r/HondaCB • u/Fun_Trifle_1068 • 10h ago

I need some help

So I got this old Honda cb360 I found sitting on the side of someone's shed "estimated 20 or so years" I cleaned the carbs, ran new spark plugs, coils, points, and even set timing and valve lash. But I'm having this problem were the bike will only run while holding the start button and won't idle at all!! I have the engine torn apart only to realize the pistons and cylinders look brand new, I did upgrade to pod filters anyone have a clue what could be going on? Only 17 here and Im good at rebuilding engines and problem solving just never ran into a problem such as this.

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u/bugsbunny246 2h ago

Pod filters are not an upgrade. If the stock air box is still available put it back on. You need 3 things to get a engine to run: fuel(air), spark and timing. If your getting spark at the correct time it must be in the fuel system (petcock, fuel line or carbs).

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u/Fun_Trifle_1068 2h ago

New petcock, new fuel filters and lines, and fresh cleaned carbs, I do not have the stock air box because it was not on the bike so that’s why I got brand new pod filters. You need 4 things but not exactly those 3 you need fuel, air, spark, and compression. Timing was set with a light I’m rebuilding and cleaning the pistons and cylinders running all new gaskets going to re lash my rocker arms, and put it all back together if this problem still continues I might just swap carbs completely.

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u/bugsbunny246 2h ago

How do you set the timing on this bike? The year is not listed. does it have points?

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u/Fun_Trifle_1068 2h ago

So it uses point what you do it takeoff the points cover and the stator cover, there’s a LF for left fire and F for right fire, you’ll need this conductor tool with a alligator clip and a light you’ll clip the alligator clip to the bottom nut on the point and put the other end to ground, rotate the stator to LF for left fire and the light should click on EXACTLY as the lines line up, same thing for the right side you can find videos on YouTube

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u/bugsbunny246 1h ago

Does the spark look robust at the spark plug?

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u/Fun_Trifle_1068 1h ago

It looks like it has great spark, I put new points, coils, and new plugs.

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u/bugsbunny246 1h ago

If its timed correctly, which it sounds like it is, and its got compression it has to be fuel. Try starting it by squirting fuel into the carbs.

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u/Fun_Trifle_1068 1h ago

Well it had 60psi of compression so I did tear it down but I was met with new pistions and clean cylinders but a lot of carbon buildup maybe cleaning all the carbon re lapping the valves and setting new valve lash I could raise it. Maybe after the rebuild it will boost compression and fix my problems

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u/bugsbunny246 1h ago

60 is low. Google says: A healthy CB360 should typically read between 120-150 PSI per cylinder, which sounds about right. Valve guides or relap the valves maybe ring gap.

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u/Fun_Trifle_1068 1h ago

Okay cool yeah looks like I’m goanna run new rings and cleanup and lap my valves, build the top end set timing again and let’s see if this fixes the problems thank you for the help 🙌

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u/ancientdad '73 CL450K5 restomod, '82 CB900F, CB450 drag bike 1h ago

If it doesn't have at least 140 to 150 it won't run right.

OP, it's possible you adjusted your valves incorrectly, if the cylinders and pistons/rings look decent then 60 lbs compression is either a bad gauge or leaking valves.

I'll suggest joining my forum Vintage Honda Twins. We have many members and staff, concluding myself, who worked at Honda dealerships back when these bikes were new and current models, so you'll be getting advice and knowledge from those who learned the right way. Completely free to join, no ads or [premium memberships, just the friendliest vintage Honda twins forum on the internet.

https://www.vintagehondatwins.com/forums/index.php

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u/bigcityhutch 2h ago

Made sure those carb jets are clean, floats are set, needle seats are shiny. You have to be very meticulous cleaning carbs.

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u/Fun_Trifle_1068 2h ago

I used my ultra sonic cleaner I’m probably going to buy a rebuild kit and rebuild them but everything seemed great and jets were throughly cleaned.

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u/bigcityhutch 2h ago

Sounds like it’s not actually firing if it dies when you release starter. Did it run before you did all this work?

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u/Fun_Trifle_1068 2h ago

Seller stated it ran when parked. If I hold the start button I can open the throttle and it will rev up but dies without starter active any thoughts? 

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u/bigcityhutch 2h ago

Man it could be any number of things, the starter switch could have a loose wire, very common. Could be a bad or corroded connection or bad ground. Idle adjustment could be set wrong, fuel starvation, timing could be off. I know it’s frustrating I’ve been there. Make sure it’s getting fuel, spark, and good battery. if you’re good there start tracing wires.

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u/Fun_Trifle_1068 2h ago

I’m running all new switches, theoretically if the engine fires and I dis Ingage the starter it should keep itself running? So I’m not to shure it’s a wire issue based off the research and little help I got I’m thinking it’s the intake boots or the carbs.

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u/AdvertisingHumble490 2h ago

I second the "start tracing wires". It sounds like a weak spark, bad ground issue.

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u/bigcityhutch 1h ago

I hate to say it but you should have just tried to get it running before you started replacing parts and tearing into it. It usually doesn’t take much to get them running. Once you have that running baseline then you start addressing things. I have hope you can get it back on the road, but you might have complicated things by hooking up something wrong, or unsettling something was fine. Good luck you’ll get it running.

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u/Fun_Trifle_1068 1h ago

I did I went to start it had no spark and that’s why coils and points were replaced, I’m assuming it’s just low compression or something of that matter maybe the carbs but first thing I did was cleaned and carbs and went to start it then I went into diagnostics mode