Carburetor FAQ

Can I get a set of carburetors for my XS650?

Could you give me a quote for a XS650 carburetor kit, shipping to Australia. Also could you break down the costs for me as I noticed your single carb price is $109.95 and it may be cheaper for me to source cables, filters, etc. here in Oz. Does the kit have both left and right hand versions, and is it possible to buy left and right singularly?

The complete XS650 kit sells for $539.95. Shipping to Australia will come to $73 for a total of $612.95 USD. It includes everything needed to install on the bike and does come with both left and right side pre-jetted VM34 carburetors. I can also supply a pair of left and right pre-jetted VM34 carbs for $339 + $62 shipping. You would have to supply any needed adapters, filters, cables and any extra jets needed for fine tuning 2 single carbs (left hand idle) will come to $199.90 + $62 shipping. You would have to supply any needed adapters, filters, cables and proper jetting.

Mikuni carb pre-jetted for alcohol?

I recently ordered a Mikuni TM28 flat slide smoothbore carb from you, can you tell me if it is alcohol ready?

I'm not sure what you mean by 'alcohol ready'. Jetting for running alcohol (or any fuel) will depend on the specific jetting requirements of your motor. Jetting for alcohol will normally require MUCH larger jets than for gasoline.

V-Force, Power Now and Power NOS units all work together?

Can I run V-force, Power Now and Power NOS units all at the same time? I would like to install them on my 2008 YZ125. Realistically what can I expect to gain from the two Power Now products?

Yes, you can certainly run all 3 together. The Power Now products cut turbulence in the carburetor. The benefit is smoother more controllable throttle response especially at lower throttle openings. It's definitely something you can feel in the slow technical or slippery sections.

Is there a difference between 2-stroke and 4-stroke carburetors?

Is there a difference between 2-stroke and 4-stroke carbs? Would I have to buy new jets for it, or can I use the ones that come with it?

The only difference between 2 and 4 stroke carburetion is in the way the jetting is set up. The carburetors come with a 'starting point' jetting setup. You will almost certainly need to have a large selection of jetting components in order to get an off the shelf carburetor jetted in for your particular setup. The chances that the out-of-the-box jetting will be correct are about a million to one. If you know of anyone who has done this particular conversion you definitely want to find out all their jetting details. Otherwise you will become a carburetor jetting expert by the time you are done.

Keihin smoothbore carbs a good update for my Bonneville?

I have several questions to ask.

• Are Keihin 35mm smoothbore carbs for a new Bonneville a good improvement over the stock ones? Even with the airbox still fitted (but with a K&N filter)?
• Are they much thirstier with normal riding? (I gather they are Constant Vacuum (CV) like the stock ones?)
• Do you sell an alternative setup to replace the airbox?
• Is there a Mikuni flat slide option for the Bonneville and if so would you recommend it over the smoothbores?
• I'm after something for improved response and power without sacrificing too much economy as most of my riding is long.

G’day mate! Here are some answers for you.

• The Keihin smoothbore carburetors will give you a huge improvement in power and throttle response over stock. The K&N filter will just help the situation.
• If jetted properly the smoothbores will have similar fuel economy to the stock carbs. These smoothbores are direct slide carbs not CV units. That is one reason for the huge improvement over the stock set up.
• I don't have any alternative setups for the airbox. You could look at individual pod type K&N filters if there is room.
• If you are experienced with jetting and fabrication you could fit Mikuni flatslides but I do not have them in a ready to install kit.
• The Keihin kit should give you the improved response and performance you are after without taking too much of a hit in the economy department. You should still have near stock range.

Summary

I have a 1978 Yamaha 175 dirt bike. If I don't start it and warm it up, at least one time every week, the carb floods out and apparently the old fuel gums it up and it doesn't run worth a dang. I used to start it every week, rain or shine. But this winter, I was not able to.

Can you tell me what is happening with it when it sits for too long? Is 'jetting' the term used to clean the carb? I used to take it in to the local Yamaha dealer, but they charge me $80 to get it running again. Is there a manual that shows the breakdown of the carb? Should I use certain fuel in it? I would like to learn to 'clean' the carb myself, to save money and time dragging it across town and picking it up again.

Cleaning the carb on your 175 should be a simple job. You want to remove the carb and disassemble it. Soak the jets in carburetor cleaner, squirt carb cleaner through the internal passages and reassemble. (Be sure and wear eye protection when doing this!)

Your carb really shouldn't need cleaning unless it has been sitting with fuel in it for 9 months or more. What is probably happening is the fuel in the carb is going 'stale'. The light components in the gasoline that will ignite easily in a cold motor tend to evaporate away leaving fuel that isn't quite so willing to burn. If it won't start easily I would drain the old fuel and replace it with some fresh stuff. If you have been trying to start it with the old gas you may have also fouled the spark plug. So replace that with a new one.

Next winter you would be better off to drain all the fuel and store it 'dry'. The fuel in the carb will go stale faster than the fuel in the tank. That's because the small amount of fuel in the carburetor is well vented. Starting it every week burns off some of the stale fuel and replaces it with less stale fuel from the tank.

'Jetting' refers to tuning the fuel delivery by changing out different size jets in the carb. If the bike runs well when everything is right you don't need to worry about changing the jetting.

From the year I assume this is an IT175. We sell a repair manual for this bike for $28.95. Click here to see this manual on our Manuals page.