tired k8 busa

[bradbusa]

what's up guys? been a while since i've posted here but i thought i'd check in and get some advice from the pro's..
long story short, i bought my k8 new in '09. shortly after i lost my job and the bike became my primary(only) transportation while i was in school. two years later the bike now has just under 40k miles on it. finally have some decent income so i took it to the local tuner yesterday to see how the engine is holding up. i wanted to put some money into it but if the engine was tired i didnt wanna throw bolt ons at it. the bike put down 154-157 hp on a total of three runs. the bike is stock as a rock, aside from a pipercross street filter.
i'm told on this same dyno, the owner's bike put down 178-180whp bone stock right off the showroom floor. considering suzuki's claim of 194.4 at the crank, i'd say that's on par. so, somewhere in the 40k miles i've done, i lost 20hp lol...
so i've decided to build the engine a little. beef it up some. get it back to stock and hopefully increase performance to at least 190ish whp. MOAR POWAAAA!
my question is, what's the best way to tell where the power was lost? top end? bottom end?
i plan on doing a leakdown and compression test to make sure everything's sealing properly. the bike runs GREAT. never had any rough running issues with it. i'm probably a little too anal about maintenance. while i was in school i regularly used seafoam in the tank, and intake to keep things clean, change the plugs and oil per maintenance schedule. i adjusted the valves myself at 20k miles. at first they were too tight, drove it for a week or two, then readjusted them on the loose side. havent touched them since. i'm wondering if having them too tight kind of wore the cams out a bit..
back to point.. provided the leakdown and compression test results are normal; where's the best area of the engine to focus on to achieve the kind of power i'm looking for? if the cams are worn, i dont wanna go into the block. and if the rings are leaking, having head work done is pointless..

how much does an intake cam on the exhaust side really help? if i were to put two new intake cams, a good flowing exhaust (i really like the hmf big bird. hear they make awesome power) and tune the ecu, will that get me in the ballpark of where i'm aiming for?
sorry this is so long, i hope all this makes sense.
what's the best way to determine whether the top end or bottom end is where the hp was lost?
and what is the best way to achieve the kind of power i'm looking for?

 

[Tufbusa]

If it were me in your position, I'd take that puppy down to the local dealer and trade it in on a new one! Start fresh rather than spending a ton of money on a used one trying to make it new. Money well spent.

 

[bradbusa]

spending 1 or 2 grand on this bike is a lot cheaper than spending 12+ on a new bike..
would be nice to be able to do that, but im kinda partial to it. i like the k8 black and grey, and a new bike isnt exactly cost efficient lol. i already own this one.

 

[Ezduzit]

Rebuild, better post pics.

 

[cheferman65]

Hey brother! Long time. How have you been?
To achieve the Powa you seek I would first paint it white.... I'd get a second opinion on the dyno #'s, sounds really
low.
You know better than most on performance. I wish I could be of better assistance. Shoot me a text when you want to go
for a ride.

 

[bradbusa]

Neil, what's up man? any idea if there's another dyno around here? i went to cunningham's yesterday. pieter swears by him. i'm inclined to believe those hp numbers, my bike feels nothing like pieter's zx14, which made 175hp

 

[cheferman65]

Brad, I'm well. If you were at Floyd's then I'm sorry to say your bike is a bit down on power. He knows a thing or two
about tuning and the Hayabusa Did you see his drag bikes?. I'm thinking we might have to dig into your engine.
Let me make a few phone calls tomorrow, I'll ask Scotto for some advise.
I'll call you in the afternoon.
Pieter's bike is scary! and what is even more scary is he rides it really well!

 

[bradbusa]

good morning, how is everyone's saturday? Just wanted to give a quick update for all those who were interested.. finally got a chance to run a compression test on the scoot this morning. i decided this was the first place to start, then proceed to leakdown test, and valve adjust, etc..
the suzuki manual gives static compression spec at 199-256psi.
my compression values are 225, 225, 230, 225.. dead nuts in the middle! that was relief. i was really concerned that something in the block was leaking. according to these values, i'd say it's safe to go ahead and skip the leakdown test. and proceed straight to checking/adjusting valve clearances and measuring cam lobes. at this point i'm thinking that it's highly possible, after 40k miles my cam lobes may have worn a little.
as we all know, static and running compression are not going to be the same. a slightly worn cam lobe may not make a difference in static compression, but running compression may suffer because of it. so this is my next step.
sorry guys, i did not take photos this morning as i was kind of in a rush to finish by noon and head back home. when i remove the valve cover i'll be sure to photo document the process. im curious to see how a 40k mile old engine looks inside too! last time i had the cover off was around 18k.
i should also note that the spark plugs looked just as good today as they did when i installed them! none of them were wet, not too hot or fouled in any way. god i love ngk IR's!

 

[dadofthree]

It's very possible that all the old dog needs is a good going over. 40K ...... valve adjustment, throttle body sync, plugs, air filter.

 

[lil charlie]

Sounds like a fun project. Be sure to post those pics.

Sent from my DROIDX using Tapatalk

 

[superbeagle]

No expert here. But I know people have put over a 100,000 miles on these engines with no issues. I agree with dadofthree she properly just needs a good going through. Keep us updated very curious on your findings.

 

[FlatlandBusa]

I doubt the engine has anything wrong with it, a good tune up, clean the throttle bodies etc.

Also the catalytic converters in your stock could be starting to plug.

 

[bradbusa]

another quick update.. finally tore the valve cover off and checked my valves. last time i adjusted them i put them all towards the mid-upper range of spec. somehow exhaust valves tightened up since my 18k mile valve adjust. two valves were well below spec. almost zero lash. the rest were all almost below spec. way tooo tight. intake valves were fine, only the exhaust tightened up. most of them will be fine with .05-.1mm smaller shim. one of them was as far off by .2mm. also measured base circle and lift height to compare with all lobes. no considerable wear to mention. maybe .01-.02 here or there.
so, while i'm waiting for shims to arrive. i'm contemplating the intake cam mod. since they're both out. i know a lot of people have done it, but recently read something that bothered me. apparently the intake cam lobes do not line up with the exhaust cam lobes, so the lobe will not rest directly on the center of the lifter. has anyone encountered this? supposedly causes premature wear of lifters, etc..
am also considering a set of aftermarket cams for more grunt. which are the best to get for gen2 engine? i know i cant go too large without pulling the head for new valves/springs. i dont just want to put the bike back to stock, i'd like it to be slightly better than stock

back to the original concern of the thread here. now that i have done the compression test and determined there isnt any leakage in the cylinders, after having checked valves and finding exhaust are all too tight; would this contribute to my poor dyno results from last weekend?

have some photos of the teardown but they're all too large. stand by for resize

 

[dadofthree]

Maybe one of the mechs will speak up, but there was a intake cam, higher compression piston mod on the Gen I that had tremendous results. Don't know about the Gen II. I think Zuki tried to get all they could out of her.

 

[bradbusa]

i know you can buy an intake cam for use on the exhaust side. APE sells them with adjustable sprockets already installed. but the lobes dont line up, i checked. they're just a little tiny bit off

 

[Petey Wheatstraw]

I see ur in Florida.....just freshin it up,and take it to Walter Sprout.Lose the stock exhaust and put a GOOD pipe on it too,that should wake her back up.

 

[GSrider]

Did you get your power problem corrected?

I'm not a bike mechanic but worked as an auto mechanic for a number of years and may be able to give you some food for thought:

Having the valves set correctly is critical to performance as I'm sure you know. Cam and ignition timing and adequate ignition advance throughout the RPM is also critical to maximum power. You should be able to find a spec. in the shop manual for your cam lobes to see if they are getting worn enough to affect performance also.

I know your compression reading were right in the middle of the acceptable range but if they were up closer to the top limit of 256 I wonder how much that would affect peak performance? You mentioned the owner's stock bike producing about 25 more HP than yours. It would be interesting to know what his compression runs on this bike or another like it that produces 175-180 HP? I've always trusted a leakdown test to tell me more about critical cylinder sealing near TDC.

Fuel delivery and exhaust restriction over the RPM range can also be factors to consider. Did the shop where you had it dynoed have any tips or diagnostic tests they can run to determine where your HP went?

good luck, Pat

 

[Draco1340]

155 HP on a Gen II is quite low. A compression test will tell you if one cylinder is different from another, but it won't tell you if the whole head has gone soft. Need to do leakdown to see what the actual health of the motor is. If you valve clearance is down to zero you most likely have exhaust valve leakage that can be confirmed with leakdown. Small amounts of leak cause these damn Ti valves to burn up very quickly. Taking the head off and freshening it up is a simple job that can be done with the motor still in the bike. A simple valve job or lap might be all you need, but you are down 20 horsepower,so find out why. Another thing to keep an eye out for is the valve springs soften on these Gen II motors very quickly. Soft springs will cause power to drop quickly at high RPMs. Mine dropped 10 - 15 lbs in the first 1000 miles.

 

[Schism]

i agree with you! if you plan on keeping her, pump some doe into it.

 

[mestona]

Maybe a carpenter port job with cams and an exhaust....

Carpenter Racing