Difference tzr125 and dt125

[Irongamer727]

@calum it must be accomplishable to port a 4DL to perform like the SP right?

[Calum]

@irongamer727 No mate, the port timings are completely different. The transfers, the fact it has auxiliary ports.

Just good TZR SP barrel and compare it to your stock DTR barrel, then you'll know what I mean.

[Irongamer727]

@calum sounds like one nice cylinder.

[Calum]

@irongamer727 Psst

£60 buys you

Again. simply doesn't warrant the price for an okay barrel.

[Irongamer727]

@calum going a bit off topic now but what would you say makes the enduro 125's cylinder's produce so much power?

[Calum]

@irongamer727 Higher compression, more aggressive port timings, bigger transfer ports, cleaner transfers, bigger boost ports. Auxilary boost ports. More spark advance. Increased squish clearance. Better designed crank journal spaced for increased fuel atomisation. Smoother inlet tracts. No emission laws to adhere to. Smaller piston to wall tolerances. Less blow by, single rings... The list goes on.

If you're really interested then I'd recommend reading a book on a the subject as it's not something I am going to describe in a sentence or two...

[Irongamer727]

@calum jeez.

[Calum]

@irongamer727 I'd recommend Tuning For Speed By Phil Irving PDF available online

http://tuningforspeed.com/files/Tuning_for_Speed.pdf

As a start

Then have a read of Graham Bell's Two Stroke Performance Tuning
Then Graham Bells Engine Performance Tuning

You always want to read in Chronological order. Phil's book was written several decades ago, Grahams during the late 80's.

Irvin was way ahead of the curve and received the highest engineering award they have in Australia. Named after him called the Irving award. The guy is a genius.

[Irongamer727]

@calum I have Graham 2 stroke at home. First time I read it I didn't understand much. Perhaps time to do it again.

[Calum]

@irongamer727 I refer you to my previous statement.

Start in chronological order. Ready Phil Irvins book first. As this will introduce to the concepts at the time, which are assumed or taken for granted in later books.

[declan]

@calum can you not just re sleeve a barrel like a blank slate and the copy what ever port you wish as long as the barrel it’s self allows

[Calum]

@declan The barrels are cast with only so much metal in them. It's not a case of inside liner. The walls are only so thick and can only be ported so much.

You could spend thousands and thousands porting the barrel, and the result is ultimately worse than a £60 RS barrel. It's cost vs Reward.

If I was going to spend X amount of money for maximum bang for buck, do an engine swap. It'll be cheaper and better.

So I'd rather swap the DTR engine out for a 2RK engine out of the UK spec TZR. Or better still Rotax 122 engine, or a YZ engine or anything else.

By all means, mildly port and tune the DTR engine, but accept that there are limitations. Ensure that what you spend, is less than what it would have to have simply swapped the engine.

That accounts for time as well as money. An engine may cost less than a decent port, but if it takes a year to fit then it's cost you time.

[declan]

@calum gotta be a yz engine

[Calum]

@declan Not great road bikes though mate.

[declan]

@calum yeah but I mean what two stroke is in the first place compared to a 4 stroke ofc

[Calum]

@declan All of them? Much higher power to weight ratio.

Even a 4T MX bike is not great on the road, albeit better than a 2T MX but it's still not ideal. Way too much compression and spark advance.

[declan]

@calum I’m talking more practical here a 4 stroke almost always wins if you have deep pockets anyway all’s I’m saying is 2 strokes aren’t really at there best when they’re practical road bikes they’re supposed to be aggressive and crazy imo

[Glynn123]

DT is a pretty brilliant road bike standard

[oldman]

IMHO accept the Dt for what it is rather than spend lots of dollar trying to make it what it isn't. If it doesn't float your boat buy what will, I have a big bike (still) but get the same if not more enjoyment out of a small lightweight bike.

[Glynn123]

The DT is still pleanty fast for what it is, a road going bike developed for teens on L plates, it's a damn site quicker than any of the 4t 125 bikes around, and they get incredible reliability when right. I plan on doing a lot of miles with long runs this year, so simply a road going mx would not work.