421cc Cheetah cub Dyno Result - 106 BHP

[Mad Biker]

I had my 421 cheetah cub on the dyno trying out a new exhaust pipe design. The aim was to create a pipe with more mid range but this one made the same peak power (98hp) and more torque, just under 48 ft lbs and produced more power all through the rev range.
Next to be done is some port work to boost the mid more at the expense of some top. I only picked up the graph from 6000rpm but you can get the idea.

[midlifecrisisrd]

That's one hellava scary curve

Steve

[marsbar350]

really

[midlifecrisisrd]

makes my quest for 80 out the 385 look possible

steve

[peacey]

Bet that goes like sh*t off a shovel

[Mad Biker]

It went really well before so im looking forward to trying it with the changes

[muttsnuts]

impressive graph, is that wheel or crank horse power ?, also what dyno was it done on, always interested in other dyno charts off other machines !

[Mad Biker]

thats at the wheel. That is on a Dyno Dynamics Dyno. I have had it dynoed before on a Dyna Pro and the results came out within a couple of horse power (slightly higher hp on the dyna pro), so i would say its fairly accurate. But as all the work is now being tested on the Dyno Dynamics Dyno i got the base run first to give a better comparison once the changes are made.

[pistanbroke]

Impressive stuff!!!

[alibongo]

Cool.

That is going to cause serious handlebar/face interaction!

[Norbo]

Holly crap that's some powerfull bike

[muttsnuts]

I'd like to see this run on John's dyno to see how its making the power etc, its 20bhp more than any of the others I am aware of, so very interested to find out what has been done to this engine to make so much power, especially if its stock

[yazza54]

Read up on plenty of cheetah cub 4mms making similar to this kinda power awesome mate keep us posted on how it rides

[tsa]

The cheetah has a much better port layout than the Athena and can get the 100bhp with minor porting. But saying that I know of a TSS 485 and thats struggling to make 90bhp at the moment.

[yazza54]

Feb 25, 2014 12:18:00 GMT 1 tsa said:

The cheetah has a much better port layout than the Athena and can get the 100bhp with minor porting. But saying that I know of a TSS 485 and thats struggling to make 90bhp at the moment.

Do you do pipes for the cheetah cub mate?

[JOHN-DYNOSTAR]

this makes for interesting reading on the horsepower obtainable

bansheehq.com/forums/index.php?showtopic=137851&page=2

[muttsnuts]

hehe, Thanks John, I am not sure if that's made it clearer or my more confusing !! - it looks like they can't even agree what one can produce !!

suppose its all academic anyway, what it makes is what it makes, how its ridden and in what chassis combined with a skilled rider makes all of the difference, for the road, 70bhp or 98bhp out of a 2 stroke in a light weight frame is going to be more than enough for most people - IMHO anyway !!

only time I am really interested in figures is when I see them on your dyno, simply because I can then draw a direct comparison to not only my own bike, but all of the others that we have done on there, one things for sure, my little LC kicking out what it does makes for an interesting ride and hopefully we will squeeze some more out of it, so it will be a complete hoot to ride then - and lets not even mention the little ZXR project - if that works then that will be plain bonkers!

[tsa]

Feb 25, 2014 13:38:15 GMT 1 yazza54 said:

Feb 25, 2014 12:18:00 GMT 1 tsa said:

The cheetah has a much better port layout than the Athena and can get the 100bhp with minor porting. But saying that I know of a TSS 485 and thats struggling to make 90bhp at the moment.

Do you do pipes for the cheetah cub mate?

I can develop a pipe for a cheetah but Id need a lot of info of the cylinder, ignition, reeds, head, carbs all these will need measuring accurately

[Mad Biker]

For anyone that knows what they are doing, 100hp is easily obtainable with a cheetah cub, through a careful assembly, set up and good exhaust design.
When I originally got the kit I was steered away from the cheetah kit with the big reed blocks as they were not achieving the same power. My goal for this project was pure and simple top end hp.....and as far as im aware im the 1st person to make 100hp from a 421 in this country.
I took it to Mark Dent (Dyna pro) as they widely accepted to give a true reading, on which it made 102hp. The most recent reading is on a Dyno Dynamic and it read 98hp, considering the fuel (Pump fuel) in it was 4 months old, the tyres have been changed for the stickiest race compound tyres I believe these reading to be accurate.
We could have a dyno debate for the rest of our lives, so instead of theorising I took it to the track and this bike would not of been able to out drag my 600cc (which produced 118hp on the same dyno) if the dyno was lying?
If I feel like getting more impressive numbers I might take it to an optimistic dyno one day!! Lol.

[muttsnuts]

um, just been reading the spec of your motor, knowing what's in it, I can see how the power is up there, I reckon you might have a fairly empty bank balance as well , still, to get that type of power out of one would require some serious dosh, so hat's off to you, impressive motor nonetheless, not sure I'd want to ride it on the road as I am sure that power comes in with a fair kick !!

[Mad Biker]

Yes it did cost a fair bit, It was over 2k and the only major parts I have left of the original engine are the clutch centre, pressure plate, 4th, 5th and 6th gears and the crank cases.
To get that power, I have only spent at most £300 more then if I done the same thing with Athena barrels. As the cubs are more expensive to purchase. All the other parts could be used on which ever barrels people choose to buy.
I ride this on the road and the power does come in with a kick, Surprisingly it has good torque to ride around the streets, it will even pull away in 3rd gear! If you really want to get cracking you would have to rev it above 7k, On the track it has to stay above 7k all the time, which is not to difficult. I have also rode Athena 421's and they come in with a kick too, if not more so as they make more mid range but run out of puff earlier.

[copper99]

Must feel bloody brilliant to ride....any pics of the bike itself mate?

[Mad Biker]

Here you go. The engine is in a Spondon TZ250 chassis

[alibongo]

Did PB do a feature on this not so long ago? I have seen it in a mag for sure.

[copper99]

Thats a stunning piece of work..where will we see that haunting the roads at then? Id love to see it in the flesh.

[begbie27]

That is pure bike porn! I love it. Well done.

[Mad Biker]

Thanks very much.
It was in PB a couple of years back, hopefully Ill do another feature with it where they can ride it.
Its usually found around the Kent area and all being well will be at Brands Hatch this year for the Bemsee meetings.

[elegy]

20 horse at 7,000rpm is awful really. Looks to me like it would be a difficult bike to ride on road or even track as a power curve that steep is not to be trusted exiting corners!!! If you could gain 15-30 horse down there it would be well worth considerable sacrifices up top and you would have a 'faster' bike.

[Mad Biker]

No its not difficult to ride on the road or track. Infact its the most fun bike ive ever rode on either.
Like ive said my goal was top end power. I could of had more tuning work done to increase the power further, but its been very reliable so i dont want to change that. Hence the reason i am having work done to increase the mid range now.
My plan is to offer this kit to people in 2 versions, the top end or the new mid range version. But i will only do this once ive proven it myself.

[Mad Biker]

Ive had a bit more work done on the bike this week. Barrels have been ported, and a lot of time has gone into the ignition curve. At the moment ive only got a picture of the graph on my phone so waiting for a better quality one to be sent over. Its making more power under 7k. at 8k its making 12hp more over the original set up and peak is now up to 106hp.
Still a bit of work to do on carburetion, but I think its just about there for this phase and looking forward to riding it.