Hi everybody,
I have my 28 with some hrc pieces,
the 030 hrc card,
full hrc jet kit with the 2 specials x and y pieces (b needle and 158 )
magtek with michelin power one tires,
Conversion front head cylinder,
dogfight pipes ...
and something more i don´t remember now.

I have some questions:
how much h.p. have my bike at wheel?
What are the best tires for ours bikes to use in track?
Can i put slicks in standar magtek wheels?
How can i have more h.p. easily?

Thanks!!!!

P.D. I finished 2nd. in s.p. 250 category in a race of two strokes,

Hey Pedro, congratulations on the podium finish!

Slicks will fit on the standard Magtek rims (if your racing class will allow it), but you will need to carefully set the suspension up to make the most of them as they will technically be over-sized, and this can ruin the handling unless done properly. Maybe look out for some RS250 NX5 HRC Magteks which will be the correct size for slicks? The rear will need to be fitted "back to front", but it doesn't matter.

As for easy* power, well that's difficult to say. If it's not been set up on the dyno then you may well find your HRC carded 28 is only making 58hp, in which case a good tweak of the carbs could liberate 3~5hp! On the other hand, it may be pretty much spot on already, and in that case you are going to find it very difficult to get any more than 62~63hp without getting inside the barrels and cases with a Dremel!

*62~63hp is the easy (if costly) bit on an MC28!
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Andy.
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Tyga performance.com sell special VHM cylinder heads for your bike which would allow you to tune your engine for more power.

They also sell HRC style reed valve rectifiers and carbon reed petals which might help.

You can buy aluminium parts which will reduce your bike's weight from Tyga too.

Many racers around the world remove their airbox completely and run 'open carbs'. Or they run the HRC airbox. Andy, who runs this website has made carbon fibre replicas of the HRC airbox (i have one), it may be worth asking him to make one for you? Just remember that any of these engine/airbox modifications may require a carburettor main jet change.

Your bike probably makes about 55-60 horsepower at the rear wheel.

The tyres you are using are very good but you can fit slicks to your magteks if you can get them in the right sizes.

Are there any photos or references on the internet of your race bike that we could look at?
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After years of moaning about immigrants now i am one...

beat me to it! sorry andy
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After years of moaning about immigrants now i am one...

I seriously doubt VHM's will give more than about 1hp over NSR heads, if that, and don't reckon carbon reeds are worth all the hype, but HRC rectifiers certainly DO seem to help the MC28. I do agree that the bike is probably making 55~60hp though, and that open carbs/HRC airbox (if not set up like that already) is the way to go to get up to 62~63hp.

I've yet to see an MC28 with standard internals make any more than that. They won't make the power an MC18 or MC21 does without getting the grinder out!

VHM's are great for ease of use though. With the O-rings instead of a gasket you can pull the heads off in no time and at no cost after a plug chop, which is far better than trying to accurately read spart plugs and risking head £10 gasket failures by trying to reuse them! You've got to use quite a few £10 head gaskets to pay for a set of VHM's though!
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Andy.
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Pedro-ktm wrote:
magtek with michelin power one tires,

What are the best tires for ours bikes to use in track?

Most of the front F250/F400 riders here use Pirelli Diablo Supercorsa's but they are very hard to find in 110 or 150 sizes and very expensive too.
A couple of them have said nice things about the Michelin Power Ones too.

If you go to a 3.5" front you could try Dunlop KR364 intermediates if class rules allow or go to the easily available 120 and 160 sized Pirelli's.

If you go to a 3.5" front and a 5" rear and your class rules allow you could also try Michelin Supermoto tyres, they're treaded but not road legal.
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Hi,
I will try to give the bike on a dyno to know the real h.p. it have.

Thanks everybody for the help.
I will try to put slicks.
This weekend i show you the photo of my bike.

Thanks

Sorry, another question.

The standar size are 110-70-17 and 150-60-17,but

the front magtek is 3,5, and rear 4,5?


i don´t find/see it in specifications.
thanks again.

The standard NSR Magteks are 3" and 4.5". RS Magteks are available in a number of sizes; most common of which are 3.5" for the front, and I think 5.25" for the rear. Someone else will have to confirm the most common rear size, but I know they are availabe in at least 5", 5.25", and 5.5".

The wider the wheels/tyres the slower the steering generally becomes, and the more important fine tuning of geometry and suspension setup becomes to overcome this. The NSR can certainly be made to work with a 3.5"/5" combination as I've ridden a couple of MC21's on these sizes that handled impeccably, but they were both running HRC F3/RS suspension too, and I've ridden otherwise standard MC21's with oversized tyres that handled awfully! Correct setup is crucial.

Once you have a reliable dyno reading you will have an idea of what options are open to you. (Ideally you want to test a stock bike at the same time, as they are bang on the restricted limit from Honda and this gives a really good indication of how accurate the dyno is in the lower range!)
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Thanks for the photos Pedro-ktm, your bike looks great!

What is the name of the club that organises the races you compete in?

Another thing to consider about tyres; alot of riders prefer to use treaded, trackday tyres such as Metzeler Racetecs instead of full slicks because at the speed they are running at club level, on lightweight bikes, its hard to get slicks to full working temperature, but treaded tyres get hotter, stickier and grip better.

One of the really fast guys i used to race against in MZ250 would cut his Dunlop slicks with a special tool to make his own tread pattern. He found it helped the tyre run hotter during a race and made more grip.
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This is right Hermit...

All the Supermoto guys cut the tires for that reason... I used to cut my Metzeler Racetec when i was racing in Supermoto... It's a very easy job to do if you have the right tool... You mark the tire fisrt with a choke and a hand made spacer so the dstances between the grooves are the same and then start to cut it... there are many different "cut noses" to choose from depending how big or small you want to make the grooves... You can also even write your own name on the tire...!!!!

Hermit wrote:Thanks for the photos Pedro-ktm, your bike looks great!

What is the name of the club that organises the races you compete in?

Another thing to consider about tyres; alot of riders prefer to use treaded, trackday tyres such as Metzeler Racetecs instead of full slicks because at the speed they are running at club level, on lightweight bikes, its hard to get slicks to full working temperature, but treaded tyres get hotter, stickier and grip better.

One of the really fast guys i used to race against in MZ250 would cut his Dunlop slicks with a special tool to make his own tread pattern. He found it helped the tyre run hotter during a race and made more grip.

This 2 stroke club (club2t):
http://www.club2t.org/

click on copa2t

Regards