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Discussion Starter · #1 ·
After logging 644 miles on the track I am pretty familiar with this powerband to say the least.

I have the bike geared way short to get maximum drive off the corners and pretty much only once was I caught 'in between' gears.

My issue is that I'm still getting pulled off of the corner by some of the new bikes. I know that I'm part of the problem as I have an issue getting to full throttle quickly coming out of right-handers especially. A quick-turn throttle is definitely on order but I think that will only help part of the issue. The ZX-7R comes to life around 10k rpm when it thrusts forward. I'd like to get some of the meat a little sooner around 8000rpm or so.

So, with that said I'm mulling over High Compression Pistons. I'm not sure if I'm going to stick with 748cc or go to 770cc or even possibly 800cc.

If anyone has any experience with high compression pistons in the ZX-7R application I'm all ears. Cams might work as well and I'll probably do Cams, Pistons, and Con rods altogether.

The other idea is to leave it as is and get either an '02 ZX-9R that I've been lusting after as of late or the new ZX-10R which I had the privilege of having someone wheelie past me coming out of turn 5 at New Jersey last week. I'll likely run the bike as is for the remainder of the season unless I come into a windfall, otherwise most work will be done in Fall/Winter as usual.
 

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Discussion Starter · #3 ·
bite the bullet and get the 10r maybe do a straight trade that MV you have...
There is no way on God's Green Earth that I'm getting rid of the F4. :rotflmao That thing's got timeless value.
 

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Cams. Screw pistons. Get some cams that bring the power in a little sooner. You may loose some bottom but you'll have that 8k hit.
 

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Discussion Starter · #5 ·
Cams. Screw pistons. Get some cams that bring the power in a little sooner. You may loose some bottom but you'll have that 8k hit.
Good call. Plus they're easy to install. Any recommendations on the timing?
 

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Discussion Starter · #7 ·
Why not build a 9 motor for your 7!:crazyloco

I've actually considered that but I'm afraid that the new weight distribution with the 9 motor installed will throw off the balanced handling that the ZX-7R has now.
 

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Who here has a ZX7/9 that can contribute to the handling aspects? 57x has had a million ZX's, maybe he has input? Anyone? Bueller?...

Kinda on handling subject, what makes our bikes sooo heavy, engine? Frame? Seems especially nose heavy.
 

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the 9 motor installed will throw off the balanced handling that the ZX-7R has now.
It will. The 9 engine is REALLY powerful, but is a gyro with that heavy crank. It makes the bike want to stand up. Plus I like revving on the track. I so much agreed with the "get a 10" approach that I got two, a 95 street and a 94 track ZX10R. I still like the 7 better for handling though.

The best single thing you can do for power on a 7 is compression. Adding cams without the compression just won't do as much. Even the Kit pistons themselves do not really raise the compression. There is not room in there to raise it. Just cut the head and put in flat faced valves. Then either put in a 9 intake cam (exhaust cam does not need to be changed as the 7 has way more exhaust flow than it needs) or get a Kent cam like green did. To get a little more, get a 91-95 crank and some 1.5mm over pistons. That with high compression and good fuel and you will be a new man!!!

I will get my 950 big bore engine out of the shop one of these days. Everything is done except the head. I am still looking for some flat faced valves. I found the intake but am still looking for the exhaust. I will eventually give in and buy some blanks and cut them. I enjoy the stock 9 engine I have in my track bike right now, but looking forward to the big bore since it has a lightened, knife edged crank. I am hoping it cuts down the gyro effect

I am already working on an RR engine 836 build, gathering parts for it. The second 96 ZX7RR I got was really rough, so it is going to track duty. I already found Kit rods, Kit 2mm over pistons, Kit cams, a Suter clutch (no horsepower, but sounds cool), a knife edged 91 7 crank. The only thing I need to find are some Kit springs (I just won't use the Kibblewhite springs) and a full set of flat faced valves.
 

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Kinda on handling subject, what makes our bikes sooo heavy, engine? Frame? Seems especially nose heavy.
Three words:

Kawasaki Heavy Industries

The engine is frankly a bit large for a small displacement engine. Take a look at the CBR1000RR. That engine is smaller than our 750cc engine.

The frame is overbuilt. No use of lightweight hardware. Suspension bushings are WAY overkill. Damn, the kickstand will hold up a fully bagged Harley. Wheels that are 10lbs heavier than what we see today on other bikes like an R6.
 

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Discussion Starter · #12 ·
It will. The 9 engine is REALLY powerful, but is a gyro with that heavy crank. It makes the bike want to stand up. Plus I like revving on the track. I so much agreed with the "get a 10" approach that I got two, a 95 street and a 94 track ZX10R. I still like the 7 better for handling though.

The best single thing you can do for power on a 7 is compression. Adding cams without the compression just won't do as much. Even the Kit pistons themselves do not really raise the compression. There is not room in there to raise it. Just cut the head and put in flat faced valves. Then either put in a 9 intake cam (exhaust cam does not need to be changed as the 7 has way more exhaust flow than it needs) or get a Kent cam like green did. To get a little more, get a 91-95 crank and some 1.5mm over pistons. That with high compression and good fuel and you will be a new man!!!

I will get my 950 big bore engine out of the shop one of these days. Everything is done except the head. I am still looking for some flat faced valves. I found the intake but am still looking for the exhaust. I will eventually give in and buy some blanks and cut them. I enjoy the stock 9 engine I have in my track bike right now, but looking forward to the big bore since it has a lightened, knife edged crank. I am hoping it cuts down the gyro effect

I am already working on an RR engine 836 build, gathering parts for it. The second 96 ZX7RR I got was really rough, so it is going to track duty. I already found Kit rods, Kit 4mm over pistons, Kit cams, a Suter clutch (no horsepower, but sounds cool), a knife edged 91 7 crank. The only thing I need to find are some Kit springs (I just won't use the Kibblewhite springs) and a full set of flat faced valves.
Thanks for the clarification. I suspected that. The 9 motor in a 7 chassis is probably better suited for the drag strip and a lengthened swingarm.

What about milling the head AND pistons? or would that be too much compression.

How much can the ZX-7R crank be safely lightened?
 

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Thanks for the clarification. I suspected that. The 9 motor in a 7 chassis is probably better suited for the drag strip and a lengthened swingarm.

What about milling the head AND pistons? or would that be too much compression.

How much can the ZX-7R crank be safely lightened?
The 9 engine is great for the street and fun times at the track (not talking about at the limit). The damn thing comes out of the corner so well that you feel like you are dirt tracking. I raise the rear shock mount most all the way up and really lower the forks to compensate. It feels more like fall in than turn in, but helps when the gyro cranks up. It takes away the stability of the ZX7 by circumventing it this way.

Milling the pistons on the 7 would take you the wrong way for compression, unless you also mill the jugs. Piston to valve clearance is the limiting factor on compression on the 7. You can fairly easily get 14:1 on these just by milling the head, so there is no reason to get into milling the pistons and jugs. I am targeting near 15:1 compression on my big bore 9 engine using the flat bottom valves and do not have to get into the pistons or jugs.

Not sure how much is safe to take off on the 7 crank. I left that to APE on both my big bore 9 and the RR 836 I am building. I could snap some pics of the 7 crank if you wish since it is unassembled to get sleeves pressed in for the 2mm over pistons.
 

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Discussion Starter · #14 ·
The 9 engine is great for the street and fun times at the track (not talking about at the limit). The damn thing comes out of the corner so well that you feel like you are dirt tracking. I raise the rear shock mount most all the way up and really lower the forks to compensate. It feels more like fall in than turn in, but helps when the gyro cranks up. It takes away the stability of the ZX7 by circumventing it this way.

Milling the pistons on the 7 would take you the wrong way for compression, unless you also mill the jugs. Piston to valve clearance is the limiting factor on compression on the 7. You can fairly easily get 14:1 on these just by milling the head, so there is no reason to get into milling the pistons and jugs. I am targeting near 15:1 compression on my big bore 9 engine using the flat bottom valves and do not have to get into the pistons or jugs.

Not sure how much is safe to take off on the 7 crank. I left that to APE on both my big bore 9 and the RR 836 I am building. I could snap some pics of the 7 crank if you wish since it is unassembled to get sleeves pressed in for the 4mm over pistons.
Sorry, let me rephrase that. I meant both Milling the head and BUYING hi-comp pistons. lol I was typing fast again. 14:1 would be great. What's stock? 11.5:1 ?

I'll probably leave the crank as is and just polish/knife edge it. I did that on my 999 back in the day and it was noticeable how much faster it spun up. I did take off nearly 4lbs though and then an additional 2lbs off the flywheel.
 

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11.5:1 is stock. Get some 1.5mm over pistons. They claim 13:1. You should not have to re-sleeve the cylinders. They seem to crack at 2mm over.

I think they took off over 10lbs off my 9 crank. It is still a heavy beast. There is no flywheel on a ZX7, so no savings there.
 

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Discussion Starter · #16 ·
11.5:1 is stock. Get some 1.5mm over pistons. They claim 13:1. You should not have to re-sleeve the cylinders. They seem to crack at 2mm over.

I think they took off over 10lbs off my 9 crank. It is still a heavy beast. There is no flywheel on a ZX7, so no savings there.
Gotcha! Thanks for the tips. This is super helpful! :crazyloco
 

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I got looking at 2004 ducati 998 senna.... good track bike?... gives me a hard on when i sit on it.... showa up front, ohlins on the back, full Ti Arrow exhaust... and has been tuned....

looks like this one but with black rims!!!


 

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I got looking at 2004 ducati 998 senna.... good track bike?... gives me a hard on when i sit on it.... showa up front, ohlins on the back, full Ti Arrow exhaust... and has been tuned....

looks like this one but with black rims!!!
Sweet looking bike. No one can deny that Ducatis look extremely sexy!

.... Having said that, what did that have to do with Turbo doing some motor work on his 7? :headscratch



:lol
 

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Swap a big bore L motor in...

Josh
 

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Sweet looking bike. No one can deny that Ducatis look extremely sexy!

.... Having said that, what did that have to do with Turbo doing some motor work on his 7? :headscratch



:lol


Had everything to do with it... UPGRADE!!!


I have been begining to feel these days that the 7R is getting lazy...

My Replica will never be sold... but for my every day rider I am thinking of swapping out at the end of the season after my house renovations are done.
 
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