125cc Supermoto - 2 Stroke goodness

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hiya

Ouch on the radiator.

RS varies. Over a few thousand miles of general use mine (34mm carb) average 55mpg. Normal use about 50 but raised up a bit from running in (and the fuel strikes - ridden like very sedately it managed 74.5mpg Razz

)

All the best

Katy
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

She is sounding pretty good considering its not fully set up and it's only done 70miles or so. I reckon it'll sound a bit different after the dyno set up though as my crap two stroke ear, says it's not quite there jetting wise yet?

Pain on the sexy Rad leak though mate. Being alloy, I reckon for someone with the right gear, it'll be a 30second job hopefully for a drink token.

My 200 rad is at the most local alloy radiator specialist, and I've give them the go ahead to do an uprated thicker alloy replica. The quote made me almost spit my tea all over the floor, as it was about double what I'd expected.

Can't really put a price on keeping a tuned hotter running engine safe though, that's what I've told myself anyway. Laughing

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Another little clip

https://youtu.be/BDzvqFOUkno

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Okay.
It's booked in for a dyno on Friday.

If I was to fit a power valve after it's been set up. Will it need re jetting again?

Probably a question for Kickstart there. 😎

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

Cool news!

I'm sure kickstart will know the answer to that, but when your at the dyno can you ask them to do a run with the power valve closed logging the fueling ratio, and then again for a run with the valve fixed open.

It would show you two things apart from the fueling changes needed. First it would show you how much midrange torque you gain with the power valve shut, and secondly where the two graphs cross it would show you the ideal rpm or close to it where you should want the power valve to open.

On my baseline run, I noticed that the fuel trace mirrors the dip in torque where my KIPS valve opens, and it momentarily goes lean, my guess is because there's suddenly much more air flow ability through the cylinder? I reckon that if your jetting is close that valve open or closed it won't change much apart from the transition between the two states.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

As standard Aprilia didn't change the jetting on the older bikes when they restricted them. But that was comparing a moving power valve with the low power position blanking plate.

I would probably see how it goes when you fit the power valve.

All the best

Katy
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Well, wont be dynoing it today.
Fucking rad has completely shat it's self.

So I've got a new one on order, should be here tomorrow.
And some new hoses as the old ones were a bit short and tightly pulled around the frame.

My pal has just bought a road legal Stomp pit bike with a CRF250 motor stuffed up it.
Cant wait to get out and have a blast with it. Wonder which bike will have the edge. 2t-125 or 4t-250.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

If you are replacing the rad anyway, as a short term bodge some epoxy putty would probably work.

All the best

Katy
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

New rad fitted and filled up with water.

Quick road test yesterday, but the temp gauge has stopped working now. Laughing

This fucking bike.
Think it's just a flat battery. It's only a cheap gauge from OORacing.

One thing I noticed with the new rad. The water flows from bottom to top.
The old rad, it flowed from top to bottom.

Is that an issue?

https://scontent-lht6-1.xx.fbcdn.net/v/t1.0-9/20992940_526670074350689_6610207483855095394_n.jpg?oh=70401454c4040aa20e08d36670ecc3dd&oe=5A1EF5B4

I'm watching a few RotaxMax powervalve units on ebay. Missed the last 2 that were for sale.
Hopefully I'll get one and fit it before I get it back in for a Dyno.

My pals bike with the CRF250 lump in it.
It's built into a Stomp KZR frame. What I'd like to frame mine into eventually.

https://scontent-lht6-1.xx.fbcdn.net/v/t1.0-9/20881850_10212147820084116_7841892453880351097_n.jpg?oh=1d841a9a4da95e462ecbb71517ac4d1f&oe=5A1C7959

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

As Pete says, but how is it plumbed in to take coolant from the top of the engine and feed it to the bottom of the radiator? From the pics it looks like it would be possible to run the pipes to the other connections on the rad.

The Rotax water pump is not particularly powerful (impeller rather than pump). Doesn't need to be normally, but if pushing against natural water flow it might well struggle.

All the best

Katy
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

Dude, I hope you can find an easy way to re route the pipes the other way, as I'd hate for you to cook a nice fresh Rotax if the current set up is an issue. If it's not cooling well enough this way, the dyno will kill it quickly, as bikes get hot quickly on the dyno anyway.

Oh and tell your mate that his bike has far too much engine forced to fit into far too little bike for anyone with an ounce of sanity! Laughing

Seriously though, a pit bike with a 14000rpm 40bhp 250 race engine must be one mean son of a bitch to try and use fully!

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Yup. Top of engine to bottom left (near side) of rad.
It used to go to top left of rad but the new rad has a different lay out.

The right side (off side) of the rad has 2 ports. 1 top and 1 bottom.

Only other option is to see if I can cut a port off of the old rad and get it brazed onto the top left of the new rad. Giving it 4 ports. And just blanking off the spare 2.

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

And the 12's are on.

https://scontent-lht6-1.xx.fbcdn.net/v/t31.0-8/21013752_527939657557064_4098178256951719593_o.jpg?oh=882b5b9814d97a8dfa6f090fa39dd5ee&oe=5A31CBF4

Have another set of rims to fit some PMT Slicks to, for the track.
The PMT BlackFires that are currently fitted are road legal. Smile

Super stick tyres too. Start riding it properly now.

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Well I should have put the thing on 12's from the start.
A totally different bike. Rides like a supermoto pit bike now. Can bank it over like my race bike without any fear of losing grip.

Went for a little rip with my pal on his 250 the other day.
Got my arse royally handed to me. No comparison what so ever!

I was hammering the life out of the Rotax, and the CRF250 pit bike was just lifting the front wheel and taking off, every time. Laughing

The thing is an absolute demon! Twisted Evil

https://scontent-lht6-1.xx.fbcdn.net/v/t31.0-8/21055846_528429804174716_5965641853653993877_o.jpg?oh=6225808617fbe164f3cf8393e514b5e5&oe=5A5B27FB

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

That thing instantly looks as fucking hard as nails, with the 12's on instead! Can't believe the difference tbh!

And I'm a fan of cast alloy wheels, and liked the look alot before. Has the gearing changed much with the new wheels?

Oh and your mate is a total deranged loonie +100 Laughing

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

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binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Cracking day on track at Rowrah.
The 2-stroke had the pace to stay with most of the CRF150s qnd the KTM105, but It was the set up and myself holding it back.

Gonna spend a bit more time working with the suspension and geometry, and have another crack at Whilton Mill in October.

Footpegs are off, I'm making up some plates to move them a good 2 to 3 inches higher up, as cornering clearance was a real issue.

https://scontent-lhr3-1.xx.fbcdn.net/v/t31.0-8/21752761_536134063404290_5106462130831485801_o.jpg?oh=2f93a3fdddeb6c1e325ca9adb4f28879&oe=5A17C91F

https://scontent-lhr3-1.xx.fbcdn.net/v/t31.0-8/21728817_536133760070987_3036132355054115531_o.jpg?oh=a4778cad6cbf05ab95e2b343e52d058e&oe=5A602C5A

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

Fucking love it!

You've gotta make that pic your screen saver too! Thumbs Up

Seeing the Rotax pit chasing down a CRF150 race bike is just epic tbh!

I knew it would have pace, I guess it's making as usable a possible and making it handle how you want it to is the key.

Need a sound clip of this thing on a track though x100! Smile

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Had a little tinker this morning.

I've gone up to a 41t rear sprocket now, making the gearing a lot shorter than it was.
Original set up was 13" wheels, with 17:40 sprockets.
Then went to 12" wheels, with 15:39 sprockets.
But now i've gone with 15:41 sprockets on the 12s, and I think, I may even get away with dropping the front to a 14 for some of the smaller tracks, as I was only getting into 4th gear at Rowrah, and that's got some long straights on it.

I've moved the foot pegs up to 320mm (From 260mm) so have plenty of ground clearance now.
Enough to drop yokes down a bit on the forks to assist with faster turning in.

I've bought a coolant temp sensor which needs fitting.

And I've fitted a new number board, without a headlight.

Full track ready now.

And I'm in talks about having a nice seat cover made up as the cheapy one that's on it has ripped.

Hopefully I will be able to get it on a dyno before Whilton Mill next month.

https://scontent-lht6-1.xx.fbcdn.net/v/t31.0-8/22047906_543561339328229_3325367266449317824_o.jpg?oh=b36996c57d2f7d45d9483164dd1cb82b&oe=5A3C1981

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stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

Looks tough as fuck on 12's with slicks! Thumbs Up

Interested to see what it makes on the dyno too! What is it geared for now 75ish?

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

Booked and paid for Round-10 Whilton Mill.

Doing double practice on the Saturday, but only racing the open class (on the pit bike) on Sunday, as I'm only there to battle for the championship.
Currently in 1st place in the open class, 2nd is about 8 points shy of me. It's all to play for.

But, booked for Stock and open practice on the Saturday, so I can take the Aprilia and have some fun again. Very Happy

https://scontent-lht6-1.xx.fbcdn.net/v/t31.0-8/22104416_544605372557159_4664412235190018679_o.jpg?oh=a650d5294f8b7b521927ce39b7cf8a8b&oe=5A4B0F8C

binge · Emo Kiddy Joined: 02 Jul 2004 Karma :

I've bought a new frame to build the Rotax into.

It's proper pit bike sized, and will work better with my seat, plastics etc.

Lighter and smaller than the current frame too.

Not road legal unfortunately, but I'm not overly fussed. I'll be sticking the old frame up for sale, along with the yokes, forks, and wheels.

https://scontent-lht6-1.xx.fbcdn.net/v/t31.0-8/22467388_550688661948830_8440321018540355688_o.jpg?oh=32b0e4e6eeea727c50900575d316576e&oe=5A714CDD