Hey all you engine gurus help Momma

[DEWIE]

I would like to know if it will be ok to change just the cam to a all around Web cam and install a 11:1 comp.std. Wiseco piston? Will this give my son more power out of his piped and jetted 2003 300ex with a K&N filter with outerwear and outerwear on the lid ? Is there anything else that I will have to change with this setup? Will he still be able to use pump gas? Thank you for any of your help in this matter. I am a single mother of 2 and need to make my $ stretch without boring it out. Will this setup keep the 300ex reliable?


Lori

[Sick0]

I can't tell you weather it needs to bore out or not thats depends how the cylinder is. But this would be a nice in provement in power, and you will have to mix gas in it(half race gas and half pump pas)to get the octane up. If you go down the compression to like 10.8 to 1 you will not have to run race gas. Plus if you don't have a pipe for it you will not see as much gains. One more thing, you are going to have rejet the carb.

[Teufel]

Since it is a 2003 I would guess it couldn't have alot of hours on it?? Unless you have a rode it alot I would'nt worry agout the piston; at most clear the cylinder up and re-ring it. Put a stage 1 or 2 cam in and maybe fmf a slip on. DO a little jetting and hit the trails.

Good Luck

[phatswinn]

the performance gains will be very noticeable, as i recall you can go up to 11.1:1 comp without using race gas, but call sparks racing or hetricks they will know the true answer, also i would go with JE pistons, they seem to be the popular choice for reliability and ive heard the compression ratios are off on the wisecos, like some people were gettin 10.8:1 with there 11.1:1 piston, you will need a race pipe for ur setup like a x-4 and duncan makes a fat boy 4 for the 300ex now that would be a great setup, obviously you will need to rejet, you may even want to try a 400ex carb to bring out some more power!:scary: <----power hungry martian

[airheadedduner]

You really need to have the piston matched to the cylinder or vise versa. I have heard of people throwing aftermarket pistons in only to find the tolerences where off and even though its new is leaking around the rings. Not all pistons are exactlly the same, no matter what size is stamped on them. Any builder should be able to help you with setting up yor motor. They are quite happy to take your money:p

[Teufel]

i would go with JE pistons, they seem to be the popular choice for reliability and ive heard the compression ratios are off on the wisecos, like some people were gettin 10.8:1

Wiseco is one of the best out there; hands down. Don't believe me ask a PRO Engine Builder. Check and see what the factory MX
and SX teams use.
The compression ratio can vary but it is not because of the piston being out of spec. It is because the deck hieght and volume of the dome varies.

I wish people wouldn't make statements like that when they don't
know what they are talking about.

If you don't know ask! Don't Tell :huh

[YZROOSTINYA]

all you need is a hone if the cylinder is clean.

no race fuel neede. 93 octane pump though

a web cam is a good choice although a hotcam is cheaper if they make it for that quad

je pistons are good along with ross

you already have a filet and slip on so jetting is the only thing beside gaskets

possibly a new rev limiter, i think the 300ex kicks in REALLY early. double check with some people that have modded there 300's

Wow you guys are pushing the ideas around LOL :)

The original posts thoughts are pretty much in the right direction and will give good gains, but there are just a few things to consider to avoid trouble in the future.

As someone mentioned earlier you may not want to just drop a stk bore piston in because there can be issues with the condition and size of the current bore. Its not a major concern since most machine shops will be able to size up the bore to match the new piston for around 30-50 dollars (not a lot of $$ compared to the other stuff) and then you will know its within spec.

I would recomend you get the cylinder measured accurately so you know where its at and then you will know if you can use a std bore or will need a larger sized piston. If theres no wear beyond std tolerences then you would be able to just have it honed and install a stk bore sized piston.

As far as fuel the popular opinion is that 11:1 and lower will not need race fuel, but the piston compression ratings are not "exact" and your motor may end up slightly higher or lower in actual compression depending on many factors. I would think that it should be ok with pump premium but only the motor itself will know and it tell you if it needs more octane by knocking etc.

There are many diff opinions on this stuff and I am going to suggest what I tell everyone else and thats to do a search here as there is some good info on motors etc and dont be afraid to talk with one of the many motor builders about your intentions and their suggestions etc. you can get a lot of info this way.

[nakomis0]

11:1 Wiseco, and an all around cam. Sounds like a good setup to me.

I would just get a stock piston size. I wouldn't really care about the bore much, just get it honed.

If the cylinder wall is real bad then you would need to bore it out, but like someone said its a 2003 ... how bad could it be.:)

[phatswinn]

Originally posted by Teufel
i would go with JE pistons, they seem to be the popular choice for reliability and ive heard the compression ratios are off on the wisecos, like some people were gettin 10.8:1

Wiseco is one of the best out there; hands down. Don't believe me ask a PRO Engine Builder. Check and see what the factory MX
and SX teams use.
The compression ratio can vary but it is not because of the piston being out of spec. It is because the deck hieght and volume of the dome varies.

I wish people wouldn't make statements like that when they don't
know what they are talking about.

If you don't know ask! Don't Tell :huh


ive been running a JE for 2 years without a problem, and i went through 3 wiseco pistons burning holes in them before i went with JE


EDIT: and plus that was my opinion, and if ya dont like it...bite me !im entitled to my opinion ,even if its wrong

[Teufel]

You Think the piston burnt a hole itself........? Man I never heard of that. I am sorry to offend you by questioning you years of engine building experience .......DOH!!!!!

I didn't say anything negative about JE did I ??? But all things being equal I would rather buy a product from a company that supports the sport; I haven't seen any evidence of JE or Ross sponsoring any events.......

Bite you???? Sorry I am not into Gay S&M Bro :huh

[phatswinn]

lol, no what i was aiming at was that the wisecos are made lighter or something, but within a couple months i put a hole through the piston on all three i put in then i went to JE and its fine, i didnt want to flame, or sound gay but i wanted to put what i wanted to say into a form of which i could use on the forums, i just dont like wiseco so i put my experiances with both pistons on the board, and i just metioned that the compression ratios were off because that is what i heard no need to bite my head off just stating my opinion!

i didnt wanna start a fight i was just saying what i beleive there both probably good pistons, i just dont use wiseco anymore

[Teufel]

No problem Bro, were all entitled to our opinion. Maybe I need to cut back on the caffeine a little. IT's all Good :cool:

[DEWIE]

Thanks for all the replies .What do you mean it will need honed?I am not questioning your judgement I just don't know how this is done? If it is stock and never been bored how could I need a bigger piston?


Lori

[sly400ex]

Honing basically "roughs up" the inards of the cylinder so that the new rings will wear or break in properly. The reason you may need a bigger piston even for a stock bore is becasue a so called stock sized piston from a manufacturer may actually be a little bigger than a so called stock piston. Wait, uh yeah, does that make any sense??

[NJ300ex]

Originally posted by phatswinn
ive been running a JE for 2 years without a problem, and i went through 3 wiseco pistons burning holes in them before i went with JE

EDIT: and plus that was my opinion, and if ya dont like it...bite me !im entitled to my opinion ,even if its wrong

Does JE even make a piston for the 300ex? I know they didn't a year or two ago.

Compression:
Stay with something like 10.8:1. With 11:1 you can probably get away with running 93 pump gas, but on real hot days or under heavy load, you will most likely ping(detonate), which is not good at all. Go with 10.8:1 or something else lower than 11:1 to play it safe with pump gas. Your son will still notice a large improvement in power.

Cam: Good idea, but I do not believe there are currently any drop in safe cams on the market for the 300ex. In order to play it safe you would need to get your rockers hardfaced and get new valve springs. If you do not do this, even though it is a new engine, you run the risk of ruining that new cam and your rockers.

My Suggestion:
Although the cam and piston are a very good idea, I first reccomend getting a headpipe and silencer. The headpipe being more important than the silencer. The stock 300ex exhaust system is very restricitive and the inner diameter of the stock 300ex headpipe is tiny. It does not flow enough for even the stock engine. You should replace it with a aftermarket headpipe and silencer. This mod will match the modifications you made to the intake and will give much better all around power. You will need to re-jet accordingly.

[DEWIE]

It already have a full DG Xcellerator, jet kit and K&N filter with outerwear and EHS Racing lid with outerwear.


Lori

[NJ300ex]

(Edit: I didn't see your post before but this may still help.)

Here is something else that may help you. This is a list of reccomended modifications by Mickey Dunlap from Four Stroke Tech. You can get in contact with them for more information.

For a pipe I think a supertrapp IDS2 full system is a good choice. It only costs around $230 and gives good power gains. If noise is a issue you can get a larger diameter headpipe that mates to the stock muffler from Tom Miller Motorsports. I hope I have helped out.

1.I'd recommend installing a pipe first. The stock 300ex uses a very small diameter head pipe. We offer a 1.5 inch head with megaphone exhaust that picks the power up considerably.

2. If you want to realize the full potential of any pipe mod on the 300EX then you will need to install a black box mod with it. This will allow the engine to utilize the extra rpm that the pipe will give you.

3. You can get better airflow from the airbox to the carb by installing an intake tube from the old 350X. We have bought up quite a few of them and sell them for $45. The really do help overcome the restrictive stock 300ex carb air boots.

4. The stock carb (29mm Keihin) can certainly stand improvement. We have a 32mm carb kit we sell with throttle cable for $210. Combined with the pipe and black box mods you will see quite a bit of improvement in the EXs bottom-end midrange and top-end performance.

5. After I had tried the pipe, black box, airbox and carb mods, I'd opt to install a higher reving cam for more midrange to top-end performance.Expect to pay from $120 and up for a reputable cam for the EX.

6. For more low-end torque I'd go with a higher compression piston kit.They sell for anywhere from $85 to $125 and are a good investment to make the honda engine pick up power on the bottom-end.

7. My best power for the money would be a big-bore (330cc) kit for the honda 300ex. We sell our 330 kit for $220 and it is a good value for the buck.

8. Once you start getting more power to the engine, you will need to do something about the increase in heat. We sell a low-priced oil cooler for the EX that lowers the temperature by 40 degrees for only $85.

9. Drill a 2-inch hole in the airbox lid, install a K&N filter and you will see a substantial gain in horsepower. On a stock motor we have found that we use about a #130 main jet at 1000 feet. A modified engine will generally run about a #140 main.

10. If you do modify the engine you will definetly need to add heavy-duty clutch springs to handle the load. We sell a heavy duty clutch kit for the EX for $17. You should also gear up a modified engine with a 14-tooth countershaft sprocket.

Nj300ex good reply, and much better than the wiseco J&E stuff.

I dont know what models each mfg offers pistons for but if there was a choice other than wiseco I would try it. I have had absolutely ZERO good experiences with there pistons in 4-strokes, but had used nothing but them in 2-strokes in the past.

My problems with them are not with the 300ex but the 400ex motor so you may very well be happy with there product for your model.

And though the problems were nothing like the hole in the piston discussed above. It was not just wiseco but J&E had similiar probs (completely diff comp than advertised on the wiseco) on a lower scale wiseco was the one not wanting to discuss or correct the problems.

Nothing is ever perfect (and usually not easy either :) ) and this stuff is a lot of trial and error.


Deff do the hone on the cylinder cause without it the rings may not seat properly, but I still suggest having a shop measure it all up so you are sure of what condition it is and what you have.

[airheadedduner]

I still don't recomend just honeing the clyinder and buying a std bore piston, even if the bike is new. They are called tolerences for a reason. When I first started riding we blew up my cousins blaster. We melted a whole in the piston and found the clyinder was within spec. We ordered the previous bore piston, installed it, broke it in, and, rode it in witch it promptly broke a skirt from excessive clearence. And I have seen/heard/felt/watched this happen several times. A NEW bike can be on the loose side of the clearence, you order a piston witch turns out to be on the tight side=big problem. Three years ago two of my friends dad's bought blasters for their younger kids, both at the same shop. One died right after break in(no compression) and the other broke a skirt not long after. We took it to a yammy shop and found that both bores where bored out oval!! Good thing both bikes were under warrenty. The bike that broke the skirt also cracked an engine case as a result of the misshap. Most likly things would be okay but that is a lot of money to be saying might. Your best bet would be to take it all to a respectable mechanic with a good rep in your area, tell him what you want and let them handle it. They will take care of you.

[Teufel]

Airheaddunner, is right on the money; never hone a cylinder and stick a in a new piston. Tolerances are there for a purpose.
Of course IT all depends on the quality of job you want. As someone said earlier this is the reason the machine shop wants the piston that is to be used when he bores the cylinder.

[kingdingaling]

I installed a .020 over high compression Wiseco piston in my 250x. Nothing has went wrong so far but I noticed that the bike does smoke a little when I first start it up. After it warms up its fine though. This may be due to excessive tolerances or improper break in, either way, nothing major wrong with the Wiseco piston.

I have done quite a few modifications to my fourwheeler and I believe the most significant one was the 400ex carb. However, I did install this after installing a full DG exhaust, high compression piston, K&N airfilter, and removing the airbox lid. The factory carb was definitely choking up the motor.Since then I have installed an aftermarket CDI box, Web Cams stage 1 cam(Why not stage 2 or 3, due to my tight budget I couldn't afford valvesprings and hardwelding the rocker arms), and I ported and polished the head. The bike runs great and with a 12 tooth front sprocket, I destroy 400ex's out of the hole (they fly by me like I'm sitting still after I hit the rev control though). I would not recommend a lower gear though unless you ride tight trails.

Hope this helps and happy riding.