Quantcast

Let's start an engine build.

Yamaha Raptor 350 & Warrior Forum

Help Support Yamaha Raptor 350 & Warrior Forum:

jasonp

Active Member
Joined
Oct 22, 2006
Messages
2,385
Reaction score
0
Location
New Richmond, WI
Well after getting a bunch of pm's about some people wanting to know about building up the 350cc engine and now having a little push from dave to get me going I've decide to help some people out. Hopefully we'll get some guys like Dave, Griff and others to chime in as well.
Figure out what you want and how much money you can reasonably spend on you're build. Also truly ask yourself what type of riding you do and what rpms do you want the most power in or where the engine spends the most rpm in. Be honest with yourself. Don't always think bigger is better. Also ask yourself what type of gas do you want to run as this will play a big part in picking out the compression you want to run for a new piston.
I would say most of you guys are going to run on pump gas and will want to spend the least amount of money but still have great performance.. I think we can do that.
Piston choice are Wiseco and JE. There are others out there like CP that can custom make you a piston which is great but there going to be a little more money then the other two manufactures.
Since were going for maxium HP and torque with little money lets go for the Wiseco, it's got 10.2:1 compression and comes in many over bore sizes. When installing a new piston you should always do a bore and hone job as it will straighten the liner out and you will get a much better ring seal. Make sure you take the cylinder and piston with the spec sheet to the machinist.
Personally I go with the largest overbore as this aids in compression and plus gives you that extra 17cc.
Next thing will talk about is deck clearance. This is when the piston is at the very top of the bore. TDC and you measure the distance from the top of the piston to the head or liner then take into account for head gasket thickness. This measurement should be close to .040". The closer you get the better and the more compression you will have. Also the engine will run a little cooler and it will resist detonation. The reason why this is important is because of the quench zone, which is the flat spot on the sides of the head (combustion chamber) get closer to the piston at TDC and will cause air to be push and mixed around very violently making the air fuel mixture mix better. To do this will use some custom made gaskets by Cosmetic. You'll have to figure out what you need.. For are propose I'll say we have .075" of deck including are stock .043" head gasket and stock base gasket of .020". Will go with there .010" base gasket,.018" head gasket and plus the .012" piston we now have are .040". You could even take the base gasket out and use sealer if you could not get that thin of a head gasket. This is key to having the engine perform right here folks is getting that .040" of deck.. Also a thing to note is that don't go under .035" of deck. Metal does expand and as you start to rev the engine harder things may touch.. So be careful.
So we spent 80.00 dollars on a new piston.
50.00 for the bore and hone job.
25.00 dollars in gaskets.
Around $150.00 bucks and I'm guessing around 11:1 compression just right where you want to be. Next will talk about cams.
 
Last edited by a moderator:

jasonp

Active Member
Joined
Oct 22, 2006
Messages
2,385
Reaction score
0
Location
New Richmond, WI
Maybe we should talk about replacing the piston as maybe some of you actually have questions about doing that? Like a how to.
 

dave76

Active Member
Joined
Feb 26, 2006
Messages
2,690
Reaction score
0
Location
Edison, New Jersey
I would also like to add that while your motor is appart, have at least a simple valve job done on the head to ensure a proper valve seal. Check the tops of the valve stem for bad wear from poorly adjusted valve clearence, replace if their very bad. A simple valve job last cost me $60
 

griff

Member
Joined
Oct 9, 2006
Messages
478
Reaction score
0
Location
Sacramento, CA
Good topic Jason.

If I may, I'd suggest the JE piston over the Wiseco. Price is close, and JE rates it at 10.5 CR with the +2mm overbore. Part# 222085

That combined with your other suggestions is a good start.

Me personally, I'd just stick with the stock head-gasket. IF its in good shape, it can be 100% safely re-used, some Copper Spray will do the trick.

I know guys that have tossed the base-gasket without issue, which I thought was .028" ?? I might be thinking of something else... anyways...

I highly recommend HondaBond as the sealer, it works better and is easier to apply than YamaBond and Suzuki's stuff IMHO. I use it exclusively these days on all my bikes engine cases.

In any case, playing with the stack/deck height will have an effect on cam timing, and thats very important!
 

jasonp

Active Member
Joined
Oct 22, 2006
Messages
2,385
Reaction score
0
Location
New Richmond, WI
Griff, you can only use the stock head gasket to a bore of 84mm. I measured this and I believe you have to have .010" for the sealing ring and with the stock gasket you don't after boring the sleeve that far.
The stock head gasket is a muli layer gasket (which is a great gasket that can be re-used) if you use Cometic you can choose what ever gasket you want and there very reasonable. Meaning muli layer, copper, etc. Also they have a great web site. http://www.cometic.com/
JE piston is a great high quality piston that I believe is lighter then the Wiseco and a little higher compression. Also the dome of the piston is .100" which is right where you want to be as far as height goes, any higher and you can effect the flame travel accross the piston and combustion chamber.. lots of power is lost because of this if the design is not right.
 
Last edited:

jasonp

Active Member
Joined
Oct 22, 2006
Messages
2,385
Reaction score
0
Location
New Richmond, WI
I also want to add a little more about the JE piston. The new designed one has a raised pad for added compression as in most pistons do this to add volume so compression goes up as there is less space in the combustion chamber. If you look at the Wiseco vs. the JE you will see that how JE has designed the combustion chamber into the piston dome where Wiseco is just a round dome. From this stand point alone you will find that you have more quench area on this type of a setup and in are case the more the better. This also will aid in a better flame front travel across the piston and allowing the piston to come up into the combustion chamber more then a Wiseco would.
So a little info and this is why this piston is about $60.00 dollars more then the Wiseco.
 

jasonp

Active Member
Joined
Oct 22, 2006
Messages
2,385
Reaction score
0
Location
New Richmond, WI
Camshafts. http://yfm350.proboards31.com/index.cgi?board=tutorials&action=display&thread=1173385110
There basically 3 manufacture of cams, 2 of which we will be talking about. Megacycle and Web. Many people think that White brothers makes cams or Duncan/Powroll. Some places tell these companys they want custom grinds like Powroll and has them manufactured through Web or Megacycle. I will stay though that Most use off the shelf stuff and just rebrand it under there own name.
Now this is where you are going to have to ask yourself what type of riding you do and where you want your engine to "live" at. What RPM do you want you're engines power in. What RPM do you ride the most in. Asking yourself these questions will better determine what type of cam will be looking for.
So rather then putting specs up that really nobody understands I will just tell you more what cam will do what and where the power will be.
Megacycle 252x2 "mid-range" .415/.395" Great torque cam and where more low to mid rpm power is needed. This will add more low end power great for woods riding and very tight stuff.
Web .390 grind 88 and powroll .390" - Great power all around and awesome mid range hit. Give you the most all around power and still have a good bottom end.
Web .430 grind 84 Good mid and top end power with out giving up to much bottom end more over rev power then the Web .390 but less low end torque.
Megacycle .450" 252x1 and powroll .430" Great top end hit and high rpm power but you'll lose a bit on the bottom when compared to the other cams.
Both cams you can get for about $120 bucks after sending your cam in for a core refund.
You'll need some HD springs as the added lift,duration and ramp angle will help hold the rocker on the lobe of the cam and not allow the valves to float. Anywhere from $65 to 95 dollars these will run you.


When doing the piston I would go ahead and have a 3 angle valve job done to it along with replacing the guides and seals. Have them lap the valves and you should be good to go.
 

griff

Member
Joined
Oct 9, 2006
Messages
478
Reaction score
0
Location
Sacramento, CA
Griff, you can only use the stock head gasket to a bore of 84mm. I measured this and I believe you have to have .010" for the sealing ring and with the stock gasket you don't after boring the sleeve that far.
Really? The older OEM used to be 85.5... hmm, guess they changed the spec at some point.

Everything else on the pistons is spot on, nice explanation Jason. Thats why I prefer JE's myself.

Definitely cant go wrong with Cometic, I've been using them for years. Their custom stuff is excellent and reasonably priced. They were able to make a head and base gasket to my exact specs for my GSXR. I highly recommend them.
 

dave76

Active Member
Joined
Feb 26, 2006
Messages
2,690
Reaction score
0
Location
Edison, New Jersey
I guess I'll add a few pics.


Ported combustion chamber

Ported exhaust runner

Oil pump and clutch side

10.5mm stroker crank


Clutch installed

Piston installed

Head and cylinder on

Cam in

Completed motor

Old JE 11.1 compression 366cc 85mm piston

Clutch cover oil cooler

Warrior oiling system

Stock cam, Megacycle 252X1, and Powroll race 288° cam


JE 10.75:1 87mm 446 stroker piston

This is were you add an extra clutch steel
 

sscrewser396

New Member
Joined
Dec 10, 2007
Messages
10
Reaction score
0
dave what kinda power gains do u have ? What kind of other fourwheelers can you run with?? Great thread by the way !
 

jasonp

Active Member
Joined
Oct 22, 2006
Messages
2,385
Reaction score
0
Location
New Richmond, WI
Most you will see out of a pump gas stock stroke motor would be around 30hp. A little more if you went with the 400cc kit from CWR, but this requires a case bore and the cases have to be split so you may as well deeper and stroke the crank as well. From what I remember Trinity did a warrior way back in the day with a 12:1 setup all tricked out and they dyno'd 32hp from what I remember.
Alba action's 400cc stroker engine they claimed 35hp.
FST 435-446cc around 40 to 45 hp.
CWR 460cc around 43-48 hp.
FST 490cc around 50 hp. Not made anymore.
I believe the 450r and 700r raptor are making that stock (45hp).
More stroke will give you more torque and usable power. More bore will give you higher HP and want to be rev'd to make it's power.
 

dons18w

Member
Joined
Nov 17, 2007
Messages
112
Reaction score
0
Location
plymouth in
ok what im needing to know is will the flywheel puller act as the press also? just bought the puller on ebay for 40 and recived 200 from the guy that sold me motor with the bas oneway thanks
 
Top