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Figuring out what degree of retard I want to go. Here's some measurements I took

Gn125 head has

Valves 25.5/22.5mm

Inlet port 25mm

IMG_20210129_195732.thumb.jpg.8ef1263ad2deecb1ed651b7c01436487.jpg

 

Dr125 head has

Valves 28/25mm

Inlet port 28mm

IMG_20210129_195722.thumb.jpg.485ff590a977af4b726d1938ae47ef2a.jpg

Dr200 head has

Valves 33/28mm

Inlet port 30mm 

 

IMG_20210129_195712.thumb.jpg.981f3b381c131924bacab24390a4a5d2.jpg

 

I could run a domed piston in the dr200 head to make up for the massive combustion chamber, but it and the ports are pretty big 

I think I could run a domed piston in the dr125 head too, but gotta check that for clearance, I think it has the tightest valve angle too so a big cam may upset it 

 

Dr125 head needs work, the others I could just put on with the correct piston cam combo. Or maybe I clearance the low dome piston I was using in th GN so the valves don't touch (not entirely sure if it kissed and bent first, or if the valves collided and then got squashed tbh)

 

 

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Looks like the gs150 piston would have more dome than the dr200 when installed. So the compression may work out. Not convinced on the big valves and ports tho,  I think with slower airfuel speeds it would big the engine at anything less than full throttle full rpm

 

 

So no issue then

IMG_20210129_200930.thumb.jpg.0a52f1098c24b8dba2a433273d0bd2fb.jpg

 

 

 

Tho

Quote

The LT230 head just measured 30cc on the chamber and a whopping 50cc on the intake port

drz125 21.5cc's chamber - intake portis 36.5cc

The lt230 head was either the same as the dr200 or ever so slightly higher compression i believe

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my eyeballs are starting to fall out in the shed, but some rough and ready measuring and i think that domed piston will work. 

The deck height (at the edge) is about 3mm taller than the low domed piston - which is heaps, but measuring from where the top ring was reaching on my other cylinder (only used with one base gasket) it looks like im getting 1mm clearance with no head gasket and the dr200 cylinder pressed onto the 150 cylinder. So depending on head gasket (i have single layer and thicker multilayer) i then have the option to use 2 base gaskets to fine tune the clearance. Will go ahead and prep that head for install and then squish some stuff to see how it and the valves go and it all good take it for some 0-10000rpm from cold test rides. 

I think  it wont be a winning combo but i cant find any one running it
(just people wanting to put a 200 head on a stock 125)

so will satisfy my and the 6 people on youtube who are interesred in ruining GNs. really wish i had a dyno for it tho

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threw it all together and the deck height is just too much. Looked back at my notes thinking i should get an lt160 conrod and make a stroker (5mm shorter). Noted the FX125 uses a 3mm shorter rod, which is other wise identical to the gn125 rod

(pretty sure the gs150 also has a 3mm shorter rod, which makes some sense, thats the piston i wanted to use). 

Dont really want to split the cases and change a conrod, but could be something to do later on (plus its about 130 for a lt160 conrod and i dont want to spend that)

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SeeIMG_20210205_142737.thumb.jpg.dd9d5ae665af2008816ba7411aa0a36b.jpg

 

Intake - 

Radial clearance 4mm

Piston clearance - 2mm

 

Exhaust

Radial clearance - 2.5mm

Piston clearance 1.5mm

 

Looks like safe r.o.t for clearance is

Intake 2mm

Exhaust 2.5mm

Radial 1.4mm

 

So that and the witness mark on the piston in the exhaust notch probably means the exhaust valve hit the piston and then the intake valve got caught on that and went 90degrees

 

Il turn a valve into a notching tool and take out the exhaust another 1mm, got a wornout piston to cut in half to check how thick itl be, should be fine tbh as the intake is milled deeper. 

 

 

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Had a look at DR125 engine

mostly full of smoooo, gear lever welded on, new clutch plates or very new ones.

pretty sure its a 6 speed, as far as i can figure out its a 1984 engine, some people say they are all 6 speeds, some say they are all 5 speeds. Suzuki says 6 speed, 'feels like' its a 6 speed but soemthings not right with the shift as the lever doesnt go back into centre and sometimes it goes into gear and sometimes i can just keep spinning it over. Probably full of smoo again. Smoo seems to be finely ground camshaft and camshaft 'bearings' where it runs in the head.

 

Plan is

- get a reamer, linish down the head and cam cover, ream cam bearings back to spec. Put in a big cam shaft

- split cases, clean out the smoo. throw cheap GN parts at anything thats stuffed

- Michio Suzuki willing its a 6 speed but if not thats not the end of the world

- excessively big bore cylinder. i.e as big as i can go

- probably stroke it depending on a few things

 

can fit a dr200 crank - and therefore a 16mm gudgeon pin to dr125 cases. but im not 100% sure on how it interacts with everything else. the primary gear i think needed to be swapped and something about the clutch basket. The dr200 crank also has about 11 mm more stroke. I have all these parts already exploded in a box so trying them out is no worries. pretty sure a 200cc sleeve needs the cases cleared on a 125.

 

TLDR, fucked old engine is fucked

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Might heat squash a Conrod to make a stroker. 

These used to be sold for the Dr and drz by Powell. But are long gone now. From what I have found out they didn't use a stock rod. Possibly so they could sell you the piston too, or possibly the Suzuki rod wasn't suitable. I think it would be ok with a forged rod, $18 China GN rod probably is fine to do this to I'm sure.

Will consider this as I look for different suitable short rods from other bikes, big end pin will be moved for stroking, so a different size is ok. Better sized small end Is also ideal for piston choice.

"Bolt in" option is a lt160 Conrod which is 6mm shorter. The old Powell kits were 8-10mm 

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16 minutes ago, flyingbrick said:

Digging the new seat! 

It's pretty hard. Be good if the GN had any degree of performance, but Luxo GN cruiser seat is fine for the casual cornering it's capable of.

It is 600g lighter tho. And doesn't allow for a pillion

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Honestly, unpopular opinion here. I dont give a shit about 2strokes. I would have to buy a lathe and a mill etc etc but i did briefly think about a parallel twin. seems like a lot of work for no return tho

 

Want a garbage Suzuki farmbike in 2stroke get one of those rego'd ts185s (would toats get a new one tho tbh)

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11 minutes ago, flyingbrick said:

 

What are your goals with this? Or just muck around until ya bored? 

Make a lol little bike for dumb adventures

 

So that means not aiming for bleeding edge performance and weight savings out if it

 

Would get something fast/capable if that's what I wanted

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