Dtr soooo slow

[DevonDtr]

Hi, so recently bought an 04 dtre 125 and need some advice. Its very slow, tops out at 45 and 50cc peds will easily out accelerate it. Will refuse to hit powerband, it has no rev counter but I would say it's not hitting over 6k in gear. Neutral and it revs to redline Powervalve goes through cleaning process but barely responds to throttle. Has a big one end can fitted too. Every shop says different, carbs, powervalve clogged, cdi unit. hoping you guys can shed some light

[Ariel Badger]

You say it has no rev counter.......Then you say it red lines. Explain.
____________________
Bikers make great organ donors, get 115 on your licence today.

[DevonDtr]

In gear and travelling it's sluggish, doesn't like revving even if you pin the throttle back and won't rev high. In neutral it will rev freely, all the way to redline/limiter, can hear it climbing revs easily

[Ariel Badger]

Clean carb, new plug and then come back to us.
____________________
Bikers make great organ donors, get 115 on your licence today.

[V2]

Personally I would start with checking that :-

a) you have the correct carb on it and it isn't dirty or clogged

b) you have a good spark there

c) compression test

d) no air leaks between carb and engine

Those are the main things you need to make engines go!

[DevonDtr]

Completely forgot about those! I changed the plug day i bought it, it was completly black with carbon. my mechanical knowledge is shocking, how do i take carb off to clean it? On another note, i have been through all electrical connections and they are all spot on

[RhynoCZ]

[DevonDtr]

Exhaust

[RhynoCZ]

Yes, I do know a can is a slang word for a exhaust system, what kind? The factory fitted stock one with which the engine was tuned or some crazy racing super magical stuff bought of fleabay?
____________________
'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[DevonDtr]

Made by dep, its my first 2 stroke so not sure if thats great or not

[RhynoCZ]

I see, well normally we tend to put everything back as it was when the motorcycle left the factory and go from there.

Can you tell the mixture by looking at the spark plug?
____________________
'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[DevonDtr]

The old plug was black with carbon, current plug is getting black. Can smell bikes running very rich though, just unsure of how to adjust

[RhynoCZ]

Start with the air filter. A clogged filter results in rich mixture. Also check the carburetor and choke functionality. If the choke stays shut, even slightly, it'll also make the mixture rich. Many problems with choke are caused by the wrong length of the choke cable and/or wrong adjustment. If there is not cable, then it might be stuck in the carburetor. (Noob question, you do know when the choke is ON and when OFF, right?)

Next, find the manual to your motorcycle (here on BCF), find carb setting. I'm not sure about your motorcycle particular, but I do believe there is a mixture screw you may adjust the mixture with. The manual will state to turn it full right and then a certain amount of degrees of turning it left (or vice versa).

If that fails, then it's time to taking the carb apart and checking there are the right jet size/s.

An open exhaust system would lead to lean mixture not rich. So I think the problem lies in the air filter and/or carburetor (choke).
____________________
'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[DevonDtr]

Have cleaned filter previously. It wont start without choke, but i shall check cable in morning

[mudcow007]

Chances are, if its been fitted with a "big one" by the previous owner, they also tried to fuck about with the carb

might be worth speaking to the people over at

https://www.dt125r.co.uk/

?

[DevonDtr]

So there is no cable for carb, the lever just raises a small pipe up and down

[Hahadumball]

[RhynoCZ]

Good, that is another thing ruled out. Time to find the mixture screw, if there is any. At this point I'd be taking the carburetor off and taking it apart. I think the previous owner was a brainiac and tried to put there bigger jet/s thinking more fuel would me more power.

I googled: ''2004 yamaha DTR 125 carburetor mixture screw'' and got this picture:
https://i.fixya.net/uploads/images/797ccb7.jpg
____________________
'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[DevonDtr]

This is going to sound so stupid, bike would access higher revs whilst off road and wheels spinning so I took cover off powervalve, removed cables and the valve itself didn't want to turn by hand. phoned local shop to take for a look, on the way I went off road, pinned throttle back and valve freed itself, completely transforming the bike. She has gone from only doing 40mph to topping 90 thanks for all the advice guys

[Paris2]

Glad its all working, but this...

[DevonDtr]

Bearing in mind I'm only 11 stone, as I say topping 90, more likely in late 80's but I was too busy looking where I was going

[Copycat73]

[Irn-Bru]

Mine used to do 85 indicated so wouldn't surprise me, I weigh quite a lot more than the OP When I first got mine (07 reg) it used to top out at 65 but I did the powervalve mod thing (earthed a wire behind the headlight) and it turned into a proper beast.

Really miss my DTR(E), was properly clean and unmolested which is unheard of for a DTR.
____________________
KTM 990 SMT & Suzuki DR-Z 400 SM

[stevo as b4]

65mph for 10-15'000miles with a restricted 15bhp is better than 85mph for a couple of thousand miles though.

I love how this is OP's first 2stroke, he has been asking lots of mechanics to look/mess with it and all he wants is for the bike to red line with some mad power band in all the gears?

I'd be learning how to strip and re-build engines and buying tools personally before de-restricting and tuning fragile 2stroke engines.

If he cries in a few months after an engine blow up, will the bike even get fixed or will it be eBay'd spares or repairs, or scrapped instead?

[DevonDtr]

No, didn't want mad power/red line, just to be able to do 60 on a 60 limit road... plan is to get everything working as it should and get bike back to original. In the 3 weeks of owning it I have learnt many things in regards to brakes, electronics, not so much engine side: / P's. I don't rag it everywhere, and the idea of asking peoples advice is to learn, like today I learnt how to dismantle a power valve, clean a Carb, etc.. as far as Im aware the bike is restricted, and will stay that way. Judging by other dt's condition this one is tidy, no rust or scratches[/img]