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Heiden Dyno Tune Needle & Jet Kit
- Thread starter Greg
- Start date
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- Tags
- carburetors
I haven't tried them but personally, I don't think they're worth it. If you know enough about carb tuning, you can usually tune the BS34s well enough using available stock parts. I would consider the Canadian needles and needle jets before that Heiden kit but neither may be needed.
The need for an adjustable needle comes into play when you start increasing your main jet size. Increase it enough and the bleed-over makes your midrange too rich. Then you need an adjustable needle your can lower (lean) to compensate. The midrange on the BS34s comes too lean from the factory. The bleed-over from larger mains doesn't hurt it, it actually makes it better.
If you want to improve the BS34s on your all stock machine, simply go one up on the mains. If you feel the midrange is still too lean, shim the needle with a washer. Also, you'll need to uncap the mix screws and reset them to somewhere between 3 and 3 1/2 turns out.
I have plenty of the shim washers if you think you might want to try this. I live close enough to you that we can probably hook up if you like. I can come by and show you how to tune your carbs. We'll get that thing purring. Send me a P.M.
The need for an adjustable needle comes into play when you start increasing your main jet size. Increase it enough and the bleed-over makes your midrange too rich. Then you need an adjustable needle your can lower (lean) to compensate. The midrange on the BS34s comes too lean from the factory. The bleed-over from larger mains doesn't hurt it, it actually makes it better.
If you want to improve the BS34s on your all stock machine, simply go one up on the mains. If you feel the midrange is still too lean, shim the needle with a washer. Also, you'll need to uncap the mix screws and reset them to somewhere between 3 and 3 1/2 turns out.
I have plenty of the shim washers if you think you might want to try this. I live close enough to you that we can probably hook up if you like. I can come by and show you how to tune your carbs. We'll get that thing purring. Send me a P.M.
TwoJugs
Excess XS
I am going to try some tuning on my 34s in the next few weeks. What is the special design that makes it a shim washer? Will a standard washer that fits work? Thickness, OD, ID?
It's just called a shim washer, basically it's any washer that will fit. I think M3 washers are what I use. I think you can get some at Radio Shack. I got stainless ones from McMaster Carr, about $2 for a 100 pk. The washers are about a half MM thick. Moving the needle clip on an adjustable needle changes the needle height by 1mm so adding a shim washer changes your setting about a half step. You use this method for fine tuning when one full step is too much.
Lunatic
XS650 Enthusiast
I've tried them and they gave me no end of problems. I ended up taking them out and using a set of Canadian needles and needle jets.
thanks 5twins i do have leanness in mid range thats why i was going to try them but i do have larger mains i will try them btw should i replace them caps i remove and is it necessary to adjust the mix screws it seems to run fine at idle and full
Leave the caps out. The mix screws on the BS34s were set at the factory (then capped) to meet emissions standards, not for optimal running. You'll usually find them set somewhere between 2 1/2 or 3 turns out when you remove the caps. Sure, they'll run like that, they just run better if you open the screws up a bit.
rwingsfan
Xs 650 Dummy
No, usually somewhere between 3 and 3 1/2. They will be less than 3 from the factory. If you do mods and increase the pilot jet size, sometimes you can set them a bit below 3 but stock jetting likes at least 3 turns, sometimes a bit more. Install the Canadian needles and needle jets and you may find slightly below 3 is OK because those parts are richer.
Every one of these bikes wants what it wants. It's not exactly the same for them all. You need to fine tune to find out what your bike's ideal setting is. When a factory spec is given, that's just a suggested starting point. Some may run good at that setting, others will need slightly different settings. The BS34s didn't have a factory spec because of the caps and emission controls. Yamaha didn't want you fooling with them. The 3 to 3 1/2 turns out is what has been found to work best as an initial setting. If your bike runs best slightly above or below those points, that's fine, that's just your bike wanting what it wants. However, 3 1/2 turns out is considered quite a lot for a mix screw, pretty much at the max point of it's desirable operating range. Going up a size on the pilots would be a good idea if you need past 3 1/2 tuns.
Every one of these bikes wants what it wants. It's not exactly the same for them all. You need to fine tune to find out what your bike's ideal setting is. When a factory spec is given, that's just a suggested starting point. Some may run good at that setting, others will need slightly different settings. The BS34s didn't have a factory spec because of the caps and emission controls. Yamaha didn't want you fooling with them. The 3 to 3 1/2 turns out is what has been found to work best as an initial setting. If your bike runs best slightly above or below those points, that's fine, that's just your bike wanting what it wants. However, 3 1/2 turns out is considered quite a lot for a mix screw, pretty much at the max point of it's desirable operating range. Going up a size on the pilots would be a good idea if you need past 3 1/2 tuns.
DirtyErnie
Renaissance Hick
*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. (posting this everywhere it seems appropriate)
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. (posting this everywhere it seems appropriate)
tcphotonyc
XS650 Member
Hey guys...gotta revive this thread! just picked up a 1979 XS. The po removed the airboxes and installed uni filters but never jetted it. It runs great choked but obviously its getting too much air and needs to be jetted.
So....What kit do I buy and should i buy? Do i need mains or pilot or change needle position? If anyone can just tell me part #'s from Mikey's or where ever that would be amazing! Thanks in advance!
So....What kit do I buy and should i buy? Do i need mains or pilot or change needle position? If anyone can just tell me part #'s from Mikey's or where ever that would be amazing! Thanks in advance!
You need to buy jets. One up on the mains maybe two. The pilots up one. In the carb guide there is a tuning section.
I can't tell you what your bike needs much more than that. All bikes are different. What works on my bike, might or might not work on yours. If you want it right you have to experiment with the tuning.
Leo
I can't tell you what your bike needs much more than that. All bikes are different. What works on my bike, might or might not work on yours. If you want it right you have to experiment with the tuning.
Leo
tcphotonyc
XS650 Member
Thanks for your Input XSleo. I'm studying the http://www.amckayltd.com/carbguide.pdf guide right now and so for I have learned I have BS38's with 135 mains and 27.5 pilots. It's lower needle one notch. Now to figure out part numbers and order jets...going to pick up a few sizes higher on both.
That would make them the 78-79 carbs. The only years they used the diaphragm and slide set like that. They used the 502 needle, and a Z2 needle jet.
I haven't run one of those sets yet. I have a set but are mostly just parts.
I've run a 76/77 set of BS38 carbs, an 82 set of the BS34's and am now running a set of the EX500 Ninja carbs on the 75.
The 81 has the 82 set of BS34's on it. Put them on while I was cleaning up the 81's carbs, All clean and ready to go, just haven't put them back on yet.
Leo
I haven't run one of those sets yet. I have a set but are mostly just parts.
I've run a 76/77 set of BS38 carbs, an 82 set of the BS34's and am now running a set of the EX500 Ninja carbs on the 75.
The 81 has the 82 set of BS34's on it. Put them on while I was cleaning up the 81's carbs, All clean and ready to go, just haven't put them back on yet.
Leo
