Don’t Ask: Rick Sieman Answers Reader Dirt Bike Questions

Oct. 02, 2012 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.

Have a question for Rick “Super Hunky” Sieman? E-mail questions to, Attn: Don’t Ask.

Previous Don’t Ask Columns
September 2012

August 2012

July 2012

Hi Rick,
Big fan since the mid '80s. Thanks for your work.
Maybe you can post the answer to this one and help more than just me: In your Starting Secrets of The Round Slide Mikuni Carb article, you end with "If it stumbles when you crack the throttle wide-open, it isn’t throttle slide cutaway. Why? Because when the slide is quickly pulled up, cutaway doesn’t have a chance to affect the transition."
So if not the slide cutaway, then what is it?
Chris Wnospam
It's probably because the needle jet is overly already rich or way too lean. How can this be, you say? Either condition will cause a stumbling because if the needle jet is way too lean, it takes a moment to pull enough fuel up through the main jet to the needle jet to make things happen. Conversely, if it's way too rich, then there's too much fuel for the engine to respond cleanly, hence the stumble.

I've read your column since high school in 1974. I have the greatest respect, and have savored each of these as both entertaining and gospel. However, I must finally take issue with the utter waste of space each month devoted to twits who can neither read the stamp on the steering head, use Google, or grasp 32:1 as THE premix ratio for the ages. Surely, there are those of us who have written to you before with more viable questions, and were passed over for such drivel on a monthly basis, see this madness end. We seek only information from a time-honored source. Not repetition and self-gratification.
Thank you.
John Fields,
John, each and every day new people come into the sport, and the new people just don't have the knowledge that we have accumulated. Are we to ignore these people and let them wallow in their ignorance? No, I think not. Therefore, every once in a while you're going to see someone grasping for the information that we take for granted. 
Dear Super Hunky,

I was reading "Don't Ask" tonight and I saw how one of your readers wanted to shift with his right boot, because he has a prosthetic left foot. You might want to steer him towards a Yamaha RT1. I'm fixing up a 1970 RT1, and it has a shift shaft that goes completely through the cases and can accommodate left or right side shifting. Why did they do it this way? I have no idea, it wasn't manufactured until 1975.  I bet Matt Cuddy knows though.

If you are shifting with your right boot, how are you using the rear brake?

Hope you're well,


They produced that particular bike to be sold in a number of countries where the shifting was on the other side. They did this with only a limited number of models. As far as a rear brake goes, you could set it up much like the Diffbrake, where the front brake cable also hooked to the rear brake and both brakes were actuated by using the front brake lever. Or you could make a simple crossover piece and actuate the rear brake in the conventional manner.  Yamaha made a brake kit, but they’re nearly impossible to find.
I have a '72 Yamaha CT1 175cc two-stroke single. It was running great all the way up to redline before I swapped the stock head for a Webco high-compression head. It now starts up fine, and runs clean and strong up to 6000 rpm. At that rpm and above it stutters and misfires. Ease off the rpm and it runs smooth again. I'd like your advice on what might be going on since that was the ONLY change I made before this stutter developed. I run the stock NGK B8E and the plug color looks good.

The bike is completely stock with the exception of an electronic ignition that uses the stock points system as a switch. I it had new points installed and the timing set at the stock setting when the electronic ignition was installed--and ran great with it before the head swap. Everything else is stock.

This problem has got me stumped. I hope you can help me.

Consider the fact that your bike is designed to run on the decent gas of 40 years ago, and you had to run the terrible gas that we use today and it's a wonder you didn't blow the bike up instead of running into a misfire. You just put on a high-compression head, which means you have to use a gas that sports about 94 to 96 octane, and not a gas with ethanol in it.  Do yourself a favor and run the bike again, this time making the motor work hard at a lower RPM, such as climbing a hill.  The misfire should happen earlier if octane is the culprit. You might be able to lessen the misfire by richening up the main and the needle jet. Give that a try and get back to us on it.  But if I was you, I’d keep some octane booster on hand, or a bit of racing gas around to mix with the regular gas.
I have an 2004 ninja 500 that I want to turn into a poor mans adventure bike. I see the UK got the KLE500 which appears to be very similar. Why don't we ever get the cool stuff? Anyway, the Ninja needs more travel and trail to not be such an adventure to ride offroad. The newer KLR has 40mm forks and not much offset from the stem which is probably going to hit the tank. The ninja has 37mm forks. Could I get away with milling the clamps out 1mm and using older style 38mm KLR650 forks? What about the rear end? Appreciate your advice.
Lenard Nelson 

Let's be blunt about this bike. It is nothing more than a street bike; it’s not a trail bike or an adventure bike of any sort.  It weighs almost 400 pounds dry and has little 17-inch tires front and rear. With a ground clearance of 4.7 inches, you would bottom out on anything much bigger than a pack of cigarettes. To make this into any sort of dirt bike whatsoever would take more time, effort and money than you could possibly imagine. Give up on this madness!
Dear Rick,
I have a 2006 CRF230F that has had the exhaust baffle removed, airbox opened, power-up kit and new main jet installed, and gearing update performed as indicated in your great articles. I recently saw the update for the installation of the 48 pilot jet to correct the "lurch", and have two questions:
1. You indicate lowering the needle clip one position - it was already in the middle position from the earlier mod - and it should now be in the second from bottom (4th) position?
2. The article also indicates adding a throttle spring to the pull cable to smooth out the action. Do you feel the improvements are good enough without that mod, or should it be a "required" fix?
Thanks for all the great info!
Jim Cucurull
Anchorage, Alaska

Don't forget that we jetted our bike at approximately sea level. You might have a totally different requirement where you live. Also, if it's cooler you might want to go a little bit on the rich side on the jetting, compared to the conditions we have in Arizona. As far as the throttle spring, it made a huge difference in how the throttle response was. Instead of lurching right off the bottom end, it was whole bunch smoother. It's a small mod but one that makes a big difference.
here goes I need to ask a question I have A Dt 125A I belive it uses 12 volt globes for the lighting circut ? I think its an AC circut ? I am having trouble keeping the lights working if one globe blows the lot blow what a pain . any ideas on what might be wrong ? is this a feature not a fault thanks Mark Sunny Australia
Mark Foster

Voltage regulator. All 12-volt electric start Yamaha's have them. Get a manual.

How did the 504 rotax powered ktm compare?
Randy Calendine

Cifu Motorsports had this to say about the bike:

When KTM built a thumper to compete in the 'growing' 4 stroke market, they went all out. In early 1982 Dirt Bike Magazine was involved in the testing and development of the prototype machine. The new KTM 504 featured all premium components. A Brembo disc-brake equipped wheel was hung at the end of a stout Marzocchi 43 mm fork, with 300 mm (11.8") of travel. KTM's first generation 'Pro Lever' single shock suspension, complete with a Fox Twin Clicker shock, provided a matching 300 mm of travel out back. KTM specified a retuned version of the Rotax thumper for the 504. It featured 504 cc versus the 498 on the Can Am Sonic courtesy of an 81 mm stroke--1.5 mm longer than the Can Am. The engine's larger intake valves inhaled through  a K&N filtered Bing carburetor (36 mm) and exhaled through a quality SuperTrapp exhaust. Controls were first rate Magura parts and Acerbis built the plastics. It was a 'who's who' of trick parts and the retail price of $3080 reflected this (34% more than a Honda XR500).

What they didn't tell you in their write-up was how the bike handled and was totally reliable.  I had one of the 504 KTMs for many years and nothing – repeat, nothing – broke on the bike during my time of ownership.  The bike was a bit heavy and consequently was not used that much for racing. But whenever I wanted to go out and thrash around for a few hours, this was the bike I chose.  I ran through God knows how many sets of tires, chains and sprockets, but nothing else on the bike ever gave me a bit of a problem. It was also very easy to start and a whole lot of fun to ride. 
i have a rm 80 1998 model i just put new piston n ring in it n i go 4 a ride n it splatters heaps b4 it hits power band could u tell me wat the problem is please

Your e-mail shows the amount of sloth that the average person has today when trying to communicate.  Is it beyond your capability to actually spell out a word? Do you find it necessary to do stupid little abbreviations in everything you write? And when you do try to find something out, is it impossible for you to tell in real language what the hell is actually happening? Splattering. What does that mean? You are a picture-perfect example of what is wrong with the youth of today. Now go away and come back when you can speak at least in a seventh-grade level.
hi i got honda mr 50 1974 i could fund the carburetor my cuestion its if can i put other carb and what tipe is goin to be please help me

Absolutely amazing! I think I found your twin brother on the e-mail directly above. You write the same kind of gibberish and the same style. Did he teach you or did you teach him? I read your e-mail several times and still have no idea what you're talking about. Are you from another planet? If so, please go back there.
"Maico trails bike"?
Come ON, kids! Can anyone distinguish the difference between "TRAIL" and "TRIAL"?
For decades I see this crap.
The Montessa Cota "Trails" bike is best.
Try riding a "trials" bike on the "trails" for a couple of hours.
Get it straight or go away!
David Fruhling

Relax, Dave, lots of people have no idea what a trials bike is or what it's used for. Calm down and have a beer. Or two. Or three.
does adding 2-cycle oil to gasoline change the octane level and if so how much does it change it?
Ken Carpenter

You bet it does. For example, back in the early days of two strokes, it was quite common to run a 20:1 ratio. Of course, then you could buy really good high-octane gasoline. Try to run that ratio today with the crap we put in our tanks and you'll foul plugs and puke the roadway. That's why it makes much more sense to run the leaner ratios now. I personally prefer 32 to 1, but there's really nothing wrong with running some of the synthetics at 40 and 50:1 ratios. Even better, keep some racing gas around to add to the regular gas. A splash of that stuff in a 5-gallon can make a world of difference. And yes, the more oil you run, the more octane you lose.

i have a 1991 kx 80 and its a two stroke and i dont know what to run in it someone please help me out
Matt Black

I must demand that you not only see the e-mail directly above yours, but for you to read the other e-mails relating to premix question.  Failure to do this will result in superior mocking.
Re: Hopetown Reunion
Such A Cool Event. Sorry I was 10 Years Ahead.
Dave Schuler

It was a truly fantastic event. Rumor has it that there will be an even bigger version next year. Stay tuned to ORC for details as they develop.

I have an older Yamaha Moto-4, the only ID number I can find is on the engine. The number is: 2HT-C53211. can you help me figure out what year this thing is? Thank you.
Mike D

Sorry, but I don't pay attention to four-wheelers. They remind me too much of three-wheelers. Contact your local Yamaha dealer.

Well, it looks like this is the month for premix questions. If after this issue you don't know what gas/oil ratio to run, then you're beyond help. One minor point, Charles. Don't type all in CAPS.
RE: Assuming this is Don't Ask
THANK YOU, THANK YOU, THANK YOU!! 44year old female here. My dad's tt has sat in his garage for 3 years because it wouldn't run. He's 77 and in good shape for his age, but lacks the repair patience he once had. I printed this page, ordered the jets and then set about doing the carb mod. I was amazed at the amount of varnish in the bowl! Took me about three hours (in 90deg Alabama humidity), but was pleasantly pleased when we hit that starter button and it fired right up and purred like a cat.

My and his plan, when I started this, was to get it running so he could sell it. Ten minutes after it started purring, he said, "You know, if it's going to start this easily, I may just keep it and ride it." Made me smile.

On drilling out the plug on the carb, I used a very small bit just long enough to be able to get a wood screw started. Then I just grabbed the screw and popped out the plug.

Is there any SIMPLE way to reinstall the breather hoses? That was a pain in the butt!

Again, much thanks for this valuable information!

Probably the easiest way to reinstall breather hoses is to soak them for a short while in very hot water. This makes them much more flexible and easier to slip in place. Give that a try, and good luck with your bike.

Kind of like when people move next to or near an airport and complain about the noise. Ashland, Oregon, a mini-San Francisco city full of burnt-out hippies, all driving Subarus, recently had a town meeting about a new cell-phone tower going up. The burn-outs didn't want one (another!)

I always wondered how many of those in attendance fighting the new tower actually had cell-phones on them. Probably most...if not all...
RIP Hopetown.
David Fruhling

Yep, that's what killed Hopetown and Lord knows how many other races around the United States.
Hey i was wondering if you can find me a dirt bike. I have looked for 2 years for a bike but I dont have a job and I get to watch all of my friends ride there quads and bikes while I am stuck with a 3 wheeler I got given to me that barely runs and i keep dumping money into it to keep it running.I only get money once in a while because I dont have a job and i pay for the 3 wheeler. I am 17 and cant find a bike that suits me because I am 6 foot 1 and 300 pounds. I am just bulky not fat and its hard to ride because most bikes dont carry me. Can you help me out?
Jacob Galusha
Might I be so bold as to suggest that you get rid of that pathetic three-wheeler, save your money and get a job. 
Will converting my CRF 230 forks to CR 125s raise the seat? As long as I'm going to do the work of a conversion is the cr125 swap better than just swapping to the larger right side up forks?

You don't have to install upside-down forks on that bike. We installed conventional CR 125 forks at first and they work just fine, and in fact they were a bit cheaper to buy. You have a range of adjustability with forks and you can raise or lower them to suit your needs.
My new book, THE LAST RIDE, is at now out. It's fiction and starts in 1969, when an 18-year-old kid just out of high school gets a chance to ride his Yamaha 250 DT1 from Pennsylvania to Los Angeles … all off-road.  His adventures are truly amazing. The book then jumps 40+ years where the same person, now in his 60s, wants to get that old Yamaha back in his possession and return it home by riding it all off-road across the country again.  The book is $15 plus $2.75 for mail anywhere in the US (or $5 for Priority Rush mail) and for more information, the email is:  

Have a question for Rick “Super Hunky” Sieman? E-mail questions to, Attn: Don’t Ask.

Previous Don’t Ask Columns
September 2012

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