DT200R powerband problems

[Curtis_DT200R]

hey, i am having trouble hitting powerband on my dt, i can hit powerband if i hold the throttle on just a tiny bit but when open the throttle fully it just flattens out about half way through the rpm range? the bike idles and feels fine downlow. it will rev high and freely when not under load. it has just had a topend rebuild, ive cleaned the carby about 20 times lol it feels like its not getting enough fuel (hence why i can hit powerband slowly), im thinking its a air leak sumwhere. ive checked the reed valves and they appear to be fine, i replaced the gasket around them also. ive cleaned the powervalve. any info would be much appreciated. me being a poor uni student i cant afford to get it checked by a real mechanic lol
cheers

 

[GarbatyA4]

I think ur bike is running lean. I'd check ur carburator boot. See if that sealed properly. You don't want to suck in un-metered air past the carb

 

[Curtis_DT200R]

ok thanks, ive orderd new parts for the carby, the rubber oring for the float bowl and the gasket around the throttle mount. just waiting for the parts..... im sure im rebuilding the carby properly, but i dont have a actual workshop manual, ive only got a crappy service manual which doesnt go into much detail, does anyone know where i can find a workshop manual? i tried ordering one from yamaha but they said they cant get one.
cheers

 

[Curtis_DT200R]

ok ive replaced the carb boot and still the same problem... but this time it died after about 2mins of riding?? any advice would be great.... im loosing my mind trying to fix this bloody thing.

 

[GarbatyA4]

Oh, sounds like the same problem I've had.

Ok, can you check to see if ur powervalve is working?

I bet you the linkage isn't hooked up, or something. LOL I put my governor in wrong when i bought my basket case. Definately sounds powervalve related.

Power valve works by restricting your exhaust port down low. as your engine speed rises, it will open up to maximize flow. Giving you a broader powerband. I'm think.

Your's is just restricting and not moving. probably needs cleaning or linkage broke/mis-aligned?

 

[Curtis_DT200R]

hey, but it still revs high and normal with the clutch in? ive checked the powervalve and cleaned it.. maybe ive put it in backwards??

 

[GarbatyA4]

Do you have the repair manual?

Possibly, needs to be adjusted only?

It will rev freely, mine did.

Is there a cap on the other side or a way to see the linkage if its moving? If the linkage is moving then that is just gravy.

Then I'd investigate the valve and stuff in the barrel.

 

[Curtis_DT200R]

ive got a service manual which doesnt go into enough detail. there is a cap on the other side so u can see if its moving, ill check it again 2morrow. ill take sum photos on which way im putting them in.

 

[Curtis_DT200R]

i have adjusted the powervalve but i still cant get the thing started. ill try to attach a photo of looking at it through the exhaust port.

 

[Curtis_DT200R]

now its running still the same(not hitting powerband) but way to rich and is just fowling up the spark plug. i think the sump may be full of fuel because i noticed that the fuel tap slowly leaks when on the off position, so im going to try and drain it. also im going to once again take the carby apart and check that everything is right.



ive adjusted the throttle needle? (not sure what its called). its the one that comes from the throttle and stops the fuel comming up into the carby. i set it at the 2nd highest height and the bikes alot better but the plug was still coverd in petrol. so i raise it to the highest and the power was similar but lasted longer. yet it still starves for fuel after u shift into 2nd and are about halfway through powerband? what else can i adjust to fix this problem?

 

[naiben]

Curtis, a haynes manual for a DT125R covers basically all things, the only difference betwen the 125 and 200 are the bore and stroke, I have a 89 DT200R, does your handbook have a wiring diagram in it? if it does could you scan it and send me a copy? ]
the jetting specs for a 90 DT125R are
main jet 210
needle 4th groove from top
pilot jet 22.5
air screw 11/2 turns out from fully screwed in
float height 20-21mm
The powervalve should be fully open at idle, with the exhaust off you should set the p/v fully open then.
John

 

[Curtis_DT200R]

hey mate cheers, i found a 05 dt 125 manual on the net the links
http://netfree1.blogspot.com/2008/09/yamaha-dt125-dt125x-dt125re-repair.html
if your interested? and the dt 200 wiring diagram is found at the end of the owners manual.the link is,
http://www.yamahaownershandbook.com.au/index.php
just enter your bikes details.
and where is the air screw on the carby? lol

 

[naiben]

It's on the left side of the carb(when your sat on it)Just under and to the right of the idle screw.
Thanks for the link.
John

 

[naiben]

Curtis, do you know what the numbers are on the jets on your 200?
John

 

[Curtis_DT200R]

hey, nah sorry i dont, i just gave my carby to the local shop.. i took some photos of it to show u guys cos it doesnt have the air screw where you said?

 

[naiben]

The mixture screw should be just to the right of top of black hose, yours is just the casting,I shouldn't worry about it as it only effects the mixture at idle but it seems strange there isn't a screw, over here I know that sometimes they make it so you can't adjust carburation but I didn't think you had it so bad over there.
What year is your 200?
John

 

[Curtis_DT200R]

9/1990 but i think the 91 model had a different carby with an airscrew? so just unlucky i guess :| . hopefully ill get it back of the moto shop soon and see what happens

 

[Curtis_DT200R]

well after 6 months of trying.... and a 50cent washer she now runs!!! :ride: . i was missing a washer between the mainjet in the carby :bang: thanks to a part diagram which the machanic had the problem was solved... thanks for ur input... now back to riding :nener:

 

[Driftin]

I have had near idnetical problems - and still do with my 1991 DT200R. The bike shop told me it was aan electrical fault with the powerband motor - despite the fact I had it checked and no problem was found.

Where do I get a schematic diagram of the carby so I can check. I'll be pissed if its a 50c washer missing after all the cash spent at the bike shop, and number of times of ridden it underperforming !!!

Cheers

 

[Curtis_DT200R]

hey mate, check out
http://www.yamahait.com.au/forum/index.php
i found it pretty helpful, as for your problem have you check you powervalve isnt sticking, incorrectly installed (upside down) or adjusted incorectly? there is a manual with a carby diagram on the forum above.