VOR jetting

[DPellarin]

Hi,

I was wondering if I could get any input on something I am helping my uncle out with. He rides a '00 VOR 400 Enduro and the bike has had jetting problems since it was new. The problem consists of loading up when ridding slow in tight areas and a sputter when the throttle is held at 1/8 throttle. It also pops a lot out the pipe when the throttle is released after being opened. The carburetor is a Dell Orto VHSB 38 flat slide model. I have tried leaning the pilot and needle clip separately. When the needle is leaned out 1 clip position it got worse, so I put it back to stock and went smaller on the pilot, this helped some but it still pops when easing off the throttle and still has the sputtering at 1/8 throttle. On slow going trails the bike will load up and stall and then it takes a while to start back up. I am thinking that the de-acceleration popping is a lean condition, but it is showing signs of being too rich at the same time. This is what is confusing me.

Any suggestions would be appreciated.

Thanks,
Domenic

 

[weimedog]

I pulled the carb off my 2001 VOR 503 V-Cross. It has a 38mm Flat slide as well. It has run crisp at altitudes from 1000ft above sea level to over 10,000. All I have done is adjust the needle. I am now running it at 1000-1500ft and here is the jetting it currently has:

Main: 185
Needle: K32 (Clip is in middle slot...I put in the leaner top position at over 7000ft above sea level)
Slide: 50
Jet for choke circuit: 40
Idle jets: 35 outer pilot jet. (There is an inner emmusion tube as well, its a 35) (I actually plan to install a 36 pilot to have it start easier at this lower altitude. Right now I have to choke it on the first kick, an then turn the choke off and it starts the next kick. When I put in the 36 it will start with no choke as it did at altitude)

My air screw is 2 1/4 turns out.

I don't know if the 2000 VOR 400 Enduro has the same carb or not.Some of the older 503's had round slide carbs. Their jetting is all different.

If you call Brad at Fun Wheels in Longmont Colorado, he may be more help as he runs a 400 V-Cross and a 503 Enduro. His phone number is: 1-303-678-7879.

Also there is a website www.vor.it Send an email and they usually answer. There is a button for the VOR usa facility as well. They certainly can help.

You may have some other issue as well. Possibly valves not adjusted properly. Give Brad a call.

I also looked at the 2001 model year service manual. It lists the same jetting for both the 400 and 503 V-cross/MX models. It lists some differences between mine and the 400 Enduro. Here are the parts listed unique to the 400 Enduro:

Needle: K29 for Enduro instead of the K32 Mine has.
Nozzle: FL262 for the Enduro instead of the FL260 Mine has. This is that tube that holds the main jet. I have no idea why these would be different.

They list your Pilot as a 36...instead of the 35 mine comes stock with.

There are substantial differences between the Enduro's and V-Cross models. Different Cam Timing, Carb jetting, and Compression. That might require the different jetting they list.

 

[weimedog]

I forgot one thing in my prior post. When you assemble the needle/slide there is a small washer that goes over the needle and clip. That washer can fit on either side. Its supposed to be on TOP of that clip, not under it. That will change the position of the needle.

Also I dug through the parts book and the Carb should be the same as the one on my V-Cross. Only differences are the ones I listed above. Needle and some jetting stuff to compensate for the different pipe, cam timing, cylinder head, and compression.

If it was jetting, the type of thing you discribed would b a miss match between the slide cutout or adjustment vs. needle jetting. Too rich a needle taper or needle position along with too lean a slide/ pilot jet combination would be my guess.

I would also make certain you have everything stock to start with and then go through that itterative process of setting your idle speed/air screw to where you have the loweest slide position. (Idle adjust furthest out to get the idle speed you want). Then turn the air screw 1/4 turn further out.

Another thing I have found it my bike runs much better with pump gas around 90 octane. If you bought that bike used and it was tuned for either race gas or a different pipe you might see jetting changes from stock. Its worth a peek.

One last possibility is the float bowls& shuttoff valve. If you have slightly lean jetting AND too high a float bowl / or even a float valve that doesn't seal well you could have that odd mix of too rich and too lean conditions. The fuel over flows into the manifold at lower speeds because the float doesn't slow it down or stop it. Then after a period of higher speed running with the float bowl drawn down..it gets lean because you were attempting to solve what appears to be a rich condition and the jetting is a little lean. I run into that situation frequently with my old Vintage bikes. Just didn't think of that type of issue with newer stuff... but why not? Another simple thing to check.:)

 

[DPellarin]

Thank you for the information, it is very helpfull. My Uncle is the first owner of the bike and it is all stock with the exception of a BigGun silencer. I have spoken to Fun Wheels and they reccomended running the needle in the upper most clip position. I tried this and the sputtering got worse and the popping increased. I will check that washer on the clip and make sure it is on top. I have thought about the float, but I am not sure how to set it on this type of carburetor where the floats are independent and ride on pins.

Thanks again,
Domenic

 

[weimedog]

I not as focused on setting the float level as having a defective valve. If the float if not shutting off the fuel flow the float level adjustments won't help.

I guess the other thing that I'm trying to get a handle on is any possible difference between the 400's we have experience and your. Do this first. It can be hard debuging an issue without actually being there. So I need to eliminate as many variables as possible when something isn't reacting in a way similar to others of the same configuration.

So far the only big picture scenerio that makes any sense is the float bowl and valve deal I discussed earlier. This is because I jerked around the jetting on My 503 to try and duplicate that condition with the adjustments available with stock jetting. I came closest with having too lean a needle position along with cranking in the air screw. It didn't really load up much, it just got hard to start, a little sluggish off the bottom along with popping like hell on de-acceleration. But again this was a 503 V-Cross and its a lot different.

I don't think the silencer can make enough difference to require a complete jetting review. There is a guy online "VOR492" who has a Big Gun brand silencer on his. I wonder if he might be able to let us know if rejetting was required with that change.

I still don't know the actual jets you have. Did you write down or posts those?

Where is your location? I have a couple of cross country treks and if they bring me around your area I could drop in and take a peek.:)

I guess with the popping and sputtering in midrange along with loading up on the bottom I would tend to wand to pull the needle out to fatten up the midrange and lean out the bottom with air screw adjustments, pilot jet changes, slide changes, or at worst case a different needle taper.

One thing that is different between the Enduro's and MX versions is the pipe/silencer combination. I wonder (even thought before I dismissed the possibility) if putting a Big Gun silencer changed the pipe charateristics to be more like the MX bikes. The MX bikes do have a different needle as I said before. Thats another (Slim) possibility.

 

[weimedog]

I suspect Brad is going to a point where his 400 works in Colorado. After I finished that last post....I remembered his Enduro had the needle in the leanest position.

Here is my littany with my V-Cross:

When I was at 5000 ft I had the needle in the most lean position with the clip. I also (even though it was wwrong) had that washer between the clip and slide. It ran best that way. That sort of split the difference between the top or leanest needle position and the middle one. Every thing else was stock. The air screw was 2 turns out.

When I came to New York I had a little popping on deacceleration but other than that things were running fine. It was a bit harder to start...5 or 6 kicks instead of one or two.

So I put the needle in the middle position with the clip on the proper side and all the popping went away. I had to re-adjust the idle and actually ended up with a lower slide position. (Idle screw out another 1//2 turn) and the air screw 2-1/4 turns out. The Poppiing is gone. It runs sharp in the woods. The Starting still takes two kick sometimes three. I have to make one kick with the choke on, then turn OFF the choke for the rest and it start easy. But not as many first kick starts like it did at altitude. I plan to put a 36 pilot jet to see if I can get back to the one kick-no choke behavior it had in Colorado. Thats How mine has reacted...but I realise its a V-Cross 503 and yours is a 400 Enduro.

:)

I will have a new 450 Enduro next week. It should react similar to your 400. I will pull IT apart and post the setup as it evolves. That 450 should be closer to your 400 than my 503.:)

The reason I am trying go through all this crap is I haven't ruled out a possible problem with the ignition or other components other than Carburation. Like a possible problem float bowl valve.:) Just want to sync up and eliminate variables so long distance help is possible.

 

[DPellarin]

Thanks for your continued support on this. I pulled the carb apart and inspected the float shut off valve and it looks good. I also set the floats per what the Dell Orto tuning manual states. This is that when the inlet needle is closed, the float arm is parallel to the base. I found that they were a little high, but not much. I lowered the arm to parrallel. I also put in a smaller pilot, a 32, the one in there was a 36. I wanted to try a 34, but could not get one from my dealer. With the smaller pilot, I moved the needle to the 3rd position down from the top with the wahser in the correct place. Is the 3rd position from the top considered the middle position on this needle because there are only 4 positions? With the richer needle position and leaner pilot, the bike runs much better. The 1/8 throttle sputtering seems to be gone and it does not pop when deaccelerating. I noticed that it takes a few more kicks when cold to start, so I might try a 34 pilot next. Things are definitly looking better! The jetting before I changed it was as specified for the 400 Enduro in the owners manual. (36 pilot, 185 main, K29 needle in second position from top). I let the bike idle for a while and there was no signs of loading up. It feels much more responsive off the bottom and does not have the flat feeling it had before. I am going riding this weekend so I will know more when we get it out on the trails.

Also, I am in California at sea level to 1000ft with temps in the 60-70F range.

Thanks again,

Domenic

 

[weimedog]

Glad you are getting some results. As far as the needle position, my needle for what ever reason; only has THREE slots. That is why I was using that washer to sort of split the difference between clip positions. Even though I knew it wasn't where the washer was supposed to be. If you can't get a 34 pilot, let me know. I can track one down and let you know where to get it.:)