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Author Topic: Cb360/390 pickup hesitation when fully hot  (Read 580 times)

Offline MiniatureNinja

  • Posts: 480
Re: Cb360/390 pickup hesitation when fully hot
« Reply #10 on: Nov 10, 2018, 21:41:06 »
have you had the carbs apart again yet? no torn diaphraghmgfhshams?
'75 Honda CB360 - thread

Offline scott_jangers

  • Posts: 68
Re: Cb360/390 pickup hesitation when fully hot
« Reply #11 on: Nov 11, 2018, 05:38:14 »
have you had the carbs apart again yet? no torn diaphraghmgfhshams?

Hi MiniatureNinja. Diaphragms are all good with no tears or holes where it joins the slide.

Offline scott_jangers

  • Posts: 68
Re: Cb360/390 pickup hesitation when fully hot
« Reply #12 on: Nov 11, 2018, 06:07:23 »
Heres a couple links to a couple pages I wrote about rebuilding carbs w pics...

http://www.dotheton.com/forum/index.php?topic=27417.msg827012#msg827012

Tis one is pretty old...Its got some different info.

http://www.dotheton.com/forum/index.php?topic=63133.0

Wow! Thanks for the help and links. These are great. Lots of interesting points that could do with some investigating other than cleaning and clearing all passages..

1 - Aligning holes in slide on the filter side. I was wondering if the holes make a difference to the speed of lift of the slide and whether their position or size could result in a lean mix as it begins to lift?

2 - Checking diaphragm top covers are sealing correctly.

3 -  Checking throttle butterfly is seating correctly. I stripped these so may have done something silly putting them back. The hinged flap can only be orientated one way if I remember?

4 - Replacing o-rings on primary and secondary jets. Some are already on order. The Keyster emulsion tunes would fall out of the orifices, so I have put the original ones back in, with the original jets, but the o-rings could do with upgrading.

5 - Float level??? I have had them at 26mm, as per the advice on off the Honda Twin forum, but then did the clear tube method and found the levels were around 7mm below the gasket level. So to get the level up to 3mm below the gasket line I have adjusted to 22mm, but felt this was a bit too high as the tang was getting caught on the rest of the float. Maybe 26mm measured with my float level gauge was cool anyway?

6 - check for air leaks at the butterfly throttle lever pivot. Could this let air in when it moves? How would I check, squirt some plusgas at it when I blip the throttle.

Blimey! Thatís probably enough to be going on with. New intake rubbers and o-rings on order. Iíll grab a fresh can of carb cleaner today. Last time I used the stuff I mnaged to squirt myself in the eye... not sure how the jet was angled!  ::)

Itíll be a couple of days before I can get Ďem back on again after this, but will post up results as soon as I have some progress.


Offline Brodie

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Re: Cb360/390 pickup hesitation when fully hot
« Reply #13 on: Nov 11, 2018, 21:01:32 »
Isn't carb cleaner in your eye just horrible.
I now wear goggles when doing anything like that. Once was enough for me.
I'm not sure, but don't ask Brodie.

Way to many build and half done projects to list here.
Sr250, Gs750, Z50A, XV1100, A10, Z160A.

Offline pidjones

  • Posts: 499
Re: Cb360/390 pickup hesitation when fully hot
« Reply #14 on: Nov 11, 2018, 22:52:29 »
I wear (prescription safety) glasses all of the time working on the bikes, but still have managed to squirt carb cleaner, brake cleaner, and brake fluid in my eyes all within the last two months.
"Love 'em all.... Let God sort 'em out!"

Offline scott_jangers

  • Posts: 68
Re: Cb360/390 pickup hesitation when fully hot
« Reply #15 on: Nov 12, 2018, 02:24:42 »
Iíve got safety glasses and a full face shield for angle grinding, but maybe my scuba mask is a better option  ;)

Offline scott_jangers

  • Posts: 68
Re: Cb360/390 pickup hesitation when fully hot
« Reply #16 on: Nov 16, 2018, 10:37:01 »
Okay, so I flushed them with carb cleaner, checked everything was clear and in the right position. No air leaks. Replaced intake rubber insulators for new Honda ones. Started it up and with a little adjustment it idles. Blipped the throttle... no hesitation or bogging whatsoever. With the bike in neutral it runs up the revs perfectly.

However.... put the bike in gear and try to accelerate and it does nothing. No power under load whatsoever. Thereís no misfiring or bogging, just no power at all. Had to sling it back in the garage as I ran out of time, but completing stumped. Will attempt to look again tomorrow.

I had the carbs balanced before I took them off and exhaust presssure was the same. Now the left is noticeably weaker and the throttle stop screw didnít appear to make any difference so have a feeling the left cylinderís not firing? Maybe only running on the right?
« Last Edit: Nov 16, 2018, 10:38:55 by scott_jangers »

Offline scott_jangers

  • Posts: 68
Re: Cb360/390 pickup hesitation when fully hot
« Reply #17 on: Nov 16, 2018, 10:58:40 »
Just had a quick check and the left plugís not getting any spark. Will run some tests later and hope to get both firing again!

Offline scott_jangers

  • Posts: 68
Re: Cb360/390 pickup hesitation when fully hot
« Reply #18 on: Nov 16, 2018, 18:46:35 »
The terminal on the left points was grounding on the inside of the points cover. A little adjustment sorted it and now the bike runs great. Having removed the intake rubbers I can see a thin hairline crack, so replacing those was worthwhile. Hopefully I can get some miles on it this weekend, open up the throttle fully and tweak the settings whilst hot, but I had a quick blast this evening and itís responding really well and accelerated cleanly with no flat spots or misfires. Thanks for the advice!

Now to sort out the clunky rear brake, knackered splines on the gear change spindle, the slight front wheel wobble, the dodgy indicator switch........

Offline irk miller

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Re: Cb360/390 pickup hesitation when fully hot
« Reply #19 on: Nov 16, 2018, 18:57:25 »
I like to paint the inside of my points covers with liquid tape.