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Topics - John Orchard

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Tech Talk / Thoughts on different transfer port bottom edge heights?
« on: November 02, 2022, 10:45:41 PM »
I have noticed in a couple of cylinders (RM125M & DT1MX) that some of the transfer port outlets, being both the middle port of a 5 or 6 transfer design, has the bottom of the port open below that of the piston crown at BDC.

Does anyone know the technical reason for this, or your own suspicion? At first, I consider a little extra cooling for the piston, but why only that part? Then I consider; as the piston approaches BDC, the flow out of that centre transfer would abruptly change, or be different in relation to the other transfer openings possible creating a 'vertical wall' at the window, or directing the flow from that port in an upwards direction? Possibly creating a better wall of mixture (when combined with the transfers) to push out the exhaust gases?

I like to keep you Guy's entertained, and me learning (just to take it to the grave).

Tech Talk / Piston skirt cut v inlet port drop?
« on: October 31, 2022, 08:45:39 PM »
Sorry for all my posts, I love the experience on here :-)

So ...... Rather than cut 6mm of the inlet skirt of my TS125 piston, surely dropping the inlet port the 6mm should give the same effect on performance, while still keeping the strength & stability in the piston in the bore .... no?

I've gone to a VM32 so the inlet port needs to be opened substantially, it's a '77 model with the reed into the crankcase, although the reed cage has been opened-up with a carbon petal.

My thoughts also consider keeping the piston-port smaller to help keep up flow inertia.

Maybe I'm a bit crazy trying to re-invent the 1977 wheel ;-)

Tech Talk / Has anyone ever welded a piston, and used it?
« on: October 31, 2022, 08:29:32 PM »
What are your thoughts on welding-up a couple of exhaust bridge lubricating holes in a piston? I imagine there wouldn't be enough heat to distort the piston?

Wanted / WANTED, STD piston to suit RM125M or TM125.
« on: October 29, 2022, 10:03:27 AM »
Would anyone have a new, or very little use, standard bore (56mm) piston for sale to suit an RM125M or TM125, I have looked at the TS125 pistons but once I shorten the inlet skirt, most of the strengthening rib along the bottom of the skirt is cut away, I want to reduce the chance of cracks appearing.

Needing a piston WITHOUT the exhaust bridge lubricating holes.

Maybe aftermarket (forged?) piston might be different, if are they better in that area I will try one, thanks.

Regards, John.

Suzuki / They are still out there.
« on: October 14, 2022, 11:54:30 PM »
So about 5 years ago my Missus brings home a TS185A ('76) engine complete (with carbs, pipe & electrics) in a bare frame from the tip where she use to work, I spray a bit of Start Ya Bastard in the carb; runs for a couple of seconds, heaps of comp through the kick lever. So I tuck it away down the back corner of the shed, I thinks to myself "that might come in handy one day".

So I just tore it down, it's never been apart before, std bore still with cross-hatch in the bore, no blow-by past the rings, it needs NOTHING, everything is like brand-new inside, I am truly amazed !

I have a TS125B rolling chassis, might see if it will fit (even if it doesn't, it will ;-) ) ........ Now where's that porting tool ;-)

Tech Talk / Toolbox tricks, what's yours?
« on: August 27, 2022, 08:09:47 PM »
Because sometimes the Missus helps me in the garage, plus my eyecrometer is starting to fail, I decided to colour match my spanners, I wrap a band of coloured electrical tape around the spanners..... 12mm = red, 13mm = blue, 14mm = yellow and 17mm = black, when I go to the drawer of the toolbox, in an instant I can spot what I need in the sea of spanners. To avoid any confusion in the future, please adhere to the above colours ;-) ha ha.

Also, my favourite tool in the workshop is masking tape, I wrap all my socket extensions with it, they are slippery little buggers with oily hands.

Wanted / WANTED, Suzuki dirtbike steel tank.
« on: July 07, 2022, 08:25:25 PM »
I'm needing a fuel tank, the '76 TS185A has a flip-cap that is rooted, I guess any TS (or TM) 125,185,250,400 will work, anyone want to sell something that I can make work?

Tech Talk / Good high temp alloy putty?
« on: July 04, 2022, 11:11:27 PM »
Hi Gentlemen,

I want to do some reshaping of aircooled 2-stroke ports, mainly inlet & transfers, Lots of different aluminium putties on the market, JB Weld seem to have a large range (appears about 5 different specs) and not super expensive, the JB Weld product that seems to have good strength & heat resistance is their 8297 product, has a good 'set time' and 'cure time', this is the one I am considering.

I have read some good reviews on JB Weld 'original', I have used, and seen used Devcon (the inlet port floor on one of my Kawa ZXR750 Superbikes was Devcon'd, it was a missile), Devcon seems a bit pricey, and I wonder how it would stand-up to thick applications?

What say you Guy's, recommendations?

I'd still be interested in any suggestions of an ex-port filler also, maybe you might use the same product in both cooler & high temp applications?

Thanks in advance for any input that can assist me, regards, John.

General Discussion / Glad you guy's are still here.
« on: June 26, 2022, 08:26:14 PM »
I come here everyday (at least once), with FB I'm glad you die-hards still come here, thankyou it gets me away from the dicks in this world. Fark I have turned into a grumpy old man ;-)

Tech Talk / RM125M piston specs.
« on: June 25, 2022, 01:30:27 PM »
Just wondering if anyone could tell me a couple of measurements of an RM125M ('75) piston please?

1) Measurement from top edge of crown down to the bottom of the skirt on the inlet side.

2) Measurement from top edge of the crown down to the top of the pin hole.

Thanks :-)

I need a new project, anyone got something they want to unload? I still have the Missus' '78 MC400 Maico to do but I think a nice, easy, cheap Suz might be what I need at the moment?

Prefer something in Vic, it wont be cheap if I have to drive interstate to collect it ;-) unless ....... if someone is coming down for the Bonanza?

Suzuki / Anyone know the rattle-can yellow for '76/'77 RM's?
« on: March 22, 2022, 04:30:53 PM »
Not sure if there is a change in the yellows from TM's to '76/'77 RM's, I painted an RM80B tank a few years ago with a rattle-can, it looked perfect but I can't remember the colour, pretty sure it was a Duplicolor (with 2-pack clear over).  I seem to think the TM yellow is a little more pale than the RM? TIA

Wanted / WANTED Suz RM125A, RM100B,C,N or TS125ER cyl & head.
« on: March 09, 2022, 11:08:20 PM »
Chasing a Suzuki RM125A or RM100B, C or N cylinder, and/or rubber inlet manifold, thanks.

General Discussion / How much $'s to be able to load pics?
« on: March 06, 2022, 07:34:26 PM »
I was wondering, how many dollars would need to be collected/donated, per year, for this site to be able to have an easy load option for pics, like most other websites? Maybe if a thread for each year could have a running total, so we know how it's going, I'm sure many would contribute.

General Discussion / Is TL125 the same mech's as SL/XL engines?
« on: February 28, 2022, 08:03:16 PM »
As the heading says, the TL125 trials iron, anyone know if the engine internals are the same as the SL/XL125's? Would the TL run a heavier flywheel, different cam timings, gear ratio's?

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