???s maybe silly....but..

[Fred1956]

Hey to all and thanks in advance,
I just put head and carb back on my '06 EC250 after RB Designs head and carb mods. Followed all instructions per Ron's sheet. Bike feels crisp after warming up but I have a couple of issues/concerns. I got to ride some single track for about 45 minutes last night before it got dark so...This may be jetting but may be something else. When rollong the throttle on from idle in medium speed, any gear, flat ground, I hear a clatter noise. Not a tinny sound but deeper. Could it be pinging? Or could it be piston "slapping"? I could not find a way to make it stay "in the noise" it only happens for a double blink but it is there. I did not pull the cylinder as the bike ran very good before, but like most of us I was trying to get a little more. :-)
Also it seems to have lost a little low end, just the opposite of expectations. It started with a 40 pilot and Ron put in a 42, I have the RB air screw and it is at 3/4 turn out, it had a N1EF needle set in the middle and sheet now says CEK-3, with 178 main (same as before). The low end feels flat and doesn't respond to the clutch as it did before. It doesn't just fall flat but seems more like a 125 with out the clutch feather boost. I was at around 1200 feet above sea level. Bike runs great through the mid and top, just seems a little 'dead' off the bottom.
Any ideas or suggestions?

P.S. I may be getting fooled, while the EC was down I've been riding an '06 GasGas TXT 280 Pro trials bike and that thing is a locomotive off idle so... something else to consider.

[jostby]

Do you use the original GG chain guide? If so it sounds like chain slap to me. Chain slap only seems to happen at low RPM's when rolling on the throttle as you describe. Tighten your chain just a smidge and try it.

[Fred1956]

Originally Posted by jostby

Do you use the original GG chain guide? If so it sounds like chain slap to me. Chain slap only seems to happen at low RPM's when rolling on the throttle as you describe. Tighten your chain just a smidge and try it.

I'll certainly check that, we put a trials tire on also and may not have the chain just right....Thanks

[Ud_luz]

I'm going with a false feeling of low end after riding the trials bike. I feel the same if I've been riding my Montesa and jump back on the GG. The machine feels weak down low.

[HuskyDude]

Originally Posted by jostby

Do you use the original GG chain guide? If so it sounds like chain slap to me. Chain slap only seems to happen at low RPM's when rolling on the throttle as you describe. Tighten your chain just a smidge and try it.

I agree at low throttle running a kinda loose chain. My Husky 510 does it so much it has worn a groove in the frame. I find a properly adjusted chain and greased will make the sound all but go away.

[seitz64]

did this mod 2 years ago to one of my sons bikes same bike as yours! FOUND WE NEEDED TO GO RICHER 45 pilot 180 main fixed his noise you could try to richen up air screw and needle clip to see if you can get noise to change also you could try some race gas to see if it goes away good luck !

[jefgil123]

I have RB Head mod and like the CCK needle, (the CEK runs too lean on mine)

[2 strokes 4 life]

The N1EF on my bike I run at the top position (leanest) and it has a mean middle flat spot but runs great everywhere eles. I suggest lowering the needle one position and see how you fair.

[Fred1956]

Thanks for all the suggestions, will try and report back.