Jets
- Thread starter Gretsch
- Start date
sweatmachine
moped
I have it and it's great! You have to be careful not to spill the mercury out, but it works really well. Just keep it hanging on a nail in your garage and you'll be fine.
sweatmachine
moped
this isn't mine, but it's an example of a bung mounted in the crossover tube:
here's the kit as it comes:
here's the bungs welded into my headers. I don't have stock exhaust, I'm running the D&D 2-1 full system and I put a bung in each header so I can put the sensor on each side and tune each carb indepently. They should be the same, but at only $8 a bung I thought it would be cool to be able to see what's going on with both carbs.
here's the pipes installed and the sensor hanging down:
here's my temp-mounted rig job, but it works. I made a little plate that the gauge mounts to, and I drilled/tapped out my top clamp on the underside to hold the plate:
fender
Street Tracker
Sweat, do you have any data logging capabilities with your setup (ie rpm and af) or are you tuning by throttle position to dial in the carb.
Whats the best way to determine what main jet to use? Is it WOT at various RPMs and check the af gauge? I know you need to dial in the main before properly tuning the pilot, needle but am wondering what is the best method to get the main right.
Whats the best way to determine what main jet to use? Is it WOT at various RPMs and check the af gauge? I know you need to dial in the main before properly tuning the pilot, needle but am wondering what is the best method to get the main right.
sweatmachine
moped
Mine has no data logging capabilities although they offer kits that do. I could buy one of the data logger units and use it with my system because they use the same brain and sensor but I don't feel the need. I just watch the gauge and compare it against different throttle positions to see what jetting changes I need to make.
To dial in the main, just ride WOT in 3rd or 4th gear for a few seconds and the gauge will only be reading the main.
To dial in the main, just ride WOT in 3rd or 4th gear for a few seconds and the gauge will only be reading the main.
sweatmachine
moped
cool! You'll really enjoy it and you will learn a ton about how your carbs work and respond to changes in jetting. After riding a while with mine I could NEVER go back to seat of the pants and rule of thumb tuning. It's all BS compared to hard data!
Gretsch
Rocker
Is there any other way to balance the carbs that wouldn't involve using mercury?
sweatmachine
moped
Aerostich has this:
http://www.aerostich.com/carbmate-synchronizer.html
I've never used one before though.
You could always make a manometer with about 20' of hose, some Auto Trans Fluid, and a yard stick. I've made one before but it was a PITA to use.
http://www.aerostich.com/carbmate-synchronizer.html
I've never used one before though.
You could always make a manometer with about 20' of hose, some Auto Trans Fluid, and a yard stick. I've made one before but it was a PITA to use.
Gretsch
Rocker
Thanks mang! I'll probably pick that up once I get back from vacation.
I swapped the mains to 127.5s and she seems to be running smoother now. Not as much power as before and their seems to be a bit of a flat spot in the mid-range. I've got shims on order from NB so I might give that a try. What do you think? I really need to get on a dyno.
P.S. 2-3 weeks ago I was completely clueless about any of this stuff. Thanks to everyone (especially Sweat) for the help and guidance. :worthy:
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sweatmachine
moped
Glad to help man! Give a shim a try, you probably will only need one per needle.
The seat of the pants way to test your main is to ride at full throttle in 3rd or 4th gear for a few seconds, then let off to about 3/4 throttle. If the bike runs stronger at 3/4 throttle than at full throttle you're probably too lean on the mains.
Another way, find a familiar stretch of highway (preferrably with no cops around) and pick a starting point and an end point. At the start point (in 3rd or 4th gear) nail the throttle (stay in the same gear) and notice what your speed is at the end point. Then, make your jetting changes and run the same stretch of highway again. Whichever main jet gives you the highest MPH at the end point is the correct size, or at least very close to it.
I'm not sure...they're coated with whatever D&D coats them with. I sprayed them with BBQ paint where the bungs were welded in. It's obvious in that pic, but now that it's all baked on it's not obvious at all.
pepper
Street Tracker
Yes, you can use vacuum gages and install in-line dampers so the needles don't swing as much. Low tech, low expense and works as well as manometers in my experience. You can buy them off the shelf pre-made or make your own.
Gretsch
Rocker
Thanks! [strike]Got a link for the pre-made ones?[/strike] Never mind I found this.
http://www.davida.co.uk/type.php?id=gauges
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pepper
Street Tracker
You got it. If you spend some time googling or ebaying you can probably find an inexpensive pre-made set. Or rig up your own if you can scrounge up individual gages with the same resolution. Hell NAPA or autozone/checkers may have gages in stock. No need to spend precious beer money on a fancy set, they all work the same.
sweatmachine
moped
nice! You won't regret it.
sweatmachine
moped
oh yeah, he's made 'em before.