DT125R FORUM

@calum said in Athena 170 porting:

@lllDennis I read that the port timings were off by 3mm because apparently the barrel was based off a dtr200. How true that is...

Would love to see before and after dyno pulls though. See how the stock Athena compares to a modified one.

I have compared Athena 170 kit vs 3MB P (and 2RH) cylinders, the only 2 things that's off the athena kit is the piston taller than the stock,the ports are exact copy off the 3MB just a bit wider and the c port is little lower and matches more a 2RH cylinder

The 170 is a mix between the 200cc casing (for the cooling canals and ypvs location) and 125 portmap internally.I searched for a piston that has the dimensions of the 56mm and with bore of 65mm but there is not,only some aftermarket forged that are max 61mm have the right piston height (pin to top).

@SpookDog yeah thats what i was planning on doing to be honest running it nice and gentle at least for the first 500 miles or so and just gradually increase it. I cant imagine the change of reeds doing a noticeable difference with the mixtures so i'll just as you say keep an eye on the plug after a couple rides or so and take it from there. Looking forward to finally getting it back on road! 🤣. Its been left in the corner of the garage as i got another bike

Sounds like you've covered the fueling system, which means it's going to be an electrical component.

You will want to buy a new spark plug, HT Lead and iginition coil to rule out those items.

Next will be the pickup, if that starts to deteriorate then it will start to missfire.

Then unfortunately the CDI. But CDI's rarely fail, but I guess it is 30 years old.