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@ridervfr I cannot argue with any of the above, on the con·trary I completely agree. the jetting, needles, float heights, and flow rates were carefully arrived at by Kawasaki for the EX. any deviation from stock causes issues (got that "T" shirt)
I have tried most combinations of everything including a set of CR's and sliders, to change how the bike runs while some worked (sort of) there was always some issue that made it not quite right, only stock seems to work best on this bike.

Note, I always had a fully working stock set, to fall back on if I completely messed it all up (and I did quite often) the testament to this is the hundred sets rebuild by @ducatiman all stock that worked right out of the box.

my 2 cents worth, until the OP returns the carbs to a stock condition, adjusts them, and does the fine tuning they may never work as they should, yes there is a remote chance he could get lucky but I doubt it, experience tells me otherwise.
eliminating that last hesitation, bogging, misfire, flat spot, jerking, may be impossible.
stock jets, #130 main, #35 pilots, N36N needles, stock floats set at the fuel bowl joint (wet tested) is the way to go.
my money is on the carb set up for all the OP's issues. it's the only thing that make sense to me.
 

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Discussion Starter · #22 ·
@ridervfr my 2 cents worth, until the OP returns the carbs to a stock condition, adjusts them, and does the fine tuning they may never work as they should, yes there is a remote chance he could get lucky but I doubt it, experience tells me otherwise.
eliminating that last hesitation, bogging, misfire, flat spot, jerking, may be impossible.
stock jets, #130 main, #35 pilots, N36N needles, stock floats set at the fuel bowl joint (wet tested) is the way to go.
my money is on the carb set up for all the OP's issues. it's the only thing that make sense to me.
95% chance carb setup, 5% chance petcock. That's my guess.

I knew as soon as I saw the K&N sticker with aftermarket exhaust though I was likely in for a bit of a treat with non-stock internals. That being said, I actually think it'll possible to get this bike running well enough with the dyno-jet needles. There is no way I can fully bring this bike back to stock because it has an aftermarket 2-into-1 exhaust on it. In all likelihood, this (paired with a K&N air filter) may warrant a single size bump on the main jet and probably a shim under the stock needle. That would mimic my experience for a bike that needed very little after an exhaust change.

The last hesitation, misfire, flat spot, jerking are all already gone. It's the bogging due to running out of fuel that I need to rectify. At least, that's certainly what it feels like. Fuel mileage may be **** though if I'm running rich on the needle. Luckily it's pretty quick to make needle adjustments--it's a bit more of a chore to be playing with jets and especially float heights.

I think everything follows the float heights though. By not doing a wet test, I've just been taking guesses. So I'll try to do one tonight. If I don't hit on the issue, I'll probably be putting in an order to Jets R Us to get some Keihin replacement parts and bring it back much closer to stock. I can't find a source for an inexpensive genuine needle though. That kinda sucks.

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my two cents, (fast back-ground on my experience with these bikes - I road raced one for a year in light weight sportsman, I owned my current street going one since 2006.) I think you should get a donor set of carburetors from ebay and start there. I have stock jetting with the stock pipes, K&N air filter with the fuel mixture screws turned out 2.5 give or take. I installed some slip ons on once but ended up selling them. I don't have the "Fog-Mod" on my air box as I feel this bike carburetes perfectly almost. Fast start up, no choke, no stumbles, my philosophy is if it runs this well, why screw with it. Oh, bike runs up to 125 mph when I feel like it, runs up to 11,000 RPM at 125. I like to take it easy on my equipment but feel that they did give us the RPM to use so I short shift at half the capacity of the engine, and when I get on the highway, I let it rev.

I had a problem with a basket case VFR that I brought home on the trailer years ago. I had buggered up jets that had plier marks on them etc etc etc. I ended up buying a set of carbs off Ebay, used an OEM rebuild kit, and everything was good. Years down the road, I ended up getting some custom hand made fuel tubes and new Viton o-rings and installed them on my v-four carbs. Good luck
These carburetors are probably better than any set I could get on eBay just given the fact it has so few miles--the needle jets aren't worn, diaphragms and slides are good, and it's cleaned up. The metering pieces could/should be replaced. Unless I could pick up a known good stock carburetor for $100 shipped, it'd be cheaper to replace all the non-stock components in the set I already have.

I can see why you may want to go away from the slip-ons on this bike. This Muzzy 2into1 is quite loud. Like, I was kind of laughing a bit to myself how loud it is. I usually like to sneak around in my neighborhood but this makes it a little bit harder.

Those hand-made fuel tubes you got for the VFR are badass. I wish I had some of those. The plastic fuel tubes on the VF500 carburetors were my biggest source of headache since they took me a couple times to set right and not have the carburetor leak. And knowing how scarce any replacements were, I felt like I was diffusing a bomb on reassembly trying to make sure not to damage them.

___

I'll update with whether I resolve the fuel starvation issue or not. If not, then I'll order some stock componentry and try again in two weeks. Thank you both for the feedback and your experiences.
 

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Hate to say it but as Dynojet instructions include permanent mod (via drilling of the slides thus enlarging lift hole) you may be best off dealing with their adjustable needles. They provide a #32 drill bit (just slightly larger than the stock opening) may want to confirm that slides have actually been modded/drilled prior to investing in N36N.
 
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hi, couple of thoughts or input you may not have thought of or be aware of (you know what I mean), first just because it has a K&N filter doesn't mean it needs bigger jets. the paper/screened element does allow more air flow over the stock sponge one but is restricted by the flow rate of the air box (which has only one) inlet hole it's just they are a better design as the sponge ones break up and get sucked into the engine. a K&N filter is recommend when doing the Fog air box mod as now more air enters the box due to the extra hole, but even then the stock jetting is best as the mod only really cures the richness at WOT the stock bike has, due to the emissions crap it has to be set up for.

Second, my Gen 1 has for all the time I have owned it been fitted with a Motad 2into1 aftermarket exhaust. it runs perfectly on stock jets, and K&N filter fitted into the air box. only slight deviation is I run the pilots 1/4 turn richer as it stops the slight popping on idle.
 

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Hate to say it but as Dynojet instructions include permanent mod (via drilling of the slides thus enlarging lift hole) you may be best off dealing with their adjustable needles. They provide a #32 drill bit (just slightly larger than the stock opening) may want to confirm that slides have actually been modded/drilled prior to investing in N36N.
the stock slides (as far as I can tell) have hole size of 3mm the #32 drill bit would be 3.2mm, so would 0.2mm make that much difference to the operation of the slides. just wondering!!.
 

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Discussion Starter · #26 ·
Hate to say it but as Dynojet instructions include permanent mod (via drilling of the slides thus enlarging lift hole) you may be best off dealing with their adjustable needles. They provide a #32 drill bit (just slightly larger than the stock opening) may want to confirm that slides have actually been modded/drilled prior to investing in N36N.
I'm wondering if I even have the capacity to measure the differences in the holes to verify if it was drilled further. I was hopeful that it may have just been a half-assed attempt that mixed Stage One (don't drill) and stage 3 (drill).
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The jet is stamped "140" and I do not remember seeing a "DJ" on it. Nor do I remember seeing the "K-Star" either though. I wasn't trying to photograph anything in particular when I took this... I should have rolled them so the markings were visible. gah.
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Looking further at the DynoJet instructions, it says the stage 3 should come with a different set of springs. I'll get a better picture when I'm not at work pretending to work--this is all I can see that I took of the slide and spring prior to cleaning. If the spring is stock, I bet there's a good chance the slide isn't drilled yet. Apologies that this is as good as I can show now.
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the stock slides (as far as I can tell) have hole size of 3mm the #32 drill bit would be 3.2mm, so would 0.2mm make that much difference to the operation of the slides. just wondering!!.
Saved me a search! Thank you.

hi, couple of thoughts or input you may not have thought of or be aware of (you know what I mean), first just because it has a K&N filter doesn't mean it needs bigger jets. the paper/screened element does allow more air flow over the stock sponge one but is restricted by the flow rate of the air box (which has only one) inlet hole it's just they are a better design as the sponge ones break up and get sucked into the engine. a K&N filter is recommend when doing the Fog air box mod as now more air enters the box due to the extra hole, but even then the stock jetting is best as the mod only really cures the richness at WOT the stock bike has, due to the emissions crap it has to be set up for.

Second, my Gen 1 has for all the time I have owned it been fitted with a Motad 2into1 aftermarket exhaust. it runs perfectly on stock jets, and K&N filter fitted into the air box. only slight deviation is I run the pilots 1/4 turn richer as it stops the slight popping on idle.
Got it. If/when I order new jets, I'll probably just order 130s then if I find the slides weren't too molested. I know my SV650 with a modified air intake and aftermarket exhaust really benefits from increasing the jet size from the stock of 137.5 to anywhere between 145 - 155 if paired with a full system exhaust.
 

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Discussion Starter · #27 ·
I did some further investigation based on the advice and comments here, and I think I'm stuck going the Dyno-Jet tuning route unless I buy new slides. They've been bored out to 3.2mm as far as I can tell. I don't have a problem doing this because I know this bike had run pretty well on this tune before. Likely not optimal, but I'm not in pursuit of perfect. Good enough and reliable would be okay by me. I just wish I could tell what kind of spring I've got.

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Anyway, I wish I'd have taken some goPro footage of the bike starving out, but I think my diagnosis was accurate. What I don't think was accurate was my attempt at raising the float fluid level to remedy the situation. While raising it allowed me to run full power to redline through first, second, third gear and up to freeway speeds, it only masked the issue as it just delayed the starving out of fuel. You can see on the wet test that I'm actually well above the appropriate level. Probably literally as high as I can go before it starts spilling out. I've got a lot more head pressure on this bench setup than would be realistic from the bike's fuel tank, but I think it's still relevant. Both float heights were damn near the same though, so that's a moral victory (lol).
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I'll be buying new OEM float heights just to completely rule out that variable. It's not expensive, and I should have done it in the first place. I think I will be purchasing a set of OEM 130 and 135 mains along with 35 pilots as well. This is the 140 I removed.
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I think there are a few possible things that could cause this type of issue.
  1. Super rich tune that's allowing more fuel to be burned than can be replaced.
  2. Incorrect float needle geometry that restricts flow into the bowls
  3. Too low of a float height
  4. Minor vacuum leak from left carburetor to petcock
  5. Incorrectly assembled (by me) or incorrectly manufactured/spec'd (all balls rebuild kit) petcock diaphragm and spring that's not allowing it to open fully
  6. Restriction from fuel outlet of petcock to fuel inlet of carburetor
  7. Restriction/blockage from debris inside the fuel rail that splits to the two carburetors
I'm going to take the suggestions of going as much stock/OEM as possible to heart. Mains, float needles, and pilots getting ordered. Sticking with the DJ needles for now based on the drilled slide.

But I couldn't help shake this quote from I,Robot out of my brain the entire time I was messing around with the bike last night due to my absolute (ir)rational hatred of vac-petcocks... "Let me ask you doc, does thinking that you're the last sane man on the planet make you crazy?" Because I think this is a petcock issue. So obviously I had to turn on I,Robot as I checked a couple other petcock-related things out... I may have timed this photo.
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Earlier this year I replaced the vacuum-operated petcock on my Suzuki Bandit with a standard ON/OFF Yamaha 2VN-24500-02-00. I pulled old vac-operated OEM bandit one... and it fits on the EX500. So I'm going to order one for the EX500 to try to rule out anything petcock-related completely. Bandit petcock on the left, EX500 petcock on the right. The red color is red rubber grease.
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So we shall see in a couple weeks whether I make things better or worse. Maybe I'll have a new rear tire by that point. Cheers.
 

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why dont you just install a Pingel fuel tap and be done with the oem stuff? I had a leak on the race track with one of those stupid things. Mine is ON/OFF thats it, you could get a reserve if you want but why - with two trip odometers your set. Nice simple bike to work on.
 

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Discussion Starter · #29 ·
why dont you just install a Pingel fuel tap and be done with the oem stuff? I had a leak on the race track with one of those stupid things. Mine is ON/OFF thats it, you could get a reserve if you want but why - with two trip odometers your set. Nice simple bike to work on.
Sorry if it wasn't clear--that Yamaha petcock I'm going to install is a simple ON/OFF valve, no vacuum required. I think it's from an ATV.

I was going to do the Pingel after doing some reading on here (might have actually been your thread or response) when I got the idea to check if the Yamaha one might fit. I just know it works and it was much cheaper but still a major 4 OEM. It works so well, in fact, I'm out on my bandit for lunch right now. And I turned off the fuel when I parked, and I will turn it back on before I head back home. Just as God intended. Haha
 

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Discussion Starter · #31 ·
600 or 1200? wanted the last Madlin blue/white Bandito, but they all ended up having high mileage. Sometimes you have to stop while your ahead if you get my jist.
600. It's a nice bike (now), but it wasn't my idea. Years ago I convinced my buddy to buy a motorcycle, and after shopping for a while he settled on a 2002 Suzuki Bandit. I rode it home for him from the dealer, but it never felt quite right. He ended up moving to another city and it stopped running altogether. He took it to a shop there that performed $954 of service on it to get it "running", but it ran like a pile of ****. He was so fed up he just wanted to sell it. I felt terrible and told him I'd buy it for the price he paid the dealer for it, I would fix it up, and if he wanted it back, he could have it back even cheaper. It took me years to get that Bandit running correctly, but it rips now.

Anyway, he ended up moving out to California, but he's come into town a few times and we've done a few motocamping trips. He takes the Bandit, and it's gone through everything. Downpours, dirt, sand.. it's seen some ****. Runs great.

I don't really like the bike. It's way too heavy for what it is. And I threaten to sell it every time I don't ride it for a few days. But I smile every time I ride it and with the amount of time I've put into it, I haven't quite been able to pull the trigger on selling it. Plus, it's nice to have it as a spare bike if/when he comes into town so we can go out.
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Of course, when I ever actually get my VF500F reassembled after powder coating the frame, wheels, and all the other work I need to do to it... it may inch closer to the chopping block. But I keep picking up projects like this EX500 that push it further back, hah. This is the last thing that's getting in the way. Then I'm reassembling.
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Discussion Starter · #33 ·
Yea, we got a Little Ripper now! I've been out of town for a bit and finally got around to working on the EX500 again. It was the petcock restricting fuel flow. It's running real well now, and I'm just really looking forward to getting that rear tire on (whenever the Bridgestone BT46 gets back in stock and shipped), so I can get this bike back into my parent's garage.

I installed the new Yamaha petcock which is almost a direct bolt-on, but you have to grind down a bit of the lever so that it clears the edge (flange?) of the EX500 fuel tank. I am a much happier soul knowing that a vac-operated petcock can't haunt me any further with this bike.

Anyway, I'm very glad I started this thread here because I learned about the importance of wet-testing fuel float levels. It's something I've never done before, and now I realize I should always be doing it when refreshing a carburetor to save the headache. I'm also very glad I started this thread because I never would realized the slide had been drilled and that I'd be best off just working with the limitations of the DynoJet needles. So thank you everyone.

I also put in new OEM Keihin float valves and got those K&L's out of there.
  • Installed new Yamaha standard ON/OFF petcock (after grinding lever to fit)
  • Installed new Keihin 35 pilot jets
  • Installed new 135 Keihin main jets (also bought 130s if I want to change later).
  • Installed new Keihin float valves
  • Fixed one of the two broken left fairing tabs with "PlasticWeld" solid goop fashioned into some sort of phallic-looking obelisk thing. idk, it works.
And it rips right up to redline and stays there. I probably sounded a little ridiculous on the freeway running in 3rd gear at ridiculous RPM just trying to starve the carburetors out. I couldn't. Nice.

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And since I'm apparently a sucker for pain and completely uninterested in addressing any of the character and/or real-life issues in my life (like the air conditioner that just crapped out or the bathroom my grandma is insisting I remodel)... I may have picked up my winter project for this year...
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Thank you for all the advice that everyone has given in this thread and in all the past threads here. I've been just soaking it up trying to learn more about these bikes. I am waiting on doing the flywheel upgrade (just going to buy one of the aftermarket ones instead of modifying a gen2) until this winter. I am going to force either my brother or my dad (since they'll actually be riding the bike) to come over and do the swap with me, so I can teach them about everything I've learned.

If you're bored and like listening to some whiny little punk talk about things he doesn't really know all that well, I put together a video of my experiences with this bike.
 

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And since I'm apparently a sucker for pain and completely uninterested in addressing any of the character and/or real-life issues in my life (like the air conditioner that just crapped out or the bathroom my grandma is insisting I remodel)... I may have picked up my winter project for this year...
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oh my god so gorgeous!! don't worry, grandma will understand when she hears the gear driven cams. awesome update!
 

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Discussion Starter · #35 ·
oh my god so gorgeous!! don't worry, grandma will understand when she hears the gear driven cams. awesome update!
Thanks Auburn. Oh yea, I'm guessing Gear Driven Cam whine is definitely going to be the tipping point! That bike is rooouuuggghhh, so it'll be a bit of a process.
 

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Discussion Starter · #37 ·
Love happy endings, is that a "mini-ceptor" 500 or what?
"Happy endings" is a long way off. It's a friggen mess. I made the mistake of pulling off a few fairings and gas tank last night just to see what I was in for. The wiring harness is cut up and wires are just kinda going everywhere and pretty beat up looking. It's been pretty abused, but we'll see what happens. It's a 1986 VFR700.
 
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