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Guide: How to change the carburetor jets on a Transalp XL600V or other motorcycle with Keihin CV 34 carbs

If you’ve changed to a slip on muffler and/or changed the air filter on your Translap, you will probably have to re-jet the carburetors, changing the jets to bigger ones. A muffler with less resistance and air filter that allow a greater air flow will disturb the air / fuel mix, crucial for effective combustion. One of the symptoms of a too lean mix is exhaust bangs when you release throttles. Another is white spark plugs.

The solution is to re-jet the carbs. You can buy jets for about 4-8 Eur at your local motorcycle dealer. There is no standard setup so you will have to buy several different sizes and try them out.

Original setup for Honda Transalp XL600V (Keihin CV 34 carburetors):

Year Main jet Pilot jet Pilot screw setting
1987-1988 Front cyl: 128 / Rear cyl: 130 38 2½ laps out
1989-1993 Front cyl: 128 / Rear cyl: 130 38 2¼ laps out
1994-1995 Front cyl: 128 / Rear cyl: 130 38 1¾ laps out
1996 Front cyl: 118 / Rear cyl: 120 38 1¾ laps out
1997-1999 Front cyl: 115 / Rear cyl: 118 38 2¼ laps out

How to do it:

Time it takes: 10-15 minutes per carburetor after you have detached them.

Tools needed: One tall and one short (90 mm) Phillips screwdriver size PH2. One flat-blade screwdriver size 2 or 2,5.

  1. Follow this guide to detach the carburetors. You only have to detach the carbs from the intakes – all wires can stay in their places.
  2. Turn the carburetors so you can reach to unscrew the floater house on one of the carbs. Note that quite lot of petrol will be in the bowl and it will be difficult to stop it from running all over the place.
    Remove the floater house from the carburetor
  3. Make sure you have a flat-blade screwdriver in exactly the right size, or you will damage the slot of the brass jet.
    Remove the main jet on a Keihin CV 34 carburetor
  4. Screw in the new jet – don’t tighten it too hard!
  5. Unscrew the pilot jet sitting a bit in front of the main jet:
    changing the pilot jet of a Keihin CV 34 carburetor
  6. Screw in the new pilot jet – note that it is tougher towards the bottom, that is normal, but be attentive when you reach the bottom so you don’t tighten it too hard.
  7. Put back the bottom of the floater house and turn the carburetors to the other side so you can reach to do the same procedure on the other carburetor.

Good luck!

6 reaktioner på “Guide: How to change the carburetor jets on a Transalp XL600V or other motorcycle with Keihin CV 34 carbs

  1. Awesome! Thanks for this post, which very likely will put a final end to all the pops and bangs I have on my alp, with slip-on.

    1. Glad we could help! Good luck with your re-jetting, and keep in mind that you may have to try a few times before you hit the right combination for your setup. But when you’ve done it once, you can do it quickly 🙂

  2. Wow! How lucky was I to have stumbled upon this page just as I’m about to rebuild/jet the carbs on my Transalp? It’s great to see there’s still current postings for this ageing moto! Cheers from the US!

    1. Hi Kyle! Glad you found it and that we could be of help! Chers from a cold Scandinavia 🙂

  3. I just changed the slow jets on my US-spec ’89 XL600V. The main jets are both #120, which is what’s specified by my factory service manual. Your pilot screw setting is correct, at 2-1/2 turns out, according to the FSM.

    1. Hi Jeff! That was interesting! I don’t remember where I got those numbers but I will check it. Thanks for the heads up! Yesterday, I re-jetted a 1994 and it had 128/130 + 38.

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