Wiseco 440 big bore kit questions

Just came back from Utah with my DRZ400. Shoulda taken my XR400. The DRZ is short on low end torque and the transmission ratios suck. I'm going back to the XRand bump it up with a 440 kit. Wiseco 440 big bore kits are dirt cheap on ebay...however I don't think the seller is 100% truthful...so I ask this question:

* The 89mm CK140 Wiseco kit with the sleeve...does it require the aluminum cylinder to be bored? If I read between the lines at lukesracing.com, the aluminum cylinder must be bored, but the cases don't require anything

Correct. The sleeve is stepped.

BIG POWER INCREASE.

Dwight

Dwight,

Going from 400 to 440, will you be able to jet it with the stock carb? or would you recomend going up to the next larger size...possibly switching out the stock for the pumper? If so, which size pumper?

by the way,

Is the quote in your sig yours? or did you hear that from someone? I ask because I'd like to use it and want to make sure i give propper credit to the author...

sorry for the post hi-jack

thx,

Dwight may answer differently, but here's my observations.

I bought my bike with most of the mods listed in my signature. I put in the 426 11:1 mod. The bike actually runs better than it used to, except starting. I either need to adjust the fuel(air? I cant ever remember) screw or go up a size on the pilot. Other than that, it runs awsomely.

I just recieved my 440 kit from e-bay(ya-baby-ya). What I have been told is yes you can us the stock carb but you will have to change the jetting. Now depending where you live and altitude this will help you decide what main you will go to. Just a question, Could I ask what prices have been charge for boring of the cylinder and also to have the sleeve installed??? :cry:

I'm currently inquiring on the price of boring the cylinder to take the Wiseco sleeve from several places...if you go to xrsonly they list prices. I'm also requesting valve job quotes, and get that done while it's apart.

A new question...does anyone know the crushed thickness of the cylinder base gasket? I don't want the full 11:1 compression....I'm not changing to a hot cam like most folks, which would drop the effective compression ratio from the mechanical 11:1. So with the stock cam the 11:1 could create knock problems down low....I'm looking to raise the jug 20 or 30 thou to get the compression back to 10 or 10.5.

I don't want the full 11:1 compression....I'm not changing to a hot cam like most folks, which would drop the effective compression ratio from the mechanical 11:1. So with the stock cam the 11:1 could create knock problems down low....I'm looking to raise the jug 20 or 30 thou to get the compression back to 10 or 10.5.

Huh?? Cams don't affect compression ratio.

Leave it 11:1 and don't worry. Even on a stock cam it's fine, and you can still use premium pump gas with no problems. Higher compression is needed to wake it up a bit more.

When I 440'd I used 11:1 and rejetted the stock carb. I forget the jet size (it came in the Thumper Racing kit), but I know it was bigger than an XR600's. It ran great.

I had the head ported and used a lighter IMS Hot Rod connecting rod too.

Sorry, but cams do affect compression ratio. There are technically two compression ratios. Mechanical compression ratio, and effective compression ratio. Mechanical is the ratio of the cylinder's volume at bottom dead center to that at top dead center. That's the 11:1.It's described in the equation: CR = (clearance + displacement)/clearance ....where clearance is the volume at top dead center, displacement is the volume of the cylinder from bore and stroke. Effective compression ratio takes into account the mass of mixture sucked into the cylinder and how tightly it is squeezed at top dead center. As a general rule, if the engine is not supercharged, effective compression ratio is always less than mechanical compression ratio. Why is this...because of the cam event. Camshafts have overlap...overlap is when both valves are open. At lower engine speeds, intake mix can be shoved back out the intake or the exhaust and not as much mix is trapped and compressed at TDC of the firing stroke. This is the phenomenon you hear and see when you have a big V8 with a high performance camshaft (lots of overlap and duration), and it has a "lumpy" or rough idle....mixture is being shoved back up into the carburetor (and not being compressed and fired)...the engine is unhappy....but come higher speeds, when the inertia of the incoming air wants to keep ramming air fuel mix into the cylinder...regardless of the fact that the piston may actually be coming up on compression....the engine runs much better & makes more power. Some folks call this "coming up on the cam" . Another cam characteristic is duration...how long the valve is open. For example, The Intake valve opens before the piston is at top dead center and starts to desend to on the suction stroke...why...because air has inertia....and the valve has to get a head start on opening, so the suction stroke can pull in the mixture.Likewise the intake valve will almost always still be partway open at bottom dead center when the compression stroke starts....all because of the inertia of the incoming mixture. Similar things happen with the exhaust event. Therefore, when you go to a high performance camshaft, (lots of duration and lift and overlap) it is almost always NECESSARY to raise the compression ratio...so the engine won't loose torque down low when you are looking for more torque at higher speed. Having an engine that's a dog down low...then torque and horsepower that rips your arm off when it gets up some revs and "comes on the cam"....like a freakin 2 stroke....is not my preference. As a result I want about 10 or 10.25:1 compression on the XR440 kit to give me the extra torque of the 440 PLUS extra torque from the improved compression ratio on PREMIUM gas, at lower engine speeds. We all know that the stock XR400 and Honda's 9.3:1 will let us run OK on 86 octane swill. I want torque..WAY down low, like a trials bike...not necessarily top end horsepower. Think of it in terms of a diesel engine that has massive torque down low...not a race engine where all the power is at some astronomical RPM..and is undriveable. You 20 year olds can hold onto those bars way up there on the top end of the RPM & horsepower curve...at three times your age...torque is easier to ride with.

My 426 makes an amazing amount of torque, down low. I'm a short shifter. I went 11:1. The first long ride, I'd have it in second, nearly stalling. I'd wack the throttle and it would pull a wheelie right out from under me (literally). I did this multiple times. I dont think you'll benefit from NOT going to 11:1. It makes huge power down low. It pulls from SO low I'm nearly stalling and it takes off like a rocket.

'Course, it runs pretty good up top.

I'm currently inquiring on the price of boring the cylinder to take the Wiseco sleeve from several places...if you go to xrsonly they list prices. I'm also requesting valve job quotes, and get that done while it's apart.

A new question...does anyone know the crushed thickness of the cylinder base gasket? I don't want the full 11:1 compression....I'm not changing to a hot cam like most folks, which would drop the effective compression ratio from the mechanical 11:1. So with the stock cam the 11:1 could create knock problems down low....I'm looking to raise the jug 20 or 30 thou to get the compression back to 10 or 10.5.

I don't know if you can get what you want that way. Keep in mind you are also changing the length of the timing chain, although there may be enough slack. Wiseco makes 10:1 pistons for the 416 and 426cc pistons, but not the 440, which is actually 435cc. Your may be able to machine the top of the piston, but that could be dangerous also. If you already have the 440 kit, I would give the 11:1 a try. Otherwise I would get the 426cc piston with 10:1.

For anyone else looking to go 440, I would buy the kit from the place you want to do your work. Such as Tumper Racing, XR's Only, ect.

You're convincing me to leave the 11:1 alone! I emailed the ebay vendor to confirm the $169 XR440 kit was the Wiseco CK140...with SRP of $234...no reply...that's bad news..your suggestions of a more reputable source are excellent. I'm in contact with Jesse @ Kientech...he did my buddy's DR435...fine job...and has done a few XR400's...he now makes a Vortec airbox for the XR400. Don't know if it is a big improvement on an XR, but is absolutely essential on a DR350 bored to 435...that setup is one strong engine...way more grunt than my DRZ400

I have the 440 with a 11:1 ratio and a Hotcam Stage 1. I gained a ton at the low end like I was told. I would recommend putting the 11:1 and a performance cam.

Sorry, but cams do affect compression ratio. There are technically two compression ratios. Mechanical compression ratio, and effective compression ratio. Mechanical is the ratio of the cylinder's volume at bottom dead center to that at top dead center. That's the 11:1.It's described in the equation: CR = (clearance + displacement)/clearance ....where clearance is the volume at top dead center, displacement is the volume of the cylinder from bore and stroke. Effective compression ratio takes into account the mass of mixture sucked into the cylinder and how tightly it is squeezed at top dead center. As a general rule, if the engine is not supercharged, effective compression ratio is always less than mechanical compression ratio. Why is this...because of the cam event. Camshafts have overlap...overlap is when both valves are open. At lower engine speeds, intake mix can be shoved back out the intake or the exhaust and not as much mix is trapped and compressed at TDC of the firing stroke. This is the phenomenon you hear and see when you have a big V8 with a high performance camshaft (lots of overlap and duration), and it has a "lumpy" or rough idle....mixture is being shoved back up into the carburetor (and not being compressed and fired)...the engine is unhappy....but come higher speeds, when the inertia of the incoming air wants to keep ramming air fuel mix into the cylinder...regardless of the fact that the piston may actually be coming up on compression....the engine runs much better & makes more power. Some folks call this "coming up on the cam" . Another cam characteristic is duration...how long the valve is open. For example, The Intake valve opens before the piston is at top dead center and starts to desend to on the suction stroke...why...because air has inertia....and the valve has to get a head start on opening, so the suction stroke can pull in the mixture.Likewise the intake valve will almost always still be partway open at bottom dead center when the compression stroke starts....all because of the inertia of the incoming mixture. Similar things happen with the exhaust event. Therefore, when you go to a high performance camshaft, (lots of duration and lift and overlap) it is almost always NECESSARY to raise the compression ratio...so the engine won't loose torque down low when you are looking for more torque at higher speed. Having an engine that's a dog down low...then torque and horsepower that rips your arm off when it gets up some revs and "comes on the cam"....like a freakin 2 stroke....is not my preference. As a result I want about 10 or 10.25:1 compression on the XR440 kit to give me the extra torque of the 440 PLUS extra torque from the improved compression ratio on PREMIUM gas, at lower engine speeds. We all know that the stock XR400 and Honda's 9.3:1 will let us run OK on 86 octane swill. I want torque..WAY down low, like a trials bike...not necessarily top end horsepower. Think of it in terms of a diesel engine that has massive torque down low...not a race engine where all the power is at some astronomical RPM..and is undriveable. You 20 year olds can hold onto those bars way up there on the top end of the RPM & horsepower curve...at three times your age...torque is easier to ride with.

Um....ya. Keep it 11:1 and don't worry. As far as four stroke motors go, 11:1 isn't even that high.

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