Honda-SOHC
SOHC.co.uk Forums => The Black Bomber Board => Topic started by: royhall on June 24, 2019, 06:38:24 PM
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Does anyone know the correct procedure for setting the valve clearances on a 450 Black Bomber. I have 3 manuals and they all tell a different tale. I think I have it right but best to make sure before I trash something. Cheers.
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I have got myself completely confused over the valve clearances on the Bomber. I have got the cams in correctly ie. both camshaft marks on the right hand side are correct on the LT mark, and that checks out every two turns of the crank. Cam chain tensioner fitted and set. Now when it comes to valve clearance I have done LT mark with the cam marks aligned then 360deg round and set the left side. Now the confusion, I turn the crank to the T mark and set one right hand side but the other side wont adjust enough, I have to go round 360deg again to set that one. Is this correct? I was expecting to set both right hand side on the one mark.
This is what the Honda manual says about it. I have no idea what they mean by type 1 and 2? The instructions in the Clymer manual don't appear to work and Haynes is a two line waste of time. Any help on this would be greatly appreciated.
[attachimg=1]
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That description suggests to me that early engines were 180 cranks whilst later were 360 BUT i have never worked on a "Bomer" so do not profess to know for certain if cranks, cams etc were different.
Basic way to set tappets/valve clearance is to get the piston on TDC(pencil down plug hole) with both valves for that cylinder moving then rotate engine one full turn to TDC again and that is TDC compression which is where you set clearance.
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As Bryan said, back to oldschool. Rotate the crank clockwise and watch the inlet valve open and as it comes to close watch the piston come to TDC ;)
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Agree with Bryan, looks like they are giving instruction to cover two different crank offsets.
Any four stroke cylinder in isolation should have both valves completely closed at TDC for the compression stroke "of that specific cylinder" you should be able to set each one with that criteria and base circle of each cam lobe would be next to followers.
Manuals on any engine try to give you the least amount of crank turns to accommodate the setting, but the wording can often confuse a sometimes simple task.
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Apologies, crossed over with Trigger there while typing :)
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Apologies, crossed over with Trigger there while typing :)
NOOOO, Not across over ! Is that the same as a cross flow :o I will just check de manuel ;D ;D ;D
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That description suggests to me that early engines were 180 cranks whilst later were 360 BUT i have never worked on a "Bomer" so do not profess to know for certain if cranks, cams etc were different.
Basic way to set tappets/valve clearance is to get the piston on TDC(pencil down plug hole) with both valves for that cylinder moving then rotate engine one full turn to TDC again and that is TDC compression which is where you set clearance.
Tried that Bryan. It appears that the 450 has to be set on a certain position on the camshaft, outside that position there is no enough adjustment to set the clearance. Tried to set the clearance on the base circle opposite the lobe, again not enough adjustment. Trigger, the engine wont turn clockwise only anti-clockwise. The next question about the Honda manual description of setting the right side is 180 or 360deg from where? This must be an easy task, am I just being thick. Cheers.
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You aint being thick, its the japanese to english translation which has got better since the 60's. With the piston at TDC (Tmark) the cam followers should be on the base circle, if you cant get a clearance there something is mechanicaly off.
As to manuel i aint watched Faulty Towers for a long time now, must get out the dvds!
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Why won't the engine turn clockwise Roy?
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It's a 450 Julie it turns from the left of the engine not the right as per a 4 cylinder.
Sent from my Pixel 3a XL using Tapatalk
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It's a 450 Julie it turns from the left of the engine not the right as per a 4 cylinder.
Sent from my Pixel 3a XL using Tapatalk
Ah, got you 👍
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Did you see the MCN CB500T Honda Training feature Roy in my Dropbox
Sorry not in Dropbox ... its here
http://www.sohc.co.uk/index.php/topic,19305.msg170703.html#msg170703
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Thanks Ash I shall give that a full read tomorrow. Had a quick look at it and left/right of the engine is as viewed from the front in that write up. That may be the reason as I am doing it as per sitting on the bike. Could it be that simple, lets hope.
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After a real good look at this problem I think I have found the issue.
First of all left and right is as sitting on the bike not from the front as per Ash's MCM 500T article. It was easy to verify as at the LT mark only one piston is at TDC so that's the left side, confusion sorted.
The problem is that the right exhaust valve will not set when it should. For those that were reading my build thread you will know that the cam and followers were reground by Newman Cams. Looking at it (hard to measure with it fitted) they have taken way too much meat off the right hand exhaust follower and taken it way out of tolerance. So a new follower is required at £105 delivered (ouch) to fix the problem.
The settings are therefore as per the Clymer manual as mentioned earlier.
Anyone got a good condition 450 cam follower going spare. Cash or donation to the site waiting. Cheers.
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Can Newman not build up the follower and regrind?
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They would normally weld on a pad, but by the time two way postage plus costs of the job are added up I may as well buy a new one. I doubt they would have the correct dimensions to work to either. Plus last time it was a two month wait.
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So the gap is too big?
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So the gap is too big?
Way too big.
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It looks like they're not familiar with that adjustment geometry specific to this engine at Newman. With a conventional screw type it could accommodate that change.
Worth taking into consideration for anyone else in same situation, unfortunately of little help here.
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It looks like they're not familiar with that adjustment geometry specific to this engine at Newman. With a conventional screw type it could accommodate that change.
Worth taking into consideration for anyone else in same situation, unfortunately of little help here.
I have at least found the problem so am happy about that. And I can put it right without having to strip the whole lot down again. Newman Cams said they had removed a very thin skim, from what I can see and measure that looks close to 10 thou plus whatever they took off the cam itself. That's a lot for the mechanism to make up, and it simply does not stretch that far. Your correct in saying they probably aren't familiar with the layout. Just unfortunate and another one of those things to watch out for, and partly my fault as I should have taken measurements before and after. O well, it's only money.
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You could fit what the yanks call a lash cap on the valve stem, its like a small hardened dustbin that fits over the end of the valve stem.
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I had a similar issue with the 250RS Roy. Newman advised me to send the cam and the rocker arms. They ground the cam and welded pads to the rockers to take up the bigger clearance. From your experience with Newmans compared to mine (earlier post) I think it depends who you get to speak with at Newmans determines the level of advice you receive. I've always been lucky and have spoken with Mike Newman who obviously knows his onions (and cams!).
Good to hear you have the problem sorted now.
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You could fit what the yanks call a lash cap on the valve stem, its like a small hardened dustbin that fits over the end of the valve stem.
That's an interesting idea Bryan. On this occasion though I think I will replace the rocker arm as any other way is just treating the symptoms and not really curing the actual problem.
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I just hope they didn't take so much off the lobe that a new follower wont close down enough. Have you told Newmans about the problem as they ought to fix it for free really.
I remember many, many years ago talking to an engineer who raced (250 K3 I think), he had a cam made and hardened it with the result it lasted less than 100 miles, apparently cams were meonitic cast iron with followers hardened and you should never run two hardened surfaces together
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Your right BryanI should really let Newmans sort it, but if you ever dealt with Ken Newman you would know why I'm buying a new follower instead. I have managed to measure the cam whilst in place in the engine and its fine. Ken Newman mentioned grinding down and welding on a pad if the followers didn't clean up. Looks to me like they may have ground it down and forgot to fit the pad and just sent them out like that. That story would fit as that Ken guy was truly hopeless.
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Your right BryanI should really let Newmans sort it, but if you ever dealt with Ken Newman you would know why I'm buying a new follower instead. I have managed to measure the cam whilst in place in the engine and its fine. Ken Newman mentioned grinding down and welding on a pad if the followers didn't clean up. Looks to me like they may have ground it down and forgot to fit the pad and just sent them out like that. That story would fit as that Ken guy was truly hopeless.
Wow that's bad Roy .. I have often thought about sending cams and followers away to be repaired and that firm seemed to crop up as being a good service on all counts, so it was always my intention to use them if I couldn't find decent used or NOS parts. I still reckon it's best to try to find original parts in good condition or NOS, as there always seems to be that nagging doubt about whether repaired parts are up to the original Honda standards. I have never risked sending a pressed together Honda crank for repair or inspection for that reason. What's best... a crank with a bit of hardened sludge in the flywheel sludge trap, that may or may not work its way into the lubrication system sometime or a wrongly pressed together crank ..... difficult one that. It's going to be a cracking good Bomber when you get it finished though and your rebuilt thread will be a great record of your attention to detail if you ever come to sell it.
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I feel there's room for mitigation here, not to make an excuse for a supplier as I have no connection with Newman, but the pure reality of accomplishing something of this type.
For an item that is effectively scrap in its damaged form this gives an approach that may bring back into service a part that may not be readily available in the condition needed. Newman appear to know their trade regarding materials and refinishing of cams etc. The specific details of geometry (this is a very tightly designed and specific engine with highly resolved components) may not be fully a part of their appreciation of the job given to them. It doesn't mean it can't be completed, but further discussion prior to event may yeald a very satisfactory outcome. You've really to combine the two elements to succeed.
I've known absolutely impeccable machinists that carry out superb work without need to know further intricacies of the component parts, but it's not always like that.
The crank assembly Ash, it would probably serve to blow steam backwards through the oil routes to flush out tarring from oil ways etc as an non invasive method to clear it out. Followed by engine oil to prevent corrosion in storage.
On that point, sludge, it's an area where "synthetic" oils seem to easily outperform previous types in tolerating higher temperature location within the engine. I agree completely with the "Dutch " view on this.
I've worked for a long time on a particular car engine that has much in common, material and temperature wise, with these bike engines. Prior to synthetic type oil they were notorious "sludgers " but are completely absent of those effects now with improved oils. They were specified and designed in the late 1950s too, which certainly doesn't tie in with "old engines need old oil " mantra often sung out collectively via the Internet.
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Sorry but I don't feel Ken Newman has any room for mitigation. After speaking to him on the phone I thought I had better back it up in writing. Attached is a photo of the letter I sent. I'm not sure I could have done any more than this, after all he's the cam expert. The issue is that I didn't pick up the advice from Laverda120 to ask for Mike rather than Ken Newman.
[attachimg=1]
When I rang him 3 weeks later he had even managed to lose the letter, and the cam and followers were lying around on his desk under a pile of paperwork. I had to resend him the letter via email as he had no idea what he was supposed to be doing with the cam. After two months he finally rushed the (two week) job back to me. That's why I suspect he forgot to weld the pad on the follower.
I shall be stripping it out again tonight so will be able to compare it to the new one (as long as it arrives today). Will post what I find.
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Did you send a full spec sheet with all the measurements and service limits ?
I had a run on Corsa 1300 TD heads in for skimming. And the customer coming back and saying, that I had skimmed them too much as, there are no saver shims available for that head. I skimmed the heads until they were flat, which the customer asked for. How am I to know that saver shims are not available at that time.
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One side of the cam adjusts perfectly the other follower has had a load skimmed off. Why different between sides, they have removed exactly the same on both cam lobes. Also, if in doubt ask, that's the engineering mantra.
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The new cam follower arrived today. Fiddly little sod to get in and out without removing the cam. Got it fitted and set the clearance first time. They hadn't removed a large amount from the cam face but strangely it had been redressed on the part that contacts the valve. I doubt Newmans would have done that, maybe a hang over from the previous owner. Anyway that's all sorted now. Back to the proper build thread for the next set of problems. ;D
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At least you've got it sorted out now.
It's interesting the interaction though as you tried to inform them initially as shown in the letter, but still there was room for a different interpretation there. It seems they are certainly capable of doing this work, which is a valuable asset for quite a few of the bikes on here. But obviously need more concise details as Trigger says.
It's something that appears in other threads though. Take Laverda's 250 single piston saga as another. The engineering supply insisting that the stated clearance is far too tight (wrongly in that case) and pushing the finished result in an unacceptable direction.
It seems common that people approaching these engines just don't really take in how very concise the tolerancing is, or just don't believe it.
It's amusing that the attributes of the first 750 are usually given as "four cylinder, disc brake, ohc, electric start" etc missing completely the real engineering attributes of exemplary production tolerancing that bike brought to markets worldwide, and ultimately underpins their subsequent domination of bike sales.
That of course began in bikes like the 450 and smaller twins.
They didn't get it then and some still don't get it now, which is why most bike manufacturing went to Japan :)