Bucket update

**stanko** · 24th May 2006, 21:56

Originally Posted by RG100!!

Sounds good ivan.

What piston are you going to get for it??

Remeber, it is still only a 98cc. That means you can bore it out to like a 115cc before you have to go to the 24mm carb.

Check the rule book.

Good luck

Not so sure about that, rulebook say "2 stroke engines over 104cc are restricted to carburetor equivelent to a single 24mm carburettor" dosent say nuffin about 115cc

**diesel pig** · 24th May 2006, 22:04

Originally Posted by stanko

Not so sure about that, rulebook say "2 stroke engines over 104cc are restricted to carburetor equivelent to a single 24mm carburettor" dosent say nuffin about 115cc

Yer Stanko you got in before me. Checked the MNZ site got the same thing

**Sketchy_Racer** · 25th May 2006, 16:55

Yeah thought so. I did remember something along those lines, Thats also why i said check the rule book as i am not that well aquanted with it.

-RG

**Ivan** · 25th May 2006, 18:24

Standered for now I want to test my port job first

**gav** · 25th May 2006, 19:33

Originally Posted by stanko

Not so sure about that, rulebook say "2 stroke engines over 104cc are restricted to carburetor equivelent to a single 24mm carburettor" dosent say nuffin about 115cc

How do they measure if a carb "is equivalent to a single 24mm carb" If you run a twin then its not necessarily two 12mm carbs then is it. And what if you modify a bigger carb? Is it just the measurement of the throat size into the intake manifold? Would say a modified 32mm carb with a 24mm restrictor in the throat be more effective than say a standard 24mm carb? I guess only an air flow bench or something would tell, wouldnt it, just interested.....

**Sketchy_Racer** · 25th May 2006, 20:26

I believe that it was worked out by someone, that Two 17mm carbs were equvilant to 24mm. Don't quote me on this.

Sleving down in teh carb can work, but in my (little) experience, it did not do much.

**speedpro** · 25th May 2006, 22:51

17mm carb has a cross-sectional area of about 227 square mm.
24mm carb has a cross-sectional area of about 452 square mm.

24mm carb size was chosen because it was the standard size carb on a lot of 125cc farm or commuter bikes and also because it was thought that it would restrict the performance of the 125cc motors about the right amount to keep everything competitive. On kart tracks at least it seems to be about right. Big fast tracks it's definitely a limiting factor, but then so is being air-cooled.

The "equivalent" word was used to stop people using a couple of carbs that added up to a big one, say a couple of 22mm carbs which would be about equivalent to a single 32mm carb.

**speedpro** · 25th May 2006, 23:00

Originally Posted by Ivan

Man 2 stroke porting is pretty easy

I can just about remember when I used to think that.

Had an AC50 at that time with a cast iron barrel. Borrowed a windy and cutters for the exhaust but did the boost ports with needle files, made them into a single bigger one. Watercooled it, homemade CDI, factory race kit wheels(no kidding), up-and-over pipe that exited under the seat with a titanium muffler. Couldn't pass that b'stard Pete Sales on his GT50 but kept him honest.

Back in the good old days . . . . . .

**Ivan** · 26th May 2006, 11:45

Originally Posted by speedpro

I can just about remember when I used to think that.

Had an AC50 at that time with a cast iron barrel. Borrowed a windy and cutters for the exhaust but did the boost ports with needle files, made them into a single bigger one. Watercooled it, homemade CDI, factory race kit wheels(no kidding), up-and-over pipe that exited under the seat with a titanium muffler. Couldn't pass that b'stard Pete Sales on his GT50 but kept him honest.

Back in the good old days . . . . . .

yea mad,

Homemade CDI how do you make those?
Hey Speed pro what do you mean aluminium slugs can you tell me where to put them?

Cheers,

Ivan

**speedpro** · 26th May 2006, 12:27

I removed the flywheel from the little boss that went onto the crank. This left just the little bit that opened and closed the points. I used the points to trigger a CDI which me and another guy designed and built. The CDI ran off a battery which was jammed into the (sheetmetal)frame. It powered an inverter which provided about 400v to charge a capacitor. When the points opened a SCR fired which dumped the 400v from the capacitor into the ignition coil and whammo. The spark easily jumped a 20mm gap on the bench and was huge and fat. We designed a de-bounce circuit into it as when I revved the motor hard the points were bouncing causing erratic sparks.

As for the slugs - If you look at the crank now that you have it out you will see that each side of where the bigend pin presses into the flywheels that there is a hole. These are for balancing and are probably originally factored for about 3-4000rpm. You need to rebalance for about 9-11000rpm. To do that you will need to reduce the balance factor and to do that you need to fill one hole in each flywheel with something. I put a slug of aluminium into each of the larger holes in each flywheel and it worked great. There was no science involved. I just knew from how and where the motor vibrated that I had to reduce the counterbalance.

**Ivan** · 26th May 2006, 13:27

sweet as for cdi ignition it might be better to run a RM125 internal rotor and stator directly to CDI then off to coil whammo (cool word) spark

**diesel pig** · 26th May 2006, 15:05

Hey Speedpro are these slugs interference fit? As in the slugs are made slightly bigger than the holes they are to fit into and neither the hole is heated up or the slug cooled down to be pressed together

**F5 Dave** · 26th May 2006, 15:14

Originally Posted by Ivan

. . . Man 2 stroke porting is pretty easy I will post a pick of what I have done, . .

Trading on the stock exchange is easy.
Playing high stakes poker is easy.
Brain surgury with a chain saw is easy.

Being successful in any of the above is perhaps a little harder.

Ending up with something that is better than before & stays together without chewing up rings requires a bit of luck if you are launching into things with merely enthusiasm.

So presumably you have measured the duration of the ports? The blow down duration until transfer opening? Time area?

Oh, that’s ok then.

Bigger is always better. Try dropping a tennis ball down any hole you find in the engine or widen until this is possible.

**saxet** · 26th May 2006, 15:43

Just a quick note to all Bucket racers.Racing is ON for the next 3 months in Upper Hutt.See scs.net.nz for details.Starts next month...At last.Dunno how the track is gonna be tho',I think it's behind the U/Hutt council buildings.