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Trimmed harness, Engine won't idle properly (KZ750F)
- Dunemaster
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23 Jul 2024 21:01 #902490
by Dunemaster
Trimmed harness, Engine won't idle properly (KZ750F) was created by Dunemaster
I'm using the engine of a parts bike KZ750 F for a project I've been working on. I got back to working on it this summer by getting rid of the excess parts of the wiring harness that I thought I didn't need. I removed all the lighting-based wiring, the speedometer, and the unneeded switches (turn signals, dimmer switch, hazards, horn, rear and front brake switches). The engine wouldn't idle properly after putting the wiring harness back in. I am unsure if it was caused by the decluttering of the harness or another issue. I have defaulted on carburetor issues but I haven't been able to fix the idle after going through the list of common problems. Is there some part of the wiring harness that I removed trying to kill the engine? I've attached the harness diagram in case that is useful.
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- Wookie58
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24 Jul 2024 00:59 #902493
by Wookie58
Replied by Wookie58 on topic Trimmed harness, Engine won't idle properly (KZ750F)
I very much doubt that this is an electrical issue, there is little that effects the running of the motor, only charging system and ignition (I assume you have ignition as you only have an idle issue) what airbox are you using ? what condition are your carb rubber mounts in ?
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- Dunemaster
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24 Jul 2024 11:01 #902501
by Dunemaster
Replied by Dunemaster on topic Trimmed harness, Engine won't idle properly (KZ750F)
Ok, I was just wondering because when I didn't have a battery it would kill the engine if not hooked up to the jump starter I was using. I made a custom foam air filter for the engine which is pretty restrictive, but may not be as restrictive as the stock air box (I never had it). It is a three-part filter, with an outer fine steel mesh, 1/8 inch coarse prefilter, and 5/8 inch of a fine 65-ppi filter foam main filter. I recently replaced the carb boots while chasing my idle problem.
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24 Jul 2024 13:30 #902507
by Wookie58
Replied by Wookie58 on topic Trimmed harness, Engine won't idle properly (KZ750F)
I would advise against trying to run without a battery (or jump pack) in the circuit as it will fry your charging system which relies on battery voltage to regulate
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- Dunemaster
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24 Jul 2024 14:54 #902513
by Dunemaster
Replied by Dunemaster on topic Trimmed harness, Engine won't idle properly (KZ750F)
That was when I just got the bike before I bought the proper battery for it
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- TexasKZ
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24 Jul 2024 16:24 #902517
by TexasKZ
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
Replied by TexasKZ on topic Trimmed harness, Engine won't idle properly (KZ750F)
The filter could be a problem. The carbs are very sensitive to airflow. Can you remove the really fine material and try running it with the rest in place?
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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26 Jul 2024 20:42 #902585
by Dunemaster
Replied by Dunemaster on topic Trimmed harness, Engine won't idle properly (KZ750F)
I found the problem. It was a combination of an incorrect fuel service level and a bad vacuum leak. I bought new carb boots that weren't sealing against the engine block. When I checked with carb cleaner I didn't notice any change in the idle but I did when I checked with starter fluid. I sealed the mating surface with RTV and the vacuum leak was gone! I have some tuning to do but the engine is running decently in its current state.
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