Author Topic: IDK Numero Dos - 1975 Honda CB400F (Read 67301 times)

minimo · « **Reply #200 on:** July 20, 2018, 07:55:55 PM »

Tear down courtesy of...

...tools of the trade #honda

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spuds · « **Reply #201 on:** July 21, 2018, 06:42:34 AM »

Got caught up quickly on this one this morning. Some highs and lows for sure. Looking forward to seeing the finished product----liking the seat shape you settled on by the way.

minimo · « **Reply #202 on:** July 21, 2018, 07:00:53 PM »

Thanks, spuds. A mix of joy and anguish...

Clearing out the innards now. Pistons are out. Here they are from 1 to 4 (rider side left to right):

I do like my marshmallows toasty, btw.
One of the rings on #3 had broken off probably as a result of me flipping the engine over (on a padded floor) to get to the bottom engine bolts. I’m wondering if maybe the ring had broken off by my sloppiness or if it had busted off while riding. The cylinders so far upon initial inspection look smooth and scratch-free. Hmmm.

Hard carbon deposits all over the place. Even some hard rock-like deposits on top of the pistons. Gonna give these a gentle bath in some Dawn soap and warm water overnight and a plastic brush scrub tomorrow mid morning. Ease it all into an ultrasonic bath maybe late tomorrow. Treating this engine like an onion and working and cleaning it in layers. I’ll even try to get some soda blast time in.

The cam chain and respective parts were suspect of some damage and there was some shearing of the engine case... Should I be concerned or is this negligible:

I was also able to pull out the Push Bar (#7 in drawing) and inner+outer tensioner springs. Not sure if I was supposed to do that as it was a bit of a struggle to do.

The Tensioner Slipper and Cam Chain Guide have probably seen better times.

I’m looking into replacing the cam chain tensioner system with those parts from TTR400, if they even still make ‘em. Or, can I simply clean up the parts I got and possibly replace the tensioner slipper and guide and chain and be good to go?

minimo · « **Reply #203 on:** July 21, 2018, 07:01:42 PM »

Also, the pistons I noticed have numbers embossed on them that don’t quite follow any sequence. Are those critical, from left to right?

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minimo · « **Reply #204 on:** July 21, 2018, 07:29:17 PM »

No coincidence; piston #3

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minimo · « **Reply #205 on:** July 21, 2018, 08:05:59 PM »

Inlet valves

Exhaust valves

Good time for a-scrubbin’ and a-lappin’

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RAFster122s · « **Reply #206 on:** July 21, 2018, 08:44:02 PM »

Do you intend to clean up the head intake and exhaust port flash if any? Nice teardown.

minimo · « **Reply #207 on:** July 21, 2018, 08:46:29 PM »

RAF, u bet I am! I was gonna blast it with soda and then a warm water bath to follow. Any other suggestions?

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RAFster122s · « **Reply #208 on:** July 21, 2018, 10:40:33 PM »

Port matching to your intake an cleaning up the intake header from carbs shortening any sync port screws so they are not in the airflow.
Exhaust port matching is tougher I think.

Light clean up is all I would do unless I was guided by someone who know what they were doing with a 400.

minimo · « **Reply #209 on:** July 23, 2018, 12:31:18 AM »

Is David Silver Spares about the only place selling new standard size piston kits (not oversized)? Checked eBay and I thought Cruzin Image (Japan) would have them but they’re all oversized.

Piston #3 is pretty heavily marred. All of the cylinders look/feel smooth; no gouges, no marring. Figured while I was in there to replace the pistons. #3 was the worst of all four. It makes sense budget-wise to replace just that one but what do you think? Should I spring for an overbore?

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minimo · « **Reply #210 on:** July 23, 2018, 12:43:32 AM »

Oh-ho! Nevermind, Cruzin Image has ‘em after all.

https://m.ebay.com/itm/75-77-HONDA-CB400F-STANDARD-SIZE-PISTONS-SET-4-PISTONS-INCLUDE-10-CB400FPS-/142127403497

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RAFster122s · « **Reply #211 on:** July 23, 2018, 01:22:39 AM »

Drop cylinders off at machine shop for measuring. This will tell you if bore is round as well as in spec. Should be $15-20 charge for that service. If bore is concentric and in spec, then I would spring for a new piston. Overbore will not be giving you any performance boost. Not enough displacement change to make a diff and real perf increases usually through higher compression...but, that brings other issues.

CI kits are pretty good quality for price and require more work to relief sharp edges, but they typically do not increase and sometimes they decrease compression.

minimo · « **Reply #212 on:** July 23, 2018, 01:42:40 PM »

Thanks for the notes, RAF.

I have access to a mill and a dial gauge so I'll give these cylinders a prelim inspection.
If all is well and within spec, I'll do a light hone. Say I end up getting the standard pistons from CI, paying note to the sharp edges, would it be worthwhile to try and deburr them or will that defeat the purpose?

minimo · « **Reply #213 on:** July 23, 2018, 01:59:27 PM »

Anybody have the hone size/diameter for 400F? I have 2-3/8" (60mm, 180SC Flex-Hone) that I used for my 550F rebuild but that's way to big?
Anybody have a hone I can borrow?

MoMo · « **Reply #214 on:** July 23, 2018, 02:43:42 PM »

I don't think the appropriate size glass bead hones are all the expensive

RAFster122s · « **Reply #215 on:** July 23, 2018, 03:27:36 PM »

With the CI kits you just need a bit of time relieving edges with sand paper , 400 wet dry used wet.

minimo · « **Reply #216 on:** July 23, 2018, 08:05:09 PM »

Thanks, MoMo. You’re right - not expensive. I’m getting 51mm at 180 grit. 180 grit seemed to work well for my 550F rebuild.
https://www.amazon.com/gp/product/B002XUL0LI/ref=ox_sc_mini_detail?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

RAF, cool cool. A light deburring is what I’ll do then. Meanwhile, I have good concentricity across my cylinders
https://drive.google.com/open?id=19_9kjxZ7mCdxisTq-pRWkMVgy-0O82RA
Used cylinder #4 as reference and went across and had within a thousandths wiggle on the spins, up and down on each cylinder and good consistency. I am pleased. Fortunately, this mill isn’t used much these days so I’m able to leave it in the vise and order the Flex-Hone and go back on the coordinates to clean these suckers up a bit

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minimo · « **Reply #217 on:** July 26, 2018, 10:13:07 PM »

51mm (2-inch) FLEX-HONE 180 grit doing its thing...

It’s not easy taking quality photos with greasy fingers but take my word for it these cylinders are looking and feeling a lot smoother and cleaner than before. Moving forward.

Next up, soda blasting parts in my 100-degree garage using a makeshift ghetto booth rig using plastic sheeting and tape

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strynboen · « **Reply #218 on:** July 27, 2018, 07:25:21 AM »

yes think the cross patters must be 20 degrees..to lead the oil..and vear the rings inn...

minimo · « **Reply #219 on:** July 27, 2018, 07:41:36 AM »

Thanks, fellas!
They might be on the smooth side now - was trying to get some of the vertical score marks out as best I could. I may have to hit these again with my dingle balls :-)

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SOHC4 Cafe Racer Fan · « **Reply #220 on:** July 27, 2018, 09:00:13 AM »

Quote from: minimo on July 27, 2018, 07:41:36 AM

Thanks, fellas!
They might be on the smooth side now - was trying to get some of the vertical score marks out as best I could. I may have to hit these again with my dingle balls :-)

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What you do with your Ben Wah Balls is your own business!

algophobe · « **Reply #221 on:** July 27, 2018, 09:13:14 AM »

nice work! to all the pros, any advantage between beads vs. the flat bars types?

minimo · « **Reply #222 on:** July 28, 2018, 07:54:56 PM »

Here's a Tarozzi front fork brace alternative from Japan (MC Again).
https://japan.webike.net/products/21955575.html

I'm quite fine with my Tarozzi still.

minimo · « **Reply #223 on:** July 28, 2018, 08:04:39 PM »

And some front fork springs, MC Again and PMC (Performance Motorcycle Creative, Japan) https://japan.webike.net/ps/#!p.m=6554&p.c=1084&p.sk=1

These companies also manufacture front fork stanchions, which are also hard to come by in the States
https://japan.webike.net/ps/#!p.m=6554&p.c=1086&p.sk=1

minimo · « **Reply #224 on:** July 28, 2018, 08:29:55 PM »

This sorta blew my mind. A Center Stand that dodges the aftermarket exhaust

Pretty brilliant https://japan.webike.net/products/21955641.html

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Author Topic: IDK Numero Dos - 1975 Honda CB400F (Read 67301 times)