Two Stroke Motocross

Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: eprovenzano on May 17, 2010, 01:01:10 PM

Title: Local races
Post by: eprovenzano on May 17, 2010, 01:01:10 PM

A friend of mine's son raced his YZ250 over the weekend at a local track.  He's 18 and this was his 1st race, he took 12th and 10th.  Not bad for his 1st attempt.  His riding buddy on a KTM 250SX who's raced off and on for years took 1st and 3rd.  The over 30, over 40 and over 50 were mostly smokers, while the "kids" rode mainly thumpers.  My friends son's buddy, the guy on the KTM also tried the school boy class...  got 5th and 8th.  I think his tank may have been empty during the last moto.... plus those guys are fast.... 

My point is that most "kids" of today don't know anything other than thumpers.  They think a smoker is difficult to handle, hard to ride because it has a tough power band, you have to keep them wrung out to get anything out if it....  yes they've all bought into the hype, it was sad to see.  Although I was amused to watch them standing by the fence when the "older" riders schooled everyone with their smokers.  The look on their faces as the over forty something rider was just hammering the little YZ125 and leaving the 450's in his wake (he was one of the fastest riders at the track).  In this case itâ??s all about the rider and not about the bike.  Someone did ask why the 125, his answer because its soo much fun....   :D

Title: Re: Local races
Post by: Recovered on May 17, 2010, 01:59:42 PM

I went riding with a buncha guys on big 4 strokes yesterday. When I pulled up with the YZ on the trailer they all looked at it like it was from another planet. Should have seen the looks when the beast made some righteous noise. And SMOKE too. They must have thought smokers were slow or something. We were in the mountains and it took every hill they threw at it. Drum brakes still suck.  ;D

Oh we're talking about a 1980 YZ465. In great shape. Balanced crank,tight top end,DG national pipe. 'Tis a dinosaur but a potent one.

The front fender

(http://img.photobucket.com/albums/v606/TRexRacing/TREX.jpg)

Title: Re: Local races
Post by: luthier269 on May 18, 2010, 08:00:56 PM

Most if not all of the "kids" rode two-stroke 65's and 85's when they started racing they just fell for all the hype from the factory riders.In this area most of the kids comming from 85's to the 250 class are now going to 3 or 4 year old two strokes and pardon the pun Smokin the kids on the four strokes!

Title: Re: Local races
Post by: Turquine on May 19, 2010, 12:43:57 AM

Hey, Big Boar, that was an interesting post to me. You say you have a 1980 Yamaha YZ 465? Well, I used to own a 1982 Yamaha IT 465. If I understand correctly, it had essentially the same motor as the YZ but in a different chassis. A wide ratio gearbox and possibly a bit more flywheel, but for the most part, the same motor. I've wondered for a few years now how that IT would stack up against modern 450 4strokes in flat out drag races, throttle roll-on drag races, etc, to the slower bike's top speed. Also how it would stack up against them in climbing steep, sandhills. You seem to be able to answer that question.

According to modern motorcycle magazines, the newer 4strokes are putting out a bit over 50 hp on the dynos, the best like KTM, a bit over that, a few a bit under. I strongly believe the dynos now are giving higher figures than the ones I went by in the late '70s and early '80s. In those days, I went by the Webco dyno figures as my standard. According to them, the YZ465 was putting out right about 42 hp at the rear wheel. That would mean it is way down on hp against modern 450 4strokes, and even considerably less than a KTM 250SX or 2010 YZ 250. I find this difficult to believe.

I'm disabled now and haven't ridden in many years so I may be very mistaken. Anyhow, going by newer dynos, the CR500s of the 1990s were more powerful than the first two CR 500s, 1984 and 1985. Problem is, almost all the magazines said the 1985 Honda CR500 was more powerful than the later models and that they deliberately cut the horsepower back a bit in 1986 forward, to make the bike easier to ride and more friendly. The Webco dynos in those days had the '85 at just under 49 hp, and the '84 air-cooled one at just under 50. if you look at the dyno figures on newer CR500s which should have less power, they test at anywhere from 55 to nearly 60 hp. As a typical example, check out the two charts here on the DB Snorkel page on the two '93 Honda CR 500s. One of them has more torque on this dyno, than either the '84 or '85 CR500s had horsepower, on the Webco dyno of the time. I know for a fact though, that the '84 and '85 Honda CR500s were indeed faster and more powerful than any of the later year Honda CR500s with the possible exception of the '88.
http://www.thedbsnorkel.com/dynamometer.php (http://www.thedbsnorkel.com/dynamometer.php)

I remember my IT was very quick, deceptively so. It would effortlessly leave 250 MX bikes in the dust. I also beat an 850 Yamaha street bike through the gears on pavement several times in a row until I ran out of top speed. Could have easily pulled a couple of more gears and wish I'd had them, lol. Anyhow, all of this has led me to wonder. If I go by the new dyno figures and they are consistent with the figures that the Webco dyno put out for bikes like the YZ and IT 465s, then I'd have to conclude that the new 450 4strokes would simply smoke your '80 YZ 465 or my old '82 YZ 465. In fact, so would a new YZ 250 or KTM 250SX which put out about 45 and 49 hp on today's dynos, respectively. That would also mean that a new KTM 250SX has more power than the '85 Honda CR500! My gut tells me no friggin' way! The 450 4strokes might beat my old IT 465 in through the gears on a long straight with good traction, but it would be by just a hair. That's how I feel, but I've never been able to test that, and may be very mistaken.

I know they cannot beat my friend's old '94 CR500 Honda, which still runs great, and my brother-in-law used to have a 1985 Husky CR500 2stroke which he sold. Nevertheless the guy he sold it to rode with a guy on a CRF450 a few years ago and always just blew it away on the straights. So, my question is, is your YZ465 running good, and if so, can it at least stay even with the new 4strokes you ride with, in acceleration on straights? You mentioned climbing hills. Did you climb any they couldn't, or the other way around? Do you feel like your '80 YZ465 is lacking power compared to the modern big-bore 4strokes, or is it equal or better? I haven't been out in several years and the seeming discrepancies between older dynomometer readings compared to newer ones makes it hard to figure these things from where I am now. I don't care about handling or suspension, just acceleration and power. I was an off-road, mostly desert rider, blasting through the desert at high speeds, hard acceleration and hillclimbing were what I enjoyed.  For fun, here's a different MX race with enduros competing on an MX track. The fight for first place is between a Yamaha TT600 4stroke and a Yamaha IT490 2stroke. --->
Yamaha tt600 v it 490 Part 2( With Sound Yeah Ha !!!) (http://www.youtube.com/watch?v=zI9VyobubyM#)

Title: Re: Local races
Post by: Recovered on May 19, 2010, 08:51:09 AM

Yeah I've seen that vid. The guy on the IT is riding that thing well. My YZ is surprising in that it is in great shape. I just added an '82 43MM fork set with Race-tech emulators. It has a DG National pipe and a balanced crankshaft. SMOOTH for a big smoker and pulls hard from the bottom all the way up. Right now I'm still fine tuning the jetting 'cause I can no longer afford race fuel. Shame that is. The bike is not particularly fond of unleaded pump gas. It seemed a little soft just off idle but ran well into the higher RPMs. Float level was a little high so that oughta fix that.Traction is the key and where we were riding it was at a premium so the got a little jump on me but I'd catch and pass them on the top. Hills? I've yet to find one the YZ won't conquer if I'm up to the task and I live in the mountains of West Virginia. I've spent a lot of time tuning the bike so it runs clean with no big traction sapping hit,just a long steady pull from just off idle.
   On track it accelerates with all but the biggest 4 strokes. I'm old and kinda,well I am a fat bastid so I must ride smooth and turn hard cause the limitations of a 31 year old bike are tiring. So I am a middle of the pack B rider against modern bikes. The occasional holeshot surprises everybody including me. But it happens. I've got plans for it that include mo' power and some brakes. At least disc on the front wheel.

in closing I'll let a comment from the guys I rode with this weekend tell the story. "Man you ride the hell outta that old thing!"

And here's a pic from a couple years ago with the old noodle forks.

Yep Excel rims and Buchanons stainless spokes.

EDIT: Had to take a photo of it clean while it lasted.As clean as it ever gets.

(http://img.photobucket.com/albums/v606/TRexRacing/bikes/10.jpg)

Title: Re: Local races
Post by: eprovenzano on May 19, 2010, 01:29:58 PM

I've seen the younger riders buy into the stroker thing, but this past weekend it really hit home for me.  Its like a smoker had some kind of voodo that myst be avoided at all costs...  then they actually try one, and you can't pry the bike form their hands as their having too much fun.

My bike is an EXC, enduro version, which includes among others things, a wide ratio gear box, and softer suspension.  Not too long a go, I let a younger rider take it for a spin.  It didn't take long until he was flying around the track.  All he could talk about was "WOW the power was just there, no hesitation, no explosive hit, jut twist the grip and hang on..."  Nothing like he remembered from his younger days...  He was having so much fun until the last down hill jump, when he landed he grabbed a handful of the happy grip....  the bike tried to wheelie out from under him.  (I think his arms may be a bit longer now).  He was laughing saying he was getting a little too comfortable and forgot and started to ride it like his stroker.  Instead of the power rolling on, it was just there... almost too much to fast.   I mentioned just think how a bike that's not 10 years old (like mine), and set up for an MX track would do...   I know I got em wondering  ;D

Title: Re: Local races
Post by: Turquine on May 19, 2010, 11:36:51 PM

When you say all but the biggest 4strokes, just curios as to which ones that might be? Anyhow, thanks for your answer. That's a beauty you've got there. I've felt for years that the YZ465 motor, although not the most powerful YZ ever made, may have been the best. Great power everywhere. My IT 465 could lug at a snail's pace and virtually idle up small hills, and instantly go into warp drive with just a twist of the throttle. Very smooth though, no explosion or surprises.

To Eprov, I think the KTM 300 is the best all-around dirtbike made today, and has been for many years. Never had the pleasure of riding one unfortunately. Can't ride anymore at all now, but if I could, and had the money to buy two bikes of any make, one would be the 300 for a do anything machine. First choice would probably be the Maico 700 though, I'm a power junky. :D

Title: Re: Local races
Post by: JETZcorp on May 20, 2010, 12:42:00 AM

If I had to choose any Yamaha to have, it'd definitely be a YZ465.  They were big motors with the ability to do some major world-shaking, but unlike the YZ490 that succeeded it, the thing actually ran for more than twenty minutes.  The YZ490 ranks at #4 on Super Hunky's list of the worst bikes of all time, whereas the 465 was so good it scared people into action.  That action, of course, was to take a 440 and bore it out, and I'll let you guys connect the dots from there.

Title: Re: Local races
Post by: evo550 on May 20, 2010, 03:01:31 AM

Turquine,
An Australian magazine did a test a few years ago between a brand new ktm 525 and a 1981 model big bore 2 stroke mx'er ( It shall remain nameless, as I would like to keep this thread a M...o free zone :D)
Anywho in continued drag races over a few hundred meters, there was no more than half a front wheel between them.
That should answer your question.
Some of those big bore 2t's where quoted at 61 hp at the brochure, something happened between there and the dirt, they seemed to lose 20 hp :o

Title: Re: Local races
Post by: JohnN on May 20, 2010, 03:15:13 AM

Quote from: evo550 on May 20, 2010, 03:01:31 AM

Turquine,
An Australian magazine did a test a few years ago between a brand new ktm 525 and a 1981 model big bore 2 stroke mx'er ( It shall remain nameless, as I would like to keep this thread a M...o free zone :D)
Anywho in continued drag races over a few hundred meters, there was no more than half a front wheel between them.
That should answer your question.
Some of those big bore 2t's where quoted at 61 hp at the brochure, something happened between there and the dirt, they seemed to lose 20 hp :o

When reading that test closely, you will discover that the Maico in the test needed a top end! Yup it wasn't even a fresh engine as it had lot's of time on it.

As mentioned before, the drum brakes leave a lot to be desired when compared to strong disc units....

That was a cool test, it's posted somewhere on the main site...

Title: Re: Local races
Post by: Paul P on May 20, 2010, 04:47:20 AM

I'm with Turquine on the new dyno test thing. Most 500's tested in the 80's were lucky to be in the upper 40's for HP, now when they test them they are in the lower 60's for horsepower. The 84 CR500 has the most aggresive porting, the 85-88 are the pooches as far as porting goes. I know first hand on that statement after years of work with them.
   I have a 99 CR250 that is supposed to have 8HP more than the 89 I have, but riding them there is no difference of 8 HP, the 99 has a bit more bottom, but hardly noticable. And, my old 81 'M' bike has a fresh top end (only 8 seasons on it) and still pulls the newer 4S 450 bikes. It was supposed to have about 47HP back then.
   I bought a 1980 465 Yamaha new in January 1980 and was not too happy with it. The motor's power was OK, but I broke the tranny twice in two months, and could not get the thing to handle rough ground at all. I sold it in May of the same year.                                                 Paul

Title: Re: Local races
Post by: Turquine on May 20, 2010, 09:58:59 PM

Evo, I posted that very article some months back because I felt the results were bogus, as far as acceleration at least. John is correct, and in fact, thankfully, Paul P debunked that article in the 2nd post right after I posted it. He's done the drag race test with a good running Maico 490 and KTM 525 and the Maico wins easily. Don't be fooled. I quote him here:  "I have done the same test with my FRESH 490 against a KTM 525 and I easily smoked the KTM, standing start and roll-on starts. It says in the test that their 490 was tired and in need of rings. Most of these 490's I've seen are set up poorly. I'm not sure if anyone on this site has seen Herbert Shmitz ride at a recent VMX race, but he has a correct running 490 also that is a better judge of what these bikes should run like.
                          Paul"
Here's the link to that thread   -->
http://twostrokemotocross.com/forum/index.php?topic=510.0 (http://twostrokemotocross.com/forum/index.php?topic=510.0)

Back to the YZ, Paul P, that surprises me, although I believe you. My bike was an '82 IT 465, but for all intents and purposes, correct me if I'm wrong, it was basically the YZ 465 motor. Mine ran flawlessly, and was rock-solid reliable, even in summer when it gets into temperatures as high as 110 or better. The only things that broke on it was flat tires, and I'd broken the shift lever when riding in some nasty rocks on Mt Franklin. What I didn't like about the bike was that it was too tall for me, I'm 5 ft 8, and it was top-heavy and bulky compared to bikes like my friend's '94 Honda CR500. My inseam is 31 inches and in rough stuff when I needed to dab a foot down to maintain stability, I had problems. Also the famous Yama-hop that their early monoshock systems were infamous for nearly bucked me off at times. On the other hand, my friend's CR 500 had a terrible headshake at higher speeds. At full speed on the IT on smooth dirt roads, I could comfortably hold the bars with my right hand while scratching my nose with my left, lol. It was very stable at speed. Anyhow, I've only heard good things about the YZ 465s over the years, and I believe, for the most part, they were great motors.

Title: Re: Local races
Post by: Recovered on May 21, 2010, 07:48:47 AM

The IT and YZ were similar engines. The IT has lower compression and slightly retarded port timing. Hits a little earlier and smoother than the YZ. If you have a YZ and want the grunt of an IT simply cut .75MM from the cylinder base,verify squish and viola! You're there.

When I first got mine the jetting was stock. So far off across the board it took a leaner needle jet,needle,pilot and main to fix. It revved slowly and then exploded onto the pipe making it feel like it made 100 HP. Now that's all smoothed out and it pulls strong and clean from just off idle all the way to the top. I'm trying hard to leave it alone but almost 50HP is there for the taking if you can tolerate losing that sweet bottom end response,which I cannot make myself do. So we're searching for a compromise. :D

Title: Re: Local races
Post by: Turquine on May 21, 2010, 02:35:27 PM

Ah, thanks for clearing that up for me, Big Bore. I'd just assumed the IT had maybe a bigger flywheel, quieter pipe, and clumsier frame with a big gas tank than the YZ. I'd only ridden a YZ 490 briefly about a year before I bought the IT and was mainly going by memory. It did seem to rev faster and hit a bit harder, and didn't seem have as wide a space going from third to 4th. It was on a loose gravel road, actually the levee of the Rio Grande river and it spun out a lot before hooking up on that surface. The guy who owned it  was racing my brother who had a '76 Yamaha TT 500 at that time. Was pretty even the first three or 4 gears due to wheelspin on that loose gravel, but the YZ pulled away after that. Down off the levee onto a grassy surface nearer the river the YZ passed him and left him right away, lol, but I only rode it briefly on the levee road, and really didn't get a good feel for it. I sure did like the bike, however. Didn't even know the guy personally and was glad to get the opportunity to ride it. Later, after I looked into it and found that I would not be able to pull of financially, purchasing an '85 CR500, I thought about that bike and went to the Yamaha shop. I didn't want the 490 YZ even if I'd been able to afford it because I'd read it was a 4-speed. I figured maybe they'd have a YZ 465 for a good price though. They had a good deal on two '82 IT 465s never ridden, sitting on the showroom floor. I wanted a YZ 465 but they didn't have any in stock and my gut told me to get the IT. I did and never regretted it. Damn fine motor either way.

Title: Re: Local races
Post by: Turquine on May 21, 2010, 02:38:31 PM

Gotta correct myself, in my third sentence I said the bike I'd ridden was the 490, it was the 465 YZ, not the 490, which I've never ridden. I ain't much at typing.