1992 FXR Convertible -1 of 23 EML3 vin red voyage/poppy Originally built by Big Al’s Cycles Fully restored paint 10/10 Flyin Iron Designs 88” evo, ev27 cam, 32.3k miles Mikuni carb w/ Big Al’s a/c 6” Big Al’s risers & bars Fresh powdered wheels w/ Lyndall rotors 6 piston PM calipers ARPs throughout OG bags Several fresh chrome parts including inner fairing. Thunderheader w/ upgraded bracket La Pera custom seat Quarter fairing w/ Altered Industries shield Alloy Arts motor mounts & pivot blocks Speed Merchant preload adjusters Speed Merchant chrome skid plate Billet rear brake master cylinder reservoir Pingel petcock $19k

Bought an 01 660 in January and it has chinese carbs. Bought a set of used oem carbs, tore em down, right side carb had a stuck fuel screw and messed up threads. Guy who sold em to me said he'll sell me another cleaner set for 150 so I atleast have spare parts and exactly what I need. Then I got the dynojet jet kit, pilots from jets r us, a mikuni oem rebuild kit, + other misc parts/tools. 2 week job so far but u wasn't working on it thru the week cuz work kills me lol

So my friend is auditioning for a musical but can't read music, I can so I'm trying to help but I'm not a singer. When the 4 parts merge down to 3, how do we know which note to sing? She is singing the Tenor part (2nd lowest if tenor isn't the correct term here, starting with a C in bar 86.) I've attached a photo example 😅

Tuning the Carburetor

Especially for motorized bikes, its one thing to build an engine, but its a WHOLE different rodeo for tuning one. One of the most asked questions that I have seen is HOW someone would go about tuning the carburetor, picking out one, and getting your engine running in tip-top shape. There are MANY ways you could do this, but I thought I would jot down my method of doing things for the reader.

Before Tuning

However, BEFORE you even start trying to tune your carburetor, MAKE SURE you have NO air leaks, you are using the PROPER spark plug (NGK 6-8 heat range), and you are using the the proper full synthetic premix oil. It is also important to make sure you are using fresh fuel and your engine is operating with the proper compression. This ensures there are no complications during the tuning process and you dont have to back-track if there IS any issues.
If your engine does not run before you start tuning your carburetor, MAKE SURE you have spark with the aid of this diagnostics guide.

Being Familiar With Your Carburetor

A carburetor uses what are called JETS, which are used to control the flow of the fuel in a specific fuel circuit. The MOST important aspect of tuning your carburetor is KNOWING exactly what you are doing. If you don't know what all the adjustments do, you could very likely DESTROY your engine when you try to tune it.
There are primarily 3 types of jets. Those being the Pilot jet, the Needle jet, and the Main jet. The pilot jet is what controls the fuel flow from idle to ¼ throttle. The needle jet manages fuel flow between ¼ and ¾ throttle. And, in similar manner, the main jet controls ¾ to full throttle.
As I said, these jetting circuits overlap a bit, as you can see.
Keep in mind that all of these adjustments slightly overlap one another so there are no dead spots. However, the places where these adjustments overlap can cause confusion while tuning, such as a bog down low in the RPM’s might sound and feel identical to a pilot jet issue, but actually requires a needle-clip adjustment.
There are also (usually) 2 adjustment screws on the exterior of the carburetor.
The first (which is usually easier to access and larger in size) is the idle control screw. This screw is responsible for cracking open the throttle (a tiny bit) in order to set the idle to the appropriate RPM speed. Tightening clockwise will raise the idle speed and loosening it decreases the idle speed.
The second adjustment screw (which is usually smaller and less accessible) is responsible for adding or restricting airflow to the pilot jet. So, by tightening clockwise, you are restricting airflow and richening the pilot circuit. However, loosening counter-clockwise will add more air, leaning out the pilot circuit.

How To Start Tuning

Now that you know all the adjustment circuits and what functions they serve, you can start ACTUALLY tuning your carburetor. Now, for a beginner, you can take 2 approaches: The blind guessing game or the educated guessing game. Of course, however, if you have tuned as many carburetors as I have, there is no guessing involved.
If your engine runs, you need to learn how to set the idle. There are many misconceptions about idle speed, etc, but the entire job of the idle is to slightly crack open the throttle in order to keep the engine running. A perfect idle is one that is
IMPORTANT NOTE:
MAKE SURE you have your engine warmed up and has been running for a few minutes before tuning. Dont worry about this if your carburetor is SO out of tune your engine wont start. Though, keep in mind that the engine runs different when warmed up compared to cold, which can throw the tune COMPLETELY off if you start tuning when it is cold.
Though, before you start messing with these adjustments, you need to learn how to determine a rich tune and a lean tune. There are many key distinctions between these two that not a lot of people know of. Firstly, lets discuss BOGGING! Many people think that bogging is a result of too rich of a mixture, but a lean bog is A LOT more common than what people think.

Rich Conditions and Bogging

You can usually tell a rich bog by these symptoms:
Hesitation and stuttering: When you twist the throttle, there's hesitation and sputtering in the engine's response.
Reduced Performance: The bike may feel sluggish and have reduced overall performance due to the rich fuel mixture.
Stuttering at higher RPMs: When you are riding or dry revving and give it full throttle, it stutters and bogs. Commonly called 4-stroking, this also results in a lot of vibrations.
Even though your engine doesn't necessarily bog down, your engine can still be running terribly rich. One way to check this is to:
Black spark plug: If you are using the correct full synthetic oil but your spark plug is covered with a dark layer of carbon buildup, your carburetor is running rich.
Check your exhaust: If you remove your exhaust system and there is liquid and/or a lot of wet residue, that is a tell-tale sign of a rich running conditions.
Check your carburetor blow-back: Remove your air filter and dry-rev your engine (revving your engine will the clutch is pulled in). If you can visually see fuel particles spraying out of the carburetor or, when you place your hand next (not touching) the carburetor inlet, your hand/finger is wet, this is a tell-tale sign of rich running conditions.
Backfires: While it might sound cool, an engine that backfires is a tell tale sign that it is running too rich. A backfire is literally caused by so much fuel in the engine, the spark plug cant ignite it and it backs up into the exhaust and then burns.
Not running at all: An engine that is running EXTREMELY rich wont even run at all. This can be confirmed if the spark plug tip is wet. This is due to SO much fuel in the engine, it cannot atomize and be ignited.
Fuel leaking/filling the crankcase: Sure, your engine may run decently, but I have seen quite a few engines that have fuel either leaking out of the engine or that has partially field the crankcase. Usually, this is due to other issues, but can be a result of unburnt fuel being pushed passed the piston rings and into the crankcase. Take note that this is more likely in a 4-stroke.

Lean Conditions and Bogging

Bogging that sounds like a gasp: One of the primary symptoms of a lean bog is hesitation or stumbling when you apply the throttle. The engine may struggle to respond immediately or smoothly, especially during rapid acceleration or under load. This can sound like a gasp of air and is basically what it is.
Even if you dont have a specified bog, there are other tell-tale signs of an engine that is running too lean:
Hanging idle: If your engine is running too lean, you may have idle issues. When you dry rev your engine and, instead of returning to idle fairly quickly, a lean tune will cause the RPMs to very slowly drop to idle or not go to idle until you put load on the engine.
Overheating: If your engine is overheating prematurely, you might want to check out the tuning, because that can be a direct result of a lean tune.
No torque: You might be able to dry rev your engine and it sounds dialed in, but if you go to ride and it seems to have a strong lack of torque, that is usually a strong indication of a lean tune.
White/light colored spark plug: If you remove the spark plug and the tip is light colored and almost white, this is a strong indication of a lean tune.
I highly recommend this FANTASTIC video about lean and rich bogging and the sound affects help a LOT. lol
Now that you know the basics for finding the tune status on your carburetor, you can start tuning.
When tuning your carburetor, you NEED to start with the pilot jet. Make sure it idles well, the throttle is snappy right off idle and returns back to idle when revved. The idle speed also needs to be consistent and there should be no to minimal bogging off the line. Remember that the fuel/air screw is responsible for fine-tuning the pilot jet circuit, which makes it MUCH easier and easier to iron out bogging issues, etc.
After you have somewhat tuned your pilot jet appropriately, move on to your needle jet, which runs directly off the pilot jet and is responsible for ¼ to ¾ throttle. This is a small needle located in the top of the carburetor and is a part of the slide. This needle has a c-clip that (usually) has 5 positions. When you move the clip a position lower, it allows for more fuel to enter the engine and a position higher restricts fuel flow. When there is a fresh transition through ¼ and half throttle, you know you got it tuned well. Make sure there is no bogging at mid throttle and give it a few dry-revs. If it doesnt bog down when you jam the throttle to half throttle, you have got it dialed in.
Now that you have done the most work, this is probably the easiest part: tuning the main jet. This adjustment controls ¾ to full throttle, so, as long as you have tuned the pilot and needle circuits correctly, tuning the main jet is a piece of cake. If you can ride your bike, jam the throttle to full throttle and if it does not bog after ¾ throttle, your main jet is tuned perfectly. When you dry-rev your engine to full throttle, there should be no bogging or hesitation and no hiccups. But most importantly, when riding, the throttle should be responsive and there should be no bogging or deadspots.

Importance of a Slightly Rich Tune

It is important to tune your bike optimally for performance, but it is VERY important to have a tune that is slightly rich. It might sound odd, but when it comes to combustion, more fuel has a cooling affect, while less fuel is the main cause for overheating issues.
Not only that, but a rich mixture provides better lubrication and is more stable when it comes to combustion. A lean tune is not entirely detrimental on some engines (as long as you are using the correctly full synthetic oil), but other engines, such as the Iron Bore minarelli engines require a rich tune or else it will seize up big time. So, while some promote the use of a slightly lean tune, I argue that a tune that is just the tinniest bit on the rich side will promote the well being of your engine and some engines REQUIRE a rich tune.

Carburetors and limitations

Now that we have discussed all of that, lets discuss what makes a good carburetor and some limitations.
A good carburetor allows you to precisely and easily tune every aspect of the power curve. Especially on motorized bikes, the stock carburetors lack a LOT of adjustments. Only having needle jet, main jet, and idle adjustments. This makes it easy to operate but does not allow you to completely dial-in your engine. A good carburetor will have an easily-accessible pilot and main jet with an adjustable needle jet. I doubt there is any carburetors that DO NOT have an idle adjustment, but you want to also have a pilot air-mixture screw.
Not only should your carburetor have these adjustments, but should be sized appropriately also. A carburetor with too large of a slide/plate will almost drown the engine, run extremely rich, and will require tuning more frequently. A carburetor with too small of a slide/plate will perform sluggishly, have less peak power, and will have deadspots throughout the RPM range. A rule of thumb is that chinadolls (66cc - 85cc TRUE displacement) are limited to carburetors no smaller than 17mm and no larger than 21mm. However, if you start messing with hybrid engines and such, you could possible use a larger carburetor.
The Mikuni VM18 and NIBBI PE17FL carburetors are FANTASTIC because they are the PERFECT size, are SUPER high quality, and they have ALL of the adjustments.
Now, we cant discuss carburetors without mentioning the PWK21, a carburetor that is cheap, SUPER easy to adjust, and performs better than (pretty much) anything else. But, there are a few limitations. Firstly, because of the size of this carburetor, it can be used to great success on the larger 85cc Chinadolls and is the go to for hybrid engines, but they perform like TRASH on smaller chinadolls, even with proper tuning and modifications.
You must keep in mind that tuning a carburetor is simple when sticking to this code of operations, but can VERY EASILY turn into a HUGE headache when you dont follow this format. I hope this helps and if you have any questions, concerns, or you just want to chat, feel free to DM me.
For a good walk-through of tuning a carburetor check out this discussion on my Podcast.

I’m considering purchasing my first bike, specifically a cafe racer, and I would appreciate any feedback or advice before making a decision. Please let me know if there is anything I should consider before owning this bike or any questions I should ask the owner. Thanks!

Hello everyone,
Last Saturday i got my hands on a lovely project bike for a measly 450 euros, a 1996 Husaberg FE 501 (on the papers it says MC 501 but i think that's the FE) It definitely is a bike that needs work, first job is a good carb clean to get it running. Then get it driving because its also missing a chain.
The plan is to make it street legal at some point, luckily it has the technical papers that are required, but its missing quite some bits like indications and buttons, speedometer incl cable, brake light cables, kill switch and probably more. The last owner made some upgrades as well, a lovely Ohlin's rear shock, Mikuni carb and an upgrade to the oil system which supplies the head with more oil.
I would love to get some advice on this project, what would be the best approach to make it street legal (as in parts). Anything i really need to look out for with these bikes? I'd love to hear some input!
Pic of the bike. It does have a headlight but just not mounted

I'm 14 so please excuse and errors in spelling, thanks. A couple years ago my dad gave me a rolling banshee frame without a motor and a ninja 250 motor and told me to figure it out so I did and made it run in under a week. I welded motor mounts and figured out wiring harness problems and issues all on my own, needless to say my dad was not pleased that I got it running under its own power so quickly so he decided that we were going to turbo it! For reference the turbo inlet is roughly the size of a quarter and is the smallest production turbo I know of, it came on diesel smart cars from Europe but it was perfect for us. I drilled, tapped and ran oil lines and mounted the turbo, however my dad welde the headers because I am an amateur welder, there were many problems with it however mainly ignition was being blown out because the stock 250 coils are not great, I tried using Subaru, and Ford coils however continued to run into issues. Later down the road my dad offered me two MSD ignition boxes (two because we needed one for each channel) I mounted and wired these and they worked great until they didn't. The main problem was huge MSD ignition ition boxes were never sopposed to have to withstand the vibration because after all we are talking about a fourwheeler. After my dad saw how much I really cared about this project he gifted me two ign-1a coils and helped me learn TTL (Transistor to Transistor logic) these work great and are currently what are on the bike. At around the same time I got Mikuni 28mm flat slides to slightly down size from the ageing stock carbs that were forced to put up with the torture of a blow through carborator setup. Both the new carbs and ignition coils greatly improved tunability and helped solve otherwise unsolvable problems, other than those parts however the motor is entirely stock and running 20+ psi of boost according for fuel flow, it is equipped with a fuel pump and fuel pressure regulator that drink from a 2 gallon harbor freight predator engine gas tank. I was unable to use the stock banshee gas tank because the cylinder head sits to high in the frame in the near future I plan on making an entire costom gas tank to fit the frame and so I can use an internal fuel pump, as well put the radiator and side plastics on. I'm am very lucky because my dad has been a tuner for 20+ years of his life and we have a land and sea 2wd chassis Dyno at our house, after strapping it down and hooking up a O2 sensor for lamda we made a few pulls and the first few were wack but then progress was made, out best pulls made over 100hp and 50ish pound feet of torque. For reference the 250r motor makes 25 HP and torque stock! My dad was worried that I would hurt myself so it sits detuned to about 80hp, we can control boost by tightening or lowering the vvt nut on the turbo. I hope to make it look nicer in the future so don't flame me too hard about the pictures, please ask any questions and I will do my best to answer them and please remember I'm only 14 years old so if something looks bad don't be too harsh anyway enjoy the pictures! I can post Dyno graphs however I have to find them and for reference some picture are older than other, the first 2 are the newest and how it currently looks on top of the graphs I can post videos of it running.

Hey y’all, I just got into mini bikes a couple weeks ago. I have a stage 2 196cc with Chinese TAV2 (red spring). Billet parts, flat top Honda piston, gov removed, Mikuni flat slide clone, 22 pound springs, .265 hot cam.
With the wheel and tire raised up, no load, the motor will rev past 6k. With me on the bike, it will run up to about 4200 on the torque converter and stop climbing. This gets me a top speed around 48. From what I understand, the TC should not hold down the RPM, but the ratio should remain constant once the TC is maxed out. I am seeing others with similar builds running 6-7k RPM.
Is it my TC holding revs down? I am also seeing some run 26 pound springs with this cam, could I be experiencing some valve float under load? Any idea appreciated.