Went on MCN weekend and put my 21 on Dyno it made 53bhp it's had wiring splice done got a high flo air filter and rejetted to 45 pilots and 145 mains is this decent considering small mods done?

Also what gains if any have been seen from Mfactory cans?
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MC21 SP

nsr Moggy wrote:Went on MCN weekend and put my 21 on Dyno it made 53bhp it's had wiring splice done got a high flo air filter and rejetted to 45 pilots and 145 mains is this decent considering small mods done?

Also what gains if any have been seen from Mfactory cans?

I would say thats okay, im sure more can be had without changing anything, just a good tweaking, My 21 has, Tyga chambers, cans, moded airbox, standard filter, hrc jet kit, hrc reeds, cages, and hiflo stuffers, set up well and to run safe im getting 58hp and she runs sweet as, other people on theis site are getting much more with similar mods, and some are getting near 70hp now, so there is always room to get more, its just how much more do you wana spend!

It not just how much do you want to spend, I'm sure Steve can get 60+ out of any fresh '18 or 21' with just a few jets, a pair of wire cutters, a soldering iron and a holesaw. It's how close to the edge do you want to jet it? I saw 4 bhp from one jet change and then probably a couple more from going down another size and putting the lid back on the airbox and it was absolutely flying and definately on the lean side, then it seized

Mid 50's (which is what the UK "full power" 250's really produced) is probably a safer number that the mid 60's we all tend to chase.

Chambers are worth a hp or 2 peak and some overrev but cost 5+ midrange so they're wasted on the road, Andy and co are trying to find some compromise there (see here), a couple of holes in the lid is better than the "proper" modded airbox, the jet kit is more to allow tweaking, you don't need it all (although the needles are nice) but you do need the jets to hand it to sort the jetting out in the first place, especially if you're chasing either hp or a nice crisp throttle respose.
And intake mods are very subjective, as RC46 found, his dyno man didn't like the carbon ones at all, I've got some Boyseen reeds, some (RC46's) carbon Tyga ones and will pick up some HRC rectifers from Andy this weekend I hope and come the nice weather I'll be seeing whats what...this is when you really need the jet kit
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I'd be happy with 60
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If you dont like the way that i ride.....Stop trying to keep up!!!!!

A '21 with stock pipes and mod'ed air box should easy see over 58bhp. I know fontyyy doesnt like dynojet dynos for some reason but even my bog stock '18 with an air box mod made just over 60bhp.

I think if your getting low 50's on any dyno there is a whole lot more to come from it as long as it has a good crank, seals and rings in it.

If your air box isnt mod'ed then this is whats holding you back. Fitting a set of swarbrick race cans lifted the '18 from 60 to 62bhp and then the tygas added another 1.5bhp. The biggest jets i have ever had to run in that are 132 and normaly run 130's with 38 pilots.

A whole load of graphs can be found in the "Tuning" section in Ignition mods.
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If I have to take the carbs off once more...

mick wrote:
I'd be happy with 60

I'm not happy with 64!

Mind you, I suppose the motor had only done about 5 miles when it got dyno'd, so hopefully was a little tight still!!
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Last edited by Andy on Tue Mar 28, 2006 5:54 pm; edited 1 time in total

64 is all youre getting for a min sunshine, you weren't to happy going as low as we did on the jetting!
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If I have to take the carbs off once more...

Well I've been studying some of my 90~93 HARC Pro spec' sheets and they are down in the 170's too, and that's on pre-mix! My F3 carbs are in the 160's, so I'm guessing there's plenty of room for improvements!

I'll put a hundred miles on it (er, maybe!!) and pull the heads to see what it's doing. Then I expect we'll be doing a Franz Klammer with the jetting, and maybe even going to 0.4mm base gaskets!!
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If your willing to go down to 0.4mm then I'm not going to use a gasket at all and I will run jets smaller than stock... so there
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If I have to take the carbs off once more...

Well, I was considering cutting O-ring grooves in the bases of the barrels like the NSR500V...
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Well maybe thats what we should try next then, lord knows we have enough dead barrels.
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If I have to take the carbs off once more...

StephenRC45 wrote:I know fontyyy doesnt like dynojet dynos

Mate, I don't dislike them and I certainly wouldn't let anyone else loose on my bikes to set them up, but I am under the impression that they do tend to read higher than a Dynopro and plenty of less honest dyno guys tweak the figures via the atmospheric variables. Witness on gaybike std CBR400's with 61bhp and then just a rejet gives 65.............really?
If you can be bothered to read this it's the bloke who started DynoJet talking about how and why (or why not).
The car world is definately full of rolling road operaters with dynos containing some very weak horses. The old Car and Car Conversions mag years ago ran some claimed 170bhp 2 litre pinto road going Escorts up on a decent dyno to find 20%+ power "missing".

It doesn't matter anyway, on Saturday if my RVF gives 45 bhp at start of the day and 50 at the end or 65 at the start and 72 at the end, the power has still gone up by 10% and that's what counts.

Then we just whack the altitude up to 15,000' and print off the resulting 95bhp graph.
Perfect...works for BDK

And Andy Harc Pro may be down to 170's, but they aren't running the damn thing flat out up hill for mile on mile in 6th with a 15st "load" (+ road kit) on it in mid winter (oh sorry, it's alledgedly spring now) are they??
And don't say you won't, you know what'll happen, Steve'll come past on a 300 (or the RC!!) and the red mist will decend
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Steve will be going passed on the F3 he hopes and I would be most disapointed if myself or Andy weren't ragging them within 1/32 of their lives!

Run lean and cover the clutch is what I say!
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If I have to take the carbs off once more...

fontyyy wrote:
And don't say you won't, you know what'll happen, Steve'll come past on a 300 (or the RC!!) and the red mist will decend

RC definitely, MC18 maybe... 300, won't happen!!

The only chance the 300 has of coming past me is if I'm sat in the BK and it goes past on the back of an AA flatbed!!
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lol hey now, the 300 isnt like that anymore, Ive done almost hundreds of yards without a prob now, though yes the '18 is still my chosen weapon.
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If I have to take the carbs off once more...