300EX Motor Rebuild

[QuadRacr57]

Hey I have a 1996 300ex and i've raced it the past 3 years. So the motor has taken quite a beating over the past 10 years. I am starting to think that i should tear the motor apart and replace the rocker arms and springs and whatnot. Do you think i should rebuild it and maybe mod the motor up a little bit, or should i just use it this season and buy a 400 or 450? Im new to this, so if you think i should rebuild it, what should i replace? Thanks

-Mike:confused:

[RiderTRX400ex]

seeing how its 10 yrs old and has been raced.. it sounds like it would be a good time to tear deep into the motor and go over everything and replace all bearings and seals, piston, rings.. all the goodies.. as far as a new 400 or 450, it depends on how fast you want to go.. it will take some money to make a 300 run with the bigger quads, so think it over before you dump a lot of money into that 300

[Lamont400ex]

I just rebuilt my 2003 400 ex to a 416 with all performance parts. Now my buddy is still running his 2001 300 ex with no problems. I have a few buddy's who race and they all agree that the 300 is the longest lasting. My experience is that a 10 year old quad is paid for in full and no matter what you aint going ot get much for them. The rebuild is quite easy so I recomend rebuild complete and go all performance. Cost is going to be alot less then new an you are starting with a new engine so giddy up. Good luck

[QuadRacr57]

Originally posted by Lamont400ex
I just rebuilt my 2003 400 ex to a 416 with all performance parts. Now my buddy is still running his 2001 300 ex with no problems. I have a few buddy's who race and they all agree that the 300 is the longest lasting. My experience is that a 10 year old quad is paid for in full and no matter what you aint going ot get much for them. The rebuild is quite easy so I recomend rebuild complete and go all performance. Cost is going to be alot less then new an you are starting with a new engine so giddy up. Good luck

I agree with you. I've been looking on ebay, and the 300s don't go for much which sucks:mad: . So that might be a good idea to bore it out to a 330 and completely build the engine up, so i could be up there with the stock to mildly modified 400's and 450's. Well, thanks for your help. Can you i do everything except bore the cylinder?

[Lamont400ex]

actually ya. I went to my Honda dealership and got the reamer and pullers I needed ( pretty cheap actually) and did it all myself except the bore out. It took me about 7 days total once i had all the parts. I went with a Hot cam stage 1, weisco piston and rings, hotcam crank and new valve guides, all new bearings and gaskets/seals. Overall with the custom exhaust (250) it totalled around 1000 for me to do it. I really recomend buying the Honda Maintance book as it gives you such a great break down and very detailed description. It was expensive but so worth it. So my recomendation is by far do it yourself. Mine runs awsome the only thing I am still playing with is the jetting which is just fine tuning. Well good luck and anymore questions just ask.

[QuadRacr57]

I have a Clymer service manual, not the honda. Is the honda one more detailed and easier to use? My brother has a honda manual for his 400, but mine just came with the Clymer. Should i just use the clymer?

[bwamos]

The clymer manual is just fine.

I have both. They are about equal. Some sections are better in the clymer, and some are better in the HSM.

IMHO if you are looking at a "complete" overhaul.. you may as well at least look into snagging a 350x engine and boring it out to a 393cc. ;)

[QuadRacr57]

Bwamos, I don't want to completely overhaul it, i just need some more power for this year and maybe next year. After that i'm going to move up to a bigger machine, so i dont want to put too much money into it. Once i get the money, im going to get the FST 330 kit. Then from webcamshafts.com im going to get the cam, racing valve spring kit, shortened valve guides, hardweld rocker arms, and valves. All this will cost about $850, is there anything else i should look into, or something i dont' need in there bwamos, or anyone else?

Thanks,
Mike