After I got my head done at nmotion, they gave me some info about the bigger valves. The stock exhaust valves seats can be cut out to +3mm bigger, but no farther. Some people were wanting to go with the +2mm intake and +3mm exhaust set up, what they told me up front, you will need a bigger carb and better exhaust. Even with the +1mm/+2mm I have, I found that out.

The stock carb and most any exhaust can't flow enough to keep up with the +1/+2 set up I have (consider my piston too) let alone the +2/+3. The 41mm FCR I have now seemed to help out. Nmotion is talking of a 45 or 48mm Mikuni carb to help the bigger valve set up along. This, coupled with mixxer's VCP Pulse Charger, will get you where you want to go.

This is just an FYI to anyone considering the bigger valves. If you want the top performance, you'll need to spend more money. If not, you'll find out like I did, that'll you'll have more motor than supporting components (carb/exhaust). Not a bad thing, but would be a waste of money for someone who can't afford the other stuff. If that's the case, a +1mm exhaust and the port, polish, flow, and unshrouding the valves will do you good.

awesome info 29!!

answers a lot of frequently asked questions about the head work!

moderators', pin this post already!!

..............mixxer

I'm on it JZ, it does get asked a lot.

Yes indeed, very good info 29. Definite candidate for the performance FAQ's.

One point to note....the oversize valves were a viable option with 29's motor due to the 99mm bore. Valves of this size will not work with a stock bore.

Does someone know what the stock bore limitations to valve size are?

One question for mix, would the the Pulse Charger alleviate some of the limitations of a smaller carb size teamed up with a standard exhaust? I would think that the smaller inlet of a smaller carb would be even more advantageous to increasing the vacuum. Yes? No?

29, have you run the PC on your bike yet?

It's on and I've dropped down a couple of main jet sizes. I'm waiting on the production head pipe to get the final tuning and dyno pulls to show a comparison.
It's got a good deep sound and rumble to it. Compared to the Sparks pipe, it's not nearly as loud and ear piercing. Of the few people who have seen it on my bike, I get stares, plenty of questions, and comments on it's unique apperance. I can't wait to show them what it can do.

The +1mm/+2mm is the biggest you can go on the head for the stock bore cylinder. Sorry, I forgot to add that in the original. I was being selfish and only thinking of my set up.

John at nmotion told me he is working on reshaping the intake port. What they are doing is using some sort of epoxy to reduce the intake port size to increase the velocity. Currently all in the testing phase. The TRX intake is bigger than the CRF, thus the benefit of the bigger exhaust valves. However, the intake is still rather big after the bigger valve install, and at the present time, isn't able to create the velocity as the CRF head. This is where mixxer's exhaust will shine. Help that flow right on in and out of there!!!

where would you find the carbs that you made refrence to?

I have no idea where they are getting them.

Here are some places I found.

Here

Here

in response to habits' question

i believe the that the tests tice and i have done that shows the extended upper rev power indicates the PC can effectively extend the max flow ability of standard size intake tracts

if you enlarge a port , you will (maybe) gain flow numbers, but usually reduce velocity and thus throttle response in the low and mid range

on one end the pc would let you keep a smaller size port and pull bigger numbers through it by increased vacuum, keeping the bottom and mid response sharp

on the other end, like in the supermoto teams' bike, tony said that the revlimiter pulled the plug at 11,500 (i think) while the hp was still climbing. so it looks to be able to pull an enhanced top end through big valve ported heads too

it will take a lot more testing to have definitive answers for all the possible combinations since this exhaust is brand new. for now we can only look at the results we have and interpolate best guesses for the rest........for now

nothing that a little time....... and a BUTTLOAD of money can't answer :D

actually tice is working at data aquisition faster than i am at this point, pretty soon you can skip over me and just ask him!

............mixxer

UGHHH, I don't think so. Humbly withdraw my name there. :blush:

Tony

I know this site is for polaris but he does sell mikuni TM45 pumpers and lectron 44 & 48mm.

later


http://www.nicholascycle.com/predatorperformance.htm


B)

I know with my old 2-stroke carbs they can be bored out 1 to 2 1/2mm. Can the same be done on the FCR? I don't want to get into the game of buying carbs for this thing. I am happy with the FCR but I want to go big with the motor and need something to feed it.

How big is enough? FCR's are run on KTM 520's, our demands can't be more than that bike.

i'm ordering my oversize valves today

+1mm\ +2mm black diamond from kibblewhite

the +1 is considered "shelf stock" in both the intake and exhaust

beyond that is custom order

when i get booster back from woolf i'll be firing up the porting bench and coming after 29ftexs' king of the hill dyno graph :D

still thinking about 14:1 480cc though......................


................................mixxer

While you got that bench wamed up i'll send you a head!

I called black diamond a few days ago about ceets, or seets and they told me I couldnt run that valve size with my stock cylinder and my Je dome top piston, is this right?

Thats untrue.
The piston (KGB 99mm JE) has reliefs cut for oversize vlaves, 29FTEX, confirmed this through Nmotion and JE.
I would definetly recommend claying the piston, however.

Mine is a 13 to 1 JE

NEVER!!!!!
Booster already had the PC and a 40mm carb when you did the dyno pulls, right? Now that I have a 41mm carb and soon-to-be complete PC exhaust, you'll never catch me... never!!! :ph34r: :D





How's that for some motivation to get it done sooner.

Ruh Roh!

I would check with whoever sold (or made ) the piston.
If the valves kiss piston, you can always have the piston flycut to accomidate the valves. CLAY IT!

mixxer, be sure to take some before and after pics of the head (ports, valves, etc.) to show the process and your progress. However, make sure you don't have straight on shots of the exhaust port for anyone to be able to make a template. :D

Git er dun.

Email from Nmotion:

everyone needs to read these articles on port\valve size and velocity

start with articles #16 & 17

click it and LEARN

high velocity porting secrets

..............mixxer

'chuck' posted this same link on atvriders Saturday evening. He locked the thread after that so no one could reply as to how he found it. I guess he's trying to get that site a little more technical than jetting and pipe choices. <_< B)

motoman has been a staple of mine for a while.
'chuck' has not...lol

ok, Now that I've read the articles (16 &17) ,I'm confused as hell.

I have the HRC kit, sparks pipe, open airbox and am installing the je 13:1 piston. Also, I had the head ported and polished with a 3-way valve grind. Does this mean the port and polish was a waste of money for my setup? I thought a few of you guys had your heads ported and polished etc.

I would very much appreciate some feedback from those of you who have a better understanding of this topic. Thanks In advance..........

Me too. I read the articles and it seems clear that his data shows bigger ports are not always better. How to tell whether a particular motor needs to go larger or smaller to get max power? I guess the obvious would be by experimenting.

Mix, would love to see you elaborate on this...

you will have to watch for ticemans posts guys.

you are fairly new here so if you dont know, ticeman is the R&D department of HotCams, and used to be the same at Factory Yamaha

he is doing headwork on his brand new TRX as we speak
there will be more info soon................

............mixxer

ok mixer how are you going to do your head? smaller or larger. also have you ever dynoed smothing bike/quad then done the head (old school) then dynoed it again with out doing any other mods at the same time? and i dont know about the whole JB weld thing. ive used it for alot of things but never that close to my piston and valves on my new baby.

what is old school about that???

as far as i know it's the ONLY school to evaluate modifications with

i dyno everything, and all mods, down to each jet size swap, and verified with a real time A\Fr meter printout on the dyno graph to track the ratio effect on hp simultaneously......................that's why i bought a dyno in the first place

when i do the head mods , i will post the info, just as i do on everything i test

in the meantime maybe you could get all the other engine builders to detail everything they do and post dyno runs for us all to learn from.......
that way we will have something to compare to when i finish mine :D

...........mixxer

I think hawk was asking about doing the head "old school". As in the conventional method of porting and polishing.

At least that's the way I read it. I might be wrong.



I'm gonna go buy some stock in crayola right now.

my bad. sorry if i read it the wrong way!

i took it as "old school" meaning to do a mod and then evaluate on its own merit, before doing further mods, and i was too esoteric to evaluate in such a standard\correct way

.......mixxer

that there is some good stuff, so on the Exhaust side you would wont to polish it right ?

polishing is only for slowing the build up of carbon, so i do it on the exhaust side

the intake i finish with 60 grit rolls

........mixxer

Thanks Mixxer

sorry mix, i must have worded it worng. habbit was right i ment old school head porting, larger more flow ports. by the motoman articals you posted it sounds like if i sent my head to duncan,sparks,or anyone that made the ports larger that i would loose HP. that would really be a bummer. and sense you posted the articals i was wondering if you were using motoman method. his method sounds good the way he explains it but it makes me feel i have been wrong in my way of thinking for the past 20+ years

sorry hawk,

let me try again.........

the big hole= go fast thing isn't so much old school as it is wrong school.
nothing has changed about engine dynamics (physics). what HAS changed is better understanding of them

i was never in the "big hole" group since i used to read smokey yunick and gordon jennings from the beginning. they always spoke in terms of volumetric efficiency rather than max cfm numbers

max cfm MAY give you a higher peak hp number at the expense of response and power everywhere else. max EFFICIENCY gives you everything you want.

from the beginning there has always been the "i got a die grinder for x-mas, ergo i am a portwork specialist" people making up the majority of the "grinders " out there. this is obiouusly as false as me buying a hammer and a saw and declaring myself a master carpenter

without much study and experimenting, those people are lost as to the nuances of the ports' shape and volume as being critical to its efficiency. they just start the grinder b4 they start their brain

i can't tell you how many times i've seen 2-stroke cylinders with the intake port "ported" all the way out to where the reed block sealing surface is.

this is rather ridiculous since there isn't any airflow back there at all, the flow comes from the tips of the reeds only. porting back there only serves to increase the crankcase volume in an area dead to airflow, yet the majority of "porting experts" grind all the way to the sealing surface. it is as ridiculous as it is commonplace.

hope this is a better answer than last time. sorry i can't give you the exact answer you were looking for. at 13 years old i was concerned with compression\octane\timing requirements, i never really attended the "old school"

......mixxer

ok mix i know one thing ill never use the term "old school" again it was just that making the ports smaller (motoman style) was something i never herd of befor thus to ME "new school". anyway do you use JB weld or anything like it in the ports? i would be worried it would breakdown over time. the other thing i have 3 die grinders but there is no way ill try to port my head! so now i dont know what to do. do i send it to one of the popular engine builders for ther port job and 1mm over exhaust valves, which acording to motoman could make me loose hp. i do know that shape is more important then size but how much power would this useally make? is it worth the money? i dont want you to give away all your secreats but i really dont want to wast time and money. thanks alot.

stay tuned ,

ticeman and i are working on builds right now

i have used epoxy on 2-strokes for decades now (i'm ancient) , without any problems

there's plenty that can be done to improve flow characteristics without doing high velocity porting, valve guide boss cleanup, valve unshrouding and more that will only increase flow but not decrease velocity in any way, like just grinding bigger holes without reguard to flow patterns will

29ftex has an extremely strong motor and his was done well without high velocity porting.... perhaps he can share some details

you may not need high velocity porting , but you certainly don't need lower velocity porting either

.......mixxer

thanks i feel like a sponge waiting to absorb everyones knowlage. i was told things like more flow= more power and break it in easy. I took it as the only way to do things so i love the info you guys post. thanks alot and keep it coming. sence im a contractor and NOT a head porting, valve grinding mechanic who would you recamend for head work?

mixxer: where do u learn this stuff? is it just trial and error, with lots of cash? i'm interning at an engine machine shop (cars) but they don't do porting. is there a book or something that could help me learn this stuff? i really want to learn how to build some kicka$$ engines, but can't afford to mess anything up (i like being able to ride my quad).

no one source will tell you what you need to know. i'm 43 and i have been reading magazines, books , sae papers..............you name it ...........since grade school. i have been spinning wrenches for that long also.

i am nowhere near done learning either. you have to hunt for all the info you can find and then still boil it all down in your mind,and also through trial and error when reasoning isn't enough to separate fact from fiction

the best primer to learning 4-stroke power is a book called Smokey Yunicks' Power Secrets".
that book should at least light the fire with some good fuel to get you going!

..........mixxer

thanx for the info. i'll get a copy of that book for sure. ATV engines are basically the same as an old lawnmower engine, right? i think imma try and do some work on my go kart engine. keep up the good work man, and thanx again for all the info u've put up on this site, i'm learnin a lot.

You can usually find that book on ebay or Barnes and noble.

ok, i just ordered it, which should i get next, after i finish with this one?

thanks mixxer.

i've read it about a million times!!

each time with a lime green high-lighter to emphasize the good stuff

my wife told me that with as much that is currently high-lighted i could have saved some time and just used spray paint to high-light with :D

the next book to read would be this one:

Click to view attachment

so when are you going to write a book?

when i have a hot secretary to do all the typing for me

I bet Mixxer will write his book as soon as the PC roll out is complete and he is rolling in the dough, right Mix? :D I have to admit, the discussion on this board has sure piqued my interest and I have enjoyed researching how tuning both intake and exhaust using sound pulse can aid in movement of fluid; namely, how and when are exhaust gases removed from the cylinder and through the exhaust and how that affects the filling of the cylinder with fresh air/fuel mixture. I am getting an understanding of how overlap comes into play as well as gas temp, RPM, exhaust length and so on. I'd just like to say thanks fellas for taking the time to spread the wealth of knowledge that you have. I really have to hand it to both of you Ticeman and Mixxer, you are sharp guys yet seem pretty open-minded for the level of knowledge and experience you have. I work in a highly technical field and can fairly say that people in my field with lots of experience tend to be on the cocky and self-assured side. There is a tendency for them to regard new or different ideas as invalid before they give a new idea even the most cursory glance. Hats off to ya. Anyway, despite my wife's protestations, I intend to spend the 6+ bills to buy Mix's PulseCharger. There is no way that I will not buy one after all the research I've done on the principles upon which it is built!

J-Dawggy

cool !! i'm glad to have another kindred spirit in the curiosity department!

very glad to have got your interest going!

i like to share info and without the org i'm afraid i don't know how i could hook up with so many tech junkies .....who also like to endanger life and limb with their choice of tech addictions

and just for the record tice is very cocky and extremely high strung. someone ghost writes his posts for him :D

i'm the nice one

.......mixxer