Idle issues '98 flhtc
Road Warrior
Joined: Apr 2016
Posts: 1,528
Likes: 933
From: Long Island
A mity-vac can be used to test your voes. You don't even need to remove it to test it. It's a vacuum switch which as mentioned can develop leak in the actual voes or the vacuum hose that goes from the carb (or manifold) to the voes. Check the link below, scroll about 3/4 of the way down for the info on testing the voes. If original, then replace it. The contacts inside the voes get worn and oxidize. Develops resistance in the metal contact. There is no way to clean the contacts.
http://sportsterpedia.com/doku.php/t...k:evo:engctl01
If not the hose or voes, give the carb a good once over (it's probably due for it) and replace the intake seals AND the carb to intake seal. Pay attention to the small transfer ports in the carb and the small holes in things like the slow jet and emulsion tube. It takes time and a couple cans of carb cleaner to really get it clean and make sure all ports are clear. Replace the needle jet also. (not the needle, but the needle jet), the hole the needle sits in gets worn out over the years.
To me, it sounds like an intake leak but check the easier stuff first.
http://sportsterpedia.com/doku.php/t...k:evo:engctl01
If not the hose or voes, give the carb a good once over (it's probably due for it) and replace the intake seals AND the carb to intake seal. Pay attention to the small transfer ports in the carb and the small holes in things like the slow jet and emulsion tube. It takes time and a couple cans of carb cleaner to really get it clean and make sure all ports are clear. Replace the needle jet also. (not the needle, but the needle jet), the hole the needle sits in gets worn out over the years.
To me, it sounds like an intake leak but check the easier stuff first.
Grand HDF Member
Joined: Apr 2007
Posts: 3,725
Likes: 3,070
From: Brighton, MI
Just remember that link is for sportsters. There is some crossover info (like the voes info) but be careful with some of the data.
Road Captain
Joined: Jun 2014
Posts: 598
Likes: 376
From: Sweden
I managed (yes I'm clumpsy sometimes) to diconnect my VOES once.
My bike did not act anything like in the description of your bike.
But that's not to say that it could not be the VOES giving you troubles in your case.
Have you checked if the enricher/choke
works as intended?
Operates from fully engaged to fully disengaged?
Choke wire is not half stuck or binding only slowly due to vibrations returning back to disengaged?
Leaking gaskets in the intake manifold can be detected by using starting gas as the motor is running, spraying towards spots were there are gaskets.
You will notice the engine revs change as the gas enters the combustion chambers.
Some say you also can use WD40 to do the same thing. Personally tested nothing but starting gas so can not verify the WD40 in this application.
Last edited by K. Lindberg; May 11, 2022 at 10:47 AM.
Thread Starter
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Intermediate
Joined: Jun 2021
Posts: 27
Likes: 3
From: Pittsburgh
Hi Everyone. Thanks for all the information and ideas. I took out my VOES and found that it was faulty. I also found that my intake manifold flanges were warped, and that the carb port on the manifold had two slight flat spots - probably dropped. So, major vacuum leaks all around. Not sure how the bike was running. Ordered new intake manifold, flanges, seals and VOES. Hopefully that does the trick. While I had it out, I also took apart the carb to clean it and noticed I have a 45 slow and 190 main, which made sense because the past owner put in an ev27, Arlen Ness Big Sucker and free flowing exhaust. I also saw he put in a dynojet. Plan on switching back to a normal emulsion tube from CV Performance and keeping the 45/190 combo. Anyone with any experience with this combo? I figure at least my MPG should go up after getting rid of the dynojet. (Have been getting 37-39ish when I take it easy on the throttle) What do you guys think? I'll let you know how it turns out when the parts get here and I put it back together. Again, thanks for all the help.
HDF Community Team
Joined: Dec 2005
Posts: 5,404
Likes: 2,605
From: NC USA
Hi Everyone. Thanks for all the information and ideas. I took out my VOES and found that it was faulty. I also found that my intake manifold flanges were warped, and that the carb port on the manifold had two slight flat spots - probably dropped. So, major vacuum leaks all around. Not sure how the bike was running. Ordered new intake manifold, flanges, seals and VOES. Hopefully that does the trick. While I had it out, I also took apart the carb to clean it and noticed I have a 45 slow and 190 main, which made sense because the past owner put in an ev27, Arlen Ness Big Sucker and free flowing exhaust. I also saw he put in a dynojet. Plan on switching back to a normal emulsion tube from CV Performance and keeping the 45/190 combo. Anyone with any experience with this combo? I figure at least my MPG should go up after getting rid of the dynojet. (Have been getting 37-39ish when I take it easy on the throttle) What do you guys think? I'll let you know how it turns out when the parts get here and I put it back together. Again, thanks for all the help.
Especially since you're replacing the emulsion tube (CVP version is same as OEM), be sure you change the jet needle. Originals are bit hard to come by in the exact size for the bike, but many here have had excellent results with the CVP needle. So replace that also.
Measure the slide spring. If it's much longer or shorter than 5.75" replace it also. Check the vacuum hole in bottom of slide. A 7/64" drill bit should not go in the hole, if it does, try a 1/8" drill bit and if it fits, might consider replacing the slide as well. 45/190 will work fine, but a 185 would be a little closer to what it needs. No biggie there...
Make sure there is not a plastic spacer under the current dynojet needle. I don't remember if that's for the plastic thunder slide or they use them in a stock slide also. Bottom line, nothing goes under the needle in the slide. You're fuel mileage will likely improve a minimum of 10% or more.
Last edited by t150vej; May 16, 2022 at 12:20 PM.
Thread Starter
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Intermediate
Joined: Jun 2021
Posts: 27
Likes: 3
From: Pittsburgh
is this what you're talking about when you said "be sure you change the jet needle"?There's also something called a needle jet CVP's website that looks like this:
Which one do you mean?
HDF Community Team
Joined: Dec 2005
Posts: 5,404
Likes: 2,605
From: NC USA
First pic is the jet needle. Second pic is the needle jet. Yeah, easy to mix up the names.
Replace the jet needle in the first pic and that's assuming yours currently has the adjustable needle with a c-clip.
And remember the jet in pic 2 - the big end, (larger inside diameter) goes UP.
Replace the jet needle in the first pic and that's assuming yours currently has the adjustable needle with a c-clip.
And remember the jet in pic 2 - the big end, (larger inside diameter) goes UP.
Thread Starter
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Intermediate
Joined: Jun 2021
Posts: 27
Likes: 3
From: Pittsburgh
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HDF Community Team
Joined: Dec 2005
Posts: 5,404
Likes: 2,605
From: NC USA
Apologies. I forgot to mention - there were 2 versions of the Dynojet emulsion tube for the HD CV40. The main jets will not interchange between the two. One version came in the Screamin Eagle DJ/Thunderslide kit and will accept stock threaded jets. The other is genuine DJ and those jets have a smaller thread, will not interchange.
Visually, the genuine DJ tube has no hex for removal, only a screwdriver slot. The SE version has no hex, but has 2 flats to use a wrench for removal and no slot. That's about all I can remember for differences, as both only had 2 tiny holes in the tube where stock has 8 tiny holes.
So if in doubt about the current main jet threads, order a 185 also so you're not (possibly) waiting extra time for parts.
Visually, the genuine DJ tube has no hex for removal, only a screwdriver slot. The SE version has no hex, but has 2 flats to use a wrench for removal and no slot. That's about all I can remember for differences, as both only had 2 tiny holes in the tube where stock has 8 tiny holes.
So if in doubt about the current main jet threads, order a 185 also so you're not (possibly) waiting extra time for parts.
Thread Starter
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Intermediate
Joined: Jun 2021
Posts: 27
Likes: 3
From: Pittsburgh
Just following up on my idle issues from above. I ended up replacing the VOES, manifold and flanges, seals. That took care of the vacuum leak and the bike ran better right away. I also decided to swap out the dynojet kit in the carb to CV performance parts - 190 main, 45 pilot, new emulsion tube, slide, etc. Basically rebuilt it. I ended up with the N65C needle because I heard good things from others that use it. I put two shims under to bring it up a little. It seemed a little long, which I thought would make it too lean. Any one else use this needle and shims, or run it without? Like to hear some input from anyone who has more experience than me. I haven't had an opportunity to take it out yet, but did start it and it seems to idle ok. I'll have a better idea once i get it out for a good ride. Thanks for all the help from everyone. Much appreciated!
