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Too rich on starting!

4984 Views 30 Replies 4 Participants Last post by  apbling, 
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OK, I am clueless now...

93 1100 VT. Cobra drag pipes, next to no baffles, K&N filter. I put the cobra jet kit in according to it's instructions, except my AF screws are at 3 turns out instead of 2.5 (to cut down on the pipe popping).

Anyway, now the SOB doesn't like to start well, esp when hot. It puffs smoke and don't even think about hitting the choke. I have the idle set on the low side. Now, when I come to a stop, hit the kill switch and then try to start it again, it fires up. But if you wait long enough to, say, gas up, you have to go WOT to lean it out to fire.

I'd be ok turning the AF screws leaner, but then the SOB pops on de-accel and has a little hiccup when I snap the throttle open hard....

I'm tempted to pull the kit out and the K&N, go with the stock filter and stock jetting like it was when I got it. This is really pissing me off.
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So I just adjusted the AF screws to 2.5 turns, and the goddamn thing still is acting like this! The only thing I can think of is it's something with this jet kit or maybe the enrichner/choke is boogered up? Everything was fine before I did anything to it.

once you get it started, it's fine... it's just starting is too rich.

Checked the enrichner valves. Everything looks great and in adjustment.
This makes NO sense to me. Why would needles and a main jet cause everything to run so rich! My plugs are literally wet. I changed nothing in this process. Took carbs out, swapped needles and jets around, nothing else. Didn't touch the floats. Didn't touch the pilots. (except the AF screws, which were about 2.5 turns out and still capped off). If anything, you would think I'd be running lean...
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Anyone got any ideas?
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It sounds like you have done the right steps, but something is screwed up. Most problems result with lean conditions, like a leaky boot. I agree that the changes you made should not make it run rich.

I would double check that the choke really does release, as this would cause your symptoms. Does it start cold now without the choke? Let us know what you find out.
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+1 on checking the choke.

While running, using choke (enricher) it should increase RPM's to "somewhere around" double your idle.... 2K, from 1K/900...whatever. And likewise, turning off choke should decrease RPMs back down to idle. Check to see this is happening.

I still think the idle circuit is only the pilot jet, A/F screw and Choke.

According to DJ paperwork, " It's important to know that your bike will start AND idle w/o your needles, slides, and main jets in place". "Dynojet will rarely alter your idle circuit, and never alter your starting circuit".
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Maybe, just let it pop a little, go for that Harley sound.
Start by adjusting the Idle up. Should be at 1000 rpm +-100, high side is leaner than low side. Opening throttle adds air not fuel, fuel flow increases with increased vacuum. Turn AF screws in some, leaner. Are the floats adjusted too high? Are carbs in sinc? All vacuum lines in place? Are there air leaks in the intake boots. Is battery being maintained on a charger during your service work? Weak battery can cause what appears to be a rich condition. Is the slow jets the stock #42? Could 1 of the choke needles be sticking open, Not seating?
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Verdeva- Yes, it starts without choke cold.
Shadow- I did try engaging the choke, initially it bogs for 1/2 second, then idle jumps to about double. Turn choke off and it returns back to normal.
93-Interesting idea about increasing idle being leaner... Problem is if I turn the AF in and adjust the idle higher, not only is the popping worse, but I develop a flat spot when I snap the throttle open, but I'll give it a shot. I would think floats are fine-I didn't remove them and they were fine before I did anything. Carbs are in synch, but I can check again. No air leaks in boots (wouldn't this be a lean cause, not rich?) Battery is brand new and strong. Pilot jets are stock.

Now, this choke hanging open is something I thought about too. I measured the slack last night like the manual says. I had about 12 mm of distanc between the nut and valve (they say 10-11mm). I would think more would just cause it to be more cold blooded. How could I tell if the choke wasn't sealing off? It does work when I activate it, but maybe it's just leaking a little bit?

This whole thing does not add up. I agree with what you guys say, so I hope I don't come across as not taking your advice. I really appreciate all your input. It just doesn't add up. I think all my vacuum hoses are hooked up properly. Wouldn't a miss routed or not hooked up vacuum hose cause a lean condition?

Having spent the money on the filter and jet kit and now it not working during beautiful weather is killing me (not to mention the bike is new to me!)
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No chance you lost the spring on Enricher plunger is there??? I had to read

I had about 12 mm of distance between the nut and valve (they say 10-11mm). I would think more would just cause it to be more cold blooded. How could I tell if the choke wasn't sealing off? It does work when I activate it, but maybe it's just leaking a little bit?
Click to expand...
a couple of times to understand what you were saying. IF the spring was gone, the needle wouldn't "necessarily" close the valve...even though the cable to lever was "pushed".

The choke Circuit works like this... I think.... Pull lever down, pulls cable, Pulling ENR Valve Open or "out" of "jet"..... Lever up (off) pushes cable, into valve, closing "jet".

P.S. Mine are a real pain to re-install..... the "spring" in the cable "un-winds" the threads from carb as you try to install it. 1 side is much easier than the other....left side being the pain.

P.P.S. No offense taken here, I understand the frustration....:wink:


Here's a thought.... remove the needle/plunger from cable (don't loose spring!) and figure way to insert/hold it in place on both carbs W/O cable....... See how she starts then. OF COURSE, BE CAREFULL DOING THIS, THINK ABOUT WHAT IS HAPPENING, MAKE SURE NOTHING BAD HAPPENS...ETC,ETC.
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Good point. I'll try that.
Going with my obssesive nature the past few days, I've been thinking about this vacuum emission routng BS. In my Haynes manual, it says that the system collects vapors from the tank and carbs and stores them in the canister, where they then are injected into the intake during starting...

Now, if I hooked something up wrong, maybe I'm getting excess fuels/vapors and thats my starting problem... I mean, if it was this rich on starting to the point of almost not starting, shouldn't I see some odd running issue once it is running? Its like when it sits, it collects and then when I try to start it, it is rich. Once it's stated, it runs like a top. When testing it last night, if I shut it down and tried to start it within a minute or two, bam, pop right off. Let it sit for just a little bit, then it'd act funny... Sure wish it was sitting in the parking lot now so I could go look, instead I gotta wait til tonight...
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Shots in the dark... Check the plug wires, make sure all four are seated and firing. Which groove did you set the needle on? Which jet # did you use? I'm still suspecting miss adjusted floats, Off just enough that once they drain a little, all is well. Is it popping more on 1 cylinder, or both? Is it backfiring, through the Intake? Test fuel pump output? What are battery and charging voltages? Vacuum miss routed to air will cause lean, but vacuum miss routed to vacuum , will cause rich. For testing puposes ONLY, try doing the vacuum as per a non California Bike. Maybe one the issue has to do with the emission system. By Bi-passing it, for diagnostic purposes, we may be able to narrow the issue down or at least eliminate a possible suspect.
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93- plugs are fine. I checked them last night while looking at the plugs. Needle is on 3rd from the top (per Cobra/DJ) and 170 mains (per Cobra/DJ). No backfiring through intake. Didn't test fuel pump, but worked ok on my 20 mile test rides. Battery is 12+ sitting and 13+ while running. I know the float seems like the smoking gun, but I find it hard to believe seeing as I didn't touch them at all...but weirder things have happened.

When I get home I'm going to double check my routing of the emission stuff. I have a sneaking suspicion I goofed up hooking the control valve on the right carb up...

How do I remove it? Cap the little vacuum port on the right carb.... leave the upper (I think #5?) hoses on the carbs open to air (I think they are vents?). What else?
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Wierd is what we are looking for... You had to touch the floats to change the jets. Don't really have to "touch" them for them to be off. Floats can get tweaked from just turning the carb over, exageration but they are sensitive. If you take carbs out again you might try the needle on the second grove or smaller jet. Only do one, Flip coin to decide. Double check choke and throttle cables adjustment and routing, look for binds and kinks.
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I did try smaller jets and lower groove, same richness on startup, but different throttle performance. So far, I'd have to say other than starting, this is a good setup so far. I sent you a PM with my thoughts on a potential mis-route.

Is there a way to measure float height without the special tool? my old KZ's you could attach clear tube to the overflow and measure fuel service level.

Also, if the floats weren't sealing, wouldn't I get some seepage out of my bowl overflows?

when we get this figured out, I'm gonna have to buy you guys a beverage (or a case) of your choice :)
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Well, everything is routed perfectly well on my bike. Was hoping that was the smoking gun. Going to put everything back the way I found it and see what happens.....
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ok, I know you guys are gonna say I did something different... but I swear to god, all I did was put my stock jets and needles back in and my stock air filter...and all is solved.

I can tell it doesn't have the ass kickin' power, but it runs nice and smooth and more importantly, doesn't flood on hot startup.

This makes no sense what so ever. Now to see if I can convince the company I bought the filter and jet kit from to refund me...

Think it's worth my time to just go up a main jet size, or just leave well enough alone and ride the **** thing? :)
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Worth your time is up to you, BUT.... If I recall you had the Cobra 170 in and if you went back to the stock 165, that almost 10 jet sizes smaller. Stock 165 is equiv. to Cobra/DJ 150 jet, the Cobra/DJ 170 is equivelent to a stock 190 jet.Keihin to Dynojet to Mikuni carb jet conversion chart - Honda Hawk GT Forum What jets are in your kit? I might try just the aftermarket needle, better throttle response. Then step my way Up jet sizes 1 size at a time, till I found the sweet spot.
But, since I would also want to RIDE the bike rather than TUNE the bike, there may be months between changes. Pulling carbs is a PIA, and since proper tuning means 1 change at a time. Getting jetting perfect can mean alot of taking carbs on and off.
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Do you trust that chart?
Just eyeballing it, I thought my 170s looked close to the Keihin 165's...haha. But I have no technical method of testing it.

One thing I haven't figured out/gotten answered yet... do you have a spacer/shim/washer under your needle? When I pulled mine, I did. Now, it doesn't show up in any manual or fiche on ronayers.com, but the DJ kit shows it like it was stock.... I left it in there, so really my needle was on the 3rd or 4th spot, but really inbetween because it was shimmed up a spot.
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You can't SEE the size difference sometimes, were talking only a few 1000 of an inch. And sometimes theres more to it than "just a hole", theres also the shape of the hole.

Per the DJ instruction, If you had them stock re-use them. Stock you had a shim.... DJ takes that into consideration when they designed the kit. The shim is like 1/2 a grove on the needle.
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I'm not actually sure if that shim is stock though.... thats the problem. Was it the PO that threw it in there or are the manuals incorrect?
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Chart seems close enough, I haven't verified it much more than, seat of the pants. The DJ 160 jet is alot richer running than the stock 165. My kit had 150, 155 and 160 jets and a different needle than yours, but it is the generic DJ kit, NOT exhaust specific like yours. The 150 felt about the same as the stock jet, just a little crisper and cleaner.
The shim and washer along with the groves are used for fine tuning the needle hieght.
Me I have the clip on grove 3, with the DJ washer and stock shim swapped. Running the 160 jet now, going to a 165 or 170 jet... When I get the urge to pull the carbs again. Exhaust is V&H Classic II with baffles, but no packing. Air fliter is UNI oiled foam, funnel removed Intake and exhaust ports are "cleaned up", ignition is advanced, slow jet is stock, but honed out a little, call it a #43-44, floats are set a little high(rich, just short of over flowing), pilots are at 3 3/4 turns.
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