Author Topic: Engine component tolerance specs  (Read 1484 times)

Offline Fenderfreak

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Engine component tolerance specs
« on: October 14, 2018, 10:43:23 PM »
Just started pulling the motor apart on my cb250k3 and looking for list of tolerance/ service limit measurements for engine components.

Anyone know where I find this info? Had a look on Ash’s list but may have missed it.

Also noticed signs of wear on the inners faces of the rotor, not major but can see where it may have been touching the rotor, is this normal? If not what causes it?

Cheers

Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline Nurse Julie

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Re: Engine component tolerance specs
« Reply #1 on: October 14, 2018, 11:11:32 PM »
Haynes manuals have the service limits etc in them.
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 AshimotoK0

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Re: Engine component tolerance specs
« Reply #2 on: October 15, 2018, 07:41:31 AM »
Should be in here John and it is still active in my Dropbox links on here.

CB/CL 250/350K SHOP MANUAL

https://www.dropbox.com/s/8i51vjqqdvllazj/CB350ShopManual.pdf?dl=0


Can you explain with a pic the rotor damage ...may be to do with starter clutch.
« Last Edit: October 15, 2018, 07:43:27 AM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #3 on: October 15, 2018, 08:36:30 AM »
Great stuff, all info there thanks.

Will send photo later.

Thanks gents
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #4 on: October 19, 2018, 03:01:57 PM »
Continuing saga of the engine strip down.

1. Cam shaft lobes measure 39.72, standard value in manual says 36.86, wrong cam shaft? Racing cam?

2. Head covers both internal bores measure  21.6, standard value 22., service limit change if more than 20, according to workshop manual! Am I reading this wrong!🤔

Answers on a post card please 😉
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline AshimotoK0

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Re: Engine component tolerance specs
« Reply #5 on: October 19, 2018, 03:28:33 PM »
Would have to check. Best thing is to post decent photo's and Measure camshaft lift (max height minus base circle) . Do rockers have 312 marked on them in the casting? Best to give us clearance between cam journals and cam cover bores.  K3 should have 312 rockers and skinny late 286 cam but sometimes they have been changed.  Main thing on cam is check for pitting & /or wear ridges on  lobes and scoring on journals plus check for bad scoring on cam cover bearing housings. Quite often it is plain obvious that these parts are toast before even measuring anything just by visual inspection.
« Last Edit: October 19, 2018, 03:32:01 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #6 on: October 19, 2018, 04:18:31 PM »
Hi Ash, yep rockers are 312 and have little or no wear.

Cam shaft lift is 6.54 and 6.58. The lobes and light scoring on the journals but appear more cosmetic than deep scoring  as can not feel with
fingernail

Measured both covers 3 times on x and y axis and used largest measurement when calculating clearance between journal nd cover bore ID.

L =0.43 R=0.48

The covers look to have been sleeved at some point, and are quite scored! One of the feed holes was blocked.

Looks like these will both have to be replaced 🙁

Will send hi res photos, cheers
« Last Edit: October 19, 2018, 04:50:03 PM by Fenderfreak »
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #7 on: October 19, 2018, 04:24:47 PM »
Forgot to add can the covers be fitted with roller bearing?
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline AshimotoK0

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Re: Engine component tolerance specs
« Reply #8 on: October 19, 2018, 06:30:48 PM »
Forgot to add can the covers be fitted with roller bearing?

Cover definitely been sleeved. You can fit roller bearings but it needs precise machining and bearings and sleeves are not cheap.... more for race CB350's than road bikes. Best to find originals ...they are out there if you search..... last nice used one I got from Frank at jap2wheelz on German eBay. I will PM with his email ...cheaper to go direct if he has any.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline AshimotoK0

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Re: Engine component tolerance specs
« Reply #9 on: October 19, 2018, 06:38:36 PM »
https://www.ebay.de/itm/CB250K-B4-CB350-Nockenwelle-Lagerdeckel-rechts-RH-cylinder-head-cover-CL-68-73-2/163227176240?hash=item2601190d30:g:28oAAOSwO6tbhjm~#

He has the other side too but I would email direct and see if he is up for a deal on b0th. His email address is on the listing
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #10 on: October 19, 2018, 07:36:12 PM »
Cheers Ash, will have a look 👍

I’ve just knocked one of the sleeves out! Looks like a piece of old copper pipe has been used!
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #11 on: October 26, 2018, 04:19:02 PM »
Thanks for the info Ash, contacted Frank and bought several bits 👍
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #12 on: October 30, 2018, 11:14:27 AM »
Ok sorry on going saga but need specifics as going to send cam off to be plated and reground.

It would appear, according to a couple of FB groups I have a later cam🤔 Hiwever they can not tell me the STD values for the lobes or end journals of the shaft.
Are they right?
All my references just seem to give the values for the cam with 36mm lobes, anyone know what the correct values are for the larger cam?

Have attached photos of the numbers on the cam to see if it helps.

Cheers John
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

Offline AshimotoK0

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Re: Engine component tolerance specs
« Reply #13 on: October 31, 2018, 10:17:56 PM »
Plenty of info on the cam journals ..it's all in the Honda Shop manual in my Dropbox links. Cam lobe changes from K0->K4 I can't find specific data on in any of my manuals (Honda, Clymer, Haynes). If any lobes were badly worn though I would think there would be a ridge either side of the area contacted by the cam followers. You can tell if you have a late cam setup by looking at the rocker markings as later ones are marked 312 (312 was the centre part no.of the SL350, which was first model to use the softer cam system). I guess the lobe measurements stated in the Honda Shop manual are for the early 'fat'cam. Typical of Honda they did an early model manual and then never really updated component dimensions for the later updates.

https://www.dropbox.com/s/8i51vjqqdvllazj/CB350ShopManual.pdf?dl=0

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« Last Edit: October 31, 2018, 10:24:16 PM by AshimotoK0 »
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Fenderfreak

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Re: Engine component tolerance specs
« Reply #14 on: November 01, 2018, 08:13:37 AM »
Thanks Ash,
I have the data from the manual which made me realise the cam was different, thought mine had grown 😉

Definitely have the later setup, the lobes look ok no sign of major wear or ridges , just make out the surface in the photos,so will probably leave those as they are and just get the mounting end journals reground to the specs in the manual.

If manage to find what the lobe specs for the later cam are I’ll let you know.

Thanks again cheers
Honda CB250K3 1971
Honda CB750FZ 1979
Harley Davidson XR1200 2008

 

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