Expansion chamber TS125?

[hmurphy]

Hey just wondering if anyone has ever made an expansion chamber for a TS125 motor? I am wondering if I can get the dimensions for making the most ideal expansion chamber for a stock TS125. At the moment it has a CR85 chamber on it and I am sure there are other tuning issues that are really not right with it, but as it is it's far too slow. I want to make (at some stage) an expansion chamber for my mates bucket so if anyone has done it before, I'd love to hear from you. I also need a sprocket carrier but that's another story.

I have looked at software that will spit out dimensions for the perfect chamber but I don't wanna spend tons of money on something like that (because those programs aren't cheap for a good one most of the time) and I don't know half of the figures I am supposed to put in (all this porting talk and angles and measurements etc etc). An example is this program http://www.bucketracing.co.nz/pipe.php and I don't know how to use it.

Cheers

[Jantar]

Hey just wondering if anyone has ever made an expansion chamber for a TS125 motor? I am wondering if I can get the dimensions for making the most ideal expansion chamber for a stock TS125. ....
Cheers

Yes, Way back in 1973 I designed a chamber for a TS125. I had it built by "Slick" Healey in Dunedin, and it performed. Other mods were to open the top of the exhaust port 5 mm and the transfer ports 3 mm, then to take 3 mm off the bottom of the piston next to the inlet port. Fit a 28mm carb (the TMs of the day were running 26 mm), replace the magneto with PEI from a TM and upsize the air cleaner. For handling I lengthened the swingarm by 25mm and replaced the standard shocks with Konis, I also made the shocks forward mounted for long travel.

It was faster than the TM125s of the day, but still couldn't match the Honda CR125s.

Sorry, I no longer have the dimensions for the chamber, but it just shows that it is possible to design your own one. I used the formula in the "Two Stroke Tuner's Handbook" written by Gordon Jennings.

[hmurphy]

Awesome thanks for your input! I think the rules state you are only allowed as big as 23mm or 24mm carb. I think it has a 23mm carb on it currently. I can arrange jets for it also if someone knows what is best.

In fact, if anyone else knows jetting tricks for this bike and the 23mm carb (even just a rough range) with a decent chamber then that would be cool too.

Cheers

[speedpro]

In the ESE thread is a spreadsheet for designing pipes. All you need to do is feed in a few numbers, make a few choices about peaky or mild and it spits out a useable design. Bit of time with a bit of .8mm mild steel and tin snips, weld it all up and hey presto - ring ding . . . .

If you have a T"F" then taking 5mm off the top of the exhaust port "may" be acceptable, same for taking 3mm off the transfers. I would do some research and make a few measurements before getting the files out. If you send me the bore and stroke, and the distance from the top of the cylinder to the top of the ports, and how far above or below the cylinder the piston goes at TDC, I can send you the port timing. You could just whack bigger holes into it but with a little thought you could end up with something very nice.

[TZ350]

In the ESE thread is a spreadsheet for designing pipes. All you need to do is feed in a few numbers, make a few choices about peaky or mild and it spits out a useable design. Bit of time with a bit of .8mm mild steel and tin snips, weld it all up and hey presto - ring ding . . . .

Chamber Design Spread Sheet (based on Blairs work) page 200 post 2988 of the ESE thread, once opened, it can be saved to your computer. 125 aircooled 2-strokes are restricted to a 24mm carb. Carbs are sized at the smallest diameter which is usually at the slide.

[F5 Dave]

I'd listen to that old bugger above, not sure which one, but I seem to remember a pretty quick TS125 being raced on a bucket at Wanganui in clubmans.

I'd change the ignition pretty quick too as if you get them to rev the enormous flywheel will snap off the end of the crank. Std they make peak power at some very pedestrian revs, probably 7 or 8000 so they will be slow until you do something about that.

[koba]

I'd listen to that old bugger above, not sure which one, but I seem to remember a pretty quick TS125 being raced on a bucket at Wanganui in clubmans.

I'd change the ignition pretty quick too as if you get them to rev the enormous flywheel will snap off the end of the crank. Std they make peak power at some very pedestrian revs, probably 7 or 8000 so they will be slow until you do something about that.

Hey!

I think My bike is topping out about there!

Yes, I'm going to do something about that very soon...

[speedpro]

There's been plenty of TSs done in bucket racing. My old RG/TS was a bit frightening at Wanganui. Some of those guys on big bikes didn't deal with it too well. As F5 says, they are tuned and balanced for low revs. They vibrate like crazy if you rev them to say 10K but it is all fixable. You need a new ignition, the originals are pretty sad and you will end up with a hole in the piston if you don't get sick of feeding plugs to it first. Don't get carried away with the piston port intake as the pistons will start cracking and if you don't catch it in time you'll do some serious damage. I did my TS100 before I knew what I was doing but still ended with a big fat 19.9hp. I always used phenolic resin cage C3 bearings on the mains and the stock rods are good enough for 11K or so revs. If you have a TS125ER they have a reasonable gearbox. RG400 pistons fitted the TS100 so I'd expect the RG500 pistons to fit the TS125. They have thinner rings and are just better.
I did a full crankcase reed valve conversion TS125 but never really tested or tuned it. That was before 125s were legal. It seemed "nice".

[Skunk]

The program on the bucket racing website is based on Bell's theories. It just a matter of plugging in the right figures.

[jasonu]

Get yourself a copy of A. Graham Bells 'Two Stroke Tuners Guide'.
Some will say it is old hat but so is the bike you are dealing with.

[bucketracer]

Port/Time/Area Jennings page 81-82 http://www.vintagesleds.com/library/...20Handbook.pdf

Pipe dimensions Suzuki RM125 B/C page 82 Bell. http://www.kreidler.nl/artikelen/per...raham-bell.pdf

Jennings and Bells books, hopefully the links are still good.

[Mcdowelly]

I'd listen to that old bugger above, not sure which one, but I seem to remember a pretty quick TS125 being raced on a bucket at Wanganui in clubmans.

I'd change the ignition pretty quick too as if you get them to rev the enormous flywheel will snap off the end of the crank. Std they make peak power at some very pedestrian revs, probably 7 or 8000 so they will be slow until you do something about that.

I used to race a tf125 in the Wanganui vmx rounds. Was a weapon of a bike until the bottom end gave up. I believe the cylinder had been bored, ported. Carb had been ported, and exhaust had baffles removed, running with a rm80 muffler.

[F5 Dave]

Nice first post. 5 odd years later. But better late than never.

[Audacious]

I was looking something related to ts125... currently on the finishing touches of a rebuilt engine ts125er. Got it ported a bit, a mere .5mil and polish. a tuned pipe DIY, carburetor 28mil, changed the internals conrods and piston, rings oversized to 57mil.

Thinking with 8 hp gain I guess. Engine will be installed on to a DIY frame with RMZ250 09 plastic kit and a YZ125 suspension. long story how I ended up like this.

Haven't bolted the engine yet. anything I should consider except for chamferring edges. How about transfer ports?