Hi all, just wondering if anyone knows why my bike seem's to be getting stuck around 7,8k -8k revvs and dosen't seem to go past these... I've taken all the restricters out that I possibly know of, and from what I've read about.. got the dep pipe, lighter flywheel, uprated clutch and have had a rebore done through yamaha themselfs, so the engine is perfect...
I've tried differnt chain/sproket combos, which to no avail, tried "raceing spark plugs/caps" made 0% differnce, carbon reeds, unnoticlbe differnce, and tried using a new carb which apparently was a "racing" carb and still nothing, I even borrowed my mates SM wheels just to see if that'd make any differnce, but nothing.. so all help would be much appreciated cheers.
Have you checked the throttle cable isnt getting stuck somewer? Av a look in the splitter box half way down the cable check tht somthing in ther isnt jammmed lube it up whilst u got it open aswell If u can look at intake of the carb to make sure the slide is opening fully
checked/tried all the above mentiond, bike revvs all the way to 12k when in neutral, but dosen't exceed 8k when going 1st, 2nd 3rd, ( i don't really dare to try in 1st + 2nd... i like my engine too much..) but 3rd onwards 8k is as high as it goes... i'm going to get new piston/rings/gaskets + conrod and bearings tomorrow, new throttle + clutch cable aswell, so hopefully these will sort it out aswell, i'm going to whack on standard exhaust too, so after I've done a good 500miles (week with my work) i'll open her up and let you know if i still have the same problem.
1 last thing... a friend of mine said "try changing the coil + cdi, or just one of them"; i'm skeptical about this because I know dodgey coils make the bike choke/stutter so I don't think it's that, and cdi's just... stop the bike running...
First thing you have to remember - the RE/X engine is designed and ported to make its peak power at 8000 rpm, so revving in excess of 8K will gain you nothing in the lower gears. Indeed, power usually drops off in excess of peak. My DT-RE is exactly the same, but it still goes fast enough to go right off the speedo when I want it to, because...
The only time you really want to rev higher than peak would be 5th and 6th, when over-rev will come into play, but again, if it is jetted properly it won't get enough fuel to over-rev too much and hence you'll get the appearance of being stuck at 8,000 rpm.
Go up one size on your main jet and see what happens in the higher gears...
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Just because I don't care, it doesn't mean I don't understand...!
I'm not sure about changing jets, I've got an original carb on atm, and idk the jet size for it, which would you recommend changing too? I'm using the DEP Expansion, so it'll have to match that am i correct?
Erm, just to be sure - you do have a 2004 onwards DT, yeah? If not, ignore this and my previous post... ;)
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The other thing you got to remember on top of everything else, the RE/X is jetted to account for strict emissions with the CAT, etc. so is as economical as it can be. This is another reason it is reluctant to rev out about 8,000rpm. Basically, in standard trim the engine is left thirsty.
Standard main is 210 here, you can safely go to 240 before it gets too rich, but I found even 240 was a bit too much, eventually settling on 220.
The good thing about the DEP is it requires no rejetting at all when used as a straight swap for the standard exhaust - in other words you can pretty much ignore it, if you see what I mean.
It's a real shame you went through all the dicking around with "racing" this and "super" that when all you really need is a £5 jet upgrade.
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Just because I don't care, it doesn't mean I don't understand...!
Okay, in that case, turn it 180 degrees. Probably upside down.
Craig,
Can you do me a favour please? Next time your exhaust is off - spin your power valve through 180 degrees and take a picture of it please, I am dying to see what this looks like. Maybe even run it for a couple minutes to see how it performs? I'd do it myself but my 125 goes to its new owner tomorrow and don't really wanna be stripping it down 1 hour before it goes!
Thanks, Malc
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Just because I don't care, it doesn't mean I don't understand...!
My DT is around 1993 - 2003, the enigne is 1993, carb etc is from a 2003 bike, im gonna buy a 220 jet and see how i get on with that, my friend said the fumes coming from the back are pretty "petrolly smelly" so perhaps I'm not getting enough oil through, so I'll change jets and referb oilpump too, see how all goes then, cheers
