Tortrons GN

[Beaver]

1 hour ago, tortron said:

Gona put a gn250 rear sprocket on (43 down to 41)

Top gears going to be useless now, not enough power

At least you're realistic

**Insert smiley face**

[tortron]

More cubes more torque

I want to drop the rpm at 100 from redline down to the on cam area rather than trying to BREAK THE LAW GOING 105

[Beaver]

Thank you for your service.

[keltik]

1 hour ago, 00quattro00 said:

When are you putting it on a dyno to see how much power it's making now

Turn up to J5s earlier on Thursday and I'll convince the local bike shop guy to let you do some pulls

[tortron]

That's very chur because I will be there Thursday arvo

[tortron]

Was going to chop up a gn250 chain guard , drill it full of holes for oldschool racer look

 

Turns out it doesn't fit. I wonder if gn250s have a longer swing arm.

 

Gn250 one weighs 700g

Gn125 one weighs 430g

 

Very solid

[hampie]

1 hour ago, tortron said:

Was going to chop up a gn250 chain guard , drill it full of holes for oldschool racer look

 

Turns out it doesn't fit. I wonder if gn250s have a longer swing arm.

 

Gn250 one weighs 700g

Gn125 one weighs 430g

 

Very solid

I bought a box of gn 250 parts from a guy who has a 125 and he thought he could swap things over too, apparently they are quite different in the rear. Seats aren't easily interchangeable between the two either btw

[tortron]

 

Looks like 2 hours of riding was enough to warm the engine up enough to kiss the valves - very slight witness marks in the carbon of the valve cut outs

 

pretty dumb

wanna know what i think the issue was

 

 

its very dumb

 

 

 

i just lined up a couple of the 150cc kit pistons. They are all different fucking heights. The last one i took out had good clearance but the one i put back in was half a mm taller on the edge

 

 

, Theres one sure fire way to get this engine to work, and thats to bore it out to 165cc because the piston is a much better match tot he head

[tortron]

also if i take the bore out as far as it will go and stroke the crank as far as i have seen done you can turn this 125 into a whopping 230cc beast

 

 

For way more money and effort than simply putting in a dr200 engine, which can easily be bored out to 230cc

and for way less reliability

 

so i will probably do that in the future

[M.H.]

Are you going to melt down some more of your titanium cutlery to make some light weight valves? 

[tortron]

3 minutes ago, 00quattro00 said:

Are you going to melt down some more of your titanium cutlery to make some light weight valves? 

not for this head, i already looked into it and would have to get valve blanks cut to length

The gn head has tiny valves 25.5 and 22.5mm. DR200 has good sized valves but the ports and combustion chamber are too big unless you are running a big piston, which i might get away with with the 65.5mm one. Probably be perfect with a stroked crank too. Theres some quad bike heads that are better for what i want to do, im just waiting for the right one to come up for sale

 

 

and then i will get titanium valves

[tortron]

Looks like I'm gone buy a cylinder that's already been sleeved and bored to 65.5mm rather than sleeve one of mine.

Anyone want to buy a 150cc kit for GN or Dr (I have both pistons) I actually have 2 of them.

Check the clearance and it should be fine with a normal boring cam lol

 

[M.H.]

9 hours ago, tortron said:

Theres some quad bike heads that are better for what i want to do

Is this one any good? 

 

https://www.trademe.co.nz/2880016702

[tortron]

i think tat will be the same as a dr125 

 

i want an lt185 head. but i might end up putting bigger valves in a dr125 head. I forget what lt160 heads were like, maybe one of those

[tortron]

18 hours ago, 00quattro00 said:

Is this one any good? 

 

https://www.trademe.co.nz/2880016702

oh actually it will be the same as a dr125

but, it and the dr125 have 30 - 26mm valves so would still be an upgrade.

[tortron]

Model...... valve size mm... in ...... ex.....length mm..in..... ex

DRZ/LT125..................... 30....... 26.....................90.3...89.3

LT160............................ 28....... 25.....................91.9...91.0

LT185............................ 30....... 26.....................90.3...89.3

DR200............................ 33....... 28.....................89.97...88.77

LT230............................ 32....... 28.....................88.66...87.84

LT250............................ 33....... 28.....................88.57...87.84

LT300............................ 33....... 28.....................88.57...87.84

[tortron]

Hotcam, (what came out of a)DR125, gn125

Looks like the Dr one has a tonne of duration on it so it might be an old dr200 cam. Should measure it. Cam "bearings" I. The dr125 head got a bit chewed as they all do in these engines, but I should be able to lap a little off the mating surfaces and run a reamer down to remove the worst of it

 

[tortron]

[tortron]

Oh also the DR had dropped a valve as well. The tip of the valve was gone (and the spring etc for that valve was missing so someone opened it up I guess) and both valves bent.

I just happen to have new valves already

[tortron]

Got some genuine China parts