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D&D racing sais peak hp on the stock f7 is at 7700rpms. My clutch was at 8100rpms and I just moved the secondary spring to get it to 7700-7800. Was that a good idea? How accurate are these tachs?
 

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BlackMagic Racing told me that it should be between 8000 and 8100 for max horsepower, which would be dam close to the chart shown.
 

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But your MAX torque is at 7700 where it counts
 

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Max torque is 7700-7800 so that is where you want to pull it for acceleration (shorter drags). On the big end when you really want her wound out (maximum track speed) rpm needs to be at 8000 - 8100 where maximum hp is. This is what keeps you rotating. On long pulls on top you should be at maximum hp without going over.
 

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gls on 8/21/2002 6:58:00 AM

The F-7 works best in most all applications when
the acceleration RPM is 7700-7800. If there is long
distance light load conditions, the F-7 will have
runover RPM to 8000 to mayby 8100 sometimes. If you
try to lighten up the clutching and make it run at
8000 all the time, you'll go slower. If you drag
racing and don't care about backshift, times are
better if it is clutched heavier. Even at RPM's of
7400-7600. If you want to increase throttle responce
and backshift, a green arctic secondary spring will do
that, at the expense of some speed. The F-7 backshifts
very well anyway. Hope that answers your questions.
 

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VFRcanada,

Do you have a chart like that for an 02 600 EFI? Mine is running about 8400-8500 RPM with everything stock. Seems high to me, but I don't know the characteristics of the engine. It runs ok, but I would like to get more low-end acceleration.
 

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Originally posted by oldfougy@Feb 9 2003, 06:17 PM
VFRcanada,

Do you have a chart like that for an 02 600 EFI? Mine is running about 8400-8500 RPM with everything stock. Seems high to me, but I don't know the characteristics of the engine. It runs ok, but I would like to get more low-end acceleration.
No I don't. Somebody sent that one to me.
 

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Originally posted by oldfougy@Feb 9 2003, 07:17 PM
VFRcanada,

Do you have a chart like that for an 02 600 EFI? Mine is running about 8400-8500 RPM with everything stock. Seems high to me, but I don't know the characteristics of the engine. It runs ok, but I would like to get more low-end acceleration.
Our 600's like this we had to loosen the secondary to get the rpm's down, much better hole shot also.
 

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Our 600's like this we had to loosen the secondary to get the rpm's down, much better hole shot also.[/QUOTE]

fast 600,

Is your 600 an 02, and to what RPM should I be shooting for?

Thanks
OldFougy
 

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F7addict. It depends what you are wanting to accomplish.
If you are wanting to do 660 drags I would shoot for 7750. IF you are looking to do long lake runs, set the rpms higher 8000.
 

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Originally posted by oldfougy@Feb 10 2003, 12:26 PM
what RPM should I be shooting for?

Thanks
OldFougy
8200-8300 with a overrun of 8400 works very well on 01-02 valved 600 efi motors. The charts I have seen shows the peak rpm of 8200-8300 rpm, hope this helps.
 

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Here is some interesting testing. I was smoking everyone by 100' and revving at 8100-8200rpms w/ my spring in the middle hole. I moved my spring to the 5th hole, and now I'm revving at 7700-7800rpms. My top speed is 92mph and I can't beat everyone anymore. I maintain, thats it! I used to pull them out of hole like a rocket. I'm going back to the middle hole just to make sure, and see what happens. No one has answered my question yet. How accurate are these digital tachs??????????? I idle at 1800 rpms and the clutch engages at 3880 rpms. Does this sound right??? Need some input guys, come on.
 

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Horny red one - do you mean 5th hole (tightest spring tension) or 5th hole (loosest spring tension) ? If you tightened the secondary you should have gained rpm's. If you lost rpms, you've got some other issues that need to be resolved. My sled pulls hardest at 7750 for 1000' drags on hard snow.
 

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that sounds about right for stock. idle should be between 1500 and 1800 and clutch engagement should be between 3500 and 3800
 

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I moved my spring to the looser setting and the rpms dropped 400rpms. Now I'm around 7700-7800. I'm wondering if my tach could be off though. I idle at 1850 and clutch engages at 3880. Could my tach be off by 200rpms? OR more?
 

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Originally posted by Red Devil@Feb 10 2003, 08:29 PM
Here is some interesting testing. I was smoking everyone by 100' and revving at 8100-8200rpms w/ my spring in the middle hole. I moved my spring to the 5th hole, and now I'm revving at 7700-7800rpms. My top speed is 92mph and I can't beat everyone anymore. I maintain, thats it! I used to pull them out of hole like a rocket. I'm going back to the middle hole just to make sure, and see what happens. No one has answered my question yet. How accurate are these digital tachs??????????? I idle at 1800 rpms and the clutch engages at 3880 rpms. Does this sound right??? Need some input guys, come on.
If that's all you changed -- putting the driven spring in the LOOSEST (#1) hole -- then for heaven's sake put it back in the middle hole and see if your performance comes back against your buds! My guess is, that it will! Me and another bud with an F7 tested different clutching set-ups for three hours a few weeks back, and we both decided for GREAT all-round trail riding performance, the box stock clutching is the Cat's meow! -- Roy

P.S. Keep us posted on your results please!!!
 

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Spring in first hole will not give you enough belt tension. You will lose holeshot and be slower in the drags. You do want to shoot for 7700 - 7800 in the short drags but should do so by loading your clutch not taking off belt tension.
 
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