Kawasaki KLR Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
I've been having backfiring since I bought my 2009 KLR over a year ago, and have finally gotten around to pulling the carb. I noticed that the choke plunger (the plastic piece that threads into the carb) is broken, so the rubber seal on the choke cable is doing nothing. My question is, could this piece being broken cause an air leak to lean out the fuel mix and cause backfiring? It's a $70 part, so if it's doubtful that this is causing the backfiring, I'm reluctant to replace it...

Thanks for your help!

Dean
 

·
Registered
Joined
·
5,597 Posts
The plastic cap fastening the "choke" cable to the carb casting is hardly a $ 70 part.

When replacing, you might consider a MadStad (Stead Engineering?) metal part; will cost you about half that; the plastic OEM replacement, much less, if I'm not mistaken.



KLR 650 Alloy Starter Choke PLunger. 1986-present day-KLRACP - Stead Engineering

Conceivably, an air leak through the STARTING ENRICHER (vice, "choke") system could produce a lean mixture resulting in backfiring, I'd think, although I defer to experts on the question.

Some "pyrotechnics" upon deceleration isn't unusual, or harmful; the air cut valve/backfire preventer/coasting enricher is explained in, "Care and Feeding of the CVK40," hosted on this website. Adjustment of the fuel screw can reduce "backfiring" sometimes.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #4
Thanks for the responses!

Damocles, thanks for the link. The metal part sounds like a good idea, since whoever had the bike before me broke the plastic part. I wasn't able to find just the plastic part online, so the plunger and cap together were about $69. At least in my search.

Toney, thanks, I'll check the exhaust.

Dean
 

·
Registered
Joined
·
5,597 Posts
The OEM cap hex is 12 mm; ain't sure, but . . . something tells me the Stead Engineering one may be 1/2".

Yeah, I see where the entire starting enricher assembly (plunger and all) is sold for $ 70. A rip-off, when all you need is the connecting cap. Makes $ 30 for the Stead Engineering part look not so bad! There may be a substitute cap available separately; some knowledgeable forum member may disclose this info.

Also: Exhaust air leak, as mentioned above, may contribute to backfiring.
 

·
Premium Member
Joined
·
6,822 Posts
Dean,
K#16012-1055, Cap-Starter Plunger, from older models 1987-2007 <$17.00, Plastic cap only!
K#11060-1108, Gasket, Exhaust at the cylinder head and / or missing exhaust flange nuts are quite often to blame for "After-fire" popping out of the tail pipe.
 

·
Registered
Joined
·
5,597 Posts
Dean,
K#16012-1055, Cap-Starter Plunger, from older models 1987-2007 <$17.00, Plastic cap only!
Good info. No need to spend $ 70 for a sack of parts you don't need, when all you want is a plastic cap.

The metal Stead Engineering cap's nice to have, but you can buy two Generation 1 plastic caps nearly 'bout for what it costs.

I think the stock caps are often broken from choke cable elbow interference when the carb is rotated. Eliminated that possibility with a straight-line "shorty" Drag Specialties Harley choke cable; took a little doin'.
 

·
Premium Member
Joined
·
3,028 Posts
Yes the stead eng. nut is larger OD than the stock one. Personally I see no good reason to replace the weak and often damaged plastic stock unit with another one just like it. YMMV

Dave
 

·
Premium Member
Joined
·
3,028 Posts
...and yes, check the exhaust header for a leak at the head......and keep in mind that a functioning AIS system is INTENDED to produce controlled backfires (pops on decel)

Dave
 

·
Registered
Joined
·
12 Posts
Discussion Starter #10
Thanks guys! very helpful. I think I'll get the the non-plastic cap, just to avoid cursing myself later when I break the plastic one :)
Will definitely check the exhaust too, would not be surprised if that is the culprit. Had noticed that mine has a "different" sound than my brother's 07 KLR, and that sound may be due to a bad/leaky exhaust gasket.

Cheers!
Dean
 

·
Premium Member
Joined
·
6,822 Posts
Yes the stead eng. nut is larger OD than the stock one. Personally I see no good reason to replace the weak and often damaged plastic stock unit with another one just like it. YMMV

Dave
Dave,
I don't see anyway possible for the Stead Engineering, Aluminum 'choke' nut to be a Larger OD than the 12mm od X 1.00mm thread pitch of the OEM Keihin plastic part!
Unless you mean the hex nut size? Which would be a PITA!
The Pro Circuit KX450F 'hot start' aluminum nut #HSCO4250, which I do stock, is a 12mm wrench size.

The KEIHIN OEM plastic choke nut prevents accidental thread damage to the $600.00 USD carburetor.
 

·
Registered
Joined
·
5,597 Posts
Can't speak for Dave, Paul, but . . . I meant: I think the HEX of the Stead Engineering is 1/2", in contrast to the Kawasaki OEM plastic cap's 12 mm dimension.

Also, the thread is TAPERED; don't know what the pitch might be, but . . . the actual diameter of the thread varies, from tip to shank. I'd think a, "12 mm od X 1.0 mm thread pitch" you mention to be constant in diameter; the choke cable connector caps have insteadtapered threads of varying diameter, IIRC.

(May show up in the image I posted above; can't look at it while I'm typing! :) )

Just took a peek--can't tell! While I recall tapered threads, that notion my be only a figment of my reckless imagination, or a function of a flawed memory. The thread diameter may be constant through the complete run.
 

·
Premium Member
Joined
·
6,822 Posts
Can't speak for Dave, Paul, but . . . I meant: I think the HEX of the Stead Engineering is 1/2", in contrast to the Kawasaki OEM plastic cap's 12 mm dimension.

Also, the thread is TAPERED; don't know what the pitch might be, but . . . the actual diameter of the thread varies, from tip to shank. I'd think a, "12 mm od X 1.0 mm thread pitch" you mention to be constant in diameter; the choke cable connector caps have insteadtapered threads of varying diameter, IIRC.

(May show up in the image I posted above; can't look at it while I'm typing! :) )

Just took a peek--can't tell! While I recall tapered threads, that notion my be only a figment of my reckless imagination, or a function of a flawed memory. The thread diameter may be constant through the complete run.
yep; i was speaking of the hex/wrench required, not the threads.

Dave
Well now, isn't that just totally silly for a company to build a tiny little part for a Metric carburetor on a Metric bike which comes with a Metric tool kit which will require an SAE wrench to use!

Of course we can't hardly use the bikes own twelve mm wrench on the OEM part very well in its location anyways!
I use a 12mm 'crowfoot' on a 3/8th" extension in the shop. Don't know what I'd do on the road or trail.
Have either of you built a "Chilliwack Wrench" for either the OEM or Stead part?
 

·
Premium Member
Joined
·
3,028 Posts
Well now, isn't that just totally silly for a company to build a tiny little part for a Metric carburetor on a Metric bike which comes with a Metric tool kit which will require an SAE wrench to use!

Of course we can't hardly use the bikes own twelve mm wrench on the OEM part very well in its location anyways!
I use a 12mm 'crowfoot' on a 3/8th" extension in the shop. Don't know what I'd do on the road or trail.
Have either of you built a "Chilliwack Wrench" for either the OEM or Stead part?
LOL; "Chilliwack Wrench"! .....no, I just used my bent needlenose pliers.

Cheers,
Dave
 

·
Registered
Joined
·
5,597 Posts
Have either of you built a "Chilliwack Wrench" for either the OEM or Stead part?
No Chilliwack so far (Did Normk invent/develop that tool?).

A riding partner had a "custom" 12 mm right-angled open-end wrench built; didn't work out too well. I bought a 12 mm crowfoot in anticipation of the application, but . . . not too satisfactory in practice. I have bent-nose pliers in the toolbox, in case I need 'em.

Mostly, I just struggle with conventional tools, striving for access, carb on or off the bike (easier to connect the cable BEFORE the carb is mounted in the hoses, I've found).
 

·
Registered
Joined
·
1,256 Posts
Ok. Where can I get one of those Chilliwack wrenches? Will it fit the wobble pin nut on my shimmy shaft? So far, the only thing I have found that fits that wobble pin nut is a thirteen point south Texas monkey wrench with a reamed barrel and a bent handle.

Being unwilling to carry bent needle nose pliers just for that choke fitting in my road kit, my solution to the easily broken plastic fitting on the choke cable was to replace the whole cable mechanism with the Cable-Less Choke Conversion Kit from Stead Engineering: Cable-Less Choke Conversion Kit [CCCK]

I removed the pull knob and extended the shaft about five inches with a piece of 3/16" flexible Tygon fuel line partly stiffened with a metal rod for easy access. Now I can just bend the flexible line and rotate the carburetor.
 
1 - 20 of 20 Posts
Top