810cc and VM24 jetting?

Hi,
If you have 810cc bigbore with VM24 and 4 to 1 exhaust. Quality pods with air corrected jets (setup should be similar to using stock airbox)

What jetting should I use then?

Right now:
Pilot: 17.5
Main: 112.5
Needle: 4th posistion

Should the pilot be smaler and main stay?

As i stated in the other thread.
You should put all the setting to stock 650 as a baseline and increase the mains for the capacity increase.
The air correctors richen up the bottom end so fitting bigger pilots coupled with these may cause over richness .

I dont wanted to spam/destroy your thread when it comes to your jets, wanted to ask all newbe questions here instead



So I should go back to pilot 15, and stay with 112,5 main?

I understand 102 is stock (650) so going to 112,5 its a increase of 10,5 for going from 650 to 810 and 4to1 exhaust.

gordone wrote: I dont wanted to spam/destroy your thread when it comes to your jets, wanted to ask all newbe questions here instead

So I should go back to pilot 15, and stay with 112,5 main?



I understand 102 is stock (650) so going to 112,5 its a increase of 10,5 for going from 650 to 810 and 4to1 exhaust.

Man with all due respect, your needlessly beating your head against the wall. zed1015 is a very experienced engine builder and racer. Please listen to his suggestions. Especially if the build or carbs are new to you. You need a base line to start from. Then you can test and tune off your given baseline. You can’t tune An engine on a Internet forum.

I have respect for all members and specily Zed and other with deep knowledge, we can learn alot from.

Some background info, I’m 90% happy with how my engine perform today, it has been back and forth over some time to find current carb setup. I was planning to keep it, until I saw these air corrected jets.

My hope was that these jets can get me to close to 100% happy....

My english is not so good, so for avoiding misunderstandings I normaly ask more then one time, for avoid misunderstandings from my side... sorry for that....

If I have understand Zed correct shall I go back to stock (650 setup) for pilot (15) and leave the main jets (112,5) correct?

Then I will do that... was never mine intension to question any thing...

How does the bike run. What do the plugs look like after a nice warmed up run at 3/4 throttle and performing a plug chop. The plugs and performance will tell you what the engine needs. I have a 1978 LTD 1000 with 1980 vintage VM28ss pumper carbs. It is stock but for the carb swap, V&H 4 to 1 and Dyna S. I installed the air jet correctors and it completely smoothed out the lower rpm. I currently have 112.5 mains and the bike runs strong. I can pull about a half bike length on my sons 2014 street glide with Stage two setup. I’d say let the bike tell you what it needs. That being said at the 112.5 your at least 4 sizes larger than stock. You can do far less damage if any to a bike running it on the fat side. It’s not just the main jet, it’s the stack effect of all needle and jets combined that need attention to tweak performance. Appears you have a manual, read the carburetor section and see what circuit is working at a specific throttle percentage i.e. 0 to 1/4, 1/4 to 1/2, 1/2 to 3/4 and then WOT. That will tell you by focusing on the main jet alone your cheating yourself out of performance.

No disrespect was intended. Your correct we can all learn from the collective experience here.

EDIT, the air corrector jets are only for the pilot circuit. They my help transitioning from pilot to the main circuit but installing them has no effect on the main jet.

Mikaw wrote: . It’s not just the main jet, it’s the stack effect of all needle and jets combined that need attention to tweak performance.

EDIT, the air corrector jets are only for the pilot circuit. They my help transitioning from pilot to the main circuit but installing them has no effect on the main jet.

As you say, The stack up of all the jets add to the final size needed for the main.
In the case of the air correctors these do affect the eventual size of the main as the richening effect on the off idle mix does transition to a lessening degree throughout the rest of the fueling
In comparison to the more complicated ,less refined and crude method of lifting the needles and fitting larger pilots to try and smooth the off idle hesitation the simple use of the air correctors often result in being able to use a slightly smaller main .

As mentioned previously Gordone, You should retain all the carbs stock settings as a baseline and start with only increasing the main jet as you have for the larger capacity .
Once you are satisfied with the top end fueling you should work down.
Any slight changes needed to richen the pilot mix should be able to be covered by adjustment on the air screw.

Mikaw wrote: .
EDIT, the air corrector jets are only for the pilot circuit. They my help transitioning from pilot to the main circuit but installing them has no effect on the main jet.

[quote="zed1015" post= In the case of the air correctors these do affect the eventual size of the main as the richening effect on the off idle mix does transition to a lessening degree throughout the rest of the fueling
In comparison to the more complicated ,less refined and crude method of lifting the needles and fitting larger pilots to try and smooth the off idle hesitation the simple use of the air correctors often result in being able to use a slightly smaller main .
[/quote]

Thank you, this is what I was trying to explain when I mentioned that it will help the transition to the main circuit. I just didn’t understand completely. And it brings to light your fact. The air correctors could effect main jet size. I understand now, Without the ACJ’s installed you more than likely will be lean on the pilots with pods. Without lifting the needle you might try to increase main jet to fatten up the transition. But then once the jet needle is lifted to WOT then main could be to big. With the ACJ installed your staring with a fatter pilot in which allows you to stay fatter through the transition meaning the main size can be adjusted to be correct at WOT. MAYBE???

Thank both !

So I will go to stock pilot 15, I need to order 4 15 jets.

From reading what you saying, it looks likte it`s a big posbility that the main jets is to big.... undersood correct?
I have spare main jets in size 120, 117,5 and 115...

So what I wanted to ask about, then when I first have to import jets from US, its way cheaper also order main jets at the same time.....

Stock: 102
Right now: 112,5

So the questions is what main jet sizes should I purchase to be covered in the tuning in the spring ?

I would say that those 112.5s to 115 are around where you need to be.
I would buy some 110s but i think you are pretty much covered with what you have and you may not need them.
Every set up is different and until you actually run the bike it's just an educated guessing game.
Just be sure to start a little large on the main and work down.

Thank you, will do that

When I shall do the 3/4 throttle and then kill the engine, I need new spark plugs each time?

No! Just use the same plugs.