Powroll 393cc horsepower?

[350XBigbore]

Hello to everyone, since I am new here I'd like to tell you guys a little about my background. I own a fairly new powdercoating buisness but have been working on and riding bikes since I was 6yrs old, now 30yrs old. In the past I have built a really quick 93 Banshee, 89 Honda 250R, numerous Hotrods etc.. and I am finishing my latest project but had some questions. I recently bought a 91 250X 4-wheeler that had a newer crate 350X engine on it but the bike had been abused so I pulled it down and powdercoated every piece I could, put all new bearings on the bike. Then I pulled the engine apart to find out it was in excellent shape but I wanted more HP so I bought the Powroll bigbore kit (393cc 11.5..1 compression), race cam, springs retainers etc.. I ported the head myself, found a good deal on a 400ex carb and I am building custom exhaust. Well I am about to crank the bike up and was wondering what kind of Hp would an engine like this make? TIA Clint

[All X's]

Yes someone please respond to this one!!!

[NOS_350X]

Impossible to gess, just pay for the dyno time. More importantly than a big engine is to get everything tuned properly. and that all your mods work good together. But tho thow out numbers would be useless.

[Duner]

Agreed. Look up a local dyno at one of the builders shops locally to you and pay the 70 bucks to have them dyno and jet it correctly. Some motors like it more rich and others like it a tab bit leaner.

[350XBigbore]

Well guys I understand where you guys are coming from but jetting the bike is not hard at all as long as you know how to read a sparkplug. My question was how much should a properly tuned bigbore, race cammed, ported, carbed, piped 350x engine make? I read that a factory 350X engine made 27HP, so by adding all of the above I was thinking it should be able to produce 36+HP or more? Any of you guys ever see this custom pipe from Powroll? http://www.powroll.com/images/PRODUCTS-WEB/18328_PARTS.jpg
I was told it would make 20% more HP over other pipes, notice how the pipes merge as soon as they come out of the head, which I was also told the quicker you merge the pipes, the more HP you will make and if they are longer it builds more torque which makes sense. I am building a pipe exactly like that one for my bike b/c that one cost $475. Later

[Duner]

Well guys I understand where you guys are coming from but jetting the bike is not hard at all as long as you know how to read a sparkplug. My question was how much should a properly tuned bigbore, race cammed, ported, carbed, piped 350x engine make? I read that a factory 350X engine made 27HP, so by adding all of the above I was thinking it should be able to produce 36+HP or more? Any of you guys ever see this custom pipe from Powroll? http://www.powroll.com/images/PRODUCTS-WEB/18328_PARTS.jpg
I was told it would make 20% more HP over other pipes, notice how the pipes merge as soon as they come out of the head, which I was also told the quicker you merge the pipes, the more HP you will make and if they are longer it builds more torque which makes sense. I am building a pipe exactly like that one for my bike b/c that one cost $475. Later


Your right, but IMO, this is old school technology. With all that is availible these days, take advantage of it. I would think that number could be achieved, but you will only be guessing.....put it on the dyno to be sure..why guess?

[jenndnn3]

Have you called and talked to Powroll themselves? They are pretty open about their stuff...

Pam who did work there a while back had one in a 250 frame as well she used for racing practice I think it was. May want to chatter with her about some of the info your seeking...

[350XBigbore]

I was just wondering if anyone had a Big bore setup that dynoed and what kind of HP was capable with these old 350X engines. This is my first 4 stroke buildup and I am hoping that it will run pretty quick. It's not going to be a drag bike or anything but more of something to play on.
Yeah I talked to Pam and she told me to expect 50% increase over stock which would put it in the 40HP range with tuning and everything spot on but I wanted to see if anyone had some real numbers. Thanks

[SWIGIN]

i dont like those powroll convertion pipes i alway just make my own

i start by streching the frame 2inch and leaning the front tubes forward to make room for the new pipe. but i cant find my finished 250x pics so here is a pic of my 350rx with the same shorty head pipe.

powroll uses 1 3/4 for the main pipe size.... i went with 2inch and couldnt be happier

[350XBigbore]

Looks nice but what about shortening the length on the primarys so it would make more Horsepower? I was told by two different 4 stroke builders to merge the pipes together as soon as possible for higher Hp, leave them long for bigger torque but to me these engines have an abundance of torque to begin with?

[SWIGIN]

thats what i did...i took about 2inchs out of the primarys.

that powroll pipe has short primarys but the main pipe is way longer then mine....and smaller too

[350XBigbore]

You have 2" pipes straight from the head? Did you just cut the flanges off a set of pipes, then went straight to 2" until they megre into what diameter pipe ?

[Rex Karz]

I rode with a dude once in Gorman who had a pipe that went each direction around the cylinder and joined behind it. Funky looking. What is the theory behind converging early?
Edit: I just asked the girl at Powroll, she said it is to keep the exhaust gases hotter (lighter, less dense and faster moving) because of the less cooling area of the single pipe.

[NOS_350X]

You looked at a picture and decided what you wanted to build. You dont realize how much goes into building the pipes, even 4 stroke pipes. Theres alot more than just welding some tubeing together and bam your done. I bet a standard pipe for a 350x would make more power than a home built one using a diffrent theory. Not impossible just un likely

[SWIGIN]

You have 2" pipes straight from the head? Did you just cut the flanges off a set of pipes, then went straight to 2" until they megre into what diameter pipe ?


i got a pic posted...it was a dg header that i shortned and instead of the normal 1 1/2 dia pipe im running 2''

[SWIGIN]

You looked at a picture and decided what you wanted to build. You dont realize how much goes into building the pipes, even 4 stroke pipes. Theres alot more than just welding some tubeing together and bam your done. I bet a standard pipe for a 350x would make more power than a home built one using a diffrent theory. Not impossible just un likely



trouble is this isnt in a 350x frame and the stock pipe wont fit, and for bigger motors like his big bore are top end motors and need to breath

[350XBigbore]

I am new to this board but far from a newbie in performance engines so I bet I can build a better exhaust than most. I also have a tig/mig welder so I can build it to suit my needs. Thanks anyways.

[SWIGIN]

yeah id just build one

[200x_Basket]

I would like to see a true dyno on an engine like that

Where is the Powder coating business located?

[350XBigbore]

My shop is in Lafayette Louisiana and I will dyno it in the next couple months. I cranked the engine up yesterday and it sounds great. I am waiting to get my swingarm back from getting stretched +4inches and I am going to start building a pipe for it this week. I cranked it with an old pipe I had, it works but looks crappy and I don't think it's very good for making HP. Later Clint

[SWIGIN]

what all did you do to the motor?

[350XBigbore]

The engine has everything Powroll sells for the 350X engines except for the stroker crank, big bore with 11.5.1 dome piston, decked .010 and ported head, race grind camshaft, valvesprings with titanium retainers for cam, cutdown valveguides for extra lift, 400ex carb and K&n filter. Only thing left is the exhaust and put the new swingarm on it. I plan on racing a 04 Honda 450r to see how quick it is next week once it's done but I don't think it will be quicker than that bike either. Later

[Insane Rider]

The engine has everything Powroll sells for the 350X engines except for the stroker crank, big bore with 11.5.1 dome piston, decked .010 and ported head, race grind camshaft, valvesprings with titanium retainers for cam, cutdown valveguides for extra lift, 400ex carb and K&n filter. Only thing left is the exhaust and put the new swingarm on it. I plan on racing a 04 Honda 450r to see how quick it is next week once it's done but I don't think it will be quicker than that bike either. Later
I'm thinking you will be surprised.

[250sx]

hey it's not a trike but you should bring that thing to our river ride in march. :thumbsup:

[350XBigbore]

Where is the ride?

[All X's]

Someone please send your moded 350x to the dyno. If i lived near a city i'd be first!

[NOS_350X]

Paypal me the money and ill take my X straight down to the dyno for ya

[350XBigbore]

Well guys I finished up today and took it for a spin, it is really strong even with a junk pipe, the bike hauls azz. I will run my buddys 450r tommorow to see how close I can stay with him but after I will build the exhaust and it should be much quicker. I also plan on racing an 05 300ex with exhaust, jetting K&N etc.. and I will post results but so far I am very happy. I have a 14tooth front sprocket and 36 rear with 18" turf tamers but it still doesn't have enough gear so I'll try some 20" tires tomorrow. Later

[250sx]

It's just north of vickburg. check out the the thread in the places to ride forum. :thumbsup:

[ADW3]

There's a kid at my office who races hare scrambles on a 300EX with a 350X motor stuffed in it. He didn't do the conversion but he claims that the guy who did it used one of those elusive 350X "crate" motors. The motor is in stock trim with the exception of pipe and jetting. He also has a 450R. He swears that the Frankenquad is as fast or faster than the 450R. He's not a big guy and likes the smaller EX chassis so maybe that has something to do with it. Sounds strange to me, but I haven't ridden either one so I can't really argue with him. Anyway, that's his story and he's sticking to it! :shrug:

[350XBigbore]

Well the 450 that I'll be racing has a high compression piston, pipe, jetted etc.. and it ran 73mph on the gps with me on it so it definately runs well. I ended up going with a 150 main jet and the plug looks perfect but I am sure the junk exhaust is holding me back, bigtime. I'll let you guys know what happens. Later Clint

[200x_Basket]

get to work on the pipe and post some pics.

I may need some PC work before too long so i want to see your work :)

[All X's]

Well guys I understand where you guys are coming from but jetting the bike is not hard at all as long as you know how to read a sparkplug. My question was how much should a properly tuned bigbore, race cammed, ported, carbed, piped 350x engine make? I read that a factory 350X engine made 27HP, so by adding all of the above I was thinking it should be able to produce 36+HP or more? Any of you guys ever see this custom pipe from Powroll? http://www.powroll.com/images/PRODUCTS-WEB/18328_PARTS.jpg
I was told it would make 20% more HP over other pipes, notice how the pipes merge as soon as they come out of the head, which I was also told the quicker you merge the pipes, the more HP you will make and if they are longer it builds more torque which makes sense. I am building a pipe exactly like that one for my bike b/c that one cost $475. Later
I'm not sure but, i believe the is a 350x conversion pipe to retro-fit a 350x motor into a 300ex quad frame?

[350XBigbore]

Well I built a custom pipe with 2inch pipe and it works great. I raced a few bikes and beat them all except for the moded 450r, which I can stay with all thru the gears until he shifts 5th so I am really happy with the results so far. I am going to advance the timing a little and try some 20" tires to see if that will help. The bike runs 70+mph for sure. I'll post some pics later this week.

[All X's]

Let me get this strait. 393cc carb, cam, springs,=stock 450r eater?

[350XBigbore]

I haven't beat the 450r yet but it's a close race until he gets into 4th and 5th gears but his bike is not stock and is really quick so I am pretty sure I could whoop a stock 450r. I also ported the head quite a bit on the 350x engine. I ran the bike yesterday with some 20" tires, 14 tooth front sprocket, 36 rear and got 73mph out of it with a GPS, the 450r ran 78mph. Later

[NOS_350X]

I dont have any problem with a stock 450. Piped, ported, high compression 450's become a problem.

[350XBigbore]

I dont have any problem with a stock 450. Piped, ported, high compression 450's become a problem.
My thoughts exactly, but my bike is also heavier than those 450rs and any 350x 3-wheeler.:(

[SWIGIN]

any pics yet of your pipe?

[350XBigbore]

I have some pics of the bike and the pipe but haven't had a chance to download them to the computer yet but will have them shortly. Later

[Tecate performance]

sweet man, sounds like a nice ride.

fwiw, i've got a 350x/300ex conversion. i used the the powroll pipe, i like the build and fit but the headpipe seems a bit long, maybe its holding back the power up top? not sure, never tried anything else. however i found a site about custom roadrace bikes where the guy was using 79-82 xr/ft 500's and he had a copy of exhaust plans w/dimensions from HRC back when they built bubba schoebert's ft500 flattrack bike. well i measured the powroll exhaust and the dimensions are the same, except for the secondary pipe length, so it can fit the quad.

as far as hp, i have a 452 kit, FST .405" 272 @.040 cam, fcr41, 10.8:1, 400ex airboot, 300ex airbox, mild ported head. with 14/36 gearing and 20's i ran 73.8mph gps with some more to go, i'd say about 75 or so. with 14/34, i'd estimate 78-80, it just takes a bit longer. i've raced piped (at least, never talked to them) yfz's on ice, and i pull them off the turns and am neck and neck down the straights. lt450's are easy picking's, piped or not. ran my buddy's 700 raptor w/pipe & programmer, pull him a bike length till 4th then we even out. also my buddies piped banshee, pull him 1-2 bike lengths all the way. no trx450's yet. never dynoed unfortunately, but with my race results i would think 40-42 is pretty close though.

how do you plan on advancing the timing?

[Black Sheep]

ooops

[350XBigbore]

I advanced the timing today by removing the flywheel cover and slotting the holes to move the magneto up about 1/4", it made a huge difference in overall power. I flipped the bike over backwards in 2nd gear, about an hour ago, by taking off just like I was doing before I advanced the timing so it definately made a difference. Now I need to get my extended swingarm finished up. Later

[Tecate performance]

yea, i was thinking of trying that. thanks for the info, keep us updated on racing that 450!

[SWIGIN]

so you moved the pickup 1/4''?

[NOS_350X]

I got to say, i think moving the pickup realy dosent sound like a good idea. If you wwant to play with the timing, pick up a dyna tek ignition for a 400ex. Then you can do what you want with the advancement of the timing. Just donset sound safe to me.

[SWIGIN]

same difference as a offset flywheei key i guess but 1/4'' is alot

[NOS_350X]

Ive also seen about 20 offset flywheel keys come appart and take out a stator. With moving the pickup you also dont exactly know what you doing to it or how much.

[Rex Karz]

With moving the pickup you also dont exactly know what you doing to it or how much.

Actually you know exactly what you are doing. That is, if you have a tape measure and know how to multiply and divide.

[NOS_350X]

Actually you know exactly what you are doing. That is, if you have a tape measure and know how to multiply and divide.

lol Ok, i advanced my timing 1/4 inch :chuckle: :nono:

Timing goes off of degrees, and good luck checking it. When you just drill some holes. You realy dont know how much your advancing the timing.

[Rex Karz]

Like I said, if you have a tape measure and know high school freshman math, this isn't a problem. (Don't forget, the cam travels at 1/2 crank speed....)

[350XBigbore]

What you guys must understand is it doesn't matter how much you advanced the timing as long as you have no signs of detonation and the bike is faster. You can only move the magneto about a 1/2" max anyway. I have advanced the timing on more than one bike like this and it always worked right but understand I know how to build, tune, jet etc.. to make engine run great, ie: it's not my first rodeo. If I can make an 8cylinder 350" engine run on pumpgas with 12.1 compression and make over 540HP, these little single cylinder engines are cake. This timing advance mod may not be for everybody but for those of us who understand how an engine works, you will have no problems. I checked the plug for detonation and it looked perfect but still a little fat. Later

[SWIGIN]

oh no...i fully understand it and agree you should run the max advance posibale for a givin octaine.

i was just unclear to what you moved....i always called it a pick up

my question is .... how did you move it a 1/4'' when there isnt that mutch metal to go that far?

[NOS_350X]

I havent taken off my side cover to check how much i could move it. But my first thought was like swigin.

But ill drop that, I dont think its a good idea to move the pickup.
The dynatek you can program to increase the advance as rpm increase, For example, at 2,000 Rpm you can have a 3* advance, and it can progressivly get higher so at 8,000 rpm you have a 6* advance. Because the way this works you can pick exactly you get the brunt of your power. You get Four diffrent curves programed into it and you can switch while you ride. Perty sweet little setup.

[350XBigbore]

I havent taken off my side cover to check how much i could move it. But my first thought was like swigin.

But ill drop that, I dont think its a good idea to move the pickup.
The dynatek you can program to increase the advance as rpm increase, For example, at 2,000 Rpm you can have a 3* advance, and it can progressivly get higher so at 8,000 rpm you have a 6* advance. Because the way this works you can pick exactly you get the brunt of your power. You get Four diffrent curves programed into it and you can switch while you ride. Perty sweet little setup.

I agree with the programmable timing box but how much does that cost and normally you want to decrease timing to make more HP in the upper rpms but anyway this is a free mod so how can you beat that? I didn't measure how much I moved the pickup but have modified a few bikes so I have a little experience with them. Later

[Black Sheep]

350Xbigbore, You have to understand NOS350X. unless he did the mod himself he doesn't believe it is anygood. if he doesn't understand how it works it must be wrong. This kid is 21years old and he knows more about 350X's then someone who's been modfying them for longer then he's been alive. this thread is a perfect example of his argumenative attitude. He does not understand or believe in moving the pickup so he tells us how wrong it is and how his dynatech ignition mod is better. yet go read his thread about trying a dynatech ignition on his 350X. arcording to his own thread he still can't get it to work. http://www.3wheeler.org/vb/showthread.php?t=30161&page=2

[SWIGIN]

350Xbigbore, You have to understand NOS350X. unless he did the mod himself he doesn't believe it is anygood. if he doesn't understand how it works it must be wrong. This kid is 21years old and he knows more about 350X's then someone who's been modfying them for longer then he's been alive. this thread is a perfect example of his argumenative attitude. He does not understand or believe in moving the pickup so he tells us how wrong it is and how his dynatech ignition mod is better. yet go read his thread about trying a dynatech ignition on his 350X. arcording to his own thread he still can't get it to work. http://www.3wheeler.org/vb/showthread.php?t=30161&page=2



thats what i was thinking.....lol

[NOS_350X]

350Xbigbore, You have to understand NOS350X. unless he did the mod himself he doesn't believe it is anygood. if he doesn't understand how it works it must be wrong. This kid is 21years old and he knows more about 350X's then someone who's been modfying them for longer then he's been alive. this thread is a perfect example of his argumenative attitude. He does not understand or believe in moving the pickup so he tells us how wrong it is and how his dynatech ignition mod is better. yet go read his thread about trying a dynatech ignition on his 350X. arcording to his own thread he still can't get it to work. http://www.3wheeler.org/vb/showthread.php?t=30161&page=2


If i rember right until about a motht ago you thought i was much older. Once you did find out how old i was you said that you where superized how smart iwas for my age. Now anything you have to say is directly related to age.:doh: and that i cant know anything because of my age :bash:

Send me a dyna and i will be more than happy to set it up on any 350x for ya. :thumbsup: I have been using what i have laying around. and thats not a dyna.

Now if somone can tell me exactly what yoru chaning the timing to rather than "I advanced the timing today by removing the flywheel cover and slotting the holes to move the magneto up about 1/4" I might be able to support it. Until i get any idea how much your moving the timing i wont support the idea.

I was ready to move on, "But ill drop that, I dont think its a good idea to move the pickup." But you mr atc have to stir **** up. Why dont ya just come out here to cali so you can give me some lessions on how to ride and build engines. :loser: well, somone will be schooling somone :salute:

[SWIGIN]

:rolleyes: :rolleyes: does it realy matter how much it is moved to you? guess you never heard of timing by ear?

moveing the flywheel or the pickup is the same thing as turning a distributer on a car...... its that simple.

your tuner is only ajusting what would be the curve of the distributer...but initial timing is set by moving it

i know in this day and age nothing done manualy can be near as good as a tuner.:rolleyes:

[Ed200X]

Ah! Exhaust pipe theory! Well folks no matter what you do. There is no "all around" pipe! A longer headpipe will move the powerband down (increase torque) shorter = more punch higher up. Yes, you can make a four stroke engine "peaky" like a 2-stroke. The way I figure stuff when I modify is; If you ported the head and put a long duration cam in it, then you have moved the band up. So to compensate that you would run a bit longer head pipe to put some power down lower. Like that.

[SWIGIN]

any pics of this pipe yet?

[cr480r]

Ah! Exhaust pipe theory! Well folks no matter what you do. There is no "all around" pipe! A longer headpipe will move the powerband down (increase torque) shorter = more punch higher up. Yes, you can make a four stroke engine "peaky" like a 2-stroke. The way I figure stuff when I modify is; If you ported the head and put a long duration cam in it, then you have moved the band up. So to compensate that you would run a bit longer head pipe to put some power down lower. Like that.

if you built an engine to perform best in the upper rpms... wouldnt you want the exhaust tuned to match? You wouldnt put a drag pipe on a stocker because it lacked top-end would you?

[armyvet]

Dont forget the high comp piston for the long duration cam...

[350XBigbore]

Finally a couple pics of the beast. http://i34.photobucket.com/albums/d107/schexnac/141_3390.jpg , http://i34.photobucket.com/albums/d107/schexnac/141_3389.jpg. How hard will it be to make a 93 CR250r engine work right on a 4 wheeler chassis? I picked up a 93CR250 for $150 and I have another 250x chassis that I am going to build it for drag racing. I ordered a new Wiesco piston, decked the head and having the cylinder ported for the CR250 engine and the FMF fatty pipe off the dirtbike will even work on the quad frame! I will take some pics next week once I get the cylinder back on the engine. LMK Later Clint

[3wheelergod]

Have you built a pipe yet? I'll give you one little secret! DO NOT have your 2 head pipes the same length! Trust me, it may run great and have more power than stock but it will be less than what it can be (2-3hp depending on motor) make them at LEAST 1 inch different, 2 inches is the max! Also LESS BACK PRESSURE=MORE POWER ON A 4 STROKE!!!!!!!

[3wheelergod]

I told my Boss about the shorter Y pipe = more horse, longer Y pipe = more torque theory, so we tryed it!!!!!!! I took 7 inches out of the Y pipes to where they join in the collector pipe (the Y) from what our previous pipe was.

Results.....................

We gained 1.5 HP. and 2 ft. lbs. of torque. So we came to the conclusion that the shorter or longer to the Y makes no difference, the shorter the pipe is the less back pressure there is, less back pressure=more power all around!:shrug: This is on a 08 raptor 700, K&N and programmer! We ran MUPTIPLE DYNO'S (6) to richen and lean, warm motor, cold motor to check differences. I imagine other motors can be different but it seems to be exaclty what we have been told. (We talked to a GM R&D guy about back pressures and race motors). Less back pressure=more power! Id love to try it on a 350X????????????????????????????????????????

[NOS_350X]

It took me a while to figure out how making one pipe to the Y longer than the other, Makes power. Now it makes sence to me. Think of it this way, Every time the valve opends it sends a pules of air, Now if there equal length then the pulse are going to try and merge at the same time thus making them croud together, (think of getting onto the freeway) Now if one path is longer you could space it our right so each pulse merge together at diffrent times, = a better flow. Now i dont know if this is the reasoning behind what chase is saying but it shure sounds dam good to me.

[350XBigbore]

So my theory was correct and I definately noticed a big difference on my 350x. Now you are saying that I need to make one of the primary pipes longer than the other by 1inch? Or was this before the testing?

[SWIGIN]

It took me a while to figure out how making one pipe to the Y longer than the other, Makes power. Now it makes sence to me. Think of it this way, Every time the valve opends it sends a pules of air, Now if there equal length then the pulse are going to try and merge at the same time thus making them croud together, (think of getting onto the freeway) Now if one path is longer you could space it our right so each pulse merge together at diffrent times, = a better flow. Now i dont know if this is the reasoning behind what chase is saying but it shure sounds dam good to me.


the thing is....you fought me one time about this and it seems i was right(common sence told me that tho)

the last thing you want is the 2 primary pipes the same lenth on a 350x due to the gas pulses....and shorter= hp

now its not as easy to do on a 350x frame but this shorty header is the way to go on a quad

[SWIGIN]

it seems i cant post a pic of my header but its posted on here someware

has anyone ever posted a dyno run on a built 350x?

[350XBigbore]

Well I redisgned my pipe to go closer to the frame but used a smaller diameter pipe but it didn't hurt topend or lowend. So I will take pics tommorow to see what youll think. I can be a tester for a CPI 350x pipe if needed 3 wheelergod.

[3wheelergod]

So I made another head pipe for the C-raptor :lmao: today an inch shorter than yesterday's and it didn't really do anything except raise the hp about 4 around 8200 rpm. It was almost dead even everywhere else. We have gained 8 hp at the peak (6000-6100 depending on warmth of motor) but the real kicker is we have gained 12 lbs or torque at 5500 (SMOOTHEST CURVE I'VE EVER SEEN) and we are 18.5 hp better at 6500-7000, then the power kinda heads in the same direction down the higher the r's go. We tryed richening and leaning but we always had about the same result with the 2 shorter pipes I've made. The 2 longer ones were about the same also, and I have used 1 3/8 head pipes on all (stock is 1 1/4). Now this is all a programmable injection system with an exhaust probe but I think it is a pretty good indication about the back pressure. I am trying 1 more pipe tomorrow with 1 1/2 heads! Just to see,,,,,, I LOVE my JOB!!!!!!:headbang: :yup:

I would stay with the same size head pipes there 350XBIGBORE, or even bigger. How close to Utah are you?

Yes Nick, they are called sonic waves and you are on the right track of thinking!

[350XBigbore]

[QUOTE=3wheelergod]So I made another head pipe for the C-raptor :lmao: today an inch shorter than yesterday's and it didn't really do anything except raise the hp about 4 around 8200 rpm. It was almost dead even everywhere else. We have gained 8 hp at the peak (6000-6100 depending on warmth of motor) but the real kicker is we have gained 12 lbs or torque at 5500 (SMOOTHEST CURVE I'VE EVER SEEN) and we are 18.5 hp better at 6500-7000, then the power kinda heads in the same direction down the higher the r's go. We tryed richening and leaning but we always had about the same result with the 2 shorter pipes I've made. The 2 longer ones were about the same also, and I have used 1 3/8 head pipes on all (stock is 1 1/4). Now this is all a programmable injection system with an exhaust probe but I think it is a pretty good indication about the back pressure. I am trying 1 more pipe tomorrow with 1 1/2 heads! Just to see,,,,,, I LOVE my JOB!!!!!!:headbang: :yup:

I would stay with the same size head pipes there 350XBIGBORE, or even bigger. How close to Utah are you?

Yeah I had to downsize the pipe to get the bend around the frame but I thought 2" was maybe too large so I plan on stepping up from 1-3/4- too 2" right after the turn. But unfortunately I found some aluminum in my oil filter last nite and think that my older brother put some 87octane fuel in the bike, (11.5.1 compression) and it detonated the piston. I will have it apart tonite to see what went wrong.:shrug:

[3wheelergod]

Ouch!!!!

[350XBigbore]

Well I tore it apart and found the crank bearings went out. So does anybody know where I can find a good stroker crank for a 86 350x engine? Also what is the biggest size valves that will work in a 350x head? I am doing a little more portwork, bigger valves and more compression so it should make quite a bit more torque and horsepower. later Clint