Honda Ctx700 Engine
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Discussion Starter · #1 ·
I don't mean by changing sprocket ratios. In particular, I'm interested in rpms over 4000 and in 6th gear.
So how about it?
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Seriously though, only thing you can do is lose total weight of the bike/rider/luggage.
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A bike with a more powerful engine! It sounds like it is time for you to up size in power. Otherwise, you are NOT going to get anything more noticeably in power from this engine!
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Discussion Starter · #5 ·
Thanks for the help and advice guys.
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Has anyone looked into changing the cams? Thats what we did on our harleys until 2014 when they finally started putting in bigger ones in at the factory.
Bryan
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Only way I know, and nobody seems to have verified whether it works, is Magnum chip. I was thinking of trying it, but decided against it as their advertising is very generic and could not find anyone on any site that tried it. Google always came up with links, but they were the same question... "...anyone tried one of these...? I saw a post here where someone added something similar, may have been a reprogramer, and swore it worked, but never really posted any numbers.
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I think you can reprogram the computer with a different map similar to Harley. Wouldn't recommend it.
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Discussion Starter · #10 ·
Eureka
EUREKA ! ! !
I have discovered a way to add 3 KW power to our little engines for very little costs. In case your wondering, that equates to slightly more than 4 HP. Taking the little engine that might to one that is slightly bigger. 46.9 hp vs 51.0 hp= an 8.7% increase in output potential. It's not a lot I'll agree. When your cruising down the Interstate at 75 mph and want a bit more speed You will have it quicker. If your on two lane roads and want to pass that car doing 50 in a 55, you can get to 85 much quicker.
The power output numbers I'm quoting are direct from Honda with with only change being the air inlet tube. Some may not have a restricted inlet hose but some just might, I did. The differences are in the inlet restriction in the Pt # 17232-MGS-L31. Fortunately, Honda makes an unrestricted air inlet hose Pt # 17232-MGS-D31. I found it in the NC700 parts catalogue. It seems to be a common modification in Europe if your willing to go outside your license class. The nice thing is that without disassembly officials are not likely to find this change.
BTW: the part is approved for use on the NC700 by CARB since it is a stock item for both the NC700 and 750.
Costs are in the $50 range and it should be available from a number of US suppliers. For those of you with DIY skills and a Dremel, the restriction can be removed with care and you will have the unrestricted version.
From the NC700 site this movie is posted:
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Thank you Ponydriver. I'll have to check this out. Might give me just a little more at higher altitude, where the engine isn't getting enough air. I remember an earlier thread that showed how to install a K&N air cleaner, but this is also good, in that it doesn't (shouldn't) void the warranty, or violate the CARB requirements. 8% might not be much at sea level, but at 7300 ft., it could really make a difference.
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Haha, a lot of work for very minimal gain. Spend $5 and put a pod filter in place of the air box while there for far more gains. Never trust a so called mechanic when most of the time they use rubber gloves! 46.9-51.0 NOT likely! Real numbers please before and after using the same dyno.
Want more power, get a more powerful bike!
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Discussion Starter · #13 ·
Rebel thank you for your ever present and all knowing response. I'm truly sorry to have put vinegar in your wheaties today.
I thought you got rid of your ol'CTX? What are you doing still hanging around?
Dave, according to discussions in Europe, the warranty is not affected since you will be using factory parts.
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Wishing and hoping for mods to improve performance to an already low powered vehicle is a waste of time, nothing but a pipe dream. It is time to upsize, that is the cold hard truth. Maybe if you read about my ctx instead of hating on members, you would see plenty of validation beyond the facts I continually present.
Your claimed 8.7% gain here is flat out laughable! It is nearly the same amount as the upgraded(750) engine. Not going to happen from a couple small tabs removed from air flow on a stock small cc, low rpm na engine. Don't believe me, then try and prove me wrong!
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Rebel thank you for your ever present and all knowing response. I'm truly sorry to have put vinegar in your wheaties today.
I thought you got rid of your ol'CTX? What are you doing still hanging around?
Dave, according to discussions in Europe, the warranty is not affected since you will be using factory parts.
I did a air box mod and opened the exhaust on a Stryker 1300 and woke it up. I'm sure this mod will help. Any time you can add more air and let exhaust breath better you will get some improvement. How much on the CTX is yet to know. When I change out my filter I will look into this restricted piece. Also will be adding a K&N filter to it.
PS thanks for posting the info
David
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If I remember correctly someone had posted this somewhere before. As best that I can remember it was when I first got on to this site and I think they were also talking about porting the throttle body. No disrespect to anyone but I don't see where this little bit would help maybe if you cut the whole metal ring out maybe?!🙄😏 You can get a 3% difference on a dyno on the same day same dyno same bike the variable is the weather.
Bryan
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.............................. Any time you can add more air and let exhaust breath better you will get some improvement. ...............
Only if the fuel system (computer, fuel injectors, pump, fuel lines, etc) is capable of recognizing the additional amount of air going into the engine and is able to add the correct amount of additional fuel. CTX's don't have a Mass Air Flow sensor so you shouldn't just assume this will happen.
Steve
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No way you're getting 4hp from that. I added a K&N airfilter to save money on filters, not to improve power.
I noticed no power increase with the high flow filter.
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Only if the fuel system (computer, fuel injectors, pump, fuel lines, etc) is capable of recognizing the additional amount of air going into the engine and is able to add the correct amount of additional fuel. CTX's don't have a Mass Air Flow sensor so you shouldn't just assume this will happen.
Steve
This is not true. The 670 twin uses a MAP sensor to measure manifold atmospheric pressure to determine how to adjust to changing conditions. Its not an Alpha-N system. Although not quite as advanced as most modern automotive engines, its still fairly advanced. The CTX uses a MAP sensor, TP sensor, IACV sensor, Oxygen sensor, RPM sensor and Temp sensor to adjust fuel, timing and the ignition system. The ECM also utilizes K memory to store engine operation information allowing it to adjust its basic mapping very similar to advanced automotive systems.This was quoted by jfc77320. Oh the word ass/u/me I don't use that word much
David
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What isn't true?
Only if the fuel system (computer, fuel injectors, pump, fuel lines, etc) is capable of recognizing the additional amount of air going into the engine and is able to add the correct amount of additional fuel.
That statement is 100% true.
CTX's don't have a Mass Air Flow sensor.......................
That statement is also 100% true.
The statement that is false is yours: - Its not an Alpha-N system.
The following statement is from Honda:
In technical terms, PGM-FI is an n-alpha mapped injection system.
Read the rest here:
https://powersports.honda.com/experience/articles/090111c0812182ba.aspx
So, regardless of how many other sensors are involved, its ability to adjust the AF mixture is limited. It will work fine as long as the owner hasn't messed with anything. After that telling someone that it will work fine is just an assumption.
BTW - I'm quoting (sort of ) my neighbor who works at a company that designs and sells aftermarket EFI systems.
Steve
Source: https://www.ctx700forum.com/threads/how-have-you-coaxed-more-power-from-the-engine.78995/
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