Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: SeanFD on December 25, 2023, 01:45:36 PM
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Hi all, Happy Christmas.
With nothing else to do before dinner this afternoon, i decided to use the time to try, finally to get my 400F2 running; yes the same one I started resurrecting during the pandemic.
Anyway, I sorted some minor electrical problems and power was getting to where it was supposed to be (and when). Even thought the battery voltage had fallen to 12,4 or thereabouts, I decided to try and start it up.
It coughed once on the kick start and then nothing. I tried it on the started and then I was hit on the head by the air filter cover.
Here I stopped, as dinner was nearly ready, and I wasn't sure exactly what this meant.
Can anyone explain and advise whether it is safe to try again with a fully charged battery, or have I done something seriously wrong in the rebuild?
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You can get a intake "backfire" in a healthy engine with build up of fuel vapour while trying to start a reluctant engine. Possibly not much wrong.
But, if there’s more common confusion in ignition system on these engine, coils connected to wrong plugs or points firing the wrong coil when inlet valve can be open, when it'll do it more easily.
Assuming no obvious mechanical conflict, then check carefully the ignition wire routing etc against manual to see if there's anything obviously wrong.
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I agree check the timing/ firing order reads like a back fire.
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Good call guys, that's exactly what the problem was; I had attached leads to wrong plugs. :-[
But now something is DEFINITELY WRONG!
Started on first press of the switch and ran quite sweetly. Stopped and started again, and then:
https://youtu.be/c-6r2hDONYw (https://youtu.be/c-6r2hDONYw)
Now the motor won't turn over with either the starter of the kickstart :( :(
The oil pressure light went out almost at once and I can see there is oil up at the valves, so my thought is that it is related to the cam chain rather than a seized piston. I can rock the crank a few degrees using the nut on the points end but nothing more.
HELP, please! And be gentle with the bad news.
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As it happened so quickly, I would say something has snapped or jammed.
Edit..... Also, if you've got oil to the cam, that doesn't mean it's not a seized piston. The oil to the top end comes up a different oilway.
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If it stopped suddenly and will not turn over possibly cam chain broken or something fell off internaly and jammed the cam/crank
DO NOT rotate the enging with the big nut on the advancer unless plugs are out, also do not rotate the crank till you have sorted what happened or you may bend valve(s)
Remove cam cover and inspect, my personal ideas would be cam sprocket bolt fell out or cam chain snapped
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Cam sprocket bolt came out, somehow dislodged the left rear dowel, which got jammed between the chain and body.
This is where the dowel ended up:
[attach=1]
This is where the bolt ended up:
[attach=2]
And this is what they looked like:
[attach=3]
The only other damage I can see is this:
[attach=4]
[attach=5]
So it looks as of I might have escaped lightly. The one question I have now is what has happened to the rest of the dowel. if this has dropped down teh cam chain tunnel, will it be safe to run the engine? Is there anywhere else it could have gone?
There is what looks like a large washer - can't think of another way to describe this - on the camshaft sprocket, which is held to the sprocket by the bolts. it looks as if it has been bent but I cannot find it on the parts fiche. will it be OK to simply put this back in place and bolt it back to the sprocket? To replace it would require removing the camshaft.
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I can see how the bolt came out if you didn't put locktite on it but I can't fathom out how the dowel got involved in the failure 🤔🤔🤔
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If you mean the big wide disc shown in my photo, it doesn't show on the fiché but they were fitted to the late F2 models, earlier models didn't have them. You appear to have a lot of scoring on the camshaft.
[attachimg=1]
[attachimg=2]
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Yes, I saw that on the photo also, although I didn't notice it on the shaft itself. I'll have a look at it in the morning. I'm (almost) sure I put lactate on the bolt, but maybe not.
And the dowel puzzled me too. I'm assuming that is what it is because it is missing :-\
I was referring to the disc. If it is not on the fiche, how can I order a new one, assuming it is available?
So is it OK to turn over the engine now to see if the remains of the dowel have fallen through, or are lodged somewhere?
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You need to remove the sump pan to see if it ended up in there before trying to turn the engine over.
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The dowel must have been dislodged when you put the cover on, if some models do not have the big washer, which i havent seen but then never stripped an F2, it should be ok to run without.
Yes pull the sump to check on bits and i would fit 2 new cam sprocket bolts plus check threads in cam for damage.
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I will do.
DSS doesn't re-open until 02 Jan, by which time I'll be back in France – replacing the valves and guides on my K2 – so Rusty's completion gets delayed once again.
For now, I'll just put the covers back, and leave the oil in place till next time.
Maybe I should hire a van :-\ ...
Just for interest, here are a before and after pic.
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I don't think the dowl was dislodged by the cam bolt I think they are two separate incidents. The dowl appears to be a 6mm item and is part of the rocker cover, I think the dowl fell out as you put the rocker cover on and lodged itself in the cam chain tunnel. When you started the engine the cam bolt hit the dislodged dowl and the shock caused the bolt to start undoing itself and fall out especially when you see the damage caused to the dowl and the speed the engine was idling at in the video.
You definitely need to drop the sump to check if the remaining part of the is in there. The sump pan also has a baffle plate and it may have landed on the top of that. It's quite easy to drop the sump, all the bolts are easy to get to with a 1/4†socket.
You could always try fishing down the cam chain tunnel using a long, thin magnet to find the remains. I dropped a head bolt washer down the tunnel once and expected to do a strip but used the magnet method and out it came 👍
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You’ve made a nice job of that 400 on the restoration Sean. I do feel for you with this mechanical failure but you might find a bit of damage limitation in there hopefully. I agree with comments here that dowel must have been dislodged on assembly. Fingers crossed you get sorted soon! You’ll soon find out if you did use loctite when you try and loosen the other bolt on the camshaft sprocket. Good luck!
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That's bad luck Sean - I've generally ensured that the dowels are on the fixed surface first so they can't drop out. It has meant I have had to replace a few as they chewed up a tad on extraction.
As has been said any unaccounted for big lumps should drop down into the sump - goes without saying to change the oil filter. Have you fitted a magnetic sump plug might be worth it as belt & braces.
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I can see how the bolt came out if you didn't put locktite on it but I can't fathom out how the dowel got involved in the failure 🤔🤔🤔
Julie, maybe Loctite is something you recommend, but there's no mention of that in the official Honda CB400F shop manual over in Aladdin's cave.
I built a fair few of those Honda engines during my years in the trade and never had fully tightened cam sprocket bolts come loose.
Bit of bad luck for Sean tho, hope he gets it sorted out.
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I can see how the bolt came out if you didn't put locktite on it but I can't fathom out how the dowel got involved in the failure 🤔🤔🤔
Julie, maybe Loctite is something you recommend, but there's no mention of that in the official Honda CB400F shop manual over in Aladdin's cave.
I built a fair few of those Honda engines during my years in the trade and never had fully tightened cam sprocket bolts come loose.
Bit of bad luck for Sean tho, hope he gets it sorted out.
Indeed you are correct Scoti but if locktite or similar had been applied, it wouldn't have come undone. It's just belt and braces really. It's like the cap / plate that holds the cam chain guide in place at the top, I would advise using locktite on those 2 bolts as well.
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I've never used Loctite on those bolts, so long as they are torqued up they should be fine.
As for the dowel, I tend to locate any dowels in the head rather than in the rocker cover, they shouldn't fall out if they are in the head, as gravity keeps them in place.
TBH I suspect the cam sprocket bolt was never tightened rather than came loose, you tend to fit one but not tighten it, just in case it locks the sprocket out of alignment for the other bolt, spin the engine until the other comes up so you can fit that and then forget you haven't torqued up the first one and move onto something else, anything can cause this, someone speaks to you, a phone call, just something that breaks your concentration, easily done.
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TBH I suspect the cam sprocket bolt was never tightened rather than came loose, you tend to fit one but not tighten it, just in case it locks the sprocket out of alignment for the other bolt, spin the engine until the other comes up so you can fit that and then forget you haven't torqued up the first one and move onto something else, anything can cause this, someone speaks to you, a phone call, just something that breaks your concentration, easily done.
Which is why I prefer to work on my own...
And I adapted the Japanese way: Edding 8750 industrial paint marker...
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So that's why I have yellow dots on my engine bolts to remind me they have been torqued up!
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Yellow paint was used by Honda on the production line for that very reason Ted, it also showed if the owner tampered with the bolts in case of warranty claims.
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Using a magnet, I was able to fish out a couple of additional bits.
Then I turned the motor over slowly - yes Ted, the plugs were out - and all seemed fine.
So now it will have to sit for a while until I get back to Belfast, when amongst the other things, I'll drop the sump, check the strainer and change the filter.
Until then ...
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That's bad luck Sean - I've generally ensured that the dowels are on the fixed surface first so they can't drop out. It has meant I have had to replace a few as they chewed up a tad on extraction.
As has been said any unaccounted for big lumps should drop down into the sump - goes without saying to change the oil filter. Have you fitted a magnetic sump plug might be worth it as belt & braces.
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Or new title: Everything happens to me!
On my enforced sabbatical from my USA trip, belfast2belfastbybike.com (http://belfast2belfastbybike.com) for those who don’t know, I decided to get this bike up and going.
I took the rocker cover off and almost the first thing I saw was the dowel I thought was the culprit; intact and lying against the oil pipe. Obviously it had just dropped out of the rocker cover when I removed it.
[attach=1]
Replacing the bolts into the cam sprocket was difficult - they felt tight. I got one in and torqued and was doing the second when it stripped! (Original Honda bolt)
I was thinking to take the camshaft out to inspect the threads more closely when I noticed what looked like a crack in the lobe where the bolt goes. I touched it with a screwdriver and the result was not pleasing!
[attach=2]
While trying to gat a hold of this piece and not being careful enough, (how could such a chunk of metal fall down that small hole?) I dislodged it and down it went. I think – I hope – that I can retrieve this by dropping the oil pan, because my efforts to find it from the top were unsuccessful.
So that put paid to my hopes of getting the bike running quickly. A replacement camshaft is on its way from Steve Cooper at 400FourBits, along with some new bolts and a gasket from DSS.
Anyone seen this happen before? No I didn’t drop it, but someone else may have I suppose. I guess I should be happy that I found it now and not when to cracked at 6000 rpm, but sometimes it’s hard to be philosophical 😢
[attach=3]
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Yes i have seen but not on 400, could be sprocket was not on shoulder properly
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I see you described your process as 'I got one in and torqued and was doing the second when it stripped!'. It is better to get both bolts in finger tight first and make sure everything is aligned before final tightening, equally, to full torque. I thought I might mention this before you put in your new camshaft. These castings are very strong in the directions they need to be but surprisingly brittle in other directions where force shouldn't be applied.
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Agree with likey cause being unintended force in wrong direction whilst tightening bolts unevenly, or missing alignment of sprocket throughout the assembley/ location part.
Good advice to get them all but fully assembled by fingers before just a tightening torque at end to finish the work.
Many years ago, watched someone tightening a jaguar XK camshaft (they are very long) by just going along from one end to the other in assembly, only to snap it in half as it bent against one of the valve springs.
Very strong in direction needed, but simply vulnerable to bending forces that are not part of running when in use.
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I did think about the possibility of the sprocket not being properly on as suggested by Bryan, and that may have been the case given the relative tightness as I put the bolts in - not overly tight, just not turntable by hand.
The first one was in snugly and I then put in the second and was torquing it when it stripped. Maybe an off-centre sprocket meant the bolt wasn’t lined up correctly so was cross-threaded.
The shaft broke after I had removed the sprocket bolts.
Good news is that I retrieved the missing part, sitting on top of the primary chains. :)
But not till I had already removed the sump …. And the exhaust to get at the bolts! :(
The camshaft I had ordered turned out to be damaged, so now on the lookout for another.
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Only one on ebay at moment and thats in us and 100 postage!
I could get that reduced via a freind but not sure by how much, dont have any 400 ones about but try a wanted on the forum somebody may well have one, if you are very flush there are a couple of Yoshi ones on ebay at just north of a grand!
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That’s be grand, sure! ;D
I’ actually off to the States next week so I’m going to see what I can find there.
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There is a cheaper one. What do you think of the wear. Or is this the one you ordered?
https://www.ebay.co.uk/itm/204863852612
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He actually had 4 of these on his website - 400fourbits.co.uk (http://400fourbits.co.uk). The one I was going to get (at £60) turned out to have a chunk missing, rather like mine.
I have found another which looks better. Just waiting on response to my offer.
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Hi everyone,
I'm back from Belfast, N America, having covered some 14,500 miles on my 750 K2. There were a few hiccoughs along the way but the old girl made it. She has a, now, serious oil leak from, I think, the cylinder head gasket joint That I will have to sort out before continuing in NZ, but that's a story for another day.
So I'm back to Rusty and her top-end. I've installed the new camshaft and sprocket. Because the washer thing I mentioned earlier was warped a bit, and Because N Julie said it was absent on all but the latest F2s, I decided to leave it out.
Sprocket was successfully attached, but I noticed there was a bit of lateral movement after torquing the bolts - about 1-2mm. I don't think this is because I omitted the washer, but what do y'all (American influence :D) think?
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I went ahead without the washer/spacer and put the rocker cover on.
Even with a;; the tappet adjustment screws fully out the cover didn't sit flat on the cylinder head, and when I rotated the engine, it moved, rocking :)up and down a bit on a L/R axis.
Hand tightening the bolts, just until they touched stopped this rocking, but I was hoping for some reassurance, before tightening everything, that this was normal.
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I went ahead without the washer/spacer and put the rocker cover on.
Even with a;; the tappet adjustment screws fully out the cover didn't sit flat on the cylinder head, and when I rotated the engine, it moved, rocking :)up and down a bit on a L/R axis.
Hand tightening the bolts, just until they touched stopped this rocking, but I was hoping for some reassurance, before tightening everything, that this was normal.
You need to be careful that nothing has snagged when the rocker cover is placed on, some using elastic bands to hold rockers in better positioning to facilitate.
I don't think there's any point that will have ALL the cam lobes pointed downwards away from rockers , which means as you tighten the bolts down to close, then you'll be compressing at least some of the valve springs. This will make it sit up until fully tightened.
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Thanks,
I spent an age trying t0 see if something had snagged, and then some more to make sure it wasn't the tacho drive not meshing properly. Then I tried with all the lobes pointing not-up, as far as was possible and this improved things a bit.
With the bolts in place, it is looking better and so tomorrow the plan is to tighten it all down.
I'd like to get it running before I head back to France on Thursday, so fingers crossed.
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A little difficult to describe remotely, but the snag comes usually from the tappet screw face that touches the valve tip "catching" on that tip as it comes down into alignment with the case/cover closing.
Diligence in looking at all of the valves at that location to see that it's not happening should let you gently close the cover by going around equally with the bolts to evenly bring the two surface together. If that makes sense :)
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I've become a little confused as this thread started for a 400F now it's presumably talking about your 750 K2 oil leak.
I know nothing about the 750s.
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I've become a little confused as this thread started for a 400F now it's presumably talking about your 750 K2 oil leak.
I know nothing about the 750s.
:)
Sorry Ted. 750 stuff was just intro. I’m onto my 400F2 now.
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A little difficult to describe remotely, but the snag comes usually from the tappet screw face that touches the valve tip "catching" on that tip as it comes down into alignment with the case/cover closing.
Diligence in looking at all of the valves at that location to see that it's not happening should let you gently close the cover by going around equally with the bolts to evenly bring the two surface together. If that makes sense :)
I understand. I retracted the screws until all were inside the rocker. It’s all done now.
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I'm with you now I used NJ's trick using eleastic bands between the opposite rockers to hold them up into the cam cover with the tapett adjusters fully retracted then when fitting the cam cover using the sequence in the manual working outwards on each side from the middle iirc - the sequence is in the manual as you will know.
I do remeber having to ask about the assembly order of the springs on the rocker shaft as I did not take a strip down photo.
Didn't take a photo but this is NJ's photo.
.(https://live.staticflickr.com/65535/54086525790_d78063e885_o.jpg) (https://flic.kr/p/2qprzLJ)WP_20181111_16_44_15_Pro (2) (https://flic.kr/p/2qprzLJ) by Macabe Thiele (https://www.flickr.com/photos/187487200@N03/), on Flickr
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Clever that; wish I had seen that earlier.
But it's on now, for better or for worse. Will see tomorrow, when try to start it.
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If it's not too late then Honda Manual here shows you how to do the valve clearances quickly and easily with the minimum of engine rotations with the spark plugs out.
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I'll be doing that particular task, which I hate, tomorrow, using my new tool, once I go and get a 9mm ring spanner that is!
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I'm the same, I don't like doing valve clearances so do my best to get each one spot on first time.
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Well, since last time ....
Everything went back together, but an electrical gremlin prevented me from trying to start the engine. So after spending Xmas at home in France, I continued my RTW trip to Belfast(s).
belfast2belfastbybike.com) (http://belfast2belfastbybike.com)) for anyone interested
I have now done NZ and Oz, then got held up by the Pakistan/India dispute, spent 2 weeks on little hired bikes with my sons in northern Pakistan, and now, because of the Israeli action in the Middle East, my 750 is being stored in The Bikers Cafe, Dubai
https://www.facebook.com/search/top/?q=bikers%20cafe%20dubai (https://www.facebook.com/search/top/?q=bikers%20cafe%20dubai) If you're in Dubai, pay a visit; the food is great and the strawberry milkshake wonderful! :)
However, every cloud .... This delay allowed me to return to Rusty the 400F2.
Without too much effort the engine started, but it was lumpy. The oil pressure light didn't go out either, and then I realised I hadn't put any oil in after the last episode! :-[. The carbs were overflowing. and the throttle grip was sticking.
So I removed the carbs, cleaned and blew through the jets, did a bench synch leaving the slides at 3mm using the idle screw, set float heights at 21+/- (range 20,5-21,5) and replaced them - what a job replacing them is! I removed the powder coating from the right handlebar and the grip started moving much more freely.
Rusty fired up with the first prod of the starter :D, responded well to the throttle but wouldn't drop below 4000. She started several times with the same result.
https://youtube.com/shorts/jydaCl9nJXU?feature=share (https://youtube.com/shorts/jydaCl9nJXU?feature=share)
Checking the plugs, 1, 2 & 4 were clean, but No 3 was black. I unscrewed the idle screw fully, and reset the air screw at 2 turns out - they were at 4 turns out!
The bike wouldn't start! There was a good spark, and fuel seemed to be getting through. At this point I noticed that the starter spun much more freely when the kill switch was off, and there was an unsettling noise from the engine when it was on. I was about to start from scratch with checking the valves and timing when I noticed some oil on the floor :o There was a hole in the clutch cover; the bolt retaining the secondary drive gear had come loose and punched it's way through the crankcase!
[attach=1]
Sorry for the biblical length of the post, but a few clear questions:
- Apart from the hole in the crankcase, what damage might the loose bolt have cause?
- I plan to try to fix the hole with JB Weld Extreme Heat; any thoughts?
[li] What can I now do the get it running again (once the hole is repaired)? Go through the usual suspect list of valves, timing and carbs :( ? Or is there something I have forgotten?
[/li][/list]
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Nearly a week later and the engine is running again.
The problem? Me!! ::)
I used JB Weld Extreme Heat to repair the case cover; it doesn't look pretty, but seems to be working. First replacement, the kick starter wasn't positioned correctly and just spun freely without moving anything. Second replacement, the clutch lifter mechanism came out of position, so the clutch lever wouldn't move. Third replacement, all went well, thankfully.
I'm not sure I followed the procedure correctly when synching the carbs, but when I started up, the engine ran, still fast and with a poor response to the throttle. Plug no 4 this time was black.
Adjusting No 4 air screw would bring down the idle, but there was little response to the other screws. Checked the plugs and switched 1 & 4. All plugs were good and the switch made no difference.
So I bit the bullet and took the carbs off again. I hadn't followed the procedure properly! the slides were at 3mm with the idle screw fully out; no wonder it was revving high.
Set things properly (?) this time: all slides bottomed out; No 4 set at 3mm using the idle screw; the other 3 then set to 3mm using the individual adjustment screws. Yes?
Then when re-assembling the carbs, the float bowl o-rings (Why did I open the float bowl when all I was doing was a bench synch? Good question!) had expanded so much they wouldn't fit back in. So I've ordered a new o-ring kit from Nurse Julie - thank you.
Meanwhile, being impatient now, I decided to try a temporary – if it works it'll stay there till it stops working :)) – fix. I cut the o-rings, removed about 2-3mm – tailored for each bowl – and stuck it back together with superglue. First test rigged on the bench suggests it's holding.
Well it's still holding, carbs are back on - what a bugger that airbag is – and tomorrow will tell.