HI Guy’s I have purchased the following and I am currently in the process of fitting it all to my MC28SE


1.) Tyga Side by Side Expansion Chambers with Kevlar Silencers.
2.) Aktive Multi Frequency Carbon Reeds.
3.) Tyga Hi-Flo Reed Valves and Stuffers.
4.) MC21 Flywheel.
5.) Modded MC28 Airbox Lid
6.) HRC Jet Kit……Still Not Opened


From what I have fitted on the performance side, can any of you guy’s give me some ball park area of what jetting to use.
(I now realise that, as I do not intend to run without a Airbox that the HRC Jet Kit is now a waste of £150)
I need to ride the bike about 40 miles to the nearest 2 stroke dyno tuner and I need some ball park figure to get it there undamaged.

I know you don’t like suggesting info like this, but someone may have the same set up and can let me have their data as a starting point that would be good.

Cheers Rob

It's a complete myth that the HRC jet kit is a waste of money.
The smallest size in both my '28 jet kits is a 170, that's only fractionally bigger (area for area) that the stock PJ and MJ in a '28. I've never run less than a 182/185, that was on stock derestricted pipes, stock '21 cans and a stock airbox for a quiet trackday (running the 030 card).
Tell you what, block the PJ's off, chuck the 170 MJ's and HRC emulsion tubes in, do all your mods and run it flat out in 6th on a nice cool evening.
I'll bet you a tenner it seizes

MY mc28 ran;

030 card
Stock replated SP barrels and heads (so, in theory slightly higher compression than std as they have to take something off)
HRC rectifiers
Tyga carbon reeds
Tyga side by side pipes
Modded air box
HRC jet kit fitted, std SJ's retained, power jets blocked off.
188MJ (rear cyl) /190MJ (front cyl), both on 2nd clip on the B needle (i.e. one clip leaner (closer to the top, "blunt end") than middle).

61.something bhp.

All other things being equal that should be OK for a base on yours.
The 030 card would appear to provide more advance than the '21 flywheel. My bike would start and run on the stock card (c/w '28 flywheel) but felt very rich, I'd guess at least 4 sizes too rich.

note;
These are my experiences, always start rich and go down, pushing a bike with a fouled plug is a nicer experience than pushing one with a wrecked barrel and 2 square inches of chrome plating floating around in the crank case.
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Last edited by fontyyy on Wed Jun 18, 2008 4:28 pm; edited 3 times in total

Thank you for taking the time again to write a lengthy and informative reply....You're a star

Do you think I should block off the power jets then and just run on the mains, even though the bike is only going to see road use?

Would the two jet combination be better and more flexible for road use or just harder to set up and have no real benefits ?.

Also upon opening my carbs up this evening I have found deposits of green/yellow substance all over the jets and float chamber, obviously from the petrol being in there for ages.

Any idea’s on how to remove it, as carb cleaner does not touch it

Cheers Rob

IMHO the PJ just adds another variable to getting the fuel/air mixture right. The flip side is that it does give you added variability to the 3 needles and MJ's supplied. However from a practical point of view most owners are going to be happy enough with what they can tune with the needles and MJ.

'Settings removed as they are irrelevant to MC28' - Shmokica

Fontyyy, I thought the needle positions were numbered from sharp end to blunt end, or bottom to top as it sits in the carb. Wouldn't 1 be the richest setting as the needle is further up the emulsion tube and as such would allow more fuel?


Last edited by shmokica on Wed Jun 18, 2008 9:51 pm; edited 2 times in total

As I (don't) understand it;

The fueling gets leaner the nearer the "blunt end" of the clip the needle is.

I have no real idea how the clip numbers are supposed to work, of from which end people count, or what is top or bottom or indeed what order you're "supposed" to list things in, top cyl/bottom cyl or bottom cyl/top cyl or whatever.

But I do know HRC say mc28 base settings are;

192/195 (main jet)
clip 3 / clip 4 (on the B needle)

and they mean;

192 MJ and the middle clip on the top cyl carb
195 MJ and the 2nd richest clip on the bottom cyl carb
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I love it, and it's why I disapprove of jetting recommendations on here!

First off, HRC say that clip 1 it the top position. Great if one person recommends clip 4 (from the top) and the second person tries clip 4 from the bottom!

Secondly, the thread is about an MC28, and MC21 jetting info has just been injected into the topic... perfect, seeing as they run entirely different carbs for a start!

If you guys REALLY want to talk about specific jet setups, then open a thread in the Members Area where it can be discussed frankly (we are all friends after all... I hope!), and let's not give any tinkering newbies (no offence to tinkering newbies) any wrong ideas!
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NSR-WORLD.COM

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An mc28 located in a cool & wet country, mc21 flywheel, race pipes, HRC jet kit, mc21 settings from a guy in a hot & dry country and a disagreement on the numbering of needle clip positions.

What could possibly go wrong

to say nothing of the fact that normal unleaded fuel in Australia has an octane rating of about 92 and I wouldn't put it in my generator
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Good on you John for posting up your jetting and discussing it here as it needs to be discussed and not something to be afraid of.....jeesh.

Fair enough comment, I have edited the post. Not having a go Fontyyy, I have just never found the literature clear on this, maybe my Australian accent. However I now know what end HRC needle positions are numbered from, so thanks.