Author Topic: CB466f  (Read 20943 times)

Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #30 on: November 01, 2019, 08:11:53 AM »
Well, that escalated quickly:

Apart from finding 2 broken piston rings, sticking oil-scrape rings, 2 hardly torqued down head nuts (the ones in the sparkplug hole), no mayor problems found (yet).

Now, I'll be on the look-out for a company who can bore the cylinders to 54,5+ mm (anyone know the piston clearance and ring gap specs on these?), and in the meantime, I will focus on refurbishing the head.
« Last Edit: November 01, 2019, 08:20:49 AM by Erwin83 »
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Offline K2-K6

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Re: CB350f (400) - big bore time
« Reply #31 on: November 01, 2019, 11:57:53 AM »
Have the piston manufacturer no data for the clearance etc? 

Differences in material can mean very significant changes to the spec compared to original metallurgy in these engines so you really need specific information to get them correct.

The ring gap is most probably going to be factory tolerances unless specifically detailed as the materials don't change much. But the piston itself can have quite fundamental impact on bore sizing.

Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #32 on: November 01, 2019, 12:25:32 PM »
There is no specific installation manual provided for this. I just emailed the people in Australia to find out if they specify anything other than standard.

Standard assembly clearance (as I understand from the service manual: 0,01-0,04 mm piston-cylinder clearance.
Ring gaps 0,1-0,3 mm.
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Offline Nurse Julie

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Re: CB350f (400) - big bore time
« Reply #33 on: November 01, 2019, 01:10:44 PM »
Definitely get the data from the manufacturer, as if you are reboring to take oversize pistons, the liners will be a lot thinner and the heat displacement totally different than standard liners / pistons. Also, are you sure it says 0.01-0.04 mm, that only equates to .3 of a thou. OEM Honda pistons need .8 of a thou and Cruzinimage pistons 1.0 thou clearance🤔🤔🤔🤔 And 0.04mm is approx 1.5 thou and the engine could smoke like a chimney.
« Last Edit: November 01, 2019, 01:18:03 PM by Nurse Julie »
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Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #34 on: November 01, 2019, 01:26:08 PM »
Found the info for the 400:
CB466f - KTM 1190 advR

Offline Nurse Julie

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Re: CB350f (400) - big bore time
« Reply #35 on: November 01, 2019, 01:28:11 PM »
Which bit are you reading, I can only see service limits NOT piston / bore clearance
Edit...i have put my glasses on now and can see better 🙄🙄🙄
« Last Edit: November 01, 2019, 01:31:09 PM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #36 on: November 01, 2019, 01:37:02 PM »
now, please correct me if I'm wrong, but I read cylinder size upon fresh install: 51,00-50,01. Piston diameter 50,97-50,99.
So 0,01-0,04 mm clearance.

I agree that temperature is more critical with less liner material. So (should no advice come with this kit), would the upper limit of the installation spec be the best way forward?
that would mean 54,50 pistons, 54,54 cylinders (EDITED).
« Last Edit: November 01, 2019, 01:57:50 PM by Erwin83 »
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Offline Nurse Julie

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Re: CB350f (400) - big bore time
« Reply #37 on: November 01, 2019, 01:44:13 PM »
No, because 54.50 pistons won't fit in a 54.46 cylinder anyway. Can't advise on this Erwin as the tolerances you are referring to don't make sense really.
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Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #38 on: November 01, 2019, 01:57:18 PM »
sorry, 54,50 piston 54,54 cylinders  :P
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Offline Nurse Julie

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Re: CB350f (400) - big bore time
« Reply #39 on: November 01, 2019, 02:05:51 PM »
sorry, 54,50 piston 54,54 cylinders  :P
Haha, yes, they will fit but the piston / bore gap sounds huge to me. I hope the manufacturer of the kit comes up with the spec sheet / tolerances for you. I do know someone else that fitted a 466 kit ( i don't know what make) and he had to strip the engine again, fit new liners and have another rebore due to a too large gap.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

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Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #40 on: November 01, 2019, 02:25:14 PM »
Ok, well you certainly triggered me to do some more research before I tell the machinist what bore diameter I want.
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Offline Nurse Julie

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Re: CB350f (400) - big bore time
« Reply #41 on: November 01, 2019, 02:33:07 PM »
Ok, well you certainly triggered me to do some more research before I tell the machinist what bore diameter I want.
Yes, that's the best thing to do. Mistakes can be very annoying and even more very expensive.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
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Offline Erwin83

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Re: CB350f (400) - big bore time
« Reply #42 on: November 07, 2019, 09:27:44 AM »
Baked this cake yesterday. It came out all black...

Got a response from Australia that there is no specific clearance advice. The pistons are of the same material as standard.

I dropped the kit off at a machinist this morning. He was confident he'd deliver a good fit based on the Honda specs.

Keen to see the result  8)
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Offline Trigger

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Re: CB350f (400) - big bore time
« Reply #43 on: November 07, 2019, 08:25:36 PM »
If you bore to Honda spec (0.02000 to 0.02032 mm ) without using Honda grade alloy pistons, they will seize and do a lot of damage.

The supplier has said, that they are the same material and what that means, is they are alloy  ??? You need to know the grade of alloy.

Offline Andych

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Re: CB350f (400) - big bore time
« Reply #44 on: November 07, 2019, 08:38:22 PM »
That 466 Big Bore kit is the same as the one that Cruising Image offer... not that it means the pistons come from the same factory as the standard oversize pistons from Cruising Image, however I would err on the side of caution and consider that you use the tolerances mentioned previously by Trigger or Julie as to when they use Cruising Image pitons.
On that bore size the sleeves will be thin so I would be wary of having the clearances as tight as Original Honda....
I have the same kit but am no where near ready to have anything bored.. its not even pulled apart yet so I am interested to see how this all goes.
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