Carbs

Are ya having a problem with your rig? We'll try to help. Share your tech tips and experiences here. Dr. Billy Glaser, author of the "Unofficial 750 Ural Service Manual" site myural.com, is moderating this section.
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Leightydenpr
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Carbs

Post by Leightydenpr » Thu Feb 07, 2019 9:23 pm

Hey guys I am a Nubie and I’m having trouble with my carbs. I am resurrecting older denpr 650engine. Just replaced ignition with type three contactless. Rebuilt both k-65 carburetors. Disconnected all old wiring and bam 💥 she fired right up. Problem is one side wasn’t firing. So I switched carbs first and it is a carb problem. Took carb apart and recleaned and reassembled. Still same problem. If I lift slid up manually that side will fire but not great. Both are factory set at 1.5 turns out. Could it be Needle adjustment ? I’m stumped do I need a new carb body?
Any ideas
currently in the stable
soon to be a denpr
Vtx J 1800
kdx 230
kids rides
cr 50,80,100
missed and thought about
gsxr600
intruder 800 and 1200

URALNUT60
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Re: Carbs

Post by URALNUT60 » Fri Feb 08, 2019 6:52 am

Switch plug wires, pull plug out on side that isn't firing check spark, could be elec problem not the carbs

Leightydenpr
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Re: Carbs

Post by Leightydenpr » Fri Feb 08, 2019 7:59 am

Yep I had started with wire switching, then moved to spark plug switching. Both made no change. Then switched gas lines no change. Then switched carbs and the problem followed the problem carb. Still stump Manet I’ll try breaking it down again, just not sure what else to do with it.
Thanks
currently in the stable
soon to be a denpr
Vtx J 1800
kdx 230
kids rides
cr 50,80,100
missed and thought about
gsxr600
intruder 800 and 1200

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Msblu79
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Re: Carbs

Post by Msblu79 » Fri Feb 08, 2019 8:06 am

There must be a blockage perhaps still in the carb body. Strip the carb and soak it for a day or two in Seafoam or whatever your favorite carb cleaner is and then use compressed air to blow out the ports see if that helps. You can also very carfully use a thin stiff wire to probe into the ports and clear any blockages. :)
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Re: Carbs

Post by Obo Scribe » Fri Feb 08, 2019 8:15 am

Float height? Does the float 'float'?
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Claus
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Re: Carbs

Post by Claus » Fri Feb 08, 2019 8:21 am

Leightydenpr wrote:
Thu Feb 07, 2019 9:23 pm
If I lift slid up manually that side will fire but not great. Both are factory set at 1.5 turns out. Could it be Needle adjustment ? I’m stumped do I need a new carb body?
Any ideas
Goingt to factory set doesn´t mean it´ll work. These are K65 carbs, no mikuni or keihin.

First check all jets and holes for clogging, clean with compressed air or with carb leaner.
Check needle height on both slides. If that is ok, here´s a quick guide to set up:

Start engine, and first lift the throttle by idle screw a bit (the hex screw on top of the carb´s slice cover). You lift the throttle by turning the screw out.
If engine starts to fire up at that side, first step is done.
Now you should set idle mixture on both carbs by idle air screw (the head screw that comes oput the top of the carb body).
Turning it out, makes mixture lean, turning in makes mixture rich.
Ground one plug out and set idle mixture on other side by turning idle air screw out slowly until highest idle rev , now turn in again until idle starts going down again. From there another 1/8 turn in. Repeat on opposite side. If done, set idle to wanted revs on both carbs by turning idle screw. (appr 900 to 1000 rpm).


These carbs have a couple of problems:
Main jet holder becomes lose, causing slide guide beeing lose, too. There should be a little black locking plate underneeth the idle jet that secures main jet holder/slide guide.
Choke plunger gets stuck or leaky, causing the carb to get too rich. Clean out and inspect rubber bottom of plunger
Float tends to drown when cracked.
Needle valve tends to lose the little sealing ring. Causing over rich mixture and overflow

Not the best carb to use, but if in order, it will be quite ok. I rode my Ural with K65 the first 5 or 6 years as a commuter with only minor problems...
owned bikes: 93 Ural hack domestic model, 01 Ural 750 hack
92 BMW R100GS, 92 Suzuki GSX1100G hack, 95 BMW R100R hack with Ural sidecar

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propwash
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Re: Carbs

Post by propwash » Fri Feb 08, 2019 10:53 am

Personally, I think it is the best carb to use when considering cost, proper jetting out of the box, simple, no rubber mounting fitting and I have only seen two things that keep them running poorly. Rarely will the carb just fail to work at all.
Claus listed them
- Main jet holder. It becomes loose and the carb will run rich. It will RUN. Turn the carb over, drop the bowl and remove the tall brass jet holder. Throw away the "D" shaped black washer and loctite the post in place, I believe it is 6mm. Or leave the "D" washer there, but the point is to loctite this part.
- The "O" ring on the float needles dissolves with ethanol fuel. Get better "O" rings from UralZentrale (https://www.ural-zentrale.de/en/motors/ ... or-sealing) or run non-ethanol fuel. Another option is to replace the float needle with aftermarket needles with rubber tip.

Set the main needles in the center position, 1.5 out on the air screws and they should run. Proper tuning will require adjusting the needle height up or down one slot, but worry about that later.

Leightydenpr
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Re: Carbs

Post by Leightydenpr » Sun Feb 17, 2019 9:36 pm

Thank you for all of the good advice. So I broke down both carbs again. Cleaned again inspected everything,removed and threw away the d washer. Blue thread locked jet basin to throttle body. All is better but not perfect?
Good carb cylinder is firing away, trouble carb cylinder is also firing away at idle( at last) I also adjust valve’s in the interim which were way off. But Trouble carb mixture screw is set at 1/8 turn out from soft set at best.Any more no good any less no good. Good carb is set at 1.5 turns out and is perfect from ear. Wanted to try to synchronize but I can’t keep troubl side to run when opposite side plug is pulled engine just dies. Should I adjust needle? Any other thoughts ?
currently in the stable
soon to be a denpr
Vtx J 1800
kdx 230
kids rides
cr 50,80,100
missed and thought about
gsxr600
intruder 800 and 1200

jeffsaline
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Re: Carbs

Post by jeffsaline » Sun Feb 17, 2019 11:44 pm

Clean the carb again and make sure carb cleaner moves through all passages including the mixture screw orifice and passage. Look into the intake tract from both sides (filter and engine) and make sure any orifices in the intake tract are clear and passing carb cleaner.

Best,

Jeff
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Mr Wazzock
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Re: Carbs

Post by Mr Wazzock » Mon Feb 18, 2019 3:47 pm

Leightydenpr wrote:
Sun Feb 17, 2019 9:36 pm
Trouble carb mixture screw is set at 1/8 turn out from soft set at best.Any more no good any less no good. Good carb is set at 1.5 turns out and is perfect ... Any other thoughts ?
Whatever that screw passes, gas or air, bad one isn't doing it, this is often because of a blocked gallery in the carb body. So what he said. Image

You may have to resort to stuffing thin wire up it and so on (carefully!) guess how I know.

:D
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(aka Oranzhevaya Opasnost, "The Orange Peril")

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