Finally got the JE High Compression pistons put in

[Sir-knob-head]

I have an xt660z I bought a mt09 tracer. Brand new in July. And my 660z has sat partially torn apart for its yearly strip and clean. It's sat. I've done more work on the vtr in the last week Than I have the 660 since late August ................ First frost of the year down here soooo major motivated to get it done. New innertube fitted tonight

[lloydie]

I pulled it out the other day just to get to something behind it ,then put it back :-( .
Think we both need to dig deep and get cracking on with them

[Sir-knob-head]

I pulled it out the other day just to get to something behind it ,then put it back :-( .
Think we both need to dig deep and get cracking on with them

My wheel will be on tonight. Waiting for powdercoating to come back then fully assemble.

I'm nearly done just been lazy lol

[freeridenick]

Is it necessary to keep the pistons at TDC when removing and re-installing? Moving them slightly either side makes it easier to remove the bolts.

Forgot this. I've just realised I'm being dumb.

[StormyRob]

Is it necessary to keep the pistons at TDC when removing and re-installing? Moving them slightly either side makes it easier to remove the bolts.

Forgot this. I've just realised I'm being dumb.

Nick...I was also thinking about this re the other engine I have with the damaged piston...please elaborate

[freeridenick]

I think....

Going back and forth through TDC on one cylinder at a time makes no difference provided the rotation is the same either side. When the pistons in go back to to the right mark on the fly wheel and sort the front.

So one might undo one bolt then rotate the crank 360 degrees to remove the.other bolt. Provided the crank is rotated back the opposite way 360 degrees after the replacement bolt has been installed then the piston is back at TDC and timing is easy.

I think. It's a bit late and wine has got me.

[StormyRob]

I think....

Going back and forth through TDC on one cylinder at a time makes no difference provided the rotation is the same either side. When the pistons in go back to to the right mark on the fly wheel and sort the front.

So one might undo one bolt then rotate the crank 360 degrees to remove the.other bolt. Provided the crank is rotated back the opposite way 360 degrees after the replacement bolt has been installed then the piston is back at TDC and timing is easy.

I think. It's a bit late and wine has got me.

How unfortunate is this timing as beer has got me!

[VTRDark]

Don't over-think the timing it's really not that difficult especially if you have the cams and stuff removed so starting from scratch. When putting things back together you have the option to start from the front or the rear. The only difference is that starting from the front you turn the crank anti-clockwise 270 degrees 3/4 turn moving from front to rear instead. Your better off worrying more about the fit of the piston and rings with the tight tolerances in the cylinder and the breaking in, everything else is just spannering.

[VT1000r]

Two quick things to add to this thread..........

The cam change is to regain the top end you loose with the piston change.
The reason you loose top end with the higher compression pistons is that the increase in cyl pressure inhibits the engines ability to rev.
This is the reason for the increase in overlap.

So if you are never going to use the upper revs (7K and above) cams will not really make much difference, in fact you will loose a little bottom end with them.



Also be careful with your rebuild....... the engine in this thread broke a rod shortly after the last post about it...... just an FYI that might be important.
Why it happened, I can't tell you as I never saw the engine in person.

How do you know he broke a rod, and what are some likely causes of his rod failure?

[8541Hawk]

How do you know he broke a rod, and what are some likely causes of his rod failure?

https://www.superhawkforum.com/forums/g ... oom-32587/

[VT1000r]

How do you know he broke a rod, and what are some likely causes of his rod failure?

https://www.superhawkforum.com/forums/g ... oom-32587/

Thank you my kind sir I was looking through his posts and couldn't find it.

[VT1000r]

Good write-up, good result, well done.
Looks like you got them the right way round- I may try that myself this time......

Glad it's feeling good; I'll be doing exactly the same very shortly. I'm just playing a little airbox game first.

I may also skim 30 thou off the heads as well, to add a little spice to the standard heads before swapping to a set I've gas flowed and will then fit oversize inlet valves. But all changes done one at a time and a dyno run in between, so that we can all see what changes get what results.....keen to see your dyno numbers, though.

Are you still running standard cams?

I know the bigger valve relief is the intake side but just to double check do you know if the front and rear JE pistons are the same? And Again thanks for all your helpful replies.

[8541Hawk]

Yes they are the same