Gas or Gasket?

[Grimzella]

I am wondering why i'm having this issue. When i start up the 300ex.. i have no problems, sounds great. When i ride softly (1/2 throttle or less) or on flat surfaces, everything sounds great. But, when i decide to climb a pretty steep hill, and when i need that low end power toward the top of the hill.. this is when things don't sound great.. it seems as if my valves are chattering as i give it gas to climb. Is this because the top end of the 300ex is really built for the 250? or are my springs and/or valves worn out? I do not blow any smoke at all. Could it be my headpipe gasket not sealed correctly? Could this possibly be a jetting/pilot issue? or airbox problem (lid on but (6) 1 inch holes cut in lid)? Could this be cheap gas? I currently use Sunoco 93 octane.

Any help or ideas would greatly be appreciated,
Thank You,
Dave

[shiley55]

hmm i think it might be something with the carb if its only on hills and not on flat casue if it was something like the valves i imagin it would do it all the time up hill down hill or flat . first iwould pull the tank off and drain it and make sure it dosent have any bits in it then id replace the fuel filter and line and also try doing it with it on reserve casue it could be that buts are rolling back and not letting it get ehough fuel and then after the new fuel filter and clean tank take the carb off and clean it and if that dosnet work come back here lol

[Grimzella]

well i can say, after my modifications to this originally stock 300ex.. i have never cleaned the petcock screen or tank before. I will do that first.. clean tank\carb\screen. I did run STP carb cleaner mixed with my gas recently (is that good or bad?) but the noise was still there. I check my valve lash every 2 months and adjust if necc.

Chatter is only present if i need bottom end climbing steeper hills, seems like once the engine needs more power to pull and i give it.. chattering starts happening.. but downhill is fine.. straight aways are fine, ect.. just when i need torque it seems to happen.

I definitely will get back to you once this is done.
thanks for the reply,
Dave

[rapple]

Sounds like it might be pre-ignition. Depending on how bad the detonation is, it can sound like a bunch of ball bearings rolling around in a can.

If that's the case, you need to address it or engine damage is certain. Pull your plug and look for any signs of corrosion.

When you drilled the holes in your airbox, did you re-jet? If not, you're almost certainly running too lean.

[Grimzella]

Originally posted by rapple
Sounds like it might be pre-ignition. Depending on how bad the detonation is, it can sound like a bunch of ball bearings rolling around in a can.

If that's the case, you need to address it or engine damage is certain. Pull your plug and look for any signs of corrosion.

When you drilled the holes in your airbox, did you re-jet? If not, you're almost certainly running too lean.

Thats why i like to put as much information in my description of modifications as possible (below).. as u can see "yes" i did rejet. 128 def is not STOCK jetting. I to think it might be a jetting/air/something type issue. But it definatly is no pre-ignition problem. My plugs are basically a dark brown or tanish color. Its been like this for 1 year to the day. and 3 spark plugs later same issue. Dr8es or whatever that NGK plug is.

[Grimzella]

I guess if you look at this post logically, both reply's suggest starvation of fuel. Is this possibly the issue?? could lack of fuel cause pinging in this situation? If so, then maybe the issue is my 128 main jet. should I bump it up? Elevation is 1200ft - 1400ft.

[rapple]

Originally posted by Grimzella
I guess if you look at this post logically, both reply's suggest starvation of fuel. Is this possibly the issue?? could lack of fuel cause pinging in this situation? If so, then maybe the issue is my 128 main jet. should I bump it up? Elevation is 1200ft - 1400ft.

Obviously 'weird sounds' are tough to diagnose on the internet :D

Jets are cheap... if it were me, I'd try a slightly fatter one and see if it makes it any better.

[shiley55]

yea i deffinatly do not think its anything actually in the motor cause if so it would do it all the time did this problem just start or how long has it been since it started happining after your last mod and what was your last mod

[Grimzella]

Originally posted by shiley55
yea i deffinatly do not think its anything actually in the motor cause if so it would do it all the time did this problem just start or how long has it been since it started happining after your last mod and what was your last mod

Yes it did do it after the mods. I did all modifications below at the same time. And the noise was there after that. Never was there with Stock setup. I will clean tank\screen\carb today.. if that don't do it I will order a 130 K jet and try that.

Thanks fellas,
Dave

[shiley55]

is it the same sound as when your in a venicle with a manual transmission and your going up a hill kind slow ish in a higher gear than you should be in and its all shaky and rattley and sounds like something is about to go out?

[Grimzella]

Originally posted by shiley55
is it the same sound as when your in a venicle with a manual transmission and your going up a hill kind slow ish in a higher gear than you should be in and its all shaky and rattley and sounds like something is about to go out?

well kinda.. but it dont sound like anything is going to blow up or break.. it just taps/chatters.. and don't seem to have much power.. but that is where it gets noisy.. kinda just like you described. If i downshift the noise stops. but.. 1st gear is not the gear i really like using on a steep hillclimb. 1st is way to slow.. and its easier to pull up the front end in first.. and that will = quad rolling down hill. or i will get stuck on the hill and spin tire. because i have no momentum at that point.

[shiley55]

well ud thats the case id deff think its not getting enough fuel for 1 reason of another whatever it is we will figuer it out and get you back on the trails

[m0t0xk1d]

honestly it sounds like your in to high a gear. i mean really my predator 500 only climbs in 2nd maybe 3rd. unless you have more torque your going to have to bump it down to first or get momentum


and my predator makes the same "clunking sound" when in to high a gear . shift down and your set

[Grimzella]

Originally posted by m0t0xk1d
honestly it sounds like your in to high a gear. i mean really my predator 500 only climbs in 2nd maybe 3rd. unless you have more torque your going to have to bump it down to first or get momentum


and my predator makes the same "clunking sound" when in to high a gear . shift down and your set

It is second i am in. i would rather not, but may have to shift down into first. I will get back to this thread after i try some suggestions here.

[shiley55]

no too high a gear isnt the problem i mean if he was climbing in like 3rd 4th or then yes that would be the problem . i climb very steap hills in 2nd on my 300 and have no problem but also when you quad start clunking and what no you can stab the throttle and break the wheels loose and it dosent clunk anymore i mean **** you can start in 2nd gear with any quad and not have the problems hes having

[m0t0xk1d]

see shiley that where your wrong. it depends on so many things like hill steepness how high it is how much momentum you have how much torque you have. you cant just go punch it right before a hill.


my predator will only go up hills in 2 maybe third. but on my 300 if ripped up hills in 3rd aometimes 4th but i start to bug right atthe top. torque has a lot to do with this. my 300 has ALOT of torque compared to my 500. there are so many variables it hard to limit it down to one with out trial and error

[Grimzella]

Exactly, and i know this, that is why i love this forum. Great guys & great information. The hills are pretty steep i climb. I thought second gear, being such, with 13 teeth and 20in rear tires, i though 2nd gear could tackle almost any hill. You think maybe my *** is too fat for this 300 in second gear. lol I am 175-180lbs. could this be why second is not pulling me like it should. just kidding.. BUT MAYBE. Jets are cheap so i am just gonna buy a 130 and see what happens. I need a 40 slow jet anyways.. winter comming up and what a PITA that can be at times. I like to start it up, , let it idle while i wait in the house. Not to come outside and there it sits stalled out and still cold.

[Grimzella]

Originally posted by shiley55
hmm i think it might be something with the carb if its only on hills and not on flat casue if it was something like the valves i imagin it would do it all the time up hill down hill or flat . first iwould pull the tank off and drain it and make sure it dosent have any bits in it then id replace the fuel filter and line and also try doing it with it on reserve casue it could be that buts are rolling back and not letting it get ehough fuel and then after the new fuel filter and clean tank take the carb off and clean it and if that dosnet work come back here lol
Well, that was it. There was crap in the gas tank clogging my screen. Never did i think it would be that easy. I cleaned the tank & screen. Took it for a ride.. and BAM!!! Ping is gone. I know its hard to figure out "Noise" over the internet, but i gotta give my man credit.. That was his first suggestion and THAT's what the problem was. THX a Million shiley55!! I'm gonna make a habit of cleaning the petcock\screens at least 1 time a year.

Thanks again,
Dave

[shiley55]

np