Don’t Ask: Your Dirt Bike Questions Answered

Nov. 06, 2015 By Rick Sieman
If you choose to email a question to this forum, then you must conduct yourself accordingly. Therefore, the following rules are in order:

1. Do not write your email to me IN CAPS. If you do so, I will print out your question and do terrible things to it.

2. Do not request a personal e-mail response. Since I get thousands of questions each month, trying to answer them all would cut deeply into my leisure time, which I value more than your current state of confusion.

3. Try to spell at least in a semi-correct fashion. If you choose to mangle the English language, expect no mercy from this quarter. You might be mocked severely.

4. Do not ask for me to send you copies of my many manuals and literature. I am not in the library business, nor do I want to spend the bulk of my day at the copy machine just because you're too lazy to ask your dealer,  or look around a bit.

5. Don't bother me with truly stupid questions, like how to get 50 more horsepower for a buck and a half

6. Now that you know the rules, think carefully and have at it!

Oh yes … I’ll leave your e-mail unedited, for what it’s worth.

Send your questions to [email protected], Attn: Don't Ask, or leave your questions in the comment section below.

Previous Don't Ask Columns
October 2015

September 2015

August 2015

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SUBJECT: THE ORIGINAL MISTER KNOW IT ALL
My friend Darrell Johnson and I were talking this last weekend up at AHRMA NW div Bushy Ranch race, and I told him about a letter I sent into Dirt Bike Magazine in Dec 1999 to Rondo Talbot and how I'd love to take a picture of it and send it to him. Well I was informed Rondo Talbot was actually Rick SiemanAKA Super Hunky who was the editor of Dirt Bike Magazine at that time. Thank you Rick, for all the laughs and thanks again for publishing my letter. I've framed and kept it the garage with my bikes for all these years.
Jim Buckalew            

The history of Mr. Know It All is as follows: I was Rondo Talbot in the early years of Dirt Bike. Vic Krause did Mr. K while I was at Modern Cycle and continued doing it through the ‘80s at Dirt Bike magazine.

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SUBJECT: 2-STROKE THUMPERS?
Oh wise rider (writer?) of the desert sage: I suspect (hope) there is no kind answer to be found here to this question, but why-on-earth are people now referring to their 2-strokes as “Thumpers” on Craigslist?  Perhaps this trend is due to the replacement breed of high-revving 4 strokes (wannabe 2-strokes), or an evil plot to erase all memory of 2-stokes.
Which brings me to my second related plea: I  read a review of dual sports where a reviewer  complained that the DRZ-400 is not high-revving enough for them -- this comment was included as an after-grouse to an otherwise glowing review of how fun the DRZ400 was to ride and how rock-solid it is in terms of longevity/reliability.

Oh great sage of many strokes--If you know of a 2-stroke-like high-revving, claw-hammer-reliable 4-stroke,  please enlighten us as to the name of this beast (Oh, it also needs to be cheap to buy and maintain, since we want it all). If this were being snail-mailed, I would have included a package of Tums.
Muchas Annoyus, 
L. Cook

Actually, of all the new motocross four-strokes, the KTM 450 seems to be the most reliable. It also doesn't seem to rev as high as the others. When it comes to reliability, you're going to have to look at the Honda XR 500s and 600s. They're heavy, but they are extremely reliable.

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SUBJECT:  WHAT KIND OF CZ?
Hi, have enjoyed your columns etc for a long time. I am having a problem identifying exactly what my bike really is. The pink slip says 1974--first sold in 1975. The "plate" says model 981.4, 380 cc, 37hp/6200 rpm 105kg. Engine #9812001959. Vehicle ID 9814005309. It has a black frame, blue tank, down pipe exiting left side rear. The original owner only rode the bike a couple of times--moved from the SF Bay area to Oroville where he & his wife became patients of mine & friends.
 
Long boring story but his wife gave me a cherry  1970 Bultaco Sherpa T250 which I competed with in AHRMA events until the engine scattered!!! Right in front of Dick Mann who was checking the section! If you would like pictures of the CZ I can send them to your computer.

I would appreciate your imput if that is possible. The bike is immaculate, non restored and currently registered. I have it listed on Craigs List Chico,Ca Redding,Ca Reno,Nv with pictures but I could send them directly to you.
 
thank you for this consideration
 
William Gilbert DDS  

We turned to Keith Lynas for the answer to this one. Even though Keith specializes in Ossas, he does a lot of work on vintage bikes. So if you're anywhere near the San Diego area, here's his contact: [email protected].
 
The CZ appears to be a 1973 "year model" 400... there were lots of unsold units in ‘73 and many were titled for the year sold... these were available as new units even in 1986. It would have a radial head and the info on the pink slip is frequently incorrect and should never be used for model year ID.


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SUBJECT: JETTING HASSLES WITH A YZ 85

Hello Rick,

I bought a 2014 Yamaha yz85 in 2014 slightly used at a local dealer, looked brand new when we got it for my son. He can ride it around the house here all day with no real issues, a little bogging here and there but easily cleaned out. The problem only comes when we go to the track. He can go maybe a lap before it starts bogging to the point that he has to pull off, within a minute kick it and it will run fine again.

This has happened numerous times. I've cleaned the carb and changed the jets to the new recommended sizes and also drained the fuel and mixed a precise clean 5 gallons of 32:1 fuel to no avail. I made sure it was not the way he was riding it, he is screaming the bike and not dogging it at all. I have to change the plug every time he gets on the bike and its bad in a lap on the track. Maybe the stator or coil? Thanks for any information you can give me.  

Kevin Siffel 

It definitely sounds like you have a crank seal sucking fluid into the lower end. Check that before you go any further. Also it could be a fuel tank vent, a bad stator, a bad connection (electrical)... or the most common, you may have the carb set so the machine will idle, these need to have the slide to close completely when decelerating in use or they will foul plugs.
 
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SUBJECT: PORTING SPECS FOR THE DT-1 MX
Hodaka Ron here up in Spokane Washington State. Moved up here after I retired and have been in the vintage cycle racing thing ever since.
I am in the process of building a 1968 Yamaha DT-1 MX replica for a racer. I worked at Don Vesco's shop in the day and built many of these bikes for 1/2 mile racing and at ASCOTT.  They were the king for a while..........
 
Anyway the reason I have contacted you is I cannot find the OEM porting specs. for the DT-1 MX?   There is a class in AHRMA for these bikes and we have one under construction. I plan to make a cylinder from an enduro cylinder but I cannot locate the Porting info for the MX?

WE have located an MX head and carburetor and I have  a couple cylinders but no port specs for the MX?  Mostly the Exhaust height and the Intake height.  We are going to run the RT1 34mm flange mount carburetor as we did back in the day and I have one after much searching.
 
Was wondering if you might have or know of a source for the information I am looking for?
 
Your notes and description did not mention that the MX also came with a close ration gear set. I worked in a yamaha shop during the old days of the DT1MX and modafied many of them for flat track and TT 1/2 milers. They were the king for a while eliminating the Spanish and Euro bikes out of the competition. This was prior to the reed invasion which we also transfered over to the DT's before Yamaha did. Did it also with the AT-1's and the Hodakas and got the jump on most models.
Even the GYT kits for the twins came with a new gear set.
Thanks so much Rick if you can help me out here.
Ron Liddle
 

Your only option here is to get hold of a DT1 MX and measure the port heights. Once you do this, it's a simple matter of transferring the measurements to a DT1 barrel.


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SUBJECT: MAICO RIDERS REJOICE
Rick, the guy on the right in the first pic with the old school look is on a bike that was built before the rest of these riders in the picture were born. The 1973 Maico 400 radial with 4 inches of rear wheel travel and a 60 year old rider was mid pack into the first turn and held its own for a few laps before fading due to fat and age.

The big Maico was the only pre 74 bike at the race at ACP in Buckeye AZ but proudly kept the memory alive of the finest motocross bike in history.
Steve Voita
 

You know, we ranted and raved as to how good the Maicos were back in the early days, so people thought we were little bit off-the-wall. But when you look at vintage racing nowadays, the Maicos seem to dominate in their classes.
 

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SUBJECT: JETTING HASSLES WITH A YZ 85
Hello Rick,

I bought a 2014 Yamaha yz85 in 2014 slightly used at a local dealer, looked brand new when we got it for my son. He can ride it around the house here all day with no real issues, a little bogging here and there but easily cleaned out. The problem only comes when we go to the track. He can go maybe a lap before it starts bogging to the point that he has to pull off,  within a minute kick it and it will run fine again.

This has happened numerous times. I've cleaned the carb and changed the jets to the new recommended sizes and also drained the fuel and mixed a precise clean 5 gallons of 32:1 fuel to no avail. I made sure it was not the way he was riding it, he is screaming the bike and not dogging it at all. I have to change the plug every time he gets on the bike and its bad in a lap on the track. Maybe the stator or coil? Thanks for any information you can give me.  

Kevin Siffel 

It definitely sounds like you have a crank seal sucking fluid into the lower end. Check that before you go any further.
 

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SUBJECT:  HOW TO WEIGH A DIRT BIKE
Hey, Hunk!

I got one for you: I went to weigh my 1979 Yamaha SR500/650 using Leslie's bathroom scale. It's digital and appears in good working order.

First, I weighed the rear and steadied it very carefully. I got a reading of "242lbs". Then I weighed the front and got "210lbs". That's 452lbs!
So, I thought "What the pluck..?" and re-weighed it.
I got "203lbs" on the rear and "200lbs" on the front! That's still 403lbs!
As I recall, it is "supposed to" weigh 353lbs...stock!
My 1977 TT500D manual says it weighs 271lbs.
 
What gives? I replaced the rear fender with a shorty fiberglass that has a little LED tail light that can't weigh more than 2 ounces, removed the front fender, replaced the steel chain guard with a trick aluminum one, lower and shorter bars...what's wrong? Is the air in southern Oregon heavier or something? Should I let some air out of the tires to lose some more weight?

Leslie got mad when she got her scale back. K70 prints and slightly caved in. Any ideas? Is my scale having problems? I mean it shows that I weigh "273lbs" and I can't weigh more than 271!
HELP!!!
 
David "Tiny" Fruhling
 

That's not the way to measure a bike's weight. If you can find a scale heavy enough, just put a block of wood on the scale and a long plank on top of that block of wood. Then, have someone help you roll the bike up on that plank and see what it weighs. Then deduct the weight of the plank and the piece of wood and you have the actual weight of the bike.
 

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SUBJECT: RAG TECH FROM AMAZING DAVE

Hello again, Rick.
 
In all the decades of reading automotive and motorcycle-related magazines, I never recalled reading anything about how to care for your shop rags. Myself, I have dozens I've stolen from mechanic's jobs over the past 41 years. Kind of a "severance pay" if you will.
 
Anyway, how to wash them. You could run them through your home washer and dryer but I consider that very dangerous! You could be severely injured or even killed as a result!

How? Electrocution? Oil fumes igniting? No, from a cast iron skillet to the head after the wife figures out how all her under-britches, washer and dryer got all oily! NEVER wash shop rags in your washer and dry them in your dryer unless you're single.
 
Here's how I did mine today: I gathered them all up and put them in a 5 gallon bucket. Then, with the wife's permission, dug under the kitchen sink, grabbed the Dawn dishwashing detergent, Simple Green and poured about a cup of each in with the rags. You cannot use too much! Then I filled the bucket about 1/2 way with hot tap water from the sink (again, with the wife's permission)
 
Take the bucket outside and work the rags around in the water/soap solution with your hands.
 
Now, take the bucket down to the 25 cent car wash. Jam about 10 quarters in and on "rinse", spray in that bucket. Spray at a slight angle from the side with the tip just below the surface. If done right, the rags will circulate around the bucket.
 
I lucked out. Some dude drove out as I drove in and left me 2:24 seconds! Fat City. Anyway, if done right, the water will no longer produce suds. Soon, you'll see the water coming out look like thinned milk. They're about done.
 
Take the bucket home, lay it on it's side and put a 2X4 or something under the bottom and let it drain for a few hours. Viola! You're done!
Next you should hang them on the clothesline (with permission of course)
 
If you have no clothesline, just drape them everywhere to dry; your trucks bed rails, porch railing, your (not hers!) shower curtain rod...wherever.
 
After they've dried maybe since you were such a good boy, you could sweet talk the wife into folding them up so they'll fit nice and purdy in your roll-a-way tool box drawer. You know, that one big, deep drawer that usually has nothing in it but cans of spray paint that don't spray because you forgot to "clear" the nozzle last time you used it.
 
There you have it!
 
David Fruhling

Your technique is good, but I gave up on rags years ago. Now I just buy a lot of paper towels and throw them away when I use them.

 

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SUBJECT: THAT SPECIAL COLUMN
Sir,

A long time ago you wrote a column about some guy riding a bike off a cliff. That really jolted me. I was wondering if you could re-print that masterpiece?

Thanks

Mike Allen

When I wrote this piece, an avalanche of mail followed. A whole bunch of people thought the story was about me, and that I had a terminal illness. Luckily, that was not the case. However, the story was based on reality. I will not say who, why, or how.


EXIT

By Rick Sieman/February 1982/Dirt Bike

It was the pain deep inside his chest that forced him to see a doctor Oh sure, he knew something was wrong, but, like most people, he put it off And put it off. How long had that pain been gnawing away? Two years? Three? At least three. It'd been there so long it was almost taken for granted.

But, lately, it had worsened. It was affecting his riding, walking, eating, sleeping and his work. Motorcycle racers don't like to go to doctors, even though they are forced to seek their services now and then. The occasional trip into the Twilight Zone, the harsh crack of bone against rock and it's Plaster City. Frank had been there before. Not too often, but enough to keep a healthy respect for just how far he would let it all hang out now.

He raced a bit more cautiously now days. Still fairly fast and competent, but the years and the close calls and the bumps and the bruises had all taken a tiny bit off that racer's edge. Still racing was fun and that's what counted, right?

Frank sat in the doctor's office idly flipping through a tattered copy of National Geographic, wishing he'd had the foresight to bring a bike magazine with him to help pass the time. He'd been in this cold, white office too many times in the last month what with all the check-ups, X-rays blood tests and other mysterious things they did to his body. The pain was still there. Always the pain.

The white-haired doctor called him in to his private office and closed the door quietly behind them. Frank knew at that moment that something was desperately wrong.

The doctor told him very quietly, patiently and calmly what was up. He did it so professionally that Frank listened in an almost detached manner, as the white-haired physician told him he had only a few months to live … perhaps five or six at the most.

What got Frank upset was that he'd never even heard of the disease. A lot of Latin words strung together. Why didn't they just call it a ball of pain in the chest?

With more calm in his voice than he could believe, Frank asked the good doctor about operations and alternatives. With an obvious tremble in his hands, the doctor explained the whynots and the where-fors of the situation. He took a long time and ignored the blinking light on his phone.

When he stopped talking, Frank fairly well understood the mechanics behind his doom. The doctor wrote out a prescription “for the pain” and told him to use it as needed and to call any time the pain got too intense. There were stronger things available for stronger pain.

They shook hands and parted. Frank drove his pickup truck home, head whirling with thoughts. He stopped off at a drive-through, ordered some burgers and junk food and ate as he put in the 22 miles that separated his home from the medical center.

By the time he got home, Frank knew exactly what he wanted to do. He grabbed a beer and sat down at his wobbly old desk. A yellow-lined pad and a felt-tipped pen were extracted from the center drawer, along with his savings account and checkbooks.

Very slowly and with much thought, Frank made a list on that clean yellow pad. After each item, he put a price. Frank knew just about what things cost. Nine hundred bucks for the trick frame. Twenty-five hundred for the bike. Exotic forks, special shock, aluminum this, magnesium that, chromoly goodies, lightweight plastic, special parts for the engine, the best tires money could buy. . . in fact, the best of everything.

When he completed the list and added it up, he gave a low whistle. The total came to over eight thousand dollars. A check of his bank and checkbooks showed that he had more than enough to cover the cost. He slowly savored three more beers that evening and made page after page of notes on the yellow-lined legal pad. Sleep came easy, in spite of that ever-present pain in the chest.

The next morning was spent cleaning out his garage. He shaped it up to perfection, then made a trip to the bank and withdrew a tidy sum of cash. Frank then stopped off at his favorite place and spent a considerable amount of that cash on new tools. The good stuff. Snap-On, S-K, top-of-the-line sockets and wrenches. And then he bought a shiny new red Craftsman two-piece roll-around toolbox.

It gave him an odd feeling of pleasure to peel off the twenty-dollar bills to pay for the tools. The salesman helped him load everything in the back of the pickup and Frank then headed down to the bike shop.

The man behind the counter knew him by his first name and they exchanged the usual pleasantries. Casually, with a slight smile of glee, Frank told the man to load that bike—that one over there—in the back of his truck, and started counting out one hundred dollar bills on the counter to drive the message home.

After the paperwork, Frank placed an order for some special parts and goodies. The man totaled it up and Frank once more proceeded to count out bills on the glass top of the display case. He was offered a discount, but refused it. His only request was that everything be delivered to his home before the end of the week.

Frank made two more stops before he headed home to his garage … one to order a special frame and another to pick up a cardboard box full of speed parts for the engine.

He spent that night sorting every thing out on his work bench and checking off items on that yellow legal pad. Sleep came hard.

Early the next morning, Frank rolled the new bike into the center of the garage and put it up on a milk crate. Parts were carefully removed with the shiny new tools and placed in various cardboard boxes that were marked with a thick felt pen; then he placed them on shelves.

By noon, only the engine sat there. Frank opened the thick workshop manual and proceeded to tear the big four-stroke engine down. He made notes, put nuts and bolts into small boxes and, at four o'clock, took the barrel down to his local machine shop with instructions to bore it out to match the new, huge piston.

The days went by slowly and pleasantly. Frank did not answer the telephone and did not open any mail. He only left the garage to make trips to the machine shop, or to the bike shop for needed odds and ends.

With the arrival of the frame and forks, the bike started to take shape. Parts started to fall into place. Some things required drilling, bending, shaping and fitting. Frank carefully fitted each and every piece with patience until he was satisfied that it was perfect.

By the time two weeks had passed, Frank was forced to stop by the pharmacy and get that prescription filled. The pharmacist looked a bit startled when he read the doctor's scrawl and placed a call to check it out. Frank took a double-dose of pain killers to sleep that night, but he woke up so fuzzy-headed the next morning that he flushed the remaining pills down the toilet.

It took one more week before the bike was completed. Naturally enough, the last two bolts were snubbed in place well into the wee hours of the morning. Frank poured some straight gas in the tank, twisted on the petcock and depressed the choke lever.

It took three kicks for the big bike to light off, but when it did, the sound from the megaphone was pure music. Frank ran the bike for three minutes, ignoring the blue haze filling up the garage, then shut off the lights and went to sleep.

Early the next morning, he rose and went out to the garage. An hour was spent checking all of the nuts and bolts with a torque wrench. Frank then loaded the bike up into the back of his truck with all of his riding gear and headed out the Interstate.

He stopped off at his favorite restaurant and had steak and eggs and several cups of scalding-hot black coffee. The waitress smiled from ear to ear when he left the whole twenty dollar bill with the check.

Twenty minutes later, Frank arrived at his favorite riding area and unloaded the bike. He fired it up and let it idle comfortably while he put on his riding gear. Frank slipped the goggles in place, then swung a leg over the bike and blipped the throttle a few times. The engine responded cleanly and instantly with a rapping snarl. Good

Frank nudged the shift lever into low and eased away. The bike pulled strongly, satisfyingly, through the gears. Not a hint of a flat spot, or even a burble, as the revs rose.

Frank followed the two-track road through the valley and then caught the old fire road heading up the mountain side. The smoothly graded road had just the perfect surface for letting it all hang out.

Once he got the feel of the bike, Frank started to stuff it into the turns with the rear end hanging out, the exhaust note wailing off the steep canyon walls.

As the road climbed, Frank was forced to use a lower gear and rev the engine harder to maintain his speed. A thin sheen of perspiration covered his forehead and face. He breathed harder, worked the bike deeper into the turns.

As Frank neared the summit, he saw the last wide sweeping corner before the road ended and the narrow trails began. It was clearly marked with white barriers to keep wayward vehicles from plummeting off the vertical drop.

Frank smiled, took a deep breath, let the revs rise and aimed the front wheel directly at the flimsy barriers. The white wood snapped cleanly and the bike sailed out into the clear blue air.

Frank held tightly onto the bars and sailed and sailed and sailed. He had always wondered what it might be like.

And now he knew.


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SHAMELESS PLUG - AKE JONSSON POSTER

In the 70s, Ake Jonsson won every race in the US against the best riders in the world on his Maico.  Here he already has a ten bike lead on the pack going down the Saddleback Park downhill … on the first lap!  After that, Yamaha signed him up and he never won another race.

He even went so far as to put Maico forks on his YZ, really pissing off the Yamaha people.  When he wanted to go a step further and use a Maico frame on his YZ, the Japanese went nuts.  Even though he had a contract into the next year, Yamaha refused to show up at the races with  the YZ-AICO.  Needless to say, they parted company as less than good friends.

The poster is 12 x l8 inches and is printed on heavy 120 pound stock;  shipped in a stout protective tube. Cost is $12, which includes free mail in the US.

Just send a check or money order to:
Rick Sieman
49818 W. Val Vista Rd.
Maricopa, AZ  85139

Or if you use Paypal, that address is: [email protected]
 
Website:
www.superhunky.com


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