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DT125R Forum -> Tuning -> Getting my bike running right (in depth help needed)
Post Info TOPIC: Getting my bike running right (in depth help needed)
Soleconsumer


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Getting my bike running right (in depth help needed)
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Hey all i have some problems with the power of my bike.
DTR125 2000 Model

Mods done so far:

Rear DEP
Gutted front pipe (supposedly, im not sure if the garage i took it to actually did it)
Inlet manifold
Airbottle taped up
Reed switch in speedo moved
Upjetted (i forget the jet i used, it was one that was reccomended allot on the old forum)
Snorkel removed
Engine fully rebuilt 6k miles ago
Stock gearing

Having the powervalve set so that when alligned with the hole it is flush with the exhaust port makes my bike feel guttless, there is barely any powerband and it struggles to make it from 65-70, acceleration is also poor i can barely pull wheelies in first by chopping the throttle, cant clutch up in second.

Having the powervalve set a centimeter or so to the left of the hole however makes the bike feel much more powerful, i can wheelie it more easily and do 70-75 (occasionally 80) allthough no matter what i still cant clutch up in second.

If you can imagine the powervalve when alligned to the hole is flush with the barrel, why is making it turn counterclockwise giving me more power? that is basically making the far edge of the powervalve protude into the front pipe reducing flow.

I am also getting better performance by having the airbox cover slightly open.

The bike was like this before i had it fully rebuilt so it cant be a lack of compression problem, I did the upjet since then and it hasn't made any difference really.

I have done some trial and error.

Reducing airflow (closing airbox cover) = reduced power
Un-taping small airbottle = No difference, allthough having it untaped may increase max revs.
Pegging powervalve in alligned open position = Weak performance, allthough slightly better then when unpegged.
Pegging powervalve to the left of allignment = Better performance, same ish performance as when unpegged and alligned to the left.

A while back i cleaned out the exhaust system with caustic soda
Recently i have cleaned it again with a blowtorch and cleaned the inside of the exhaust port and removed and serviced the powervalve, no difference.

My thoughts right now are this is an airflow problem, jetting? or maybe i need a front dep pipe, but my exhaust should allready be gutted and i heard that has almost identical performance to a dep pipe.

I hear of people pulling wheelies off the throttle in first and second and there are some video's of people clutching it up in third and fourth on youtube, why is my bike so slow? it does 75-80 but i cant even clutch it up in second there is not enough power.

Suggestions anyone? :/

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Gixergav


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What did you do to the inlet manifold? The stock unmodified manifold works best of all.
Which air bottle was taped up? The one on top of the inlet manifold or the one on the hose at the rear of the carb
But deffo put the snorkel back on and put the standard jet back in to start with

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Soleconsumer


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As instructed on dtr125.net i cut the nozzle off the inlet manifold.
I never found much difference when running with the snorkel or not, other then the sound is much nicer without.

*Update*

I just cleaned the carb/manifold/reeds/airbox and regreased a few of the seals, i was running a 160 main in the carb, i just swapped it back for the stock 140.

There seems to be some improvements, throttle response is better and power is up with the powervalve in the aligned position, however the improvements are minor, no second gear clutch wheelies.

I am going to try moving the powervalve to the left again and see if i get results.

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delboy


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put a 210 main jet in in m8 and buy a new pair boxers when test ride it : )

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delboy


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got 3 pair for 5 pound brand new if u want them for fiver

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Soleconsumer


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A 210 jet would surely be far too lean.

*update*

Having a 240 jet in and the powervalve to the left of the 'hole' is much more powerful then having it alligned on the hole.

this is SO confusing, why is it doing this.

Is there a chance my powervalve is working wrong or something, when its alligned to the hole it is flush with the exhaust..that is how it should be i thought

With it like that i can just about clutch it up in second. Can you lot really clutch it up in second and third so easily?

I allready do 0-60 in 6-7 seconds, to have the ability to wheelie in the first three gears would drop that time down to less then 4 seconds..which is impossible. what the hell???

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Gixergav


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You will need the standard 240 jet in the carb.If you have modified the rubber manifold that attaches to the reedblock then try a stock one because its not a restictor as standard.Make sure the jet needle has its clip 4th from top too.Mixture screw at 1 1/2 turns out.
Replace the snorkel.It flows too much air in without it.Make sure that front pipe has deffo been gutted
Any healthy dt should wheelie up in 2nd without the clutch

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Soleconsumer


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lets get this straight. by a second gear clutch wheelie i mean this:
Sitting as normal can even be leaning forward, slip clutch, pull throttle
Is that what you mean by a clutch wheelie?

I can of course pull them if i sit back a bit and pull on the bars or yank the bike back.



Right now i can pull a wheelie in first sitting normally with the clutch or just chop the throttle

Second i can get some lift sitting normal and clutching it up, or i can sit normally chop the throttle and yank the bike up

Third i can stand up chop the throttle and yank the bike up

Fourth havn't tried much, probably cant though


Unfortunately i cant alter the mixture screw as it has decomposed and crumbled, i belive it is at the normal 1 1/2 turns out as i have never touched it


It gets to 70 pretty damn fast then will crawl to 75 maybe 80 (my speedo only goes to 80)
However it seems restricted in the top of the rev range, i have to push it to get to 65-70 in fifth gear it doesn't want to rev out.

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Soleconsumer


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After being out for a ride i can get to 60 really easily, but there seems to be so much restriction in the high revs, it doesn't want to go past 8.5-9k in gear 5/6

The year of the bike is 2000, i have done the reed switch behind the speedo but is there any other sort of electronic restrictor limiting the rpm?

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delboy


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****ing jet man not all dtr hav 240 as std ****ing put a 210 ur fly man

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delboy


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my std jet 210 my 1 2001 and gix not all dtr hav 240 main jet u fOol read up on it man

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delboy


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u allways say std jet 240 1987-2009 i dont think so no it all hump.gif read up befor u giv ppl info

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delboy


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his mix is 2 rich thats y it wont rev high

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Gixergav


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How do you know your 210 is a stock jet?
Haynes list a 210 and many people have swapped from 240 to 210 because of this to then find out it runs better with the stock yamaha jetting of 240.You plonker

Have you tried the jet needle settings?
Have you fitted a recent plug.If its slightly fouled it can be difficult to spin up high rpm
And it is common for 6th to turn into a 'overdrive ' gear with the valve open


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delboy


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well got say my std jet size 210

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Soleconsumer


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My bike came with a 240 stock.

This is really getting weird, the further i take the powervalve to the left hand side on the allignment hole the more power i get.
This doesn't make sence as it is in effect closing the valve...its going backwards...

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RudiRulez


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Just a thought but maybe your powervalve is in upside down, some of the powervalves were fitted like this to act as a restrictor.

-- Edited by RudiRulez on Friday 21st of August 2009 08:14:01 PM

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Soleconsumer


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These pictures reprisent the powervalve in my bike
The result of paint and a few minuites...

The open position is where my PV is located when at the hole
The Closed position is where it turns to the right to give more bottom end power
The Backwards position is the setting where i have to run it to get any power

The bike feels totally restricted and gutless when alligned to the hole like this

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Soleconsumer


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anyone? :(

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Gixergav


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Your first diagram is how the valve needs to be to be open.Picture 2 is the wrong way altogether.Picture 3 shows the valve closed.
In pic 1 the bike should fly when hitting 5.5k rpm but be a little flat below this.In pic 3 the bike should have strong bottem end and tend to die off at around 8k rpm

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Soleconsumer


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hang on...what?
But the powervalve turns to the right when at low revs (picture 2) and then turns to the left at full revs flush to the hole (picture 1)

For what your saying my powervalve should be turning left at low revs then right at high revs

http://www.youtube.com/watch?v=-4Xhmw5zIi4

That is the video of someone's powervalve, that is what mine does


Should mine be turning differently then? do i need to cross over the wires?

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Soleconsumer


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Allthough!
Compared to that video my valve moves much further to the left, i know there is a short servo pulley and a long one, maybe i have them the wrong way round

But still it would make the valve like in picture 2 when at low revs

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Soleconsumer


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http://www.youtube.com/watch?v=UsWwQssiK-w&feature=related

Another vid of the powervalve... see it moves into the position in picture 2

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Gixergav


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Ok try this.Picture 1 is were the valve should be when fully turned to the right.If it rotates too much the valve can hit the piston which is kinda like what pic 2 looks like.Pic 3 shows the valve closing the exhaust port off.This is what it does when it turns left.
Are you looking up the exhaust port as this is the far easiest way to determine the valves position

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Soleconsumer


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your powervalve turns left? look at the video

http://www.youtube.com/watch?v=-4Xhmw5zIi4

does your powervalve move like that?

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Gixergav


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If your looking at the barrel from the left hand side of the bike then the valve turns left to close,right to open.

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Soleconsumer


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what year is your bike?

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Gixergav


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All dtr and tzr engines operate the valve in this direction.My advice is take the front pipe off and look at the valve directly to determine its position.
It looks like the valve is sitting wrong.It should only move between position 1 and 3. 3 is closed,1 is open.

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Soleconsumer


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Did you check out those videos i linked? it shows the powervalves operation, when you hit the ignition it does its cleaning cycle and alligns to the hole (fully open) then when you start the bike it moves to the right (closed) then when you get to the high revs it moves left again to the hole (open again)
There is no way this would do that if the valve was turning to the left as you say.

Here are some video's showing powervalves turning to the right

http://www.youtube.com/watch?v=-4Xhmw5zIi4

http://www.youtube.com/watch?v=GJ-MLVAFGLo&feature=PlayList&p=4CD7D886206E658C&playnext=1&playnext_from=PL&index=21

http://www.youtube.com/watch?v=vPGTb0yg1UA&feature=PlayList&p=DFF43F78205C0792&playnext=1&playnext_from=PL&index=6

http://www.youtube.com/watch?v=ukYuCMsCZhg

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Gixergav


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Have you looked up the exhaust port to check?
In this vid the valve is actually fitted upside down but it turns left on its cleaning cycle instead of right

http://www.youtube.com/watch?v=UsWwQssiK-w

The cable set up is the wrong way.In your pics no.3 is the closed position for the valve.

In this pic you can see the lip of the powervalve in the exhaust port.Its true open position is a few more mm rotation.Its sits flush with the port with no lips
dtbarrel003.jpg

 running with the valve rotated towards the piston can result in a piston strike if turned too far.The valve blocking the port is inefficient here.It blocks too much of the hole
dtbarrel002.jpg



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