KLR You Experienced? I am now...

Re: KLR You Experienced? Err, kinda not really.

Duly noted, thanks for the direction - as soon as I get back from the mother-in-laws then that's what I'll do.

I did follow your advice - got the bike up to running temperature by riding it around the hood for 15 mins, then pulled the plug and gave it a good clean before replacing it. Then fired it up again and let it idle for 3 or 4 mins, and then pulled the plug again. It looked like this -

UY2g6qL.jpg


Rich idle, right? So cleaned it, replaced it and fired up the bike again, turning the idle screw to its lowest setting without stalling. I had to chop up a screwdriver bit to get to the idle screw but it was still pretty tricky to reach - not entirely sure I achieved a great deal as I kept burning myself on the exhaust. Still belching black smoke. But at least I've discovered that the bike is idling rich, so there's that.
 
Re: KLR You Experienced? Err, kinda not really.

Okay, don't get offended by this question but is the choke off? That honestly looks like a plug that's been run a while with the choke on.

I had what I thought was a situation with my airhead. The thing just went out of sync after I did a bit of work on it. I went about re-syncing the carbs and rode it around. It rode okay, but nothing like it was supposed to. Baffled, I pulled it back in the garage to give it a look. I had the choke cables disconnected, so I didn't consider the possibility. Turns out, the right side carb choke must've gotten hit and it was engaged.
 
Re: KLR You Experienced? Err, kinda not really.

Dude I literally never need the choke on this bike. Unless something is fucked up in the choke mechanism that I’m unaware of, I never have it on.

That plug got that black in the three minutes the bike was idling. Think the choke might be messed up? I did replace the lever but not the cable.


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Re: KLR You Experienced? Err, kinda not really.

For me the choke being on would explain a lot of your symptoms. Has to be very rich to turn the plug that black. Something is way off for sure. Good luck with it, I hope it doesn't drive you crazy. Tuning carbs can be painful
 
KLR You Experienced? Err, kinda not really.

Tell you what though, went to sleep thinking about the choke and it was the first thing I thought about when I woke up.

First time for everything I guess.

So I’m going to take a look at it this morning before the trip to the in laws. Been reading up on the Keihin CVK40 carb and its choke. Turns out the choke mechanism on this carb is less of a choke and more of a “starter enricher”, in that it doesn’t starve the carb of air when activated, but allows more air and gas into the carb body/cylinder. It’s a plunger set-up, not a butterfly. So when the plunger is pulled (the “choke” is on) it’s not choking the air but enriching the air/gas. That’s my understanding anyway.


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Re: KLR You Experienced? Err, kinda not really.

Yup
It opens a little passage and allows more fuel to flow in so the mix gets richer.
 
Re: KLR You Experienced? Err, kinda not really.

A cold motor should always need a littke choke to start and full if very cold temp outside. If you never need the choke its way to rich and will just get worse when warm. Maybe the choke is stuck open on the carb?
 
Re: KLR You Experienced? Err, kinda not really.

Pulled the whole choke assembly apart and it is possible that the cable was not fully extended, meaning the plunger may not have been fully closing in the carb. Can't be 100% before, but I'm fairly confident now the choke is working as it should. Off for the weekend, when I get back tomorrow I'll pull the plug and clean it, then fire up the bike again and let it idle (I'll see if starts up right away or if it needs choke), then pull the plug and see what it looks like.

Went for a ride after re-installing the choke - still blowing clouds of black smoke when I blip the throttle. Clouds.
 
Re: KLR You Experienced? Err, kinda not really.

The Jimbonaut said:
Pulled the whole choke assembly apart and it is possible that the cable was not fully extended, meaning the plunger may not have been fully closing in the carb. Can't be 100% before, but I'm fairly confident now the choke is working as it should. Off for the weekend, when I get back tomorrow I'll pull the plug and clean it, then fire up the bike again and let it idle (I'll see if starts up right away or if it needs choke), then pull the plug and see what it looks like.

Went for a ride after re-installing the choke - still blowing clouds of black smoke when I blip the throttle. Clouds.

Maybe it's just a diesel and you don't know it ;)
 
Re: KLR You Experienced? Err, kinda not really.

I dunno man, after making sure that the choke was working properly (99% confident it is now) the plug still gets really sooty after a couple of minutes of idle only (no throttle at all). It also started up with no choke.

So the carb is dumping way the fuck too much gas into the cylinder before I even get moving. That’s not the main jet I now know, but the pilot circuit. I’m going to pull the carb out, switch everything back to stock and see what gives.

Stock needle too? Right now I have the DynoJet needle set at stage 2. Guess I’ll switch that out as well. That way I’ll be back to baseline and can take it from there.


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KLR You Experienced? Err, kinda not really.

The Jimbonaut said:
I dunno man, after making sure that the choke was working properly (99% confident it is now) the plug still gets really sooty after a couple of minutes of idle only (no throttle at all). It also started up with no choke.

So the carb is dumping way the fuck too much gas into the cylinder before I even get moving. That’s not the main jet I now know, but the pilot circuit. I’m going to pull the carb out, switch everything back to stock and see what gives.

Stock needle too? Right now I have the DynoJet needle set at stage 2. Guess I’ll switch that out as well. That way I’ll be back to baseline and can take it from there.


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Is the float valve working properly?
Maybe the valve isn’t closing and the bowl gets overfilled?
Overflows cleared?
 
Re: KLR You Experienced? Err, kinda not really.

Well I'll be dipped in shit.

Said my goodbyes to the Ottawa inlaws in double-quick time, hurried the missus out the door and dropped the hammer all the way back to Montreal yesterday. Got home, dumped the toothbrush and got straight to the garage to do what was suggested - tear the carb down and replace all the DynoJet stuff with stock.

There was gas everywhere - in the intake and outlet rubber boots, the venturi itself was dripping, man it was seriously flooded. Something was pouring gas into the carb no doubt, but that much was already obvious. Checked all the specs though and I'd definitely followed the DynoJet instructions to the letter. Still unsure as to what was causing the over-gas, but hey. Couple of hours later I got the freshly rebuilt and cleaned carb back in the bike and took the old girl out for a spin and whaddya know. Idles great, throttle response great, no plumes of black smoke when I blip the throttle. Thrilled - if I had a tail I'd wag it.

So thank you for you help and perseverance guys, once again your long distance assistance has got me in the saddle rather than sitting on a shop stool staring at it.

What I noticed -

- Still need to get WOT as only took it around town, but I thought I felt a little more vibration through the footpegs
- exhaust sounded quieter (that's a good thing, just ask the neighbours)

Will get it out again today and will take it through the throttle positions and report back. I still don't entirely understand how stock jetting/needle/idle screw etc can provide enough gas for the big bore, but as someone mentioned maybe that's balanced out by the less restrictive exhaust and modified air box?

But for now, thanks again. You got this guy doing laps on Rhonda and now El Verdito is chomping at the bit. Muchas gracias one and all.

Probably should get some glamour shots of the bike up soon too 8)
 
Re: KLR You Experienced? Err, kinda not really.

Huzza!!

If there was that much gas in there I'd bet that your floats were not adjustred right or sticking open. Either way congrats on getting it up and running!

If you think about the basic function of the carb:
The piston goes down and causes an air void that atmospheric pressure feels the need to fill. The air flows through the carb at high speed and runs over the jets, this vacuum effect sucks fuel up the jets into the air stream (and then into the cylinder). Stock you're getting a certain amount of air flow through that carb orifice.
When you go up in bore that "void" gets bigger so you need more air to fill it. The only way to get more air through that same carb in the same timeframe is to pull it in faster, which increases the velocity over the jets and sucks more fuel in. So on the same carb settings with a bigger bore you get more fuel than you did with the stock bore.

It's not always linear because it all depends on the design of the carb, size of the jets, etc etc but in general that's how it works.

Now that it's running close to right you can do some plug chops to see if that fixed the issue or not, you could still be rich or lean with the stock jets and you'll likely need to fiddle a bit to get it right.
 
Re: KLR You Experienced? Err, kinda not really.

The Jimbonaut said:
Well I'll be dipped in shit.

Said my goodbyes to the Ottawa inlaws in double-quick time, hurried the missus out the door and dropped the hammer all the way back to Montreal yesterday. Got home, dumped the toothbrush and got straight to the garage to do what was suggested - tear the carb down and replace all the DynoJet stuff with stock.

There was gas everywhere - in the intake and outlet rubber boots, the venturi itself was dripping, man it was seriously flooded. Something was pouring gas into the carb no doubt, but that much was already obvious. Checked all the specs though and I'd definitely followed the DynoJet instructions to the letter. Still unsure as to what was causing the over-gas, but hey. Couple of hours later I got the freshly rebuilt and cleaned carb back in the bike and took the old girl out for a spin and whaddya know. Idles great, throttle response great, no plumes of black smoke when I blip the throttle. Thrilled - if I had a tail I'd wag it.

So thank you for you help and perseverance guys, once again your long distance assistance has got me in the saddle rather than sitting on a shop stool staring at it.

What I noticed -

- Still need to get WOT as only took it around town, but I thought I felt a little more vibration through the footpegs
- exhaust sounded quieter (that's a good thing, just ask the neighbours)

Will get it out again today and will take it through the throttle positions and report back. I still don't entirely understand how stock jetting/needle/idle screw etc can provide enough gas for the big bore, but as someone mentioned maybe that's balanced out by the less restrictive exhaust and modified air box?

But for now, thanks again. You got this guy doing laps on Rhonda and now El Verdito is chomping at the bit. Muchas gracias one and all.

Probably should get some glamour shots of the bike up soon too 8)
You most probably have a worn/sticking float valve! At first they just stick and leak sometimes, eventually they leak all the time.
 
Re: KLR You Experienced? Err, kinda not really.

The vibrations may, and are most likely, a thumper thing. Could be the balance on your rims, too, but my F650 tends to be buzzy between 20mph and 45mph. Once I get above 45, it smooths out. Cruising the highway at 60 mph+ it's smooth as silk, even with Karoo3 dual sport tires.
 
Re: KLR You Experienced? Err, kinda not really.

Right on Jimbo

Now you just need to find some fields to go tear up

b0d1a9da4acef331de20da968aa7ed88.jpg
 
Re: KLR You Experienced? Err, kinda not really.

farmer92 said:
Right on Jimbo

Now you just need to find some fields to go tear up

b0d1a9da4acef331de20da968aa7ed88.jpg

Ye gads, if that was my view I'd be a blur in it every chance I got!
 
Re: KLR You Experienced? Err, kinda not really.

Another ride yesterday and the difference is night and day. I'm not sure if it was the pilot/idle circuit that was drowning out the carb, or the float. I checked the float needle and it didn't appear to be sticking at all, and I'd already adjusted and measured the float height and it was spot on. I'd love to know or figure out what was causing it, but perhaps it'll be one of those things that'll become apparent with more carb tuning experience. I really enjoy the diagnostic/remedial process (thankfully!), and have learnt a lot already from this KLR.

Raining cats and dogs here today. Need to address the leaky petcock - it's not the petcock itself but rather a stripped captive nut inside the tank that the petcock bolts into. I need to tap the bolt and that should take care of it. It's not leaking badly, but incontinent gas tanks aren't much of a cause for celebration.

Another thing - Irk you reminded me that I need to balance the tires. I'd already ditched the huge lead weights clamped to the spokes like tiny sloths - I used CounterAct Balancing Beads (they're like Dyno Beads) in the Honda which worked well so I'm going to use them in the KLR as well. They're arriving today, along with some S100 cleaning stuff so Rhonda can get a long overdue brush up.
 
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