yz426 vs yz 250......

[00YZ426FMRCD]

I hear you - I told myself this too as I did not have a 2smoke for the woods - I had a yzf and WR450....no problem starting , never fell etc....but for the majority of newer riders - a 426 w/o decomp mod will hate the starting technique...seen it many many times.. and then they bought hondas.

now a 285 kit on the yz just may be the power ticket...or a 300Ktm...

I hear ya Ga. I would take the YZ250 with a 285 kit setup correctly over a KTM any day of the week. Hard reality is that if you go to a major off-road race such as a GNCC, almost everyone is on 2-Strokes and most whether 2 or 4-stroke are on KTMs. Still quite a few YZ & RM's. I raced the Sr. B class (my age is now showing) at the Triton GNCC in Florida early this year and people looked at me like I was crazy sitting there on the line with my 426. After 3+ hours & 2 tanks of gas into the race I confirmed I was...Sorry to hijack the thread but I would still take the 426...or better yet, a new 450 over a YZ250 ?

[stillsun]

hands down....for the woods a YZ250 w/ Flywheel weight would be my choice.....the 426 is a big ole pig in the woods and w/o auto decompression it plain sux especially when you stop or fall on any steep hill IMO:excuseme:

It's all in what you're used to, I'd be willing to bet I can start my 426 with decompression lever faster than a guy with auto, I know right where the stroke is VERY easily because it doesn't have auto and then hit it bam, all really quickly. And yes I also own bikes with auto... with that taken care of whether I fall on a hill and how hard it is to get going is usually more to do with how high the 426 sits, and I'm 6'4".

J

[grayracer513]

It's all in what you're used to, I'd be willing to bet I can start my 426 with decompression lever faster than a guy with auto, I know right where the stroke is VERY easily because it doesn't have auto and then hit it bam, all really quickly.

I'm your huckleberry.

By the time you find compression an reset the lever, I will have kick mine, possibly twice, if necessary. I have absolutely no interest in where the compression stroke is when starting a hot 450. ? So far, I've made $25 on bets like that.

[jayh300]

from a guy who thought his 400 was way easy to start hot before I put a hot cams exhaust auto decomp in it......

there is no way you could start it quicker with the lever.

as gray said, once it is warm, just kick it. Mine 99.9% of the time starts on the first kick no matter where it is on stroke.

jay

[stillsun]

from a guy who thought his 400 was way easy to start hot before I put a hot cams exhaust auto decomp in it......

there is no way you could start it quicker with the lever.

as gray said, once it is warm, just kick it. Mine 99.9% of the time starts on the first kick no matter where it is on stroke.

jay

From a guy who owns both types of bikes right now, I will argue with you on it... while yes I COULD start the auto faster at times, if you don't happen to be in the right part of the stroke on that first kick, you're not starting until the second, in this case I've already got the 426 started (because I'll start it on the first and only kick every time), in the situation where you're already in the vicinity then yes, the half second it takes me to push to TDC you've got me beat; so generally speaking you'll kick your bike 3 times for every 2 I kick mine which is what how I should clear up being "faster" overall over the entire day.

Having said all this the only benefit in having the auto then rests with not having the extra lever... the benefit of having the lever is being able to do certain things like blow the motor out if you go swimming, flood it out by endowing... things of this nature; and for all the guys who've never dealt with manual decompression, an semi-auto-theft device when your bike is sitting around camp. ?

J

[642MX]

It still amazes me that people think a decompression lever is an asset. ?

[grayracer513]

if you don't happen to be in the right part of the stroke on that first kick, you're not starting until the second,

I've never found that it makes any difference where it is when it's hot. It will start kicked from anywhere in the engine cycle

Having said all this the only benefit in having the auto then rests with not having the extra lever... the benefit of having the lever is being able to do certain things like blow the motor out if you go swimming, flood it out by endowing... things of this nature; and for all the guys who've never dealt with manual decompression, an semi-auto-theft device when your bike is sitting around camp.

Yeah, they always try the anti-theft dodge, don't they? ? Also makes it tough for you pals to start the bike when you hurt yourself and need them to help.

The exhaust valves and an open throttle will clear the cylinder at least as fast as a valve lifter. And the bike will bump start like a 200cc two stroke. Let's say you kill the engine blasting into a turn by getting carried away with the brakes. With manual decompression, there are two things you can do, you can let off the brake, pull the compression release and leave the clutch alone, hoping the engine will start to turn before the engine stops, and that you'll have time to feed the release back out smoothly enough to get it to fire, or, let off the brake, pull the release and the clutch, dump the clutch, feed the release out and get the engine to fire before it runs out of forward momentum. Being raised on big British singles, I'm intimately familiar with this procedure, and everything else that you do with this device.

In the same situation with auto-decomp, you let off the brake and flick the clutch once, same as a two stroke. No problem.

Before I owned my first YZ450, I almost bought a 426 instead just because of all my experience with MCR's and all the tricks you can do with them. I haven't missed it since the first week. There is no advantage to them whatsoever, and they belong on the shelf with mechanical ignition advances, and the rest of the antiques.

[felix 222]

the extra weight hasn't really affected me.

[rulingtheroost]

cool thread,this is the same debate as ford vs chevy,both good machines just difernt.i've owned 98'yz400,98'wr400',00'yz426' and currently own 05'crf450x 05'yz2502s,07'ktm525xcw.i'm a big guy at 6'4'' and 300lbs and i will admit that the four strokes got me much easer to ride,controlable smooth fast power.now as for the yz250 that thing is serously fast hardhiting and explosive.yes its lighter and more flickable but for me i can ride smother and faster for longer on the 4stroke.its a shame the yz250 dosn't have a 8sp tranny cus that thing just rips but runs out of gear for me,maybe 65mph with stock gearing.this weekend i'm going down to south jersey to do some riding in the sand,i think thats were the 2stroke will work the best.i'll bring the yz and the ktm,i will say this about the yz426 i had mine for 5yrs and never did a top end or adjusted the valves very reliable bike and once you get used to the manual decomresion lever its not that big a deal. most people can't chew gum and walk let alone start a 4stroke.

[rulingtheroost]

I've never found that it makes any difference where it is when it's hot. It will start kicked from anywhere in the engine cycle

Yeah, they always try the anti-theft dodge, don't they? ? Also makes it tough for you pals to start the bike when you hurt yourself and need them to help.

The exhaust valves and an open throttle will clear the cylinder at least as fast as a valve lifter. And the bike will bump start like a 200cc two stroke. Let's say you kill the engine blasting into a turn by getting carried away with the brakes. With manual decompression, there are two things you can do, you can let off the brake, pull the compression release and leave the clutch alone, hoping the engine will start to turn before the engine stops, and that you'll have time to feed the release back out smoothly enough to get it to fire, or, let off the brake, pull the release and the clutch, dump the clutch, feed the release out and get the engine to fire before it runs out of forward momentum. Being raised on big British singles, I'm intimately familiar with this procedure, and everything else that you do with this device.

In the same situation with auto-decomp, you let off the brake and flick the clutch once, same as a two stroke. No problem.

Before I owned my first YZ450, I almost bought a 426 instead just because of all my experience with MCR's and all the tricks you can do with them. I haven't missed it since the first week. There is no advantage to them whatsoever, and they belong on the shelf with mechanical ignition advances, and the rest of the antiques.

man thats scary i wouldn't touch that decompresion lever with it runnung i've heard of guys bending there exhaust valve doing that on these new yamahas

[yamaha racing 230]

i didnt know new 450s had manuel decopresion releases

[grayracer513]

man thats scary i wouldn't touch that decompresion lever with it runnung i've heard of guys bending there exhaust valve doing that on these new yamahas

If you pull the lever with the engine really revved up, there's a possibility of breaking or damaging a lifter, but we used to use them as kill switches back in the day without problems. I've heard stories, too, but never seen it.

And anyway, no one said anything about using them while the engine was running. I was talking about restarting a dead engine on the fly; bump starting. That's totally different.

[stillsun]

The exhaust valves and an open throttle will clear the cylinder at least as fast as a valve lifter.

I guess you missed the point on this... the MCR just makes it easy to sit there and spin the engine over and over to "de-flood" it, I'm not talking about actually using the device itself to open that one valve to "de-flood" it, come on now, you're better than that... ?

[642MX]

the MCR just makes it easy to sit there and spin the engine over and over to "de-flood" it, I'm not talking about actually using the device itself to open that one valve to "de-flood" it

Actually what allows you to spin the motor over is the ONE VALVE THATS OPEN.

When you pull the decompression lever on the bars, it has a device that puts pressure on the right exhaust valve and opens it. It stays open as long as your holding the lever. As long as the valve is open, the motor won't gain full compression, and that allows you to easily spin the motor over.

[stillsun]

Actually what allows you to spin the motor over is the ONE VALVE THATS OPEN.

When you pull the decompression lever on the bars, it has a device that puts pressure on the right exhaust valve and opens it. It stays open as long as your holding the lever. As long as the valve is open, the motor won't gain full compression, and that allows you to easily spin the motor over.

Maybe if we were in person I could sign it for you instead of trying to type it out so you'd understand...

Let me ask you this, when the motor is spinning over does it not open the other exhaust valve as well? How about the other three intake valves? I suppose those don't open either?

In other words, I'm using the MCR to make the motor easier to spin (yes by partially opening that one valve) but then by allowing the motor to easily spin I can "de-flood" it faster by opening all the valves when I"m kicking it over.... this was in rebuttel to Grey's comment about blowing out any flooding through the one valve opened up by the MCR.

Do you follow now or should we chat about it on the phone so I can explain it better without having to type it out?

J

[642MX]

Maybe if we were in person I could sign it for you instead of trying to type it out so you'd understand...

Let me ask you this, when the motor is spinning over does it not open the other exhaust valve as well? How about the other three intake valves? I suppose those don't open either?

Do you follow now or should we chat about it on the phone so I can explain it better without having to type it out?

When the motor spins over, yes, the camshafts open and close the valves. But, you would never get the piston in motion without some sort of decompression device.

You can defend the manual compression release until your blue in the face, but the reality is, they are history and there is absolutely no reason to have them.

[642MX]

I'd be willing to bet I can start my 426 with decompression lever faster than a guy with auto

Do you really think this is true? ?

[stillsun]

When the motor spins over, yes, the camshafts open and close the valves. But, you would never get the piston in motion without some sort of decompression device.

You can defend the manual compression release until your blue in the face, but the reality is, they are history and there is absolutely no reason to have them.

The point was being made of how I use the MCR to TURN THE MOTOR OVER to then CLEAR the motor out by passing AIR through the motor without having to actually put any effort into the kicking, not what is allowing you to turn the motor over.... which is obviously the MCR... if you're still confused and think I don't know how the MCR works then just leave the thread because that's not what I was evening talking about.

[stillsun]

Do you really think this is true? ?

Well having bikes with both (CURRENTLY AT THE SAME TIME, none if this "I used to have a MCR now I have auto" like a lot in this thread are stating) I can say I can consistently kick and start the 426 in the same amount of time EVERY SINGLE time (lets throw an imaginary 2 seconds out there) where as with the auto yes it might be 1.5 seconds a lot of times but then sometimes (when it takes a second kick/stroke) it takes 3 seconds.... the point I was trying to make was consistency plus speed.

This is really stupid that this thread has gotten to this point since I was initially responding to the guy who was whining about having to start a bike with MCR and how "hard" it was...(for those literalist out there, "hard" meaning while he's on a hill, etc)

J

[grayracer513]

Are you guys done yet?

What I said was that an AD engine will clear a flood at least as fast as an MCR engine, and that's not really arguable. In fact, because the lifted exhaust valve kills the intake signal, an MCR engine may not clear as fast as an AD engine with the throttle held open.

This thread has outlived its usefulness.