Heiden Dyno Tune Needle & Jet Kit From Mike's xs ???

Update: Put in a smaller idle air jet, all the dealer had was a #133.8 (wtf?) Works pretty good with the #45 pilot, but still a little on the lean side. Low midrange was kinda flat with the stock air jet, that came back quite nicely. Still not convinced I need to go smaller than a #145 main, but I did pick up a 142.5. Maybe if I get bored some day I'll put it in... and probably watch my upper midrange go flat. :p
E
 
i just installed the kit as the direction said and i even drilled the larger slide lift hole (that was very simple). After installing the kit my bike runs like shit!! it bogs out during acceleration and at higher cruising speeds. Any suggestions??????

i'm running filter pods with a stock exhaust. used the new needle in the kit, the 145 main jet and 45. idle jet. it says to adjust the fuel mixture screw, but i dont think my carbs have one?
 
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I don't think you know much about carbs, let alone the BS34s on your bike. Yes, they have a mix screw but it's capped over from the factory. Also, that Heiden kit pretty much does not work here in the States and usually not unless you install the other goodies with it. They fail to mention that in the sales pitch. Spend another $800 or so for the 2-1 exhaust and big bore kit, then the carb kit should work.
 
Got mine sorted out, seems I had the valve lash set too wide. Once I put that close to standard everything just fell into place. Bike wants the 47.5 pilot, 142.5 mains and the needles in slot 3. Now it runs clean, no stumbles, lots of power. 52mpg.
I really think the 2-1 pipes have a hugely different vacuum signal at the carbs, and that's what these needles are for.
 
*ZOMBIE THREAD RESURRECTION!*

This just in from Heiden tuning:re needle kit:

Hello
It can work with the Y0 and also with the 336 Y0 (needle jets)
The kit must work with the 2-1 exhaust.
Regards
jerry

It sounds like he's saying it was developed for the 2-1 exhaust kit that Heiden developed and Mikes XS sells. This fits with what I've learned tuning the 2-1 with the needle kit and with stock needles.
 
I have my kit installed with Pod filters and Pandemonium exhaust.. the bike was running. It seemed to respond well with the mods... but.... I have a backfire in one cylinder that I was unable to tune out because my rings in that piston need replacing.

By the end of the week I should be able to reassemble and tune. I will post a video of the results.
 
thelowlife said:
I have my kit installed with Pod filters and Pandemonium exhaust.. the bike was running. It seemed to respond well with the mods... but.... I have a backfire in one cylinder that I was unable to tune out because my rings in that piston need replacing.

By the end of the week I should be able to reassemble and tune. I will post a video of the results.
Click to expand...

How did it turn out?
 
Glad @DirtyErnie you posted your findings for your 2-into-1 exhaust. They may help me with my Heiden tuning needle kit. I was running the kit with ya mama pipes and stock airbox. I used the stock needle, 137.5 main jet, 45 pilot jet, 132.5 air jet and the air/mix at 2 3/4 turns. The BS34s liked that combination with the ya mama pipes; however, the MAC 2-1's do not. I am going to try the heiden needle in clip position 3 and see if it smooths out the flat spot at 4500 WOT area. I haven't drilled the hole in the slide yet, because I am still a little hesitant. I may try it because the slides could probably be updated to new ones if It starts to flutter.
 
Ok here we go for my record and your viewing pleasure. My setup is 1980 XS650G with Mac 2-1 and stock air box w/ k&n filter. bs34 currently with stock needle, drilled carb slide, 145 main, 45 pilot, stock air fuel mix screws at 3 turns out , and stock 135 air jet reinstalled. Runs good with a slight stumble at absolute WOT.

Today’s trial:
After yesterday (see above post) it ran lean in the mid / top range. So today tore off the top drilled out the slide and installed Heiden needle 3rd position. This as well as 137.5 main, 45 pilot, 132.5 air jet, 2 3/4 turns on air fuel screw. Ran lean in the mid range.

Tore off bottom and installed 145 main jet. Stumbled at idle giving throttle.

Reinstalled stock 135 air jet with no change.

Reinstalled stock needle and now we are talking. I can ride it down the road without an issue. I am going to check valve clearance once it’s cool for shites and giggles to see if it is off. I really doubt it is and I think maybe a 142.5 main will solve the WOT tiny stumble. I didn’t read the plugs at WOT but will probably do that next time I go out.

I have tried researching what the air jet on the air box side does with not much luck. Does anyone know what in the scheme of things a size smaller will adjust for? I was assuming it would richen the idle, but that’s just a guess.
 
Yes, that air jet controls the air supply to the idle circuit. A smaller size (less air) would make the idle circuit richer. Supposedly, it doesn't have as big an affect as changing the pilot jet size so that would make it a way to fine tune the idle circuit. For instance, if one size pilot jet was too lean but the next size up made things too rich, you could get a richness level somewhere in between those two sizes by fooling with the air jet size. The E.P.A. mandated U.S. models came with a 135 air jet. The rest of the world got a 130.
 
The main circuit never turns off: even at idle, it feeds the engine through the slide cutaway. That's why a change of a single step in needle position will often force a compensating change in pilot jet size.
 
If it ran lean in the mid-range, raise the needles? Gotta work from a point of being too rich and then pulling out fuel. To really dial in the needles, start from about 2,000rpm in 3rd gear and go WOT. The main jets take over about 4,000rpm, any misbehavior below that is the needle. If it rich-stumbles anywhere or everywhere in that range you learn things about needle taper and/or position. But you HAVE to get it to being too rich, lean is dangerous during tuning.
 
So I got the mid range and full throttle pretty much nailed. I think I only need to adjust the air fuel screw or swap pilot jets. Once it was warmed up it wanted to die on decel until I gave it more throttle. I didn’t mess with the choke while it was about to die, but did let it sit at idle and check the plugs. The plugs seemed to be lean so I will fine tune the air fuel screw before I make any other changes. When I rev’d it at idle it didn’t give a lean or rich indication. Right now I have 140 mains, 47.5 pilots, 135 air jet (stock), stock needle, and at 2 1/2 turns on air screw.
 
I adjusted the air fuel screw to 3 turns out and took it for a ride. I turned it up to 3 1/2 when I got gas, but it got a slight stumble so turned it to 3 1/4. The bike is definitely faster and runs highway speeds at lower rpm. I thought about trying the smaller air jet, but I am going to call it good as it sits. I let it idle for a minute before cutting it off and checked the plugs once it cooled down. One side a good chocolate color the other a little blacker so I turned it in an 1/8 of a turn.
 
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After running the bike a few days I had to fine tune my carbs once again and believe this time I found the right combination for my 2-1 setup. Today I am running 142.5 main, 45 pilot, 132.5 air jet, stock needle, and 2 7/8 turns on air fuel screw. The tuning came after I took an experienced rider course and spent all day in the low rpms. I was a little rich on the pilot so after adjusting that I was a little lean on the main. Now it seems just right with only butt dyno and feel. If anything I may read plugs in the three ranges to adjust if needed.
 
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So just thought I’d give an update on my carb adjustment for my Mac 2 into 1 exhaust. Just as @DirtyErnie was hypothesizing the Heiden needle kit does seem to be specifically fix for the flat spot in the 2 into 1. After many different combinations there was no way I could get my stock needle to not have a slight hesitation at WOT around 4500. My setup differs from dirty ernies so may be why mine is slightly different. I am running stock airbox with aftermarket k&n filters. So I found running 140 mains, 45 pilots, 132.5 air jet, Heiden needle at 4th clip from top, and my air fuel mix screw turned out 2 1/2 turns. I am not sure why the air mix screw had to be turned in almost a whole turn from what I had it set with the stock needle. I thought it would be leaner at idle with the Heiden needle since it was longer but I am guessing it has more of a taper.
* I have changed my performance a little since this post now I am running 706 cc, shell #1, Kibblewhite springs, Andrews 2.8 ohm ignition, K&N conical filters, and Mac 2-1. The bs34 gave the Heiden needle 4th clip from the top, air fuel screw 3 turns, 140 main, 45 pilot, 32.5 air jet, drilled slide, plug gapped .032”
 
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