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Discussion Starter · #1 ·
I finally got to ride my 01 ZR 800 with the newly built engine. I now have weisco pistons/ rings, heads were cut .15, and the schlag was cleaned out of the ports. I already had SLP twins on it before the rebuild. I jetted up five sizes to begin with to allow for the extra power I thought I'd have. While riding it, it revs exactly like it did before- right up to 7800rpms and pulls to 8000.

I have two questions:

If it still pulls to the rpm I set it to before this stuff, and haven't re-clutched it, doesn't this mean it isn't making anymore power? How can this be? Just a new top end should make more power much less w/ all of these additions.
The plugs look pretty close, but the pistons look clean, like it is way too rich. I have probably put 40 miles on it. When are you able to read the wash on new pistons? Do they look rich, or are they just new looking?
I am still on my first tank of gas which I mixed 100:1
Thanks
 

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<div class='quotetop'>QUOTE (zippy 8 @ Jan 9 2007, 01:22 AM) <{POST_SNAPBACK}></div>
I finally got to ride my 01 ZR 800 with the newly built engine. I now have weisco pistons/ rings, heads were cut .15, and the schlag was cleaned out of the ports. I already had SLP twins on it before the rebuild. I jetted up five sizes to begin with to allow for the extra power I thought I'd have. While riding it, it revs exactly like it did before- right up to 7800rpms and pulls to 8000.

I have two questions:

If it still pulls to the rpm I set it to before this stuff, and haven't re-clutched it, doesn't this mean it isn't making anymore power? How can this be? Just a new top end should make more power much less w/ all of these additions.
The plugs look pretty close, but the pistons look clean, like it is way too rich. I have probably put 40 miles on it. When are you able to read the wash on new pistons? Do they look rich, or are they just new looking?
I am still on my first tank of gas which I mixed 100:1
Thanks[/b]
You may have more power, but if your not clutched for it, then that power is going no where. You changed your engine, but you now don't know where the peak power is being made. You may need a dyno run or two to find out where your peak torque and power are now being made. Then clutch for it from there.
 

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The difference seems to be tighter heads and "cleaned up" ports. You won;t get any more power from the pistons and you had the pipes on there before. Sometimes just cutting heads is not good enough. You have bumped up the compression, which in basic terms could make more power with the right octane level fuel, but if the squish profile is not right the cut may not be as effective. I would nopt think that you would have to make any jetting change, or that much of a change. You were jetted for the pipes before and raising the compression will require higher octane to resist detonation, not just more fuel. Have you checked with SLP to see if they have an RPM recommendation for their pipes with the head cut? I also think you need more miles to get enough carbon on the piston domes and more colour on the plugs. Start by reading your plugs, but if I understand things correctly you be way too rich with the jump in jetting for just a head cut.
 

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Discussion Starter · #5 ·
Thanks for the responses. I will call SLP and see what they say. I am also going to jet down a little (even though the plugs look good). I would like to see it out rev what it used to (hence more power), then clutch it accordingly. I guess I will have to wait to read the piston wash until I get some more miles on it.
Thanks again!
 

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Just cleaning the ports and cutting the head probably only gave you about 3HP. If you jetted up you probably over compensated for any gains you may have gotten.
 

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Discussion Starter · #7 ·
<div class='quotetop'>QUOTE (scrat600 @ Jan 9 2007, 09:52 PM) <{POST_SNAPBACK}></div>
Just cleaning the ports and cutting the head probably only gave you about 3HP. If you jetted up you probably over compensated for any gains you may have gotten.[/b]
Just having a new top end compared to a 2500 mile top end I would have thought would give me 3HP. Add to that the cut head and the cleaned ports, I thought I'd see more. You're probably right- maybe we overestimated.
 

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5 jet sizes is a pretty big step, start leaning it back down to where it is running crisp and clean. You aren't going to pick up a lot of power over what you had before if it was running strong. However let the motor break in before drawing any conclusions.
 
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