Tweet
Dynojet kit 98-06 600 Post How to Tune Carbs with Infared
There seems to be quite some misconception of dynojet kits for the post kat's on this forum. The Dynojet kit for the post kat's is a great addon to any modified or stock bike that comes with everything you need including directions (with bad advice). A well-tuned Dynojet kit will bring out the beast in these bikes.
First here are a few links that will give you good advice on cleaning and the basics for understanding the Mikuni carburetors on our motorcycles.
CARBS 101: http://katriders.com/vb/showthread.php?t=63344
CARBS 102 (Video): http://katriders.com/vb/showthread.php?t=131010
Doing an idle drop (after tuning) http://katriders.com/vb/showthread.php?t=76286
Dynojet's PDF for this jetkit (for general guidance) http://www.dynojet.com/pdf/3159.pdf
Factorypro CV carb tuning (help decipher where your problem may lie) http://www.factorypro.com/tech/tech_...m_engines.html
**NOTES**
Dynojet uses a different numbering scale than FactoryPro and OEM, so please understand that and do not confuse the two.
Again, your carbs MUST BE CLEAN before starting this process otherwise you're just adding more complications onto a bad problem. Also make sure all of your o-rings are in good condition and sealing properly.
**Tools Required **
1. Phillips and flathead screwdrivers
2.Set of allen wrenches
3. Infared thermometer
4. Synchronizing tool (homemade or otherwise)
5. Much patience as this will require multiple tear-downs to get perfect.
Getting started, remove your carbs from the bike and drain the fuel properly. We'll do the longer part first. Remove the bowl carefully and remove the main jet.
The Dynojet instructions (Do NOT folllow the Dynojet instructions) says that it recommends DJ110's for OEM exhaust systems and DJ116's when using the K&N air filter. You should NEVER use the K&N air filter as these carburetors rely on having a proper vacuum in the air filter box to pull in the proper amount of fuel.
My recommendation would be to run a DJ114 jet for OEM exhaust systems and DJ116 for aftermarket exhaust systems (stock headers or aftermarket). There will be fine tuning in this later.
Screw in the new jet that you have chosen and while you're in here verify the floats are set properly. It is recommended to set the floats at about 14.6mm from the bowls surface. I have chosen to do 14.86 which is a negligble difference. Set the carbs on an angle that will allow the metal flange to touch the needle but NOT compress under the weight of the float. It's semi difficult to understand. You will notice the floats being in 3 different positions as you tilt the carbs.
The 1st position which is with the carbs vertical, you will see the floats completely relaxed with no pressure on the needle.
For the 2nd position; as you tilt the carbs more; you will see the floats just land softly onto the needles with their own weight not compressing the flange onto the needle.
The 3rd position; with the carbs more horizontal; you will see the float drop a considerable amount under its own weight.
Below is a picture of the carbs taken in the 2nd position. This is the position of which you measure the float heights.
You want to concentrate on lining up your measurement tool with the middle of the float (the middle is the highest point when they're at the right angle)
Do all 4 jets and all 4 floats. Reassemble the bowls and we will now move onto setting the idle screw.
From the factory there is a copper plug that must be removed on the idle screw. Carefully remove it (further instructions in dynojet kit) and then snugly screw the idle screw in all the way (do not force it, just naturally screw it in until it stops itself) From this point, unscrew each screw 2.5 turns. I count each half-turn as "50" and I count to "250" to help reduce A.D.D. errors and having to start over.
We're now done with the belly of the carbs.
Remove the carb boot covers; the boots; the white plastic clip with the spring attached; and then the needles. Install the "C-clip" (from dynojet kit) CAREFULLY on the Dynojet needle in the THIRD POSITION FROM THE TOP (dynojet instructions posted above have the correct directions for this)
Take the plastic spacer from the OEM needle and place it underneath the C-clip. Also take the OEM spacer that was above the OEM C-clip and now put it on the dynojet needle above the dynojet C-clip. Note the image below.
Reinstall the needle into the boot, then place the white plastic clip WITH SPRING back onto the needle. Use the OEM long springs that go between boot and the cover. Do not use the Dynojet ones. Reinstall boot into carbs and replace cover.
Reinstall the carbs into your bike with airbox but leave gas tank off. Some people use a lawn mower gas tank elevated above bike, or a longer tube with the stock gas tank elevated above the bike. Personally, I hold the gas tank above the bike, fill up the carbs (using the PRIME position) then return the petcock to the normal position and carefully set aside the gas tank. This requires refilling the carbs several times throughout the procedure if you're slow.
Using your carb tool of choice (I use a homemade tool) synchronize your carbs. Remember to place a fan blowing the radiator and engine from the front to cool your bike during this procedure.
After your carbs are sync'd, let the bike cool a little bit, then start up the bike. Use your infared thermometer to get a reading from the exhaust manifolds. Read them all in the same position. I choose right on the peak of the curve coming out of the heads.
The sweet area (after bike is heated up) seems to be about 450F. I'm fine with 405 - 460F. Please understand you are NOT tuning to get a certain temp, but to verify that all carbs are indeed running at about the same power.
As the bike is heating up, keep hopping to the next cylinder and getting a reading so you can see the rate at which they heat up. They should be heating up at a consecutive rate. This method is the easiest to catch a cylinder running rich (heats up slowly) or a cylinder running too lean (heats up very quickly)
If you find all your cylinders are running correctly (preferably within +/- 25F of eachother), you can put the bike back together and take it for a run. Your bike should pull very hard 7500 RPM's to redline. You should be able to give it full throttle in any gear WITHOUT BOGGING DOWN.
Please check the FactoryPro carb tuning page for understanding WHY picking the main jet is the most important before fiddling with anything else. http://www.factorypro.com/tech/tech_...m_engines.html
If your cylinders are running close to eachother and your bike is a raped banshee, you're done!
If your bike just doesn't run right, cylinders aren't running close to similar temps, or the exhaust note doesn't seem "balanced" at cruise speed; time to adjust the floats again. Make note of which cylinders have a different rate of heating up than the others and follow this formula again:
Cylinder running rich = heats up slowly (slightly lower the height of the float using same method as pictured above). Cylinder running too lean = heats up very quickly (slightly raise the float using the method pictured above). Remember, you're comparing all 4 of them together and finding the oddball.
Resynchronize your carbs and check the temps again. Do this method until they're all running close and you won't regret it.
From here I recommend using the Factorypro website for fine-tuning certain RPM ranges.
First here are a few links that will give you good advice on cleaning and the basics for understanding the Mikuni carburetors on our motorcycles.
CARBS 101: http://katriders.com/vb/showthread.php?t=63344
CARBS 102 (Video): http://katriders.com/vb/showthread.php?t=131010
Doing an idle drop (after tuning) http://katriders.com/vb/showthread.php?t=76286
Dynojet's PDF for this jetkit (for general guidance) http://www.dynojet.com/pdf/3159.pdf
Factorypro CV carb tuning (help decipher where your problem may lie) http://www.factorypro.com/tech/tech_...m_engines.html
**NOTES**
Dynojet uses a different numbering scale than FactoryPro and OEM, so please understand that and do not confuse the two.
Again, your carbs MUST BE CLEAN before starting this process otherwise you're just adding more complications onto a bad problem. Also make sure all of your o-rings are in good condition and sealing properly.
**Tools Required **
1. Phillips and flathead screwdrivers
2.Set of allen wrenches
3. Infared thermometer
4. Synchronizing tool (homemade or otherwise)
5. Much patience as this will require multiple tear-downs to get perfect.
Getting started, remove your carbs from the bike and drain the fuel properly. We'll do the longer part first. Remove the bowl carefully and remove the main jet.
The Dynojet instructions (Do NOT folllow the Dynojet instructions) says that it recommends DJ110's for OEM exhaust systems and DJ116's when using the K&N air filter. You should NEVER use the K&N air filter as these carburetors rely on having a proper vacuum in the air filter box to pull in the proper amount of fuel.
My recommendation would be to run a DJ114 jet for OEM exhaust systems and DJ116 for aftermarket exhaust systems (stock headers or aftermarket). There will be fine tuning in this later.
Screw in the new jet that you have chosen and while you're in here verify the floats are set properly. It is recommended to set the floats at about 14.6mm from the bowls surface. I have chosen to do 14.86 which is a negligble difference. Set the carbs on an angle that will allow the metal flange to touch the needle but NOT compress under the weight of the float. It's semi difficult to understand. You will notice the floats being in 3 different positions as you tilt the carbs.
The 1st position which is with the carbs vertical, you will see the floats completely relaxed with no pressure on the needle.
For the 2nd position; as you tilt the carbs more; you will see the floats just land softly onto the needles with their own weight not compressing the flange onto the needle.
The 3rd position; with the carbs more horizontal; you will see the float drop a considerable amount under its own weight.
Below is a picture of the carbs taken in the 2nd position. This is the position of which you measure the float heights.
You want to concentrate on lining up your measurement tool with the middle of the float (the middle is the highest point when they're at the right angle)
Do all 4 jets and all 4 floats. Reassemble the bowls and we will now move onto setting the idle screw.
From the factory there is a copper plug that must be removed on the idle screw. Carefully remove it (further instructions in dynojet kit) and then snugly screw the idle screw in all the way (do not force it, just naturally screw it in until it stops itself) From this point, unscrew each screw 2.5 turns. I count each half-turn as "50" and I count to "250" to help reduce A.D.D. errors and having to start over.
We're now done with the belly of the carbs.
Remove the carb boot covers; the boots; the white plastic clip with the spring attached; and then the needles. Install the "C-clip" (from dynojet kit) CAREFULLY on the Dynojet needle in the THIRD POSITION FROM THE TOP (dynojet instructions posted above have the correct directions for this)
Take the plastic spacer from the OEM needle and place it underneath the C-clip. Also take the OEM spacer that was above the OEM C-clip and now put it on the dynojet needle above the dynojet C-clip. Note the image below.
Reinstall the needle into the boot, then place the white plastic clip WITH SPRING back onto the needle. Use the OEM long springs that go between boot and the cover. Do not use the Dynojet ones. Reinstall boot into carbs and replace cover.
Reinstall the carbs into your bike with airbox but leave gas tank off. Some people use a lawn mower gas tank elevated above bike, or a longer tube with the stock gas tank elevated above the bike. Personally, I hold the gas tank above the bike, fill up the carbs (using the PRIME position) then return the petcock to the normal position and carefully set aside the gas tank. This requires refilling the carbs several times throughout the procedure if you're slow.
Using your carb tool of choice (I use a homemade tool) synchronize your carbs. Remember to place a fan blowing the radiator and engine from the front to cool your bike during this procedure.
After your carbs are sync'd, let the bike cool a little bit, then start up the bike. Use your infared thermometer to get a reading from the exhaust manifolds. Read them all in the same position. I choose right on the peak of the curve coming out of the heads.
The sweet area (after bike is heated up) seems to be about 450F. I'm fine with 405 - 460F. Please understand you are NOT tuning to get a certain temp, but to verify that all carbs are indeed running at about the same power.
As the bike is heating up, keep hopping to the next cylinder and getting a reading so you can see the rate at which they heat up. They should be heating up at a consecutive rate. This method is the easiest to catch a cylinder running rich (heats up slowly) or a cylinder running too lean (heats up very quickly)
If you find all your cylinders are running correctly (preferably within +/- 25F of eachother), you can put the bike back together and take it for a run. Your bike should pull very hard 7500 RPM's to redline. You should be able to give it full throttle in any gear WITHOUT BOGGING DOWN.
Please check the FactoryPro carb tuning page for understanding WHY picking the main jet is the most important before fiddling with anything else. http://www.factorypro.com/tech/tech_...m_engines.html
If your cylinders are running close to eachother and your bike is a raped banshee, you're done!
If your bike just doesn't run right, cylinders aren't running close to similar temps, or the exhaust note doesn't seem "balanced" at cruise speed; time to adjust the floats again. Make note of which cylinders have a different rate of heating up than the others and follow this formula again:
Cylinder running rich = heats up slowly (slightly lower the height of the float using same method as pictured above). Cylinder running too lean = heats up very quickly (slightly raise the float using the method pictured above). Remember, you're comparing all 4 of them together and finding the oddball.
Resynchronize your carbs and check the temps again. Do this method until they're all running close and you won't regret it.
From here I recommend using the Factorypro website for fine-tuning certain RPM ranges.
Comment