Jetting with foam filter and aftermarket exhausts

I have a VF1000 engine and it has a aftermarket foam air filter.
I had hard starting and running and I increased the idle jet from #38's to 40's.
It starts much better now when cold or warm.

Now I am working on the main jets. I started with 125's and just went up one step to #128's.
Seems to have better response after 1/4 throttle and no back firing .

Has anyone been through all of this before.

I know many VF1000R and F owners have after market exhausts but if the air intake has modifications like a foam filter it would seem that rejetting would be necessary.

Has anyone got any info on this???

 

So NO ONE has any experience rejetting a vf1000R or VF1000F ????

 

Where did you get the Jets for the carbs. I am in need of jetting my carbs due to some major hesitiation that I have been fighting for a while.

 

Factory Pro ,San Rafael California, 1-415-491-5920

#40 slow jet

 

Bikes at that altitude always need SMALLER jets because of the thinner air. MISTAKE.... LEANER JETS-sorry.
Kawasaki actually sells their bikes in some geographic locations already re jetted from the factory to account for high elevations

The VF 1000F shop manual shows #150 mains for the front and #145's for the rear on the VD72A carb (49 state) I think HONDA was making sure the engines did not get too hot on those 1984 first year bikes.


The VF 1000F California model with VD75A carbs are #112's for the front and the rear are #110 main jets.
The VF 1000R 49 state AND CANADA are VD 77A and VD85J carbs with #125 mains Front and rear.
The VF1000R California model are #122 front and 120 rear. VD78A carbs. (stingy in 100º weather) not good.

VF1000R is 36mm throttle bore. VD series.
Vf1000F is 36mm throttle bore. VD series.

So you can see that mains as large as #150's were used in 49 state areas. A wide range.
I do not know if the needles were different.

Also the float level in VF1000F's was .300 49 state ANd California.
The float level in the VF1000R's was .350 Canada and .33 in California.

Remember that CANADA is VERY cold so it can handle more gas.

 

Whoops!!! must be getting tired - sorry.

 

Thanks for catching that TinkernWstuff!!

 

Donald don't you have long intake manifolds on that engine? That's going to give you a weaker signal at the valve at idle and lower rpms. You will need to richen up. For test purposes you may have to drill some jets outs. Do this by hand using a pin drill. Doing it that way the drill bit acts more like a reamer. Then you can spin the jet along the flutes of the drill for smoothness of the hole. Start with an under sized (to what you want) bit and work your way up. The jets should work fine for testing how big you may have to go. Then with proper plug testing you can adjust your A/F ratio for higher rpms. You may have to richen the other jets depending on throttle position and rpms.

1) air screw Idle to just off of idle (not the idle screw)

2) pilot jet 1/16 to 1/4 throttle

3) jet needle 0-1/2 throttle, work with the needle shape first, then the clip
position

4) needle jet 1/8-3/4 throttle, also called nozzle, most Keihins don't interchange

5) main jet 1/2-full throttle

 

Thanks for the info. I am using the stock carbs now. Actually a set of carbs from a vf1100.
I could not use the long intakes and the twin carb set up because the needles for those carbs have been discontinued.

 

Yes BUT... I do not have stock exhausts so the flow is increased.
Also I was looking at the main jets I took out and mistakenly thought they were #125's but upon closer inspection
I see that two were#120's and two were #128's so now all 4 jets in the engine are 128's.
The stock engines probably need that because of the fairings, and the fact that those front cyclinders are right behind the radiator and are running hot.
I noticed that early in the morning that the front two cylinders (with stock jets) were making a little steam from condensation way before the rear cylinders.
I have my front and rear exhaust seperate, no balance chamber. But I have equal length front and rear headers.

My engine has NO fairings around it, and the radiator is not right up against the front cylinders.
Lots of air all around.

 

After changing to the 128 mains in all four cylinders I had to re sync the carbs. Much better now. nice and crisp throttle response.

BTW I really like the Motion Pro sync tool that I bought.
Works well and not complicated at all/ I wish it came with a cloth pouch or case though or if they would sell one for it.

 

you need a different gas tank, that peanut just doesnt flow well

 

Ok got it. Your basically back to stock carburation and manifolds. Now that you have it running better with larger jets you can start to tune with the needles. Not sure about your carb needles having grooves in them for adjustments. Most likely not. You can mic some very small washers for calibrating. You need washers with about .020" thickness. That's close to what the cut grooves were spaced at. If you need more fuel just add one washer under each needle for starters. If those carbs have the plastic twist cup to hold the needles in, then you may only be able to add two or three at the most if needed. If you need more than three then you need different needles. (more taper) Also if still lean on startup and shortly after before it gets hot raising the float a tad may help along with more pilot gap. It will also give you more fuel though most of the carb openings. Looking good. Hows that thing sound with your kind of straight pipes? Loud?

 

I might build a custom tank later this summer or this winter.
The carbs are off of a VF1100 so I do not know or remember what the needles were.
Have to re check.

Thanks for the comments.

 

ima call that the "double deuce"

 

Forgot to tell you about the pipes. Sounds like a sprint car but not too loud.
I will try to make a video and post it this week.