Reduce Pod Air Flow vs Rejetting

[Darin Jordan]

My GS850G with 4-1 Header and Stinger insert, running K&N Pods, has the Dynojet Stage 3 kit installed. However, their recommended 160 Mains were WAY too rich... WAY. The bike wouldn't bust 70 climbing over Snolqualmie Pass (3500ft).

I've been running it with their 155s for about 13,000 Miles and it's generally fine, but still was "fat" during the hotter summer days.

I just did some "minor" carb work (replaced the needle/seats, bowl gaskets, readjusted floats) and decided to take the opportunity to re-jet. Bought the Dynojet 150s, and opened them up (VERY carefully) with a 1.65mm Jet Drill, which turns it into roughly a 152.5 or so.

Road it last night for the first time and it feels crisper and seems to be just about right.

As many will say here, Pods can be a pain in the butt, especially for those who aren't "mechanical". However, if you can wrap your mind around the jetting procedures and what adjustments affect which part of the cycle, it's not really brain surgery. On mine, the only adjustments I've really had to make after installing the Stage 3 kit per instructions, and once the carbs were setup and balanced and the float levels set correctly, was to swap the main jets, which can be done with the carbs on the bike.

Once it's setup, it's excellent running, and looks pretty cool as well.

 

[TxGSrider]

My GS850G with 4-1 Header and Stinger insert, running K&N Pods, has the Dynojet Stage 3 kit installed. However, their recommended 160 Mains were WAY too rich... WAY. The bike wouldn't bust 70 climbing over Snolqualmie Pass (3500ft).

I've been running it with their 155s for about 13,000 Miles and it's generally fine, but still was "fat" during the hotter summer days.

I just did some "minor" carb work (replaced the needle/seats, bowl gaskets, readjusted floats) and decided to take the opportunity to re-jet. Bought the Dynojet 150s, and opened them up (VERY carefully) with a 1.65mm Jet Drill, which turns it into roughly a 152.5 or so.

Road it last night for the first time and it feels crisper and seems to be just about right.

As many will say here, Pods can be a pain in the butt, especially for those who aren't "mechanical". However, if you can wrap your mind around the jetting procedures and what adjustments affect which part of the cycle, it's not really brain surgery. On mine, the only adjustments I've really had to make after installing the Stage 3 kit per instructions, and once the carbs were setup and balanced and the float levels set correctly, was to swap the main jets, which can be done with the carbs on the bike.

Once it's setup, it's excellent running, and looks pretty cool as well.

View attachment 54947

Every Dynojet kit Ive owned was too rich. Ive got them in my ATVs and have used them on bikes and they are always that way. I suspect its for safety. A slightly rich engine runs cooler and is less likely to cause damage. On my ATVs I ended up lowering the needles 1-2 positions and using smaller mains. I have bungs welded into the exhaust on two of them to confirm my findings with a wideband. They are still slightly rich.

 

[Agemax]

My GS850G with 4-1 Header and Stinger insert, running K&N Pods, has the Dynojet Stage 3 kit installed. However, their recommended 160 Mains were WAY too rich... WAY. The bike wouldn't bust 70 climbing over Snolqualmie Pass (3500ft).

I've been running it with their 155s for about 13,000 Miles and it's generally fine, but still was "fat" during the hotter summer days.

I just did some "minor" carb work (replaced the needle/seats, bowl gaskets, readjusted floats) and decided to take the opportunity to re-jet. Bought the Dynojet 150s, and opened them up (VERY carefully) with a 1.65mm Jet Drill, which turns it into roughly a 152.5 or so.

Road it last night for the first time and it feels crisper and seems to be just about right.

As many will say here, Pods can be a pain in the butt, especially for those who aren't "mechanical". However, if you can wrap your mind around the jetting procedures and what adjustments affect which part of the cycle, it's not really brain surgery. On mine, the only adjustments I've really had to make after installing the Stage 3 kit per instructions, and once the carbs were setup and balanced and the float levels set correctly, was to swap the main jets, which can be done with the carbs on the bike.

Once it's setup, it's excellent running, and looks pretty cool as well.

View attachment 54947

Dynojet jets are measured by size, so a 150 DJ jet is 1.50mm, therefore you have just drilled your jets out to 1.65mm, or a 165 main jet!

 

[Darin Jordan]

Dynojet jets are measured by size, so a 150 DJ jet is 1.50mm, therefore you have just drilled your jets out to 1.65mm, or a 165 main jet!

Sorry, but that's not correct... 1.65mm = 0.0649"

A DJ150 = 0.064" = 1.6256mm (1.6mm)
A DJ155 ~= 0.0665" = 1.6891mm (1.7mm)

A DJ165 ~= 0.0715" = 1.8161mm (1.8mm)

So, a 1.65mm = 0.6496 = 0.065" = 1.651mm, so between the DJ150 and the DJ155, hence, ~ 152.5.

I own jet drills from 1.6mm through 1.8mm, and verified the sizes prior to drilling. All coincide with the cross-reference charts.

 

[Agemax]

Dj jets are measured according to size of hole, in MM. Mikuni jets are measured by flow rate, cc/minute

 

[Darin Jordan]

Dj jets are measured according to size of hole, in MM. Mikuni jets are measured by flow rate, cc/minute

I just posted all the information above. According to the Cross Reference charts, and to actual measurements, a DJ150 is NOT 1.5mm... It's 1.6mm, just like the cross-reference chart indicates. And, the DJ155 is NOT 1.55mm, it's 1.7mm, which is what I physically measured mine to be.

Not trying to be an ass, but this is what the numbers and the charts show.

 

[Darin Jordan]

Dj jets are measured according to size of hole, in MM. Mikuni jets are measured by flow rate, cc/minute

I contacted Dynojet and they confirmed that a DJ155 IS 1.55mm, as you suggested, so it's not that I don't believe you. It's just that the actual jets didn't measure to these numbers.

Either way, the Jets I have now are working, so that's what really matters to me. What they are suppose to measure, and what they physically measure, seems to be at odds with the sets I have.

 

[Agemax]

if you look closely at a DJ main jet they are slightly tapered, or "venturi machined" as DJ like to call them.
This can understandably lead to inaccurate measurements

 

[Darin Jordan]

if you look closely at a DJ main jet they are slightly tapered, or "venturi machined" as DJ like to call them.
This can understandably lead to inaccurate measurements

Sounds reasonable. Well, what I have now is physically sized between a 150 and a 155, and the bike is running cleanly, so I'm going to go with that for now.

 

[Burque73]

Not to get this thread sidetracked but this may be pertinent here.

I saw a buddy's 78 KZ 1000 on Sunday and the carb boots to the head were badly cracked. He said they were recently replaced too, which was weird.

Do the carbs bouncing around, without the airbox to support the back side, tend to stress the boots, shortening their life? Maybe you guys that run pods already thought of that and support them somehow.

 

[Nessism]

The carbs do hang unsupported when using pods, but that typically doesn't cause issues as long as the boots are fresh.

 

[Darin Jordan]

Sorry, but that's not correct... 1.65mm = 0.0649"

A DJ150 = 0.064" = 1.6256mm (1.6mm)
A DJ155 ~= 0.0665" = 1.6891mm (1.7mm)

A DJ165 ~= 0.0715" = 1.8161mm (1.8mm)

So, a 1.65mm = 0.6496 = 0.065" = 1.651mm, so between the DJ150 and the DJ155, hence, ~ 152.5.

I own jet drills from 1.6mm through 1.8mm, and verified the sizes prior to drilling. All coincide with the cross-reference charts.

View attachment 54955

Agemax, I owe you an apology based on the information we exchanged yesterday. You got me thinking about things, and so I went home to double check and, though I'm confused as to how my physical measurements were so off, YOU WERE CORRECT! 1.65mm was chosen based on that Jet Comparison Chart, which seems to get referred to here and on other sites a LOT, but it's physical diameter measurements are INCORRECT in regards to the equivalent Dynojet offerings.

As you stated, the DJ150 = 1.50mm, which is 0.059", not 0.064", as the chart shows. Same for the others.

Everything I was calculating was based on that chart, which clearly is incorrect for the DJ sizes. So, you were right... 165s were what I had in there. Would have been a disaster trying to head into the mountains.




Please forgive my ignorance. I rejetted back to the 155s last night. That, combined with the correct float levels seems to have put the mixture very close.

 

[Agemax]

Agemax, I owe you an apology based on the information we exchanged yesterday. You got me thinking about things, and so I went home to double check and, though I'm confused as to how my physical measurements were so off, YOU WERE CORRECT! 1.65mm was chosen based on that Jet Comparison Chart, which seems to get referred to here and on other sites a LOT, but it's physical diameter measurements are INCORRECT in regards to the equivalent Dynojet offerings.

As you stated, the DJ150 = 1.50mm, which is 0.059", not 0.064", as the chart shows. Same for the others.

Everything I was calculating was based on that chart, which clearly is incorrect for the DJ sizes. So, you were right... 165s were what I had in there. Would have been a disaster trying to head into the mountains.


View attachment 54976

Please forgive my ignorance. I rejetted back to the 155s last night. That, combined with the correct float levels seems to have put the mixture very close.

No worries Darin, just glad you got your bike sorted out finally.

 

[PardonMe4687]

Not to get this thread sidetracked but this may be pertinent here.

I saw a buddy's 78 KZ 1000 on Sunday and the carb boots to the head were badly cracked. He said they were recently replaced too, which was weird.

Do the carbs bouncing around, without the airbox to support the back side, tend to stress the boots, shortening their life? Maybe you guys that run pods already thought of that and support them somehow.

I hadn't thought of this, but I'm glad you brought it up. I see that Nessism stated that with new boots this isn't an issue. I do have new boots on my bike, but I'd rather be safe than sorry. So I'll probably go ahead and fashion some sort of support for the carbs to ensure the longevity of the boots.