NEED HELP WITH DNA 50 AGAIN!

[ashh v]

Hey, i have a dna 50 unrestricted.

Right, when i go to pull away, it pulls at around 4500-5000rpm, then takes absolutley ages to reach top speed, but it wont go past 7000-8000rpm at full, and soon as i reach the slightest one degree incline, the bike will just start losing power, rpm will reduce, and speed plummets down. I have absolutley no idea whats wrong. Also i have done a few plug chops, and its running extremely rich, (blacker than black plug) and it has a 75 main jet in, so i bought a 68 and it was running too lean, then i bought a 70 cos thats all they had, and it started to cough and do strange things to me. Would appreciate it if there was brilliant help out there, cos ive heard these bikes go about 59 unrestricted stock, and im getting 30-40 on flat, 50 at a push down a mile long steep hill. hmm thanks (ALSO BY SAYING IT PLUMMETS, I MEAN I GO ABOUT 15MPH MAYBE LESS!!)

[TUG]

Ah my 50 DNA did 45 on flats and 50 down hills, up hills was 25ish.

They have an automatic choke on the DNA so i would first check that isn't sticking on before ripping everythign else apart.

If its running rich and the jet size is stock then the choke sticking on is a safe first bet. I would only suggest you check this via workshop manual and that you are good with spanners, if not walk away.
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Haz ER-5, innit!

[jjdugen]

Hi
Not done a 50 but quite a few 125's. The autochoke is a known problem on these, there is a manual choke replacement available, but.
All the ones that have had the sticky choke problem has been down to the electrical connector to the choke becoming full of crud. It is located on the exhaust side, right in the firing line of road muck from the back wheel. (I seem to recall two connectors around there, give them both a good clean and fill with dialectric grease). It works on raw AC from the alternator melting a wax slug that then releases the choke, any poor connection will leave the choke on all the time you are running, causing exactly your problem.

[Livefast123]

As above and check your air filter is clean and unobstructed.
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Current ride - Yamaha MT-07

[ashh v]

So if the choke is stuck, that means it would be stuck in the bottom position, or if it wasn't functioning correctly, so if thats the case, why would the bike be running rich, because the choke would be stopping the fuel, therefore making it leaner? hmm

Regards with the jetting, it had a 56 stock in, but there is a sports exhaust so rejetted it. 75 is too rich, but 68 is extremely lean, (wont even pull away), and 70 doesn't seem to work either, it just cuts out at full throttle.

Does anyone know the operating rpm of these DNA's, such as going about 40ish mph, what rpm should it be because mine sticks at 7000rpm and if it goes down hill, the rev needle will try to go up to 9, then fall back, then go back up, etc :/

So regards to the choke issue, i dont actually think its working, because when its cold, im guessing the choke needle protracts to let more fuel through?

Thanks again, appreciate all the help.

EDIT: The bike revs perfectly on the stand, straight up to 9000-10000, its as soon as its under load it won't... hmmmm

[Livefast123]

Choke makes the mixture richer

The way I understand it works is that the default position for the choke is on, so that when the bike is cold etc it will start without any issues. When the engine starts current is fed into a small heater which melts a wax pellet and your choke goes off. If the choke connector is full of crud/faulty or the choke is faulty then it will be jammed on as there is no current for the heater. This will make your bike extremely rich all the time giving you the symptoms you describe.

Get a manual choke conversion for it as the electric ones are expensive and troublesome. When you have eliminated the choke from your list you can get on with the rest of it. You are never going to get the jetting right with your choke stuck on.

Engines will usually rev up on the stand as there is no load on it. Mixture effects it much more under load.

The other issue it could be is that your rollers are too light / heavy for the new exhaust you have put on. Rollers should be the correct weight to allow the engine to stay in the powerband and it depends on the exhaust where in the RPM range this lies. If you haven't changed them I would contact the exhaust manufacturer and ask what they recommend.
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Current ride - Yamaha MT-07

[TUG]

Urgh....

The choke blocks off air to make the fuel/air mixture richer. The autochoke plunger sits down to start with then when warm it will raise in theory it will know when to do this through a sensor on the engine block or the same way a thermostat works but I'm not100% certain on which it uses.

Check that the connections to the auto choke are connected and are not corroded then remove it and block off the exposed gap and try and start the bike, if it runs then you have found your issue.
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Haz ER-5, innit!

[ashh v]

Okay its not the choke, becuase its completely off and doing nothing.
thanks for the help everyone

[TUG]

[ashh v]

[adamcfc]

Could it be anything to do with a weak spark? - just throwing ideas

Adam

[Rogerborg]

Honest question: do you Gilera pedbois receive some sort of owner's manual which recommends that you TITLE ALL YOUR FORUM POSTS IN CAPS?

I have to ask, because you all seem to do it. Frankly, I'm amazed that you put the bike in the title - usually it's just "NEED HELP" or better "URGENT NEED HELP NOW!!!!11!!". We can just assume that those posts are about a ped, almost certainly unrestricted, and likely a Gilera.

I know this isn't helpful, but... I have to know.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[TUG]

[GREENI3]

Your exhaust might need a de-coke.

My 2t ped did the exact same thing (wouldn't reach full speed etc).

Take the exhaust off and ride it up and down the road and see if the performance improves.
It'll be noisy as hell, but it'll eliminate a lot of factors and save a load of time if it happens to be a build up of carbon causing your problem.

[TUG]