300EX Top End Noise

[Darrell]

Guys,

I asked a question about cylinder interchange between a 250X and a 300EX.

But, heres the real deal: I have not tore the engine down yet to see what my problem is. I have Top End noise when its cold. The noise seems to go mostly away after the engine warms up (I'm thinking piston slap). I have taken the rocker cover off and it seems to be in pretty good shape (thats as far as I have gone).

From what I can tell the cam chain is tight and appears to be in decent shape, as the same for the cam.

Before I tore the rocker cover off, I did adjust the valves, and this made little to no differance. The noise is a knock, sounding like its coming from the upper end.

The engine runs good, it'll wax a stock Warrior, but the noise worries me.

Anyone have any thoughts on this? Or experianced something of the same?

Thanks again in advance.

[300exazzkikr]

when my 300 is cold the valves tap like crazy, once it's warm it goes away. But you said you adjusted them, i would check it again. Otherwise it could be the wrist pin bearing. Since your ripping it apart anyway, might as well replace it, it's only like 2 bucks.

[sprtrx300ex]

my 300 make a knocking noise too. It sounds kinda like a hammer hitting something. Describe the noise a little better. Also, does it kinda humm and vibrate alot at half to full throttle?

[Darrell]

Yeah, I suppose a light hammer tapping noise would descibe it. I never have noticed a vibration or hum though.

How long have you had your 300? I guess maybe this noise isn't much to worry about.

I have been a automotive mechanic to long I guess, I'd worry about this sort of noise in automotive engine, maybe some 300's just do this huh?


Thanks

[sprtrx300ex]

actually mine didn't do it until like 3 month after i bought. It is getting worse though. I think it might be the cam chain. It is annoying and i need to get it fixed.

[Darrell]

yeah, I suspected the the chain, but it appears tight to me.

[Rebel300]

I think it is normal for a 300ex to make a noise like that. Mine does it whenever it is cold out. So it is most likely normal.

[300exryder]

if you are "waxing warriors", then i wouldnt worry about it. You must have some super engine or something. (the warrior has 66 more cc's and an extra gear) i dont know who you raced but all the warriors around me are equal or better than me, unless someone lets their 10 year old son ride it.

on my 300ex, i have an obnoxiously loud tapping noise that did not go away after adjusting the valves, cam chain, switching oils, and even after a new piston and rings. im thinking that it is ok to ride like it is. i had a mechanic take a look at it and he said the wrist pin hole was worn and was larger than it was supposed to be.

[Darrell]

Actually I don't have a "super" engine on my 300EX. It has been bored, has a DG pipe, KN air filter, re-jetted carb, modified air box and the gearing has been slightly geared up.

As far as my comment about waxing "stock" warriors I don't see how that was a far fetched statement, as I never went into details about my bike. And if you must know it wasn't a "10 year old" riding the warrior. I don't know maybe Warriors are faster in your part of the country (yeah right). With thier extra gear they do have an advantage on the very top end, but through the first 5, I have had "two" (I did say two) stock Warriors trailing behind me. (nuff of that)

Thanks for all the comments from everyone, and even for 300EXRyders comment on the explanation of the the wrist pin noise (makes sense), but I could have done without his sarcasm.

[300exryder]

Sorry about that, but I was just having trouble believeing you. I have a Jet kit, FMF pipe, and a 14 tooth C/S sprocket (geared up), and I still have trouble beating all the warriors, even some stock ones. I'm not brand loyal or anything, but i think my old warrior was superior to the 300ex.

Back to the top end noise - It should be fine to ride and if you have some free time and are mechanically able to rip off the top end and check it out, try looking at the wrist pin and maybe even replace the top end. I have been riding for abuot 3 years with the noise both before and after a rebuild with no negative effects. I'm putting some trust in Honda, ill add gas and change the oil and clean the filter, just keep me riding!!

[countypark]

QUOTE: I'm not brand loyal or anything, but i think my old warrior was superior to the 300ex.

You've got to be kidding.

Check the GNCC SPORT Class stats to see how many yamaha's are in the top 10.

I think they are superior if you compare them to a riding lawn mower.

[ghak99]

I am with country park, I would take my x over a warrior any day. The last time I was on a warrior and got any air on it at all, it felt like riding the top of a crashing building to the ground......lol......sorry, just my .02 And that fmf pipe might be slowing you up a little too.


Back to the noise,
If you had the cam cover off, was there any markings on the side next to the cam bolts. Sometimes these bolts work loose and will "nock" as the spin. This will be very easy to see if it is.

[300expimp]

ya my 300 does the same thing and it is brand new with under 50 hours with bout 15 rides but it seems to want to die after i cross the creek and it barely goes over the pipe then it starts to click like the soft hammer and i let it rest but it does worry u when u are away from home. i just let it rest for a minute i can keep up with a warior and have yall ever raced a z-250 well try it for fun u will smoke them in 3rd gear!

2003 HONDA 300ex
-FMF POWER CORE 4
-DYNO-JET KIT
-K&N AIRFILTER
-OUTERWEAR PREFILTER

MANY MORE MODS TO COME

WAT R SOME GOOD TIRES FOR CREEK RIDING?