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| KH500 random hesitation http://www.kawi2strokes.com/forum/viewtopic.php?f=14&t=14296 |
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| Author: | nvshadow [ Thu Nov 19, 2020 10:02 pm ] |
| Post subject: | KH500 random hesitation |
HI everyone. My first visit to the Forum. It looks like there is a lot of good info here! My experience is mostly with British bikes and magnetos, so this problem has me puzzled. I searched the old postings for opinions on what could be happening with my KH500, but no luck. It feels like it is misfiring without sounding like it is. There seems to be no change in the engine sound on accelerating or at steady speed, but there is a barely noticeable hesitation – feels like you gently tap the rear brake or you have an overly tight chain. This happens every couple of seconds and gets annoying, fast. As long as the engine is running it does this. Otherwise, the bike runs great. Pulls strongly, doesn’t bog down if I give full throttle, etc. I have changed plugs, moved around plug leads, tried a couple of used coils, raised/lowered the needle, changed main jets up and down, cleaned and adjusted the carbs several times, but with no change to the sensation of hesitation. I have checked cylinder head temps after a ride with the center one is hotter than the outers, but not a big difference. Does anyone have a suggestion? Is this a symptom of failed crankshaft seals? Thanks in advance for your suggestions! Sam. |
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| Author: | Evans Ward [ Fri Nov 20, 2020 7:01 am ] |
| Post subject: | Re: KH500 random hesitation |
Welcome Sam! When you cleaned your carbs, did you remove ALL brass including the pilot jets and emulsion tubes? Also, did you verify both float and fuel height? If you could post a short video of you riding it when exhibiting this issue, it may help diagnose the problem. Baffles cleaned and repacked too? |
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| Author: | Ja-Moo [ Sat Nov 21, 2020 9:26 am ] |
| Post subject: | Re: KH500 random hesitation |
If you have that horrid air filter extension, take it off. And start adjusting your air screws in a 1/8 of a turn to see if it gets better. You may also try raising the needles. I hope you didn't put in rebuild kits as they are literally junk and will not work. |
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| Author: | Jim [ Sat Nov 21, 2020 10:15 am ] |
| Post subject: | Re: KH500 random hesitation |
Another possibility: A random hesitation at steady speed and when accelerating sounds like maybe a cylinder misfiring occasionally, possibly caused by: * failing coil (did you try swapping all three, one at a time?) * problem with "distributor" section of alternator (you can check this by temporarily grounding all three coils instead of having them connected to the three distributor wires) * dirty connection, or wire insulation worn through, shorting on frame somewhere If this happens any time the engine is running, you might figure out which cylinder it is by using a timing light on each plug wire and see if the flashing stops occasionally for one cylinder. |
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| Author: | scouse [ Sat Nov 21, 2020 11:40 pm ] |
| Post subject: | Re: KH500 random hesitation |
Can we have some history of the bike? Was it running fine and this has just developed? Full restoration and 1st ride out? I would check the earth strap is present from the engine to the frame Gary T |
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| Author: | nvshadow [ Sun Nov 22, 2020 10:44 am ] |
| Post subject: | Re: KH500 random hesitation |
Hi Everyone. Thank you for all the good suggestions. To answer each one: Evans. I took out all the brass in each carb. In the paper-file that came from the P.O, I found he had replaced components using 3 SUDCO 025-601 kits for H1 D/E/F 1973-1975. The bike came from MN originally to an owner in NV and then to me. It had sat for 30 years or so before. I'm at 4700' so it bogged down with hard acceleration. I tried several needle positions and main jets and now it goes really well - except for the little pulses of hesitation. I'll try for a video if it warms up soon -temps in the 20s to 40s today. Thing is, there is no audible indication of a misfire, only a tiny feeling as it happens. The hesitation is for a fraction of a second. I took out the baffles and put them in a hot BBQ for a couple of hours to get rid of the burnt oil and wire brushed them. They do not have anything I would call "packing". What should be there? Ja-Moo. It has a black plastic dome shaped filter. Today I will get the bike out of the back of the garage and see what it may have there as an extension. I have tried air screw adjustments and needle position, plus different jet sizes. All changes done one at a time. Jim. I need to get a coil that I know to be good. I bought some used ones online, but they could have been sold because they were faulty. I see some newly manufactured ones for sale and will buy a set and try them. Does anyone have a recommendation for a reliable maker? Before that, I will try your grounding and timing light suggestions. Gary. As above, this was a bike from another state and lower elevation. It sat for many years under cover and is a very good condition, original bike. It did not run properly when I got it. Maybe that is why the P.O. sold it. With the jet and needle adjustments I have made, it now goes very well -except for the tiny pulses. I will check for an earthing connection. Thanks again, everyone. I'll get the bike out and see what I can learn. This is my first experience with a K. Anyone comment on the effect of bad crank seals? Would they have any effect on running beyond their job of managing oil? |
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| Author: | Jim [ Sun Nov 22, 2020 11:41 am ] |
| Post subject: | Re: KH500 random hesitation |
If it were mine I'd get genuine Mikuni jets and replace the kit jets. They are an unknown, and it would be best to get back to the original jetting and go from there. |
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| Author: | H2RTuner [ Sun Nov 22, 2020 3:46 pm ] |
| Post subject: | Re: KH500 random hesitation |
If you don't get it dialed by the end of winter, let me know, I will help in person if you so desire. By that time, I will have recovered from both the Brown Recluse spider bite to my left hand, and the January, 2021 left hip socket replacement. Also, look up a board member named "GUTS", he just went though this will his bike,and got it fixed. I live in, and, my shop is in Yerington. The ride between Yerington and Minden is good, but you do have to slow down a touch passing through Smith and TRE. |
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| Author: | Ja-Moo [ Mon Nov 23, 2020 11:02 am ] |
| Post subject: | Re: KH500 random hesitation |
The kits are crap, If the needles aren't marked, then the search is on for you. Get stock jets as Jim posted. |
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| Author: | nvshadow [ Thu Nov 26, 2020 10:21 am ] |
| Post subject: | Re: KH500 random hesitation |
Thanks for the good suggestions, guys. I'll do as you suggest and look for Mikuni parts. H2R tuner. I'd be pleased to meet you when you recover and it warms up a bit. I'll try some remedies as suggested, over the winter.Thanks for your kind offer to help! I have made the ride to Yerington several times recently. |
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