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Discussion Starter · #1 ·
This is dyno results on my 900 after modifying my cobra longs. The combo is 1 3/8" head pipes 12"long stepped to 1 1/2 " for 18" or so. 1 3/4 straight through after that. Sorry the air fuel is blurr. I keep it under my seat and it got wet. I am thinkin about doing a low buck cam swap this winter just havnt had time yet. I made a mistake in my post before stating the before and after combo. Both runs are with the same pipes but with different mapping. I apoligize. I was not trying to misrepresent anything.When I took the bike to the dealer I was having it tuned because of the changes I made to the pipes. So my mindset was I was going to see how my new pipes did compared to my old ones.I was really happy with the results,but as someone pointed out to me my dyno chart is not one set of pipes to the other. It is just the mapping the new pipes required and the results of that mapping. I am so sorry for the confusion. I was not trying to mis-represent anything. I feel like an idiot.
 

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Discussion Starter · #3 ·
pretty good gains...almost 10%
I would like to see what it does with different air/ful ratios. The dealer pretty much sets all bikes up at 13.5 to 1. That is probably a good place to start but not necessarily the optimum ratio for every engine.
 

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This is dyno results on my 900 after modifying my cobra longs. The "before" is cobra longs,custom breather and power commander. the "after" is 1 3/8" head pipes 12"long stepped to 1 1/2 " for 18" or so. 1 3/4 straight through after that. Sorry the air fuel is blurr. I keep it under my seat and it got wet. I am thinkin about doing a low buck cam swap this winter just havnt had time yet
Have you posted pics previously of your exhaust mods?
 

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I would like to see what it does with different air/ful ratios. The dealer pretty much sets all bikes up at 13.5 to 1. That is probably a good place to start but not necessarily the optimum ratio for every engine.
The buttons on the PCIII make it easy to try richer/leaner without altering the map.
 

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The 900's are flat once you get to mid range. I haven't seen an aftermarket cam for the 900 but they sure do need one. Do you know the EGT with the 13:5 fuel ratio?
 

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I would like to see what it does with different air/ful ratios. The dealer pretty much sets all bikes up at 13.5 to 1. That is probably a good place to start but not necessarily the optimum ratio for every engine.
13.5:1 is fairly lean considering Stoichiometric air-fuel ratio for gasoline is 14.7 to 1, but we all know that Perfect Combustion only happens on paper...
 

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Stoichiometric air-fuel ratios of common fuels
Fuel By mass By volume Percent fuel by mass
Gasoline 14.7 : 1 — 6.8%
Natural gas 17.2 : 1 9.7 : 1 7.9%
Propane (LP) 15.5 : 1 23.9 : 1 6.45%
Ethanol 9 : 1 — 11.1%
Methanol 6.4 : 1 — 15.6%
Hydrogen 34 : 1 2.39 : 1 2.9%
Diesel 14.6 : 1 0.094 : 1 6.8%
 

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Discussion Starter · #11 ·
So I have a few questions. How do I use the buttons on the power commander? What kind of gains and where would those gains be with 2 into 1 exhaust? And If I set my factory cams straight up would my torque curve be about the same just moved forward on rpm scale. I have three choices with cams.
A. retime factory cams
B. 800 cams which are believed to be a drop in but not verified yet.(I have a set)
C. I have a nationally known cam grinder who has been wanting to grind a cam for the 900, who has offered to regrind mine for 150 bucks

Any thoughts comments?
 

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not knowing the 900 cam grinding may do you no good. if you need more duration and lift, you will need a NEW cam(s) set
 

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So I have a few questions. How do I use the buttons on the power commander? What kind of gains and where would those gains be with 2 into 1 exhaust? And If I set my factory cams straight up would my torque curve be about the same just moved forward on rpm scale. I have three choices with cams.
A. retime factory cams
B. 800 cams which are believed to be a drop in but not verified yet.(I have a set)
C. I have a nationally known cam grinder who has been wanting to grind a cam for the 900, who has offered to regrind mine for 150 bucks

Any thoughts comments?
I like the idea of re-griding your cams, especially for $150. You will be able to, respectively, go as mild or wild as you want with those cams.

Keep us posted as to what you do. I for one am really interested in hearing more about having your cams re-done, if you choose that route.
 

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how will you grind wild, from the stock cam, to get more duration and lift you need more material...you cant grind material ONTO the cam
 

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how will you grind wild, from the stock cam, to get more duration and lift you need more material...you cant grind material ONTO the cam
Yes you can and that's what's done. The cams are ground down, built up (welded) with "hardface", then gound to new profiles. That's the industry standard proceedure.
 

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yes i understand, but you cant just grind....
 

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not knowing the 900 cam grinding may do you no good. if you need more duration and lift, you will need a NEW cam(s) set
how will you grind wild, from the stock cam, to get more duration and lift you need more material...you cant grind material ONTO the cam
yes i understand, but you cant just grind....
Obviously.

13.5:1 is fairly lean considering Stoichiometric air-fuel ratio for gasoline is 14.7 to 1, but we all know that Perfect Combustion only happens on paper...
13.5:1 is richer than stoichiometric. Max power A/F's vary but 12.5 - 13.5:1 are common. BSFC requires more sophisticated equipment but is a better indicator.
 

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how will you grind wild, from the stock cam, to get more duration and lift you need more material...you cant grind material ONTO the cam
Regrinds are typically created by reducing the base circle of the camshaft. The heal area is usually reduced to create more lift. Thus, total lift is limited to the amount of material that can be sacrificed on the heal. One problem though, If too much material is removed off of the cam heal, the lifters may forced to over extend in order to reach the cam. This can lead to premature wear of the lifter. For cams that use shimmed valve clearances, this is usually not a problem.

The camshaft can also be reworked by welding, grinding, and re-plating for whatever lift and duration needed. This process would provide the wilder cam profiles.
 

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Regrinds are typically created by reducing the base circle of the camshaft. The heal area is usually reduced to create more lift. Thus, total lift is limited to the amount of material that can be sacrificed on the heal. One problem though, If too much material is removed off of the cam heal, the lifters may forced to over extend in order to reach the cam. This can lead to premature wear of the lifter. For cams that use shimmed valve clearances, this is usually not a problem.
Yes, but it's not usually done in this type application, they're always hardfaced regrinds
 

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Regrinds are typically created by reducing the base circle of the camshaft. The heal area is usually reduced to create more lift. Thus, total lift is limited to the amount of material that can be sacrificed on the heal. One problem though, If too much material is removed off of the cam heal, the lifters may forced to over extend in order to reach the cam. This can lead to premature wear of the lifter. For cams that use shimmed valve clearances, this is usually not a problem.

The camshaft can also be reworked by welding, grinding, and re-plating for whatever lift and duration needed. This process would provide the wilder cam profiles.
generally cheaper for the layman to by a new set
 
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