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Jetting the Valkyrie

by LaMonster

  Many of us have done mods to our bikes that may or may not require that we re-jet to compensate for the modifications. The most common mod is a pipe mod. The most common pipe mods are.
  • Cutting the "Piggies"
  • Drilling or punching out the baffles
  • The "Shrimplin Cut"
  • Glass Pack Mod
  • TBR 6 into 6
  • TBR 6 into 2
  • Cobra 6 into 6
  • SuperTrap 6 into 2
  • Jardine 6 into 2
  • Pro Dyno Glass Pack

  Everyone wants to know if they need to re-jet when they add anyone of these mods. The answer is, maybe. I have seen dyno charts with these mods that have gained power by re-jetting, and have lost power by re-jetting. The only good way to tell is to do a before and after dyno run with a gas analyzer if you can find one. The fact is that not all Valkyries are alike. At one time I thought that re-jetting a glass pack mod would always gain power. I jetted a bike that proved me wrong on that one. It ran much better and had more power with the stock jets. When we jetted my buddies bike, that had the same mods as I did, he needed one jet size lower to produce max power. Neither one of us were running any leaner with the glass pack mod, but we were looking to get some more power out of her. We did gain about 4 to 6 hp with the glass pack mod and jetting.

 So how does this help you. Well it may not, but I am going to tell you how to re-jet your bike if you feel you need too. The poor mans way of telling if he needs to re-jet is by taking a plug reading before and after. Remember that taking a plug reading at idle only tells you how you are running at idle. You need to shut your bike down at different RPM ranges while under load and then pull the plugs to see where you are at.

 Ok, you looked at your plugs, or you did a dyno run and you figure you need to re-jet. By the way if you installed any of the 6 into 6 pipes you just lost about 6 hp. You can gain most of that back by re-jetting but you are not likely to get anymore than what you started with.

 So what jets should you start with you ask. I would start with 105 to 110 mains and 38 slow jets. The stock jets are 100 mains and 35 slow jets. You could start right in the middle with 108 mains. I would still go with the 38 slow jets just because the will still work on the low end, and will work much better on the high end.

 So where do you start. It would help if you have a shop manual but if you don't that's ok too, will get you through this. This is where you need to start.

  • Remove the gas tank ( make sure you take the petcock switch off before pulling the tank) that thing is plastic and breaks real easy
  • Remove the air box ( this is kind of a pain, not near as bad as putting it back on)
  • Remove all six intake manifolds and plug the heads with a rag

jet2.JPG (49429 bytes)

 Ok that wasn't so bad right. Now here is where I can save you some time. The Honda manual tells you to remove the carb bank. Forget about all that, you can leave all the cables hooked up and just take a bunjee cord and strap up the side you want to work on to your handle bars. The first time I re-jetted it took two guys 6 hours. Now I can do it by myself in about two hours. That's if the air box doesn't fight me going back on.

  Now that you have the one side bungeed up, go ahead and drain the bowls and drop them. You may find you have a bunch of junk in them.
          jet1.JPG (68789 bytes)                               jet3.JPG (38369 bytes)

Go ahead and pull all your mains out on one side and replace them with the new jets. The mains are the little ones, and the slows are the long ones.
jet6.JPG (38747 bytes) jet5.JPG (36900 bytes)

Now go ahead and change out the slow jets (the long ones)

jet7.JPG (24547 bytes)


  When you get both sides done it is time to reverse the order of the tear down. You made it this far, I'm sure you can do the rest just fine. The only thing you may have a problem with is that air box. It can be a real booger to get it to seat right. I'm sure glad your doing that part and not me.

Speaking of air box's. If your thinking about modifying your air box, forget about it. I have done it all, and the thing just runs better with the stock box. Here is a pic of the "baffle mod". Big mistake, thing had a real flat spot when I did this and I couldn't jet it out. Yes I tried drilling holes in the air box too. Good thing I had some duct tape to fix that one.

jet9.JPG (37165 bytes) 
Just get you a K&N and call it good. I removed the pre-filter.

jet8.JPG (37626 bytes)

As far as shimming the stock needles, or using after market needles, I'll leave that up to you. I didn't have any luck with the after market needles or shimming the stock needles. That doesn't mean it won't work for you. This is pretty much a guessing game. I kind of like fooling around with it all myself. Hope you do too.

By the way your going to need a pilot tool to adjust your pilots. You can buy one from Honda or make one from a car antenna. It's a little D looking thing. I would start your pilots at 1 1/2 turns out. This adjustment makes a big difference through out the power band.   Message Board    ShopTalk    Just Pics    Valkyrie Hot Links