What should i do

[2007TRX400EX]

So i am thinking about doing some mods this winter. Nothing too big, maybe a cam, timing key, header.. something along those lines.... nothing to big or expensive.. any suggestions??

[PaRedneckRiders]

Well, what kind of riding do you do?

[2007TRX400EX]

sand pits.. but i have a feeling there gunna kick us all out this up coming season.. but.. sand pits, open trails, and a occasionally tight trails

[PaRedneckRiders]

If it were me i would go with say an 11:1 416, its not all that expensive but still gives good results, also a stage 1 or stage 2 cam.
I wouldn't worry about a head pipe right now, yes they do show increases in power but not that much for a nearly stock motor.

If u can do that work yourself you could have a 416 with a stage 1 or 2 cam for a decent price
87mm 11:1 wiseco (from wiseco) $201.99
(From ebay) around $150 or so
Hot cams (from ebay) around 130$

Having the cylinder bored out by a local shop should be around 50$

So there ya go, around $350 you could have a good running EX that isn't to crazy but still should ripp

[2007TRX400EX]

I appreciate that a lot.. If i run the 11:1 am i going to have to run a race fuel mixture? or a different gas.. what am i going to have to do with the jets? and am i going to have to replace the studs?

[jensenracing77]

i would not go over 10:1 on the 400EX for what you are doing. the head bolt design is not friendly to anything over that without spending more money.

[2007TRX400EX]

will that require a mixture?

[jensenracing77]

with 10:1 you can run pump gas. i would go with premium.

[CJM]

Originally posted by jensenracing77
i would not go over 10:1 on the 400EX for what you are doing. the head bolt design is not friendly to anything over that without spending more money.

11:1 poses no problems, now 12:1 is another story. If you want insurance do the heavy duty studs from GT Thunder just to be safe for 100 bucks. Might as well have them bore it to if your gonna have it done (what I did).

I cant really suggest more than PA did, thats pretty much my setup and I love it.

[426kidz]

Ill tell you what, go on ebay and buy through them. Have Heavy duty studs put in my GTthunder, 416 11:1 comp I love wisco, send it to get bored out I like dealing with advanced sleeve they do amazing work also get the stage 2 hotcam. Run some 89 octane gas and call it a day, if you really wanna make sure your motor will never give out get the crf cam chain its HD, thats a solid and nice motor and you will have room incase of disaster, Id get the cometic gasket kit also there wonderful!:macho--- and No you do not need the HD studs but if you want to make sure of no problems and be safe I would do it, and there just a good idea any how!! Once again the extra step will just make you feel much better!

[jensenracing77]

if you run 11:1 with pump gas you had better make sure your cam has a tighter lobe separation than the 2 cams that hot cam offers.

that is the problem with the net. you don't know who to believe. i can give you my credentials and experience history but you still have to choose who to believe. this is why i don't hang out here to much.

[2007TRX400EX]

i appreciate all posts. I am trying to make a fast quad, and at the same time i am not trying to sacrifice reliability. So if that means going 416 with a 10:1 then so be it..

[PaRedneckRiders]

Originally posted by 2007TRX400EX
i appreciate all posts. I am trying to make a fast quad, and at the same time i am not trying to sacrifice reliability. So if that means going 416 with a 10:1 then so be it..
Still think 11:1 is the way to go, if you want to run the gtt head-studs just for extra insurance then go head.
You can run pump gas with 11:1 just dont run an advanced timing key.
Its up to you in the end but personally like my 11:1 426 alot.

[BenHonda400ex]

Ahhh! I have a question doe's a hmf full exhaust have the same ammount of horsepower as the curtis sparks exhaust? Doe's the curtis spark have the loudest db?

[426kidz]

you can actualy call HMF and have them set it too any DB you want my buddy did it and it was pretty crazy loud COPS COPS!! but from what I hear sparks gives you the most HP and they sound really good!

[BenHonda400ex]

The only reason I thought about the hmf is because the price is 480 for a full system!

[426kidz]

yeah def beats the 600 your gonna pay for a sparks but idk depends on what you want, sparks is pretty much the rich man system!!:D and does give you the power without callin the cops

[CJM]

Originally posted by jensenracing77
if you run 11:1 with pump gas you had better make sure your cam has a tighter lobe separation than the 2 cams that hot cam offers.

that is the problem with the net. you don't know who to believe. i can give you my credentials and experience history but you still have to choose who to believe. this is why i don't hang out here to much.

How come tons of people have no problems with that setup?

I use 93 octane or 100 if I can find it, no issues ever and I beat mine every time I go.

See the specs in my sig. I rebuilt the whole topend this past summer and have at least 40-50+ hours on it with no motor problems at all. It runs like a top, never failed me.

[jensenracing77]

Originally posted by CJM
How come tons of people have no problems with that setup?

I use 93 octane or 100 if I can find it, no issues ever and I beat mine every time I go.

See the specs in my sig. I rebuilt the whole topend this past summer and have at least 40-50+ hours on it with no motor problems at all. It runs like a top, never failed me.

i have built 100s of 400EX engines. i have built many with that very setup. most of those run pump gas. half of those have blown head gaskets and pulled head studs. even large head studs.

i have a 416 with 10:1, a GOOD cam, my slip on exhaust, stock head pipe, stock porting, stock crank, and a very nice carburetor. it was also assembled by me. i can smoke 450s all day long with it. even 450s with good mods. i have 2 full race seasons on it and 5 years of non racing on it. runs like i just built it. with the cam i have i could get away with 11:1 on pump gas but i choose to run 10:1. i do have one other $80 mod that is a must on the 400EX but that will not be posted.

i'm done here, i just can't take it. i don't mean to degrade what anyone said but i have seen it all and done it all with 400EXs

[rubbersdown]

Haha, 8 posts and hes out, done and done I guess eh. Funny though. Seems at least 80% or so of the people I have talked to, or know, that have work done to their 400 seem to run 11:1 and have a cam and pretty much none of them have pulled studs or are constantly blowing head gaskets. If 50% of jensenracings motors are blowing maybe its not the 11:1 and a cam on pump gas, maybe its jensenracing or his super secret must have $80 mod that he for some reason mentioned and then wouldnt say what it was... just saying.

[jensenracing77]

lol

[rubbersdown]

Originally posted by jensenracing77
lol

Just bustin your balls buddy, stick around, this really is a great site. Everyone's got their own opinions and the consensus on here is that 11:1 with a cam and pump gas will do just fine and thats just because A LOT of people on here seem to run that exact setup with no problems. If youve built that many 400ex motors then youll be an asset to the site, lots of squids who need help with their bikes not running right.

[bherriman]

I've got an 11:1 416 with stock head studs and a cam (no idea what cam, it has no decompressor, and the only markings on it and a circled H and a circled M) it runs on pump gas all day long. Never had a head gasket problem either.

[jensenracing77]

Originally posted by rubbersdown
Haha, 8 posts and hes out, done and done I guess eh. Funny though. Seems at least 80% or so of the people I have talked to, or know, that have work done to their 400 seem to run 11:1 and have a cam and pretty much none of them have pulled studs or are constantly blowing head gaskets. If 50% of jensenracings motors are blowing maybe its not the 11:1 and a cam on pump gas, maybe its jensenracing or his super secret must have $80 mod that he for some reason mentioned and then wouldnt say what it was... just saying.

i say lol because what you said would appear to be very true to all of you. i have seen most everything you can imagine on the 400 engine. i make my recommendations to my customers and they think they know best so i build what they want. ALL of the engines i built that went by my recommendations are great engines. i'm not going to go into formulas and cylinder pressure and cam dynamics but if you do the math the hot cam with most advertised 11:1 pistons needs at least 99 octane.

i am a 3 wheeler rider now and spend most of my time on 3 wheeler sites.

sorry i took your thread off course.

[CJM]

If that was the case and I needed 99 octane then it would ping. At no point have I ever had it ping or have an issue at all.

Im not saying your wrong, but in my experience no one has ever had an issue with running pump gas and 11:1 with hotcams and such on this site or elsewhere I know of. Maybe 12:1, but not 11:1.

Gotta remember too, the 400EX headgasket is rather thick and you tend to lose some compression anyways. Stock comp ratio is only 9;1 anyways, most swap to 10 or 11 with no issues. Using to high an octane robs power as it burns to slowly.

[jensenracing77]

stage 2 hot cam has just a little lower cylinder pressure than stage one. most people get stage 2 anyway. most people in my area want the stage 2 because they think it is "more power" than stage one.

[2007TRX400EX]

kj

[2007TRX400EX]

My primary concern is the gas. If i run 11:1 everyone says i should run a higher octane (not race fuel). If i run the 10:1 what will that require?

[426kidz]

sun some 89 on the 10:1 and some 93 on 11:1

[bherriman]

It is hard to give you a real answer. Everyones bike is different (even with the same setup bikes will vary), and as most people will run 93 on an 11:1 and be fine some people will have to run higher octane. Same goes for a 10:1 some people can get away with less than 93 some can't. There are too many variables to factor in, the best way is just to build one and try it lol. Personally I would never run less than 93, even in a stock machine.

[426kidz]

very true, But i ran 93 on my stock 400 and man it hated it,not good at all. that being said they all varie and just see what works best for you!

[bherriman]

Originally posted by 426kidz
very true, But i ran 93 on my stock 400 and man it hated it,not good at all. that being said they all varie and just see what works best for you!


When Mine was stock, she would take 93 all day long. Our 400 rancher runs great on 93 too, its all stock besides a snow plow. Just goes to show you that they are all different.

[2007TRX400EX]

I know that if the gas doesnt have a high enough octane that it will ping... does that have any other affects that could cut the life of the motor short?

[bherriman]

Pinging is the fuel detonation before the spark plug ignites, and that explosion is trying to force the piston back down before its at the end of its stroke. Pinging is not good for performance, but more importantly it puts much uneeded stress on your internals.


I would be willing to bet if you built an 11:1 (which in reality is around 10.8:1) you will be fine with 93 octane, but if you are that worried about it just build a 10:1, its still gonna be a strong motor.

[rubbersdown]

Originally posted by bherriman
Pinging is the fuel detonation before the spark plug ignites, and that explosion is trying to force the piston back down before its at the end of its stroke. Pinging is not good for performance, but more importantly it puts much uneeded stress on your internals.


I would be willing to bet if you built an 11:1 (which in reality is around 10.8:1) you will be fine with 93 octane, but if you are that worried about it just build a 10:1, its still gonna be a strong motor.

Thats close but actually a bit incorrect. What you described is not detonation (what most people call pinging), what you described is pre-ignition. Pre ignition is MUCH more dangerous than detonation but detonation is still no good. you would be surprised how many people dont know the difference between the 2 so I am going to explain, not to be a smart *** at all so please dont think that, I just want people to know the difference because its a good thing to know when diagnosing a motor problem.
Detonation is actually the spontaneous combustion of the end-gas in the chamber. It ALWAYS occurs AFTER normal combustion by the spark plug. The initial combustion caused by the spark plug is normally followed by a normal combustion burn. For some reason which is usually heat and/or pressure, the end gas in the chamber spontaneously combusts all at once rather than fizzling out. The key thing here is that detonation occurs after you have initiated the normal combustion with the spark plug. This will usually cause your blown head gaskets, pulled studs and that sort of thing that is usually "fixable."
Pre-ignition on the other hand is combustion of the mixture BEFORE the spark plug fires. Anytime something causes the mixture in the cylinder to combust prior to the spark plug it is classified as pre-ignition. The usual culprits that cause this are overheating, the wrong sparkplug (too hot) and can even be cause by carbon buildup as the carbon can get extremely hot and actually turn to ember and will cause the mixture to combust before the sparkplug ignition The two (detonation and pre ignition) are completely different types of abnormal combustion. BUT as said before detonation is still not good and will cause blown head gaskets and pulled studs while pre ignition can very easily cause catastrophic engine failure.

[CJM]

hey, wait a sec...


Originally posted by jensenracing77
if you run 11:1 with pump gas you had better make sure your cam has a tighter lobe separation than the 2 cams that hot cam offers.



Originally posted by jensenracing77
stage 2 hot cam has just a little lower cylinder pressure than stage one. most people get stage 2 anyway. most people in my area want the stage 2 because they think it is "more power" than stage one.

Way to contradict yourself buddy....sorry but it had to be said.

All I know is I have no issues at all period and Im very happy with my setup. If it was gonna blow it wouldnt done it by now too, many hours racing at the sand pits means it gets beat on and thus no issues. Course Im also of the school of beating the hell out the engine to seat the rings too.

About all that could make me happier is an LTR-450, which if I had the cash I would get-but the EX still and always will be a budget riders dream imho. Handles well, likes engine mods to a degree and is reliable to a degree depending on your mods.

I think a 416 with a cam and a slip on will make ya happy. But do whatever you like in the end, its your quad and your cash.

[smoke tractor1]

Everyones opinions are different, If you have a good motor that isn't in need of rebuiding don't tear it down,Trust that time will come soon enough if you ride,A slip muffler from any of the top manufactures is a good start the stock head flow pretty good unless you build a fairly large motor,A bored carbuerator is the best bang for buck!It is fairly inexpensive and you think you almost doubled your power.But in aspects of changing compressions,If you do any high compression piston installing put in gt thunder hd studs it save you alot headaches and that and clutches is 400 weaknesses with more power.By the way I have about 4 ex's 2 440's and big and small stroker all with 12.5 or greater compression and 2 have been raced going on 5 years with no failures other than clutches hinson 8 plates with hd backing plates solved the exploding basket problems, A good 440 with and FCR will spank a vast majority of the 450's!Good luck with your 400 hope you get as much pleasure from yours as I have!