Lots of questions (new here) 300ex

[BKB]

I was not able to find solid answers to my questions using the search. My 93 300ex has a K&N, lid removed, jet kit, and i plan to use a stock 400ex muffler with a larger header. I need a boost in mid range for the tight woods riding i do. Some upper RPM power would also be nice for the coal pits. I dont plan on replacing the stock piston anytime soon. I also dont plan to ever rev past the stock limiter.

First what is stock compression on my 92 300ex. Do i have a bottom cylinder gasket i can remove? Do i have a thinner top gasket avalible? What would my compresion be after this?

I plan to P&P my head, are there any thin spots i need to know about. Would larger valves help me much with what i plan to do? If so can i just do the intakes? Do new seats need to be installed or can the stock ones be cut for 1mm lager valves.

Would a 400ex carb be a good upgrade or overkill for my very mild quad.

What would be a good cam for this combo? Do i need hardened followers?

Is the 400ex muffler really restrictive on my 300? I have a RCM(i think) and it is so loud i cant stand it.

If there is something im missing here let me know. Im cheap so any other free mods let me know

Thanks
Brian Bitner

[300EXrider02]

how the **** did u put a 400ex muffler on a 300ex?? its 2 into one header, unless just the slip-on....and there is no 92 300ex, there is a 250x.....getting a nice pipe like the t-4, wb, or yoshi (good all around pipe) will really help, the 300ex is starving for air

[BKB]

Sorry its a 93 300ex. Yes i used just the 400ex muffler. I do not want to use any aftermaket muffler unless its a must. After 10 years with supper loud pipes i have had enough. That and the pipes i had did little for mid range power.

Also how are Razors tires in mud? My stock tires are finaly getting worn down and im looking for replacments. I think 400ex stock tires are the way to go since my stock ones seemed so good for the riding i did. Any other good choices in a larger tire 22-25''

[Steve-o 400EX]

Razrs are the best all round tire period. I'm about to purchase some this week. Everypne i talked to said to get em. I would stay with 20" tires on a 300ex. 22's will take away way too much power from a 300. Only get 22's if you absolutely need the ground clearence. if not stay with the 20's. ;)

[300EXrider02]

there all right not the best but will get u out of the mud holes, the knobs are farther apart so mud cant stick to your tire, and really add traction, go for the yoshi pipe, it isnt that loud already, but if u want get a thing called a T.E.C. kit for it, there silencers, that barley reduce power and give more low end, that wwhat i did, there are 2 in the kit, i picked the bigger silencer but will soon take it off

[Butters]

how did you get a 400ex exaust on a 300ex? what header did you use?

[BKB]

I used the RCM header and rewelded the front of the muffler to match up. Dont ask me how it runs or sounds because i dont know yet. I had a little problem with water in the fuel and am waiting on some new jets to arrive. The carb rusted up pretty good.

[300EXrider02]

Originally posted by Steve-o 400EX
Razrs are the best all round tire period. I'm about to purchase some this week. Everypne i talked to said to get em. I would stay with 20" tires on a 300ex. 22's will take away way too much power from a 300. Only get 22's if you absolutely need the ground clearence. if not stay with the 20's. ;)

you obviously dont know too much because ethe 300ex stock tires are 22".....i got the 22" razrs and felt more power than stockers, the amount of weight in razrs from 20" to 22" is very little, so i wouldnt even say that

[Butters]

yeah put 22's on there. i have them and like them. then if you want you can put 23's on the front. i think thats whats recommended for 300's, since they are trail bikes and all. i think i read that somewhere about the tires though.

[BKB]

What about my motor questions. Lets get off of the pipe and tires.

[300exazzkikr]

If you want more compression then your best bet is to get a high compression piston, you can get them with standard bore. As to takeing off gaskets or thinner ones, I don't think it works the same as a two stroke plus i wouldn't recommend it. If you want to keep the stock bore but you want more mid range to upper power look into a new cam, that will get you some oomph. For the stock motor that you have the 400 carb is overkill. They work the best with modded motors that need the extra gas to keep them revving high. Just my 0.02.