300ex problems

[hondardr4life]

Ok, my friends 300 was smoking and making a loud ticking noise when the motor was inder stress. So we tore it down and found it already had a wiseco 11.1 .040 piston in it and he was running 87 octane in it, thats why it blew. Well we put in an .080 over, and it still makes the loud tickign sound when you hammer on it, but if you ease into the throttle, it doesn't make it. I am 100% positive that I did the motor right, because I have done many 300ex motors, and I have worked for my grandpa who used to professionally rebuild car engines. I cleaned it out good, ported and polished it, ground the valves, replaced the seals, and adjusted the valves. I am thinking the reason is that he has 22 inch razr tires on the rear and his 300 motor just wont pull them, and that is why it makes the noise, because it is being stressed out a lot. These tires ran fine on my 300 when I had them, but thats a 330. So I think its just the sound that his makes when it bogs. What do you guys think.

[dirtmomma]

It sounds like it is running HOT to me!! Mine does the same thing @ the dunes when it's warm out & it's been ridden hard, might wanna try an oil cooler thats what I plan on doing for the real hot heat!!

Are you SURE your valves are adjusted right?? might wanna check them again, one of the little nuts could of backed off :)

Hope your running higher octane fuel in this time :)

[hondardr4life]

Yea, I put the same 94 octane in it that I put in my 330. He is in SC, so I have been rebuilding it for him. I'll check the valves again. Hmmm, maybe I'll try putting in one of my NGK plugs. He has a champion in it. Maybe that is the problem :confused: :confused:

i think that your jetting is screwing you up, and the 22s arent helping, try some 20s next time

[hondardr4life]

I'll throw my 20's on there, and see how it does.

[rooster300ex]

the 300ex come with 22in tires stock. mine never had a problem with 22's. is it like valve spring ticking?

[RiderTRX400ex]

how much time on the motor after rebuild? cam chain?

[300ex mxracer]

my 300 pulled 22" shredders jus fine

[bwamos]

You're running a bit lean.

It causes your engine to get hotter.. and causes detonation and/or pre-ignition under load on an 11:1.

Turn on your choke 1/4 of the way. Gun it the same way (under load) and see if it gets better. May sputter, thats ok (means the choke went beyond to the rich side), as long as it doesnt ping, the choke method isn't exact it's just a quick check.

If it stops the pinging.. then increase your main jet 2 sizes. Basically, if your running a 140 go up to a 145.

FYI: I run 22" tires just fine on my 11:1 330cc with Premium Pump (87 octane).

With the work you've done and a 2mm (0.080") overbore you should be running between a 138 - 148 main jet.

What size main jet are you running, bro?

[hondardr4life]

I've got a 130 in there. Maybe that is too lean???

a 130 is way too lean change it out to something bigger and try adjusting the fuel screw while your at it

[300exOH]

Originally posted by hondardr4life
I've got a 130 in there. Maybe that is too lean???

I would say definitely too lean. I have a 135 main on mine with a sparks x-4, UNI filter and a STOCK engine. My needle is in the stock position and I'm running a 42 pilot jet. I jetted according to sparks recommendations. Mine seems to be perfect so I'm guessing with and overbore you may need a size or 2 higher on the main jet. I am also using 87 octane with no problems.

[bwamos]

Put a 140 in there.

That will be a good place for you to start.

[hondardr4life]

It suprises me that I would need to run a 140 in a true 300 when I have , well had now I have a lectron, a 148 in mine. I don't have any 140's laying around, but I'll try a 135, and a 142.

[hondardr4life]

Ok, I fixed it. I put in one of my NGK plugs and it fixed it instantly, he had a champion in it..... :confused: . The jetting is perfect, it runs light brown on a plug check.

Oh yea, and will it hurt it that I used hondabond as a base gasket because I accidentally ripped the base gasket I had and I had to throw it out. I have heard of peopel doing this before, so I think I'll be ok, because theres not really compression pressing on that area.

[xx3003xrdrxx]

it better be ok god dammit lol no but ser. do you guys no if that is gonna be ok ?