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Do pods and shorties hurt vacuum pressure petcock?
- TimKz44082
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1981 KZ440 LTD
1982 KZ440 LTD
1974 Honda Trail 90
1982 Honda Express NC50
1982 Honda Trail 110
Electric scooter
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- loudhvx
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- KZr Legend
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1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- Grumpy Ole Artist
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- Eschew Obfuscation!
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1978 KZ650 B2
Former rides...1976 CB360T, 1985 Shadow 700, 1985 GPZ750Turbo
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- baldy110
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- Jrbrownie00
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baldy110 wrote: No, the vacume to operate the petcock does not change with pods and shorties. Your engine problem is with your shorty exhausts.
That's pretty vague. I believe what he's trying to say is that your shorty exhaust may not be allowing sufficient backpressure which could be causing your low rpm problems.
82' kz750 ltd.
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- TimKz44082
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1981 KZ440 LTD
1982 KZ440 LTD
1974 Honda Trail 90
1982 Honda Express NC50
1982 Honda Trail 110
Electric scooter
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- martin_csr
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The idling problems could be the pods. Sometimes the rubber of the filters blocks the small carburetor openings. Something you can try is to add extenders between the carburetors & filters.
Mufflers. Search JCWhitney or JPCycles for Dunstall mufflers. Emgo & Helix racing are a couple of brands.
Fuel valve. If the bolt hole spacing is 34 mm, here's a topic: KZRider --- Manual fuel valve option
I prefer the vacuum petcock, so I replace the diaphragm when needed & expect to do so every couple of years or so.
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- TimKz44082
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BTW, I just drilled out my primary main, the one next to the secondary main (the one under the needle). The primary main has that little hole that feeds fuel to the pilot jet under the plastic cap. I bought a jet kit and the final step is to drill that main out if I still have trouble at low rpms. The kit had a 0.6mm drill to start with, but the jet was already that size, the .6mm pushed right thru it so I drilled it out with the 0.8mm bit. I will be testing this jet mod on Saturday and will update if it got rid of the flubbering when starting off.
1981 KZ440 LTD
1982 KZ440 LTD
1974 Honda Trail 90
1982 Honda Express NC50
1982 Honda Trail 110
Electric scooter
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- martin_csr
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This may not be a problem w your carbs.
The extenders would be about the same size as the ducts but more substantial to support the filters. Adding them was someone else's suggestion, but I don't know of anyone who has done it. The idea is that doing so will help to stabilize the air flow into the carburetors.
The vacuum petcock allows fuel flow to the carbs by gravity --- the same as a manual fuel valve.
A vac petcock is automatic --- when set to ON or RES, fuel flows only when the engine is running.
To check it: prime the carbs by setting it to PRI for a minute or so, then set it to ON. Disconnect the fuel line & Install a long section of clear tubing onto the petcock & direct the open end into a fuel container. Start the engine --- fuel should flow into the container. Stop the engine --- fuel flow should stop. Do the same test w RES. Next, set it to PRI: fuel should flow --- engine stopped or engine running (note: you may have to re-prime the carbs once or twice).
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- TimKz44082
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1981 KZ440 LTD
1982 KZ440 LTD
1974 Honda Trail 90
1982 Honda Express NC50
1982 Honda Trail 110
Electric scooter
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- Tyler
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bike ran great that way, did 90 on the highway with is pretty Damn good for a lil 440 with my fast ass on it.
If I knew what I was doing all the time life wouldn't be any fun.
'80 KZ650 E 700cc, dyna ignition and coils, frame up restoration, daily driver
'81 KZ1300 A3 full restoration, custom big bore pistons, 1400cc 6 cylinder super bike
"77 KZ650 B1 - Barn Find, work in progeress
"74 Yamaha DT 400 Enduro
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- TimKz44082
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I did three things this weekend; 1) I drilled out the primary main to 0.8 mm as directed with the jet kit. 2) I then put the original air box inlets on the carbs (to make sure the air inlet ports were not at all blocked as mentioned by Martin). I put a pvc 90 degree elbow into that and then put the pods on the other end of the elbow. 3) Filed down the top of the jet needle enough to loosen it in the slide with 2 washers underneath it. (I had previously put in the 102 secondary main jet). With these alterations it was like a miracle change in the way the bike ran. I'm not sure which one had the most effect but I'm not touching anything! I would think that the primary jet size drillout fixed the low rpm starvation that was happening, the extenders made sure the air/fuel mix was as it should be and filing the top of the needle made sure the slides would drop down as quickly as can be (returning to idle rpms was delayed because the needle was too tight in the slide.)
I would say for anyone having low rpm problems who has pods and shorties on, do those alterations, one at a time if you prefer and your problem will go away.
1981 KZ440 LTD
1982 KZ440 LTD
1974 Honda Trail 90
1982 Honda Express NC50
1982 Honda Trail 110
Electric scooter
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