stock carb and pod filters

[marcelm]

UPDATE :
I have increase pilot jet from stock 35 to 38 and main jet from stock 115, to 120 (maybe 121 due to manual drilling).
The engine start verry well and is running quite OK up to 1/3 or 1/2 throttle, then engine starts to stutters and has no power (I cannot say that till 1/3, 1/2 throttle has plenty of power, neither )

Then I did following trials : I removed the pod filters and run with open carb, but bike were running worse. I pull the choke and bike was running better.
I didn't pull the plugs yet.

My thinking is that is still lean and need to drill bigger holes into jets, or at least the main one.

hmm ...

[daves79x]

I think I mentioned before, you need to go to at least 130 on the main if you stock ones are 115. Yes, you are still way too lean.

Dave

[marcelm]

I think I mentioned before, you need to go to at least 130 on the main if you stock ones are 115. Yes, you are still way too lean.

Dave

Shoul I increase also the pilot one to 40 ?
As I said, bike is starting well and run well up to 1/3 - 1/2 of throttle, but maybe doesn't have maximum power, even in this in this range, also.
Just your toughts.

[daves79x]

No, just the main jet - it will take care of the whole range due to the large increase in size.

Dave

[marcelm]

Step by step, improvement is done .. many thanks to this forum members !

With the main jet increased to 130 :

The bike doesn't stutter anymore, has only a "dead point" at about 1/3 - 1/4 of WOT. After that the bike is revving quite OK.

The problem is that the spark plug is absolutely white. I never saw a more beautiful white color than this sparks ...
When throttle is more that 1/2 open, if applied chocke, instantly you feel much more and brutal power. If throttle is less than 1/2 open, when applied chocke, the bike is running worse.

Could be that the pilot jet is big enough, but the main one is still to small .... increase main to 140 ??

A little concern about the mileage. I didn't check in detail, but seems like the mileage increase, or can be due to our tests, when we open wide the throttle ....many times ..

[daves79x]

Yes, that's an indication you are still too lean on the top end (main jet). The white plugs and mileage INCREASE indicate that as well. With CV carbs, the plugs do burn pretty light in color, keep in mind. I'd hate to say 140 is right, but might be.

Dave

[Gearheadgregg]

sounds like it is having a hard time from the transition from idle circuit to main jet, think you may need one more step on the idle jet, 90% of most street use and cruising is in the idle circuit range, should help that flat spot

[marcelm]

I have increased the main jets to 140. This week, will do the test ride.
So, just to remember, actual situation : pilot jet is 38 (stock were 35), main is 140 (stock were 115), stock air box is replaced with pod filters.
Also, sorry I forgot to mention, I have put, from the beginning, a small washer under each jet needle (when I did this, my thinking was that, if I make the holes into the mains too big, maybe I can compensate, little bit, by removing the washers ....).
Out of the last riding test : when throttle is between 0 - 1/2 open, if choke is applied, the bike is running worse. This could mean that the bike has enough fuel in this range, which is controlled by the pilot jet. I'm afraid to increase the pilot. Let's see what the drive tests says. I should test each throttle range and then check the plugs ....

Marcel

[daves79x]

You're on the right track - no need to go bigger on the pilot. This is what using pods does to jetting. Hard to believe. I think you'll be pretty close with the 140s.

Dave

[Gearheadgregg]

IF your plugs are still white ! you are still lean!! The Only Way you can Check your Main Is WOT and Shut your engine down with NO idle, How many turns is your mixture screw out ? And does turning it in & out make any difference, you should be able to darken your plugs at idle or cruising with the correct slow jet, 3 1/2 turns Out with No change would indicate Too small slow jet, If not getting color on your plugs

[marcelm]

Mixture screw is 2,5 turs out, actualy.

[daves79x]

All bets are off with pods, Greg. He's on the right track and I think will be close with the 140s. Fiddling around the edges is OK after getting the mains right. CV carbs properly jetted burn on the scary side of tan anyway.

Dave

[Gearheadgregg]

too confusing, if you do 2 jet mods at the same time it is impossible to understand where the improvement has been determined, been through this with friends helping them, Started back to original and make ONE change at a time, never make 2 changes at once, I have found that the only way to get rid of the flat spot has only been accomplished by stepping up the (Needle Jet) not the (Jet needle) on a modified bike with Port and free flowing exhaust with no back-pressure, But ? starting with the idle circuit until i get some color on the plugs and even fowling them out going that extra step to far for over-rich without the ability to lean out with mixture screw will assure me that it is no longer lean,and go back to smaller slow and work it out , also My Mikuni on one of my bikes has a Fuel Mixture screw that is Reversed from a Air Mixture screw, meaning Turning it Clockwise "In" will Richen mixture unlike the CV, still think no harm done trying one more step on the slow, but if you are reaming your Jets by hand you can't go back to smaller...good luck remember One Change at a time, after reading your post we can't make a opinion on what helped the most? Slow or Main ?

[marcelm]

I understand, but I don't have to much free time to do a test ride after each single mod ... this is the issue.
After both jets size increase, I can say that I feel improvement in all throttle ranges, but specialy in 1/2 - 1/1 range, means on the main jet.

OK, test with the 140 main was done (about 20 km of riding) : spark plugs are still white. The bike was tested in all throttle ranges and spark plugs were white all the time.
Anyway, since beginning there is a huge improvement, bike has much more power. Maybe now we are around the final set-up ....

Thinking to increase main to 145 and also the pilot one to 40 ....

[Gearheadgregg]

just do your self a favor ..try the Main increase ....or the Slow jet increase only.....do Not do both at once...but your really should try the slow jet..just to be clear a Main jet increase was a must but i can't tell you how many times i got rid of a stumble and poor acceleration from a week idle circuit