DT125R ARCHIVE

Victor · Guru

Flat spot?

Calum122 · Guru

Victor wrote:
p.s Did you shave down the pv with your rebore and bleed the oil pump? also wtf is a industrial piston should go with known brands mate.
-- Edited by Victor on Saturday 27th of September 2014 05:48:53 PM

LOL

The_DtR_Maniac1991 · DTR Senior Member

It now splutters! Could be air filter for sure I think, it's got a slight rip on the yellow part underneath. And also the bit at the top is slightly coming away. I put a 240 in when I got the DEP system and it didn't make any difference for some
Reason, so I whacked the 250 in and it's fine now, also I may need my power valve setting up I think that could be the reason why power is crap between 5-7k.

The_DtR_Maniac1991 · DTR Senior Member

It is a known brand. Khc industries lol that's what I meant. I used them all the time and never have problems. My last piston lasted 23,000 miles lol. I'll clean power. Able out and my power valve opens at 7,000 works fine. May just need a good cleaning

The_DtR_Maniac1991 · DTR Senior Member

also can i shave power valve myself? just pop it out and file it down a little bit right?

Calum122 · Guru

So as said, a change in main jet of 10 is only to get the fueling right. You probably won't feel any difference. In fact the main jet ONLY affects 3/4 to FULL THROTTLE. So everywhere else you won't notice it. the needle and idle jet effect the rest.

Yeah, the powervalve only needs modifying after a good few Oversize pistons. If you're 0.5 OS then it won't be necessary. But yes, it's ally so actually very easy to modify.

The_DtR_Maniac1991 · DTR Senior Member

Yes It's only been put to a it's now bored to 56.65mm Think i should leave the power valve alone? Just clean it,

by the way, im sorry asking all these questions... i feel like a right dumb ass lol. but i guess thats what this forum is here for :P

I got a new air filter.. HI-FLO one, see if this helps a little bit. I may have to take the carb to a shop to get new screws on them, I cannot un-do any of them, they are well and trully fooked! My friends dad done the jetting for me, and as normal someone else had to screw all the screws up. but hopefully all I need is a little adjustments or a dyno test and it should be all good.

Calum122 · Guru

You'll be able to tell if the jettings out. The temperature spikes, and it won't run very smooth. If you're a NOOB then check the carb section for the carb tuning tutorial I put up there. Loads of information regarding how the bike will feel when not jetted correctly.

The_DtR_Maniac1991 · DTR Senior Member

Oh it runs very smoothly thru the revs untill 5-6k then once the power valve kicks in, it's lovely. just seems strange! I got a new air filter anyways. and i will clean the power valve. I could spray carb cleaner into air filter box into carb ? Or does that stuff make NO difference.

Calum122 · Guru

Is the powervalve in correctly and setup correctly. Sounds like as the motor opens it's affecting the bike. I've got videos on how the powervalve should be setup and you need to make sure it's not upside down.

The_DtR_Maniac1991 · DTR Senior Member

Thanks bud, I'll take a look after work tomorrow and let ya know whats the crack

scrimsmustang · DTR Mechanic

The_DtR_Maniac1991 wrote:
Okie dokie. thanks :) i can't remember if needle been adjusted. but it's always worth a try. If i remember , I upjetted to 250, then moved the needle down 1 notch. (240 didnt do any difference to standard jet ( strange) so i went to a 250. or even a 260, i really cant remember it was a long time ago. but i will defo get that brand new filter anyway

Just read through this, bogging in the mid range and you wonder why lol.................... after lowering the needle clip height and removing the snorkel from the airbox ! Cracking mid range fuel air mixture right there NOT ! Your over fueling it in the mid range put the needle back to standard to lean it back out and stick the snorkel back in unless your prepared to get the low end correct for the extra air pissing about for hours with pilot jet and airscrew tweeks that's not going to do a thing on a standard engine anyway.

3 things about 2stroke carbs, 1st airscrew and pilot jet controls up to 1/4 throttle, needle clip position controls 1/4 to 3/4 throttle and main jet controls 3/4 to full throttle with them all slightly overlapping. If it wont tick over properly clean the pilot and passage then start with standard airscrew position and take it from there. Sounds OK at the topend from what your saying and seems to be running OK with a decent plug colour at the topend.

Once you do it a few times and it all sinks in its a doddle as long as your carb is not f****d. I spent a full day last week with 3 carbs all set to standard on the same bike and still couldn't get it to run properly..............