Accelerater pump Carburetor

[Douglass]

Hahaha! You didn't read all my all of my post did you? That's ok. I live near Charlotte NC. The center of all the NASCAR teams. Home of the Carolina Panthers. Close to the Lancaster Motor Speedway (the fastest 1/2 mile dirt track in the south). About as US as you can get. lol

Your 100% right . You had already answered the question when you told me you lived in North Carolina when I asked about the Altitude LOL.... I was going to fast bouncing around on the two sites. The site listed in Euros threw me off. Thank you for the links. I'm going to pick up a Carb for sure, and check out the Orion site.

When you adjusted the Needle clip, do you remeber what slot it ended up in? Do you know what style/brand of jets the new carb uses?

[Megadan]

Originally Posted by pete

didn't you have a koso flat slide to put on...



.

A couple of them. I have a 32mm Koso with a power jet and I also have a genuine Mikuni VM30 with a UFO on the slide.

I have quite a carb collection going lol.

[Its_not_a_honda]

[QUOTE=When you adjusted the Needle clip, do you remeber what slot it ended up in? Do you know what style/brand of jets the new carb uses?[/QUOT]

So we don't get mixed up in which direction:


I had originally ordered a jet kit from 6sigma. You tell them what you have and any modifications you have done. They send you a kit to optimize your carb. I never installed it in the original carb so I just used the main jet for this pumper carb. The other jet was made a little different so I didnt change it. Took a chance ***got in a hurry to try it***.

[Douglass]

So we don't get mixed up in which direction:

Its_not_a_honda : Perfect thank you for confirming. Last question, Did you get the pilot jet size by chance? I have a feeling I should be able to jet this carb very similar to the Mikuni. You are running the same size Main jet as a buddy of mine in South Carolina who is at about 800ft on the same bike as ours.

Megadan: I bought a Keihin Brand PZ30 pump carb. How close do you think the jetting will be on the Mikuni vs the Keihin as far as fuel supply go? I have a 30/120 in the Mikuni, should I just buy the equivalent sizes in the Keihin brand? I would plan on buying a few different sizes.

[Megadan]

Using the VM26 jetting as a starting point isn't entirely a bad idea, but you will likely have to tweak the jetting a tiny bit to run better with the pumper.

In this case, the keihin pilot jet size will likely be around a 40 (38, 40, 42). The main jet, if we are comparing genuine jets, would be around a 138 - A mikuni 120 orifice size and a Keihin 138 are the closest equivalents to one another. Wether this holds true with the jets from other companies is a different question.

[Douglass]

Originally Posted by Megadan

Using the VM26 jetting as a starting point isn't entirely a bad idea, but you will likely have to tweak the jetting a tiny bit to run better with the pumper.

In this case, the keihin pilot jet size will likely be around a 40 (38, 40, 42). The main jet, if we are comparing genuine jets, would be around a 138 - A mikuni 120 orifice size and a Keihin 138 are the closest equivalents to one another. Wether this holds true with the jets from other companies is a different question.

Awesome, thank you for confirming.

[Its_not_a_honda]

Originally Posted by Douglass

Its_not_a_honda : Perfect thank you for confirming. Last question, Did you get the pilot jet size by chance? I have a feeling I should be able to jet this carb very similar to the Mikuni. You are running the same size Main jet as a buddy of mine in South Carolina who is at about 800ft on the same bike as ours.

Megadan: I bought a Keihin Brand PZ30 pump carb. How close do you think the jetting will be on the Mikuni vs the Keihin as far as fuel supply go? I have a 30/120 in the Mikuni, should I just buy the equivalent sizes in the Keihin brand? I would plan on buying a few different sizes.

The pumper came with a 112. I put a 115 in it when I did the install. Keep in mind my bike is stock. Exhaust, air box, and spark plug. These jets have a "K" then the number on them. Here is what you get from 6sigma for the completely stock Apollo 250.

Like I said, I just used the 115 main jet from the kit that was for my original stock carb. The pumper carb had an adjustable needle already so didn't need the shims. The pilot jet was made different so I didn't change it. I could not tell what it was either. If there was a mark on it, I could not see it.

[Douglass]

The pumper came with a 112. I put a 115 in it when I did the install. Keep in mind my bike is stock. Exhaust, air box, and spark plug. These jets have a "K" then the number on them. Here is what you get from 6sigma for the completely stock Apollo 250.

Like I said, I just used the 115 main jet from the kit that was for my original stock carb. The pumper carb had an adjustable needle already so didn't need the shims. The pilot jet was made different so I didn't change it. I could not tell what it was either. If there was a mark on it, I could not see it.

Right on, this gives me a great starting point. I'm going to set the carb up just like the Mikuni as a starting point, and buy a few extra sizes. Thank you for providing all the feed back and links. I ordered the carb this morning, ill probably see it with in two or three weeks.

Douglass

[Weldangrind]

Originally Posted by Its_not_a_honda

The pilot jet was made different so I didn't change it. I could not tell what it was either. If there was a mark on it, I could not see it.

If it interests you to learn the slow jet size, you can use a hillbilly method that will get you in the ballpark. If you buy a numbered drill bit index that ranges from 61-80 (generally in the $4.00 range, including shipping from China), you can find the bit that matches your slow jet and then measure the bit with a vernier caliper. Don't trust the size marking on the index; you have to actually measure it to know for sure.
A Metric measurement will be equivalent to a Mikuni jet (eg. #38 = 0.38mm). Once you know that number, you can cross-reference to a Keihin chart.

The index will come with a pin vise, which allows you to chuck the bit and drill a jet. I've drilled several slow jets that way with good results. Here's one: https://www.ebay.com/itm/17pc-Fine-T...UAAOSwR2RaJ9~m

[Its_not_a_honda]

Originally Posted by Weldangrind

If it interests you to learn the slow jet size, you can use a hillbilly method that will get you in the ballpark. If you buy a numbered drill bit index that ranges from 61-80 (generally in the $4.00 range, including shipping from China), you can find the bit that matches your slow jet and then measure the bit with a vernier caliper. Don't trust the size marking on the index; you have to actually measure it to know for sure.
A Metric measurement will be equivalent to a Mikuni jet (eg. #38 = 0.38mm). Once you know that number, you can cross-reference to a Keihin chart.

The index will come with a pin vise, which allows you to chuck the bit and drill a jet. I've drilled several slow jets that way with good results. Here's one: https://www.ebay.com/itm/17pc-Fine-T...UAAOSwR2RaJ9~m

I thought about doing that. I used to race go karts and had to drill all my own jets back-in-the-day. There is an art to doing it correct. Thanks for that link! I am going to get that set. I have lost some of mine through the years.

[Weldangrind]

Beware that a cheap numbered index between 61-80 has a high likelihood of being a jumbled mess. I took the time to measure all of the bits and arrange them; there are duplicates and triplicates of some and zero of others. At that price, it doesn't bother me at all.

[Its_not_a_honda]

The more I ride with this new carb the more impressed I am.

One thing that is baffling me. Vibration. Lack of vibration I should say. On the dirt I can't tell that much. On pavement it is just amazing how much smother it is. I have been racking my brain trying to make sense of this. How can changing a carburetor make an engine vibrate less? I did get quite a tingle on the pavement in the pegs, seat, and grips with it stock. I did change the steel gas tank to a plastic one when I changed the carb. I wonder if that has anything to do with it?

[Douglass]

I would be willing to bet the Gas tank made the improvement. I bet the plastic absorbs some vibration, vs the metal. Being that it connects to the seat it makes sense.

[Weldangrind]

You could always put the metal gas tank back on for testing.

[ChondaChondaChonda]

Well, you convinced me enough to try a pumper carb... on my CR125 Zong powered bike. It has great torque, but is not snappy. You have to get on the throttle waaay ahead of time to get a reaction from the motor.

Hoping this gives it a little more snap.