58]

IIRC I used a small metal fingernail file. Instead of trying to fit the file inbetween the gap, I just pushed the ends apart vertically as the ring would sit in the cylinder, just enough to expose the end of the ring. But I'm no actual mechanic, perhaps one will post a different or better procedure?
T.C.

[mainlylinux]

Here's an inexpensive bench mount ring filer from summit racing. I've never used it so I can't attest to it's quality, but it looks convenient.

Dan

http://store.summitracing.com/partde...5&autoview=sku

[79XS11F]

Ya I guess you don't want to be using an aggressive file because were talking 1000s of an inch changes here. I think I will go with a course finger nail file and see what happens.
Rob

[posthuman]

has anyone bothered to weight balance these pistons to the 'nth degree, like within a milligram or so?

[79XS11F]

The guy at the machine shop seems to think that is already done at the factory. He told me to not even mix up the wrist pins from their original package locations when I received the kit. So that's what I have been doing .. keep all components together as was supplied.
Rob

[mro]

Balancing act

Factory balancing uses tolerances that can be met by mass production. Seldom will there be a problem with this, but you can balance the rods/pistons yourself using one of these and get a near perfect job.


Weight each piston/rod against each other. Find the lightest. Remove metal from all the others to match the lightest one. Can make a noticeable improvement, smoother running, allows higher revs more safely, engine may last longer.


mro
works for all engines, even outboards

[79XS11F]

That would make sense but I don't have reason to remove the con rods so I will go as is I think. thanks for the info just the same.
Rob

[79XS11F]

Yet another question ... What sort of carb jetting are those with installed 1179 kits using?
Rob

[TopCatGr58]

Hey Rob,

It's not so much the big bore, as the other mods, Indy Filters and aftermarket pipes that drive the rejetting process. I went up from 110's across to 117.5's, runs fine, but could probably go up another size, as per the Dyno run! This of course is on my 81 machine and carbs. You've got the 79 with the stock 137.5's, so if you have both types of mods, you'll want to look at 145's. I have same OEM Pilots, jetting guides states to go up one size, but I just turned the pilot jet screws out a couple more turns, worked fine! YMMV.
T.C.