06 300 de powerband issues

[Powerhouse]

06 300 de powerband issues *fixed*

Hi everyone, first post here.I recently picked up a rough running 06 300. After reading thru threads here I got her running much better. The bike had real good bottom end and slightly into the midrange and then it would just flatten out and not rev. What I found was an almost completely clogged turbine core assembly in the silencer. Also found a 45 pilot,ddk needle on middle clip and a 158 main jet in it. After disassembling and cleaning the silencer I installed a 42 pilot,cck needle in top clip and a 175 main. The problem I'm having now is getting it into the powerband. It has strong low and mid power but again flattens out past the midrange. If I hold it wide open when it's doing this after 5 seconds or so it will slowly hit powerband and rev out or if I stab the clutch as soon as it starts to flatten it hits the powerband much harder and revs out. I'm thinking I have a jetting issue but wanted to get some insight from anyone that has had this issue and fixed it. Thanks Andy

 

[dANbOT]

Maybe someone who is familiar with the needles you have will chime in, I'm no help there. Have you have tried your needle clip in a richer position? The way you describe it being flat sounds lean to me.
Pretty easy job to pop an exhaust valve cover, and rev the bike in neutral just to be sure the exhaust valve is operating.

 

[Cox76y]

Sounds rich to me. Try a smaller main..

 

[motopsycho87]

Check -

Spark plug (use iridium, i only get 3 rides out of a standard)

Power valve adjustment

Float height

Then try the jetting in my Sig, or close to. The needle jet (not needle) has a tendency to wear over time so leaner needles are required.

Silencer (standard ones break down) (not applicable to you)

Make sure you have a resistor type spark plug cap, non resistors kill cdis QUICK on these

If it's still there. HT Coil, stator coil, cdi. Check all earth points and contacts before changing things.

 

[Powerhouse]

If I drop the needle it looses it's crispness down low. Powervalve was checked and is opening .

 

[Powerhouse]

Plug is a new iridium - br9 eix ,float height is good. This bike has definitely seen a lot of time, it was raced, but was maintained. I am thinking it might be a worn needle jet based on the fact that I need to run the top clip. I also don't think it's idling solely on the pilot curcuit as the idle screw is almost all the way in and the air screw has no noticeable effect anywhere from a half turn out to 3 turns out. I have a new carb on the way and will have it this week. I will set that up with my current jetting and then reassess. Thanks for the replies

 

[Powerhouse]

Got a chance to try a new needle Tonite. It's out of my old Suzuki rmx 250.... 1472 ... equivalent to a dgn. According to the keihin chart it's leaner than the cck at 1/8-1/4 throttle and richer from 1/4-3/4. I installed it on the middle position. After warming the bike up I gave it a quick ride down the street. It definitely smoothed out the power down low but still had plenty and was good til wot. Then It just flattened out, definitely lean. I then swapped out the 175 main for a 185. This worked wonders. Smooth power all the way. No sign of a powerband hit just smooth revs to redline. I'm gonna pick up a 180 main and play with the clip position to try and lean it out a little so it's not so 4 stroke feeling but definitely made steps in the right direction.

 

[motopsycho87]

That's surprising, mine rips your arms clean off!

 

[julianorettore]

Got a chance to try a new needle Tonite. It's out of my old Suzuki rmx 250.... 1472 ... equivalent to a dgn. According to the keihin chart it's leaner than the cck at 1/8-1/4 throttle and richer from 1/4-3/4. I installed it on the middle position. After warming the bike up I gave it a quick ride down the street. It definitely smoothed out the power down low but still had plenty and was good til wot. Then It just flattened out, definitely lean. I then swapped out the 175 main for a 185. This worked wonders. Smooth power all the way. No sign of a powerband hit just smooth revs to redline. I'm gonna pick up a 180 main and play with the clip position to try and lean it out a little so it's not so 4 stroke feeling but definitely made steps in the right direction.

Did you check the ignition timming to see if it is correct? It may be that the ignition is with the delayed point and this inflates directly in the acceleration of the motorcycle (translate by google )

 

[Powerhouse]

That's surprising, mine rips your arms clean off!

Im feeling it's a little too rich thru the mid and top right now which is softening the hit. I ordered a couple different needles in between the cck and the dgn plus a 180 and 182 main and will keep testing. This engine is all stock also so I'm sure it has a huge squish area and lower compression than yours which certainly doesn't help powerwise. It feels about equal in power to my 450 exc ktm but not even close to my CRF 450r

 

[risk74]

If you haven't cleaned the powervalves, do so. Mine had a lot of hours on it running/racing single track, felt a bit flat on top. When I took the main valve out there was so much carbon build-up it could not open up all the way.

 

[Powerhouse]

Powervalve was checked and was fairly clean . It is opening all the way. I'm convinced at this point it's all in the jetting. Plan is to tune it best I can for now and ride all summer. Will get new topend and head mods over the winter. I need to get the suspension set up for my weight (220# with gear) before any engine mods. Lots of roots and rock gardens where I ride and this thing is like a jackhammer right now.

 

[Powerhouse]

Just an updated. I have tried a few different needle and main jet combinations and have settled on 42 pilot with airscrew around 2 turns out,DEL needle on middle clip and a 178 main. This was the best all around setup. The ddk was good down low but to rich in the middle and up top and the cck was to lean everywhere. I do have a n3eg needle on the way and will try that when it arrives. I did change out my springs for .46 front and a .56 rear and it is much better in the rough stuff. This bike is turning me on to 2 stroke enduros again. Been on my ktm 450exc in the woods for years and love the grunt it has but the weight does take it's toll on you after a while. And while the 300 doesn't seem to have as much power , low or high, it's plenty enough to get the job done and the lighter weight takes less energy and is far better thru the corners.

 

[Powerhouse]

After playing with jetting and getting the bike to run much better I still wasn't happy with the power...or should I say lack of power so decided to pull down the top end for new rings and head mods. Piston still looked and measured good so I applied a moly based skirt coating and cut 1.25mm off of the head to get the squish to 1mm. Only took a few CC's out of the chamber to keep compression high ( I always run 50/50 race and pump gas) hopefully this will give me the power the bike seems to be lacking.

 

[Powerhouse]

Bike is back together and running. Did a compression test before starting it. Compression now cold is 185# vs. the 125# cold before. While the piston still measured in spec. The ring gaps were in the 1.25 mm range. No signs of leakage past the top ring but clearly worn and out of spec. The bike was assembled before with a .5mm base gasket and squish measured in the 2-2.25mm range. I assembled with 2 gaskets measuring .8 mm . This aligned the top of the piston with bottom of the ex. Port. I removed approx. 1.25 mm from the head. This resulted in a squish area of 1 mm at the area near the cylinder wall and 1.25 mm at the inner edge of the squish band. Bike started right up and seems much more responsive. Ran for about 5 minutes to heat cycle. I will let cool and retorque head and base fasteners. Will take the bike out for a ride later with current jetting ( 42 pilot,n3eg middle clip,178 main, air screw around 2 turns) and reassess and make changes as needed.

 

[motopsycho87]

I use the KTM spec as my ring gap, which I believe is about 0.3-0.5mm, worth noting

 

[Powerhouse]

Gap with new rings was right at .5 mm

 

[Powerhouse]

Got out for a quick ride and definitely found the power it was missing. A little rich down low and getting a little pinging at mid rpms but clears up as it hits the powerband. The bike pulls real hard now mid to top end. Plan is to go to a 40 pilot and retard timing just a touch and reassess. Very happy with the results so far.

 

[(F5)]

So chamber looks nice but you should machine head squish to match piston as wedge shape, we'll was on mine. I had to take quite a bit out to reduce compression once that was done.

Compression gauge will lie to you. Throw it away and use a burette to measure actual volume available online.