1397 vs 1441

jumjum01

jumjum01

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Hello guys. I just finished upgrading my gen1 from 1397 to 1441cc. I did before and after dyno, expecting more torque in low/mid rpms, but got the opposite.. more top end power. Dyno operator compared my run to a gen2, which made more power from 3-5k rpm. I dont understand how a stock gen2 can make more power in that range. I have stock gen1 intake cam and gen2 ex cam degreed to 102/107. CR is set to 12.88:1. Compression test is 200psi on all 4 cylinders.

Blue is 1397, red is 1441cc

1441 dyno.jpg
 
Shows you how good Suzuki engineers are when they can make a stock configured bike run so well....

The gen 3 is proof of that.

The operator should have compared your 1441 to that of a ZX14R.

Even ZX14Rs don't run away from Hayabusas-they are fairly evenly matched.
 
Where’s the dyno sheet for that gen 2? Just curious if it’s a huge difference or you just chasing a number lol

Cam timing moves power around, change the timing of u want more down low. It’s “cam manufacturer recommendation” is a starting point.

If this is the bike with the gen 2 stuff, why gen 2 everything except intake cam? Pretty sure it’s got more lift, and I don’t think u said u have hardly any head work. Probably makes a difference. But someone’s else made a good point-when are u at 3-5k? I’ll tell u, cruising on the freeway or cruising the streets. 50hp is good enough for that lol don’t stress it, specs sound Pump gas reliable and it’ll always start. I bet u don’t even need a second battery
 
Dnyce said:
Where’s the dyno sheet for that gen 2? Just curious if it’s a huge difference or you just chasing a number lol

Cam timing moves power around, change the timing of u want more down low. It’s “cam manufacturer recommendation” is a starting point.

If this is the bike with the gen 2 stuff, why gen 2 everything except intake cam? Pretty sure it’s got more lift, and I don’t think u said u have hardly any head work. Probably makes a difference. But someone’s else made a good point-when are u at 3-5k? I’ll tell u, cruising on the freeway or cruising the streets. 50hp is good enough for that lol don’t stress it, specs sound Pump gas reliable and it’ll always start. I bet u don’t even need a second battery
Click to expand...
Thanks for your reply.. I bought a set of second hand gen2 cam to install, but the intake cam was bend somehow and did not run true in the head, so I didnt use it. But the stock timing was 103/107 on those original cams, which is close to my current setup anyway. Since the gen3 busa has even smaller intake cam lift and duration, and still can make around 70HP@4000rpm, my conclusion is that the gen1 intake cam is not the curprit in this case.
But I dont understand how a bike with 100cc extra and more compression and similar setup can have less power i that range. Mabye the compression test is a little on the low side at 200psi

1397 vs gen2.jpg
 
jumjum01 said:
But I dont understand how a bike with 100cc extra and more compression and similar setup can have less power i that range. Mabye the compression test is a little on the low side at 200psi
Click to expand...

Your bike has a single-sided Akro correct? That is designed for maximum flow. While I have no knowledge on how well the engine setup is working, the fact is that unrestricted flow is the utter enemy of low-end torque. The flow and scavenging created by that exhaust will disrupt the low end of any engine that otherwise wants some pressure build up from the exhaust side. Just my uneducated opinion, but the engine is an air pump having some fundamental operational aspects not to be overcome, even by the significant changes that you made.

For sure a dual exhaust would reverse this aspect of the power curve, bringing down the peak and boosting the low end.

I am surprised that the peak number is not a little higher, however the consistent increase or volume between the curves above 7,000 is really big. I see that as a win for you!

With respect to how you want it to ride, a gearing change could get the engine out of that slump more quickly.
 
Gen2 cam has more lift than the gen one.

But-you talking about 5hp. That could beexhaust, velocity stacks, the smaller cam u have. 5hp is nothing. Personally building a 1441 with gen 2 specs is silly, put some real cams in it, port the head, etc.

Suzuki didn’t build the gen 2 by just adding 2mm to the crank and using gen 1 parts. They changed the cams, valves, head, compression, fueling etc to maximize the results. You should do the same if u want maximum results.

I’d bet money your bike is more fun to ride than that gen 2
 
Hayabusa Wannabe said:
Your bike has a single-sided Akro correct? That is designed for maximum flow. While I have no knowledge on how well the engine setup is working, the fact is that unrestricted flow is the utter enemy of low-end torque. The flow and scavenging created by that exhaust will disrupt the low end of any engine that otherwise wants some pressure build up from the exhaust side. Just my uneducated opinion, but the engine is an air pump having some fundamental operational aspects not to be overcome, even by the significant changes that you made.

For sure a dual exhaust would reverse this aspect of the power curve, bringing down the peak and boosting the low end.

I am surprised that the peak number is not a little higher, however the consistent increase or volume between the curves above 7,000 is really big. I see that as a win for you!

With respect to how you want it to ride, a gearing change could get the engine out of that slump more quickly.
Click to expand...
Yes I have the full system akrapovic with single carbon exhaust. I think you could be right about the exhaust pressure could be it.
I suspect my local dynoshops numbers are on the conservative side - I got 7HP more on another dynoshop with same setup when i did the 1397 conversion.
I really like the stock gearing and bike is plenty fast. I just like to have the power ready on tap at any rpm..
 
Dnyce said:
Gen2 cam has more lift than the gen one.

But-you talking about 5hp. That could beexhaust, velocity stacks, the smaller cam u have. 5hp is nothing. Personally building a 1441 with gen 2 specs is silly, put some real cams in it, port the head, etc.

Suzuki didn’t build the gen 2 by just adding 2mm to the crank and using gen 1 parts. They changed the cams, valves, head, compression, fueling etc to maximize the results. You should do the same if u want maximum results.

I’d bet money your bike is more fun to ride than that gen 2
Click to expand...
By changing to "real" cam and ported head will the focus the power towards high rpm and leave my with scooter power in low rpm... No thanks :-) Not for at street bike
I think the hayabusa has plenty top end power stock, but low rpm is no better than a SV1000. Now a hayabusa with both top end rush, and low/midrange that will blow your socks off, thats cool in my books :-)
 
jumjum01 said:
I suspect my local dynoshops numbers are on the conservative side - I got 7HP more on another dynoshop with same setup when i did the 1397 conversion.
Click to expand...
Using the same correction? Look at the top right, see the "SAE"? If the other shows "STD" that makes sense as the "SAE" is far more accurate and often times one of the most overlooked items when comparing dyno numbers.

There are many variables and even other ways to play games...this is why someone who isn't really chasing a number to make them look good is always best as accuracy and repeatability is for trying to do what you are.
 
Both dynoshops use SAE. One straps bike down, one dosent need straps. I look at the differences between the runs. But comparing to dyno sheet from US most are STD which seems to produce bigger numbers for similar bikes
 
So I watch a guy on YouTube and all he does is dyno motor combos on a engine dyno. And he talks a lot about cams, heads, intake and exhaust. Most of the time the stock stuff is better for low end power. So maybe the exhaust and ported head you have is what’s causing for the low end power decrease. I’m lower rpm’s the small the port is better as it speeds up the air flow. From what I get when watching videos. I would think if you took a stock motor and up the compression, bigger bore or longer stroke it would make more power all over.
 
I wonder if my piston rings have failed seating correctly. Shouldnt a bike with 12.88:1 compression and stock cams be able to produce more than 200psi in compression test?? Just did some reading about break-in on new rings. Mabye I was wrong with going very gentle on the rpms and throttle during break-in.
Just checked the spark plugs, they had oil on the threads below the sealing washer. Shop manual states that i stock gen2 busa should be in the 198-256psi range.
I dont know if its of any use, but I put a bag on the crankcase breather hose, and in 90sec it filled the bag. (blowby?!)

blowby.jpg
 
we both got same problem low hp and torque but different issues - i think

for my 2 penneth your Gen1 cam is not right for 1441cc , are you sure you have high enough compression 200 psi cranking pressure is a little on the low side, look at my issues on the same ALL MOTOR site
i also have low down power issues - but i am making good power 15hp over my modified 4in1 mapped 1340
205 hp at 9800, 116 lbft at 7400 but less hp and torque than my old 1340 below 6k

in my case i am sure it is big port head - mixed with free flowing 4 in 1 = low air speed up to 5k

im going to get a stock gen2 head and put my cams on my 1407cc
 
jumjum01 said:
I wonder if my piston rings have failed seating correctly. Shouldnt a bike with 12.88:1 compression and stock cams be able to produce more than 200psi in compression test?? Just did some reading about break-in on new rings. Mabye I was wrong with going very gentle on the rpms and throttle during break-in.
Just checked the spark plugs, they had oil on the threads below the sealing washer. Shop manual states that i stock gen2 busa should be in the 198-256psi range.
I dont know if its of any use, but I put a bag on the crankcase breather hose, and in 90sec it filled the bag. (blowby?!)

View attachment 1651783
Click to expand...
how do you know you have 12.88:1
did you check volumes of combustion head and piston etc ?
deck height calcs

just saying ?
 
mark3evo said:
how do you know you have 12.88:1
did you check volumes of combustion head and piston etc ?
deck height calcs

just saying ?
Click to expand...
My conclusion is piston rings did not seat, due to improper break-in and cylinder got glazed. Leak test showed too much air escaped through piston rings and out of crankcase breather hose. I compared leak to my stock spare gen1 hayabusa motor. My cam choise is selected towards low/mid rpm power. Bigger lift/duration cams and thereby bigger overlap will trade low end for top end power.
My setup is measured down to every little detail and calculated, thats why I know the static compression ratio is 12.88:1. I could have gone higher, but I want to run on pump gas and still have a reliable motor.
If a stock gen2 can make 230-250psi compression test, mine should be able to make 250psi - ish with basicly gen2 like cams.
How much psi does your bikes make? I am sure that a ported head with bigger ports will trade some low end for top end power.

CR.png
 
why did you not add gasket thickness 0.76 mm i believe this will lower your compression to 11.5 or something - you say you measured everything if you have a Gen1 head normally they are 18cc, but presumably you measured using a burette and flat plastic plate??

my cranking pressure is 225 psi

the rings were broken in on the dyno 6 hours running time
 
jumjum01 said:
My conclusion is piston rings did not seat, due to improper break-in and cylinder got glazed. Leak test showed too much air escaped through piston rings and out of crankcase breather hose. I compared leak to my stock spare gen1 hayabusa motor. My cam choise is selected towards low/mid rpm power. Bigger lift/duration cams and thereby bigger overlap will trade low end for top end power.
My setup is measured down to every little detail and calculated, thats why I know the static compression ratio is 12.88:1. I could have gone higher, but I want to run on pump gas and still have a reliable motor.
If a stock gen2 can make 230-250psi compression test, mine should be able to make 250psi - ish with basicly gen2 like cams.
How much psi does your bikes make? I am sure that a ported head with bigger ports will trade some low end for top end power.

View attachment 1652480
Click to expand...
1655639956682.png
 
jumjum01 said:
Due to headwork, cc volume has gone up. Why would I go lower in compression than i stock gen2, which run fine on 95 ron pump gas?! Pistons are adverticed as 12.8:1 for a 1397cc motor and have APEs blessing to run on pump gas all day long..
Click to expand...
i am not saying you should run lower, i just wondered why you did not add the thickness of the head gasket
 
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