Finally done the first step of work for my MC28 today, however the dyno graph is showing a stock MC28 has power of 58hp and my mc28 only has 48hp, I thought the MC28 only had ~40hp, the unit is SAE corrected horsepower, does that make the different?
Anyway i knew my MC 28 is not giving the right power at high rev as compare to my friend's MC28, it start to seems a bit slack after 10000rpm, but before 10000rpm it seems to be fine, the feeling from riding really agrees with the dyno curve. The wired thing is i already got expansion chamber fitted, although I dont know what brand, but is definely not the stock one, and i ask a few machinic they said my pipe is good ones and not need to replace them, so howcome my bike is producing 10hp less than stock? I realise that i need to repack my end can muffler as is damn old, could that be the reason? or the jet setting is not tune properly, maybe bigger jet is needed?? _________________ MC28, Repsol
Stock MC28 is 40hp. 48~50hp is about as good as you'd expect with a set of pipes and a rejet, with no other modifications. _________________ Andy.
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If thats the case, the dyno must have error? The dyno shows the peak power (48hp) produced at 10,500rpm for my bike, and for the stock bike is at 11,000rpm (58hp), this dont agree with the stock specification though both rpm and horse power value. _________________ MC28, Repsol
Well the "stock" MC28 they are using as a comparison obviously wasn't stock! Either that, or as you say, there is a real problem somewhere, but 48hp out of an MC28 with nothing more than a set of pipes is nothing more than you can expect.
A 58hp MC28 would indicate quite a lot of modification. Fontyyy's makes more than that, but he's using an HRC card, open airbox, race pipes, etc.
Stock NSR's (in good condition) tend to make bang on what Honda say on a good dyno. _________________ Andy.
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A genuine 58bhp is going to need at least some pipes (maybe modded Honda ones), airbox mods and a '21 flywheel along with a decent setup. Tyga only got 58.5 without the card (see here, the dyno chart for the standard one (the blue trace here) agrees totally with what you say, revs to 10,000 or so then (just as a modded one starts to really go) it fades away.
Mine (Tyga pipes, HRC smartcard, open airbox, HRC jetkit) made 57 with a nice safe setup, 60.7 on the day then probably 63 or so jetted nearer (too near ) the edge.
The power you've got sounds about right and you want to be checking the jetting before you mod it any further (i.e. don't just drill holes in the airbox), the power of the standard one is just flat wrong, it's either a complete lie or not a standard bike. _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
Juls wrote:If thats the case, the dyno must have error? The dyno shows the peak power (48hp) produced at 10,500rpm for my bike, and for the stock bike is at 11,000rpm (58hp), this dont agree with the stock specification though both rpm and horse power value.
The other thing you have to remeber is Dyno's from garage to garage can varie alot in there readings.
And to confirm that your reading is okay!! My Stock 21 had 46HP by the time i spent some serious cash im now looking at 58hp, the mods i have are, HRC jet Kit, Modded Box, HRC reeds, cages, stuffers, Tyga chambers n pipes and i have had the full derestriction done (wire splice) ! ! so i would say your doing fine!!!
here is a before and after shot and youll see 46hp at 10500 rpm
It's all true. My old 28SP made 60.2 with the same mods as Fontyyy has on his, Tyga pipes, HRC 030 card, jet kit and open box. So they're all pretty similar, i'd say even on different dynos... That was with a CO2 reading of around 6-6.25% throughout the range. _________________ NSR300R - Why did i ever have a 250...
Andy wrote:Love the new signature Fontyyy! I reckon I can get mine down to at least the low 170's!!
You know smaller is better... I proved that when I introduced you to HQ last August!!
Yeah yeah yeah, and I've not been the same since, westerners are just too much hard work and not really worth the hassel.
Dyno's do vary but not by enough to have a stock '28 make 58bhp (about 45% out) _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
ic, dont know what wrong with it then...
Anyway, my bike does feel less power than my friend's MC21 which has pipe, wire splice, mod airbox and jetting, but the power only comes after 10,000 rpm at least on the MC21, for my MC28 power comes much earlier and makes it easier to accelerate out corner thru the mountain.
My bike only have pipes, but next week gonna re-jet, mod airbox and MC21 flywheel see how it goes... The mechanic said his gonna put bigger jet for me, and whats the different from like those HRC jetkit? _________________ MC28, Repsol
Last edited by Juls on Sat Apr 15, 2006 1:44 pm; edited 1 time in total
Make sure your mechanic knows what he's doing, modding the airbox and changing the timing ('21 flywheel) is when you start to need a lot bigger jets. The HRC jet kit has massive (170 mains is as small as the '28 kit goes, 140 mains is std) jets but is designed to run without the powerjets. I'd say probably start at 160 mains if you're just fitting bigger main jets and retaining the power jets.
***DO NOT RIDE THE BIKE WITH MODDED AIRBOX, 21 FLYWHEEL AND STANDARD JETTING OR IT WILL SEIZE*** _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
Thanks for advice! I will definely check with the mechanic and makes sure everythings cool, his one of the best in town here for 2-stroke. My friends MC21 really only have the real power at really high rev is that normal, can he get more mid-range by bigger main jet? _________________ MC28, Repsol
There's not many 100% stock 28's that actually break the 40hp barrier. That's what we found out here anyway. Paul's 28 was a very miserable 38hp, much to his dismay!!! We soon had it up to 60+hp. But that was over 10 years ago and the only thing left on that bike now is the frame and swingarm.
You can't always take dyno numbers too seriously. There are allot of variables that can effect the outcome of the numbers including what gear your in, tire pressure, the person operating the machine, and the particular machine. Most the guys I know that use dynos regularly only use them for final tuning and don't take the numbers too seriously.
I know on my race car that the third run is usually the best. Then heat soak starts to effect the intake system and the numbers fall off slightly.
I'm not saying you don't have a problem, but if your not doing back to back tests with the other bike then the numbers don't mean much in absolute terms.
--
james
Its not how fast you go...Its how you go fast.
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