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Reasons for a low dyno reading

7K views 21 replies 13 participants last post by  performula 
#1 ·
So I got my K8 dynoed on Saturday wit lower results that I expected when compared to similar bikes. (DynoJet Eddy current - recent model)

My bike read 168bhp with a full Yoshi system, BMC air filter, blueprinted & perhaps other work done to it (its a ex Formula Extreme race bike with 9000km on the clocks). I will ring the engine tuner tomorrow to see if any other work has been done also. Apparently the engine was freshened up for the 2010 season but never ran because the team switched to CBR1000's & that's how I ended up with the bike.

- The exhaust is rattly as hell - all the joints have worn loose & leaking a little
- The oil level is a little high - reads just above the top mark with the engine stone cold so obviously goes a bit higher again with normal temp oil.
The bike has been little used for almost 2 years now so maybe the injectors are a little bit blocked?? (There was fresh 98 Octane fuel in here for the run)
- The AFR was reading at 14.0-1 consistently across all the RPM on the run
- It was 30oC on the day but the dyno should have compensated for that.

The race team I bought the bike from said it was a 190bhp engine so that's why I'm a bit upset with the reading being so far away. I thought it would realistically pull over 180bhp & I'd be happy with that. It feels bloody fit on the road compared to my stock K6 when riding back to back though but the gearing is a little shorter also so not really a fair comparison.

Would normally not be in the least upset except I thought for a race bike it would do close to what I was promised when I bought it. With the AFR being so far out & consistently out at 14:1 am thinking the injectors may be a little gummed up. Also with the oil level being a little high it may have dragged the torque down too sue to extra crankcase pressure. The bike wasnt tied down either on the dyno - operator just clamped the front wheel. Would all the above have a big influence on the overall output or am I just fishing for BS excuses?

I dont want to spend any more money on this engine if it's weak in the first place. Will do a compression test soon to see if that's in good nick. What is normally done to 'freshen up' a Superstock engine for the next season from a reputable engine builder?

For comparison other bikes on the day gave the following results:

- 2012 ZX14R (stock) - 185hp
- 2012 ZX10R (stock) - 178hp
- 2012 ZX6R (stock) - 111hp
- 2012 CBR1000 (stock) - 159hp
- 2005 ZX10R (slip-on) - 153hp
- 1998 CBR600 (stock) - 85hp
 
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#2 ·
I wouldnt stress about it too much. All dynos read differently(my buddys new 14R made 195rwhp stock). Now if there was another stock K8(or one with known mods) there with you that same day it would be a much better way to evaluate&compare your numbers to his. You could always do a leak down to see the condition of the top end. Also,what fuel was the race team using&tuned the bike with? Were you using that same fuel when you dynoed? That could also contribute to any horsepower loss especially if they tuned with oxygenated fuel compared to non-oxygenated fuel.
 
#4 ·
I'm not too concerned on the actual HP reading its more like what I expected it to be in especially as I bought the bike based on info from the team. Am just wondering if I was told some fibs or if the HP was lower for another reason (wear on the engine, over filled oil, leaking exhaust, map being too lean, tyre slip on dyno, etc.) I bought the bike mainly because it had a blueprinted engine, a full Ti system & top notch Ohlins suspension fitted. Would be very disappointed if the engine was weak with all that blueprinting work done.... Am just looking for a few answers really

Good info on the oxygenated fuel btw - that may explain the consistently lean AFR but I though oxygenated fuel would have called for a richer map myself??

Will do a compression test soon enough. Is a leak down test a far better indicator of the state of the top end? What's involved in a top end freshen up anyways? Is it just rings, valve guide seals & camchain or more involved??
 
#5 ·
none of the bikes you compared have any relivance if they were not strapped anything over 750cc needs to be strapped you will always get wheel slip.
you should run your stock k6 back to back to see what the diff is. then you would know how much power it would be up. (add 5 hp to what ever the k6 pulls) you need to know what compression the engine has to know what fuel to use 98 oct will almost always read lower then less oct. yes oxignated fuel would have alot richer map. (12.5-12.8) but achohal content in the fuel will very afr readings significantly.

jason
 
#6 ·
168 whp is damn good compared to the stock what....155? but if you want some REAL power you shoulda got a 10R like they had on the dyno. then you'd have 178 ;)

also depending on how leaky the exhaust really is, i bet if you fixed the leaks or got a new one, you'd be over 170. maybe throw a lil injector cleaner in there and lose a few ounces of oil but that shouldn't really make too big of a difference i wouldn't imagine....but i know for a fact a leaky pipe is leaking hp as well.
 
#7 ·
Did they refresh the motor before they sold you the bike or are you riding it after 1-2 seasons of racing worn out the engine....you didn't mention that.

Race engines require a lot more upkeep than unmodified street motor. If you are expecting a race motor (and potentially a race motor with who knows how much mileage on it already) to give you years of maintenance free service then you have the wrong motor sitting in your bike.
 
#8 ·
Thanks guys.

The ZX10R run was done with the bike strapped down but I cant recall if any of the other bikes were strapped down after mine.

I rang the engine builder & although he remembered the bike it was over 2 years since he did the work so can’t recall exactly what was done. The engine was ‘built’ (blueprinted I assume he means) with a refresh (piston, rings & bearings, springs & valve clearance, clutchplates, etc.) but stock otherwise. Power was 183bhp rearwheel after it was dynotuned with a PC3. Think that’s all I can get out of him as he was a bit dismissive otherwise especially as he didn’t know me from Adam.

The bike was sold to me with a ‘fresh’ engine rebuild so all I can do is believe them. However judging by the fact that the exhaust being worn & some weeping oil seals I am inclined to think that maybe t has done a full season – only a compression check will tell I suppose. I did expect this engine to hold together for years as it was/is supposedly rebuild & I wont be taxing it very heavily on the roads. Again i’ll need to do a compression test methinks to get a better idea but I could be wrong. I’ll try & contact the previous owner later for his view.

I suppose what I really want is for someone who knows about this things to tell me that if you consider all the factors above (high oil level, lean AFR, leaky exhaust & bike not being strapped down) that you dyno reading is a bout 10-15bhp down from what it should be for a fresh blueprinted motor with stock internals & a full system/filter on 98RON gas.

Anyone care to do that?!
 
#10 ·
I have full leo vince exhaust, BMC race filter, and pcIII w/dyno tune and my bike dynoed at 167hp on Ryan schnitz dyno. Then a few days later it dynoed around 158 (dont recall exact number) on dyno at Honda East Toledo.

Your difference is probably the dyno.

The zx10 number you posted is about the same as my cousins. He has 05 zx10 with two brothers slip on and pcIII dyno tuned. His was like 156hp
 
#11 ·
Since you're in Melbourne. To put you're mind at rest you may want to have PTR (Phil Tainton Racing) dyno it. He is the boss of Team Suzuki Australia and has set up and tuned shitloads of GSXR's in all different forms, road, superbike and superstock. He'll be able to tell you exactly what numbers it should be running.
 
#12 · (Edited)
Seems like I was slightly mistaken with the dyno results (more like I was given mis-information). On the face of it now the bike doesn’t seem weak as I feared.
Comparing the results below the against my K8 for me shows that the bike is 13hp up on 2 fit & healthy current model stock CBR1000’s & a piped 2005 ZX10R. Seeing as the Akrapovic website dyno has both bikes reading within 3hp of each other stock that’s a good sign. More tellingly it’s 3ft/lb stronger in the midrange than the other literbikes which is a bigger indicator of how fit the motor is & a good indication of compression, parts wear etc. Am positive now with less oil in the sump, a well sealed exhaust, clean injectors, the bike strapped down to the dyno rig & the correct AFR tuned to the bike I would see another 5 or more ponies liberated which would put it into modern litrebike power – happy days 

May get a dyno chart readout also – stay tuned. When I get the bike converted back fully to road spec I might take a trip to PTR for another dyno run.

Year Bike - Kilometres - Max Power - ft/lbs


2012 - Kawasaki ZX14R - 15,000 - 184.60 - 109.82
2012 - Kawasaki ZX10R - 6,800 - 174.76 - not avail
2008 - Suzuki GSXR1000 K8 - 9,500 - 168.80 - 77.98
2012 - Hands CBR1000RR - 3,300 - 156.25 - 74.97
2008 - Honda CBR1000 - 88,000 - 155.71 - 74.69
2004 - Kawasaki ZX10R - 57,000 - 152.94 - 75.17
2009 - Kawasaki GTR1400 - 16,000 - 138.60 - 92.34
2001 - Honda CBR929 - 47,500 - 126.94 - 64.12
1998 - Yamaha R1 - 130,000 - 123.53 - 67.59
2012 - Kawasaki ZX6R - 14,048 - 110.73 - 43.53
1998 - Kawasaki ZX7R P3 - 136,000 - 105.58 - not avail
2008 - Honda CBR600RR - 30,900 - 99.40 - 40.65
2008 - BMW F800ST - 30,000 - 85.93 - not avail
1998 - Honda CBR600 F3 - 131,000 - 85.42 - 39.69


From the above chart it shows that higher mileage bikes still make good power as long as they’re taken car of. Also BMW seem to underquote their power figures - just like their cars....
 
#14 ·
WTF!!!!!??? My dyno said my dick was 13" long! Are you telling me that number might be incorrect? :scratch
 
#16 ·
Nothing to do with Dick measuring Guys. I paid for a bike with a certain amount of HP so I am just looking to see if I got that (or close enough to it). Am well aware that you can get a dyno to read however you want it

If you read the post you should see that I’m only comparing relative readings & not absolute figures. Like I said 13hp above 2 identical stock CBR1000RR’s on the day & 3ft/lb extra torque is proof enough to me that my motor is fit & doesn’t need a rebuild. I’ll do a compression test to be sure but otherwise I’m happy.
 
#18 ·
Just busting your balls. The point being dynos are good for tuning, not so good for comparison. Temp change alone, same day, same dyno, could change your readings in the 8 hp range.

I believe they said mm not inches.
But it's rock hard baby! :lol
 
#20 ·
Got my dyno printout last night. AFR is not great & this was after the operator adjusted it to richen it up for the last run but it didn’t have a marked effect on power.

Again am not looking for a figure to wave about in the pub – just an indication of engine health & rudeness.

 
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