Ke125

[kel]

Looking at the last post it would seem I got ahead of myself with the racing bug comment.
While I haven't got myself back to the track I have continued to develop the bike (its becoming quite the dyno racer )
Have ditched the Kawasaki dished piston and have replaced with a more typical domed piston, also Re-profiled the head. This will aid cooling and give a touch more top end. Street test suggests power wise everything is good, but the thing still gets very hot.
I've also started on the A motor. This will have a slightly different crank build, still using a DT125 rod kit but a longer one this time, plus it gets a RGV250 big end bearing as it drops straight in. The transfers will be a direct copy of the last motor but with more timing. The exhaust port is the big change as the new cylinder is now a triple porter. Time angle area calcs show this new layout is good for another 5hp at the crank. I need to come up with a decent air cooled head that can be adapted to the cylinder as the standard unit is not up to the task, perhaps something like this

74kx125 works racer

[husaberg]

Looking at the last post it would seem I got ahead of myself with the racing bug comment.
While I haven't got myself back to the track I have continued to develop the bike (its becoming quite the dyno racer )
Have ditched the Kawasaki dished piston and have replaced with a more typical domed piston, also Re-profiled the head. This will aid cooling and give a touch more top end. Street test suggests power wise everything is good, but the thing still gets very hot.
I've also started on the A motor. This will have a slightly different crank build, still using a DT125 rod kit but a longer one this time, plus it gets a RGV250 big end bearing as it drops straight in. The transfers will be a direct copy of the last motor but with more timing. The exhaust port is the big change as the new cylinder is now a triple porter. Time angle area calcs show this new layout is good for another 5hp at the crank. I need to come up with a decent air cooled head that can be adapted to the cylinder as the standard unit is not up to the task, perhaps something like this

74kx125 works racer

Ask fletner and get one for Rob at the same time

[cotswold]

[QUOTE=kel;1130614941]
I have continued to develop the bike
I have ditched the Racing and have replaced it with becoming quite the dyno racer. Everything is good, but the thing still gets very hot.
I need to come up with a decent air cooled head that can be adapted to the cylinder as the standard unit is not up to the task.

Kel, could you not get much bigger fans on the dyno to force more air across your original head ?

At least yours goes

[T.W.R]

. I need to come up with a decent air cooled head that can be adapted to the cylinder as the standard unit is not up to the task, perhaps something like this

74kx125 works racer

Try some of the VintageMX sites to see if someone has a DG Performance radial fin head Goldies used to be the thing for MX before water cooling arrived

[Moooools]

perhaps something like this

74kx125 works racer

Could you fabricate one? I don't know about the thermal conductivity of an Ali weld, but I imagine it is close to the rest of the material.

Just make some fins and a simple jig, and design it so one it is possible to weld every fin with a decent bead. Leave yourself a couple of datum surfaces to clock it up and machine it afterwards. May need to do something about vibration to stop the welds cracking. I have seen down to 0.8mm Ali welded nicely so heaps of 1-2mm fins could be a possibility.

The other place there are big gains to be made on bikes is in proper ducting to the head. The aim is not to make high pressure in front but to drop the pressure behind the cooling fins, the air pressure in front never gets much higher than atmosphere as it just creates a blockage and tries to take a path of lesser resistance. So creating smooth ducts that run out to low pressure areas (under the seat or behind the rider or his legs - think stagnant air following the rider) will be the best way to get more air through the fins. And yes you want as much air as possible going through them. And no it doesn't need some time to 'soak up the heat'. (The common things that get tossed around when it comes to cooling.)

Increasing the mass air flow over the fins is probably going to be easier than sourcing some funky head. Make a duct, go to the track with some wool tufts out the back and see what happens to the tufts and to engine temp and try again. If the tufts are going the wrong way and engine temp is up you then your outlet is at a higher pressure than your inlet.

[kel]

Finally got the KE back onto the dyno.
The motor has had a top end rebuild - new and improved piston, rings and combustion chamber ... and wouldn't you know it the bloody horsepower has dropped by over 20%
It would be greatly appreciated if anyone knowing the whereabouts of my missing 5hp horsepower could contact me before the 7th of December.

[koba]

Finally got the KE back onto the dyno.
The motor has had a top end rebuild - new and improved piston, rings and combustion chamber ... and wouldn't you know it the bloody horsepower has dropped by over 20%
It would be greatly appreciated if anyone knowing the whereabouts of my missing 5hp horsepower could contact me before the 7th of December.

It must be catching, I just lost 7.7!

Hmm, you with the missing 5 is still more than me with the 7.7 still on board.

Bloody flighty things these horses, they spook too easily.
We should invent something mechanical to replace them perhaps?

[chrisc]

So keen to see this at Tok!

[cotswold]

Finally got the KE back onto the dyno.
The motor has had a top end rebuild - new and improved piston, rings and combustion chamber ... and wouldn't you know it the bloody horsepower has dropped by over 20%
It would be greatly appreciated if anyone knowing the whereabouts of my missing 5hp horsepower could contact me before the 7th of December.

they are in my 50

[Fastmark]

Ah the old KE125, the first bike I ever rode, which was actually my mates, brand new just three days old. Being the great mate that he was he let me have a go. Now nice and steady, secure footing (don't want to drop it) check, select first gear - check, slowly increase revs and gently engage clutch - check, beautiful smooth take off - check, man this is easy, check where you are steering erm.... no. Hit raised kerb - check, drop bike - check (but luckily on me so no damage to bike) smell of burning flesh on exhaust- check.

Huge embarrassment that gave years of piss taking - check

But for some reason I still have a soft spot for these old smokers

[F5 Dave]

Nice mate, fantastic story for a friday morning.

[jasonu]

Nice mate, fantastic story for a friday morning.

Queer.


Happy thanks Giving by the way.

[F5 Dave]

Charming.

Yes, thanks giving, of course. thats now is it?

We're happy that we managed to chase those damn Brits out of our colony. Oh wait. . .we haven't done that yet.

[Bert]

Finally got the KE back onto the dyno.
The motor has had a top end rebuild - new and improved piston, rings and combustion chamber ... and wouldn't you know it the bloody horsepower has dropped by over 20%
It would be greatly appreciated if anyone knowing the whereabouts of my missing 5hp horsepower could contact me before the 7th of December.

Despite the shit storm I managed to create in the other thread....
I have to say I was really impressed with the way in-which the KE ran at Tokoroa.

Had really good straight line speed (and handled really well by the looks); and sounded on the money.

So tell the story about the wheel bearing???

[kel]

I have to say I was really impressed with the way in-which the KE ran at Tokoroa.
Had really good straight line speed (and handled really well by the looks); and sounded on the money.

I totally agree Bert - great speed and handling (and a totally intoxicating exhaust note if you're a 2 stroke fan), was only the rider holding it back. I was starting to get the hang of things as my fastest laps came in the last third of race 2 when I was totally exhausted.
Was the usual troubled meet for me; sprocket carrier/wheel bearing failed during first practice, crashed out of qualifying, had an electrical fault (thankfully had the laptop which showed up the fault in the test settings), and then found the front wet was flat but all in all a really good day! Bike was awesome, racing was fun and great catching up with the South of the Bombay crowd.
Big thanks to Rick who lent me his spare wheel bearing, really grateful :

While I dont have 100% committement from the wife yet, it does look promising that we'll be coming down to Taumranui. 5th wont be good enough this time so watch out