Sparks Key and Rev Box

[Rohr397]

Okay so I wanted to add a Sparks timing key and Big Gun Rev Box. First of all I can't find the timing key on their website and second what do you guys think about the Big Gun Rev Box? I need a fairly reliable motor to last me the whole season and I hear a lot of bad things about Big Gun but I am running Open class this year and need every boost of power I can get for a decent price, I don't make a lot of money since this is my first job.

[honda400ex2003]

i wouldnt waste my money on a rev box but that is just my opinion on it. if you are running that high in the rpms long enough to need a higher limit you might as well shift to the next gear 99% of the time.

key and a stage 1 would be my choice of additions if you are looking for some extra power on a small budget.

sparksracing.com has the key on their site

http://www.alwaysopenmall.com/layouts/02/unsecure/item.asp?SiteID=223&DepartmentID=85&CategoryID=949&GroupID=7033&ItemID=31633&StartNum=1&Sort=&ShowPics=0&ListByCode=1&Brand=&GenderAgeGroupID=0&MaxPrice=&SearchString=&ItemCode=&IsOnlyOnSale=0&FromHomePage=0&FromFamily=0&ProductFamilyID=0&RelatedItemID=0

might work for you, otherwise it is under 400ex- electrical- first line in that page

steve

[01boneless]

yeah they stop making power befor the stock rev limeter thus the aftermarket is a wast imho a key and stage 1 cam will wake it up good!

[Rohr397]

Okay cool thanks, idk why the timing key wasn't showing up last night.

And yeah I'd heard mixed stuff on the rev box but I figured who better to ask then the forum?

So on that note is there anything else besides a cam and timing key that's cheap to help boost my quad? You can see everything I've got already in my signature.

[ish416]

I would suggest an 04-05 450R carb or an FCR if you can find a good used one at a decent price.

[01boneless]

yup the biggest power boost i ever added was the wiesco 11:1 piston and these ex motors are super easy to work on imho :D

[Rohr397]

Haha not sure I can afford a piston right now!

With the 450r carb what would be the benifit over my current carburetor? I currently have a carburetor bored to the same size as a 450r carburetor.

[CJM]

The pistons well worth the money, only about $120-150 + bore if you can put the piston in yourself

Otherwise id suggest a stage 1 cam-BUT the big thing is if you go to a higher compression piston you really should have a stage 2 hotcam, but if you stick with stock stuff you want a stage 1.

[honda400ex2003]

unless you want to go 10:1 compression, stage 1 is a better cam for that imo.

steve

[01boneless]

well with the bored carb a 450r carb probley wouldent be any better and nthey both carb and piston only run 150 bucks

[Rohr397]

True true, right now I can only afford the timing key though which is why I'm looking at inexpensive. I know everyone says to do the piston but it's practically
My entire paycheck and I've gotta pay for a lot of other stuff too (gas, entry fees, random repairs)

[CJM]

Ive ridden one with a key, honestly I didnt notice anything better about it.

[ish416]

With the 450r carb what would be the benifit over my current carburetor? I currently have a carburetor bored to the same size as a 450r carburetor.

I wasn't aware you could bore the stock carb to a 42mm. Isn't the stock carb 35.5mm up until they gave it the 450R redesign in 04 or 05 and went to a 38mm?

Regardless, the best carb you can get would be a 39mm FCR and there is a very noticeable gain from making the switch.

[Rohr397]

I'm not sure what year of carb this machine has, the people who built it did not cut corners on anything and it actually used to be a 440, they swapped the jugs for reliability and a fresh top end and sold it. It was a dealership race quad and everything, 100% paid for by sponsors. So I would imagine they put the better 400ex carburetor on it. Whatever the bore is I can tell you it's the absolute maximum bore because this quad runs with more power then my Trx450r did with just the air filter, exhaust and carburetor. My 450r had a pipe and that was it.

[atvrider13]

Remember that you are going to need a flywheel puller to install that advance key.

[honda400ex2003]

if you buy a sparks one it comes with the puller.

steve

[honda400ex2003]

if you buy a sparks one it comes with the puller.

steve

[atvrider13]

you could save yourself alotta work by just buying a aftermarket revbox. It will have a more aggressive timing curve.It will do the same thing as the sparks advance key.I have my White brothers revbox for sale for $40 if interested? Pm me

[CJM]

Originally posted by atvrider13
you could save yourself alotta work by just buying a aftermarket revbox. It will have a more aggressive timing curve.It will do the same thing as the sparks advance key.I have my White brothers revbox for sale for $40 if interested? Pm me

That revbox is nothing more than a XR250 revbox they rebadged (not trying to diss you or your sale). Which makes the quad much harder to start if its cold or not jetted exact.

See here for more info: http://www.atvriders.com/articles/askmickey1.html

Anyways, a timing key is much preferred to a revbox anyways. Still I rode one with it, didnt seem like it was any better than having the bike properly jetted. But you must remember im used to riding something comparable to a 450r in power delivery.

[atvrider13]

So if you have your quad jetted right with a good battery it will (should) start right up. I noticed a gain in power when i installed my aftermarket White brothers box. Even if it is "just" a rebadged xr250 box , There is a reason why people run them = MORE POWER !!! 400EXs need every little thing to keep up with todays higher technology atvs

[finsteratv]

I'd remove your choke do a sparks key and airbox lid delete if you ride drier area then rejet. IMO the sparks key was worth it and seemed to get rid of a little bog/hessitation i had and made the throttle more responsive.

[01boneless]

Originally posted by atvrider13
So if you have your quad jetted right with a good battery it will (should) start right up. I noticed a gain in power when i installed my aftermarket White brothers box. Even if it is "just" a rebadged xr250 box , There is a reason why people run them = MORE POWER !!! 400EXs need every little thing to keep up with todays higher technology atvs

Ok lets get something strait a aftermarket CDI does not give more power! it raises the stock rev limet up 1000 rpms to help stretch out the gears longer but they are basicly worthless without alot of engine mods becuase a mostly stock ex stops making power BEFORE the stove rev limeter let alone a aftermarket one . And when you dont belive just ask CJM or another know member :D

[ish416]

Even if it is "just" a rebadged xr250 box , There is a reason why people run them = MORE POWER !!!

Show me 1 dyno graph that shows any improvement over a stock cdi. Good luck with that.

The cdi boxes hardly change the timing at all, maybe +1-2, not enough to notice much of a difference. Also, they usually only do this at certain rpms, notably the midrange where you may feel more oomph, but in fact it isn't any faster, just seems more "snappy".

As for raising the rev limit, you would be better off changing the gearing. EX engines aren't high rpm horsepower engines. They stop making power around 7500 rpm, even full out drag motors stop making power around 8000 rpm. So revving it out to 10,100 rpm is a waste and just adding more wear and tear to the internals.


Whatever the bore is I can tell you it's the absolute maximum bore because this quad runs with more power then my Trx450r did with just the air filter, exhaust and carburetor. My 450r had a pipe and that was it.

So, do you know if your EX is a stock bore/piston engine or is it a full race motor on the biggest bore possible?

[01boneless]

So, do you know if your EX is a stock bore/piston engine or is it a full race motor on the biggest bore possible? [/B][/QUOTE]

pretty sure he was talking about the carb bore :D

[dxcody]

remember, in the future when/if you redo the top end and say, make it a 11:1+ compression, it is reccomended to remove the timing key.

[Rohr397]

For sure I will do that haha, hoping to get a whole race season out of this top end before I go with a high compression 416 build. The 440 top end that used to be on my quad lasted the guy 8 years of racing and still worked when he sold the quad but they swapped to the stock 400 top end because the 440 overheated even with the oil cooler by Four Stroke Tech.

Also my carburetor is bored to the maximum, choke removal mod done. Top end is completely stock.

[Rohr397]

Just one thing to add, I do ride like I'm on a 125 2-Stroke when I'm on the track so idk if that makes a difference.

[01boneless]

keep er pinned your fine :D

[CJM]

Im not gonna debate why the revbox is worthless, already been answered for me.

Anyways, good luck with your build rohr.

[finsteratv]

Originally posted by Rohr397
Just one thing to add, I do ride like I'm on a 125 2-Stroke when I'm on the track so idk if that makes a difference. Thats how i ride...so i bought mysef a 125 2 stroke and 450. hahah