Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Drew400 on November 02, 2014, 05:27:12 PM
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Hi all,
My next expression of lack of experience...
The Haynes manual shows some chap neatly fitting the cam tensioner cap and two bolts... looks easy. However, on mine the blade stands proud and requires considerable pressure against the springiness of the blade to locate, never mind tighten, the two bolts. Clearly, something's not right and so I've not tried to fasten it in, pending responses from you.
Have I done something else wrong?
1. the blade appears to be seated in the U bracket at the bottom of the barrels
2. the spring adjuster is compressed so there's no pressure from it on any part of the tensioner blades/chain
Thoughts anyone?
Ta (again),
D.
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Hi,
if you are absolutely confident that the lower end of the blade is seated correctly in the U shaped block in the tensioner arm and that block is fitted and seated correctly, then the blade will stick up (not sure exactly how much as I haven't accurately measured a new one recently) The next stage is to fit the top cap and press it down to put the curve into the blade to push against the chain (I usually use a wooden dowel for pushing as screwdrivers often slip) It's now relatively easy to fit the high tensile bolts - and I always loctite those. Then you can release the tensioner bolt to take up any slack. It will still need further adjustment when the engine is running.
Are you using new parts?
Let us know how you get on
Ian
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Thanks Ian,
Yes indeed, all my parts are new ones from DS: u-shape bottom, blades, chain. Only the adjuster springs are not new.
Maybe I just need to push harder than I thought - it does indeed bend the tensioner blade towards the chain. Naturally, I don't like to force things without checking!
Cheers, D.
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Drew are you saying that once the blade is in with the plastic cap on, you put the top cap on and you can not get the two 6mm flange bolts to go in the threads???
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That's it Trigger.
If you look at this picture from my cam shaft query of a few days ago, you can see the blade standing proud:
http://www.sohc.co.uk/index.php?action=dlattach;topic=7335.0;attach=7725;image
I have to push down hard, bending the blade towards the chain, to get the top cap down to the top of the cylinder head. I haven't got as far as trying to locate the bolts as it didn't feel right so I stopped pushing and wrote this thread.
Hence my question about having done something else wrongly, to add to all my other learning!
Ta,
D.
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Looks a little high but, i am not with it to put my finger on it. I would try to locate it at the bottom again and try it with the M6 bolts. The blade needs to flex a bit but, may be because it is new. Is the blade a OEM or repro?
Put the cap and the 2 bolts on it. The bolts are 16mm long and you should be able to get at least 6mm of the bolt in before any presure is needed. You will not snap the blade but, could pull the thread.
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Thanks again.
The blade is a repro from DS. I'll take it out, compare it to the old one (maybe try popping that one in too to see how they compare). I have no doubt I'll be able to locate the bolts, I just didn't fancy pressing down too hard to do so.
Job for the weekend, probably.
Cheers, D.
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Be careful..... The small damper location block that sits in the horseshoe arm can sometimes pull out when the tension blade is withdrawn !.....
Usually a snug fit but worth watching as the blade is lifted out.
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Gotcha, ta, D.
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Hi Drew,
That really does not look right. No force should be needed to position it right. Looks like you forgot to lock back the tensioner plunger with the locking bolt before assembling the crankcases :-\.
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Thanks Lynx,
I compressed the springs and then tightened the locking nut on the outside of the crankcase before joining the crankcase halves. So currently, the damper should be well clear of the chain/tensioner. Thus, if I slackened off the locking nut now, it would decompress and spring into the chain to tighten it.
Half I done that correctly and thus countered your suggestion?
Cheers, D.
p.s. I have to split the cases again having forgotten to fit the starter cog retention bolt... oh joy!
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No. That sounds right.
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Thanks Oddjob,
The U-shaped bracket is clear (and shiny) when peered at down the hole after removing the blade... and the rubber damper is fastened to the blade end.
Hmmm???!!
D.
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I think I will have to do yet more dismantling to get to the bottom (like what I did there?) of this. Guess where I'll be this weekend?!
Cheers,
D.
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That's life Drew but, at least you are learning. You have all winter to get it right and you will in the end. A book can not tell you everything.
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Drew...
Further to Oddjob's post, with the rubber damper removed from the blade does the blade drop down significantly further?
If so, warm the rubber damper, wet it with oil, .... and try locating it via (eg) a piece of dowelling which enables it to deform as it enters the U bracket - before then pushing in the 'lubed' blade.
Just a thought...worst case it misfits / drops in the guts.... but you were planning to go there (again) anyways!
Simon
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Thank you Lobo,
All ideas greatly welcomed.
As Trigger said, learning.
Cheers,
D.
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Finally sorted it...
Had to split the crankcase to fit a gearbox part I'd forgotten, doh! (only the starter gear locking bolt & tab washer, so nothing important!!!!). Had to remove the barrels, thus I could be absolutely certain that the cam tensioner blade was correctly seated before eventually clamping it down (under spiring pressure from the blade) when the head finally went back on the rebuilt engine.
By the way, the manual says it's possible to work on the bottom end without removing the top end. Not sure how I would have got a torque wrench on the two crankcase bolts sited at the front of the engine below the barrels. The overhanging cooling fins would stop direct access hence decision to dismantle the whole bloody thing again.
Cheers all and thank you for your contributions... again, as Trig said, it's all learning.
D.
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True Oddjob...
I can only think that it wasn't seated properly in the shoe. When pushed down from the top of the cylinders, it appeared to engage and peering down with a torch (no endoscope available... nurse Julie?) I couldn't be sure. With the barrels off and the blade seated properly, it projects forward by c.30 degrees from the vertical. This leads me to think that, with the chain in place, I couldn't push it down at the correct angle to engage properly.
I was very reassured when reading the dismantling instructions that confirmed the cap is untightened under pressure from the blade's bending.
All I need to do now is see how this baby runs, although there's a big IF in front of that sentence!
Cheers, D.
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Me and my Endoscopes have been in some very dark, tight places over the years but I have never thought about inspecting the internals of an engine with it !!! What an excellent idea. The other day when I wanted to get the swing arm bushes out after I had cut them with the hacksaw blade, I used an instrument called an Osteotome, used regularly in Orthopaedic surgery, fitted perfectly down the side of the bush to help remove it. All basic woodwork instruments really but perfect on bikes too. (These were old knackered osteotomes I hasten to add, didn't take them from the kit in the Operating theatre ;) ;)
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Had to Google that...
Looks like a chisel!
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Looks like something that my dentist would use.
Says its a bone chisel Steve.
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Had to Google that...
Looks like a chisel!
Same here. Thing is, orthopaedic surgery is sometimes rather like carpentry. I have a massive pin down the middle of my left tibia. I've seen the same operation on telly done on a femur. They just welly it in with a hammer. Don't suppose it's called a hammer in that context but you'd doubtless find one useful for fitting bearings...
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Thanks Nurse Julie (et al),
Does your industry have anything with a strange thread... as I seem to have inadvertently created here?! :D
Cheers, D.
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Nothing specific for strange threads Drew, like most carpenters, mechanics, bodgers etc we just make a bigger hole with a tap and die and put a bigger screw or bolt in it to hold it together and if in doubt put a bit of bone cement in it. I have a couple of dodgy bolts on my 400 where the heads have sheared off so I'm sure i will end up with threads not known to the engineering world !!!
Julie
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Nothing specific for strange threads Drew, like most carpenters, mechanics, bodgers etc we just make a bigger hole with a tap and die and put a bigger screw or bolt in it to hold it together and if in doubt put a bit of bone cement in it. I have a couple of dodgy bolts on my 400 where the heads have sheared off so I'm sure i will end up with threads not known to the engineering world !!!
Julie
That's quite a scary statement Julie, having been in agony since some botched surgery last year:o Not so keen on getting it corrected now! lol
Sent from my GT-S5839i using Tapatalk 2
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Don't let me put you off Hairy, it's a shame it didn't go well for you but sometimes, like everything in life, it just don't work out well all the time. Better luck next time an fingers crossed.
Regards
Julie
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If I'm honest, I don't trust them anymore, misdiagnosis, mistreatment, left with permanent damage, given unnecessary drugs which caused a stroke, the list goes on! But none of it has put me iff Honda's, even though I can't physically ride my 750 at the moment, stuck with a Honda 90!
Sent from my GT-S5839i using Tapatalk 2
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Drew,
I'm building up my spare engine now. Here's a picture of my cam chain rear blade. Too short if anything :o ;D.
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No if I remember right that looks good if the horseshoe is fully pushed back.So when the cap is on and you let the tension-er go it should adjust correctly.On another subject Hairygit I have total sympathy for you.Similar like you I let the french have ago at my back only because there super surgeon told me if I do not have it done I would end up in a wheelchair.Well 3 years down the line I am still some days days in agony and feel shit most of the time.The only painkiller that works is scotch.I can now walk a fair bit and I can ride my bike OK so I am with you all the way on this.I just hope in time you may return to some kinda normal and bearable way of life.
Keep your chin up mate
Bitsa
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Let's not hijack a good thread but Jesus hairy/bitsa - get well soon lads.... :)
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Hi Lynx,
I am by no means an expert (as many people on this forum appear to be). However, here is my experience to date, albeit on an engine that I haven't yet tried to start as it's still on the bench.
The dismantling instructions in my Haynes manual reminded me that the blade is under tension so that the cap will rise as the bolts are untightened.
When I then separated the crank cases, I was able to be absolutely certain that the bottom of the blade was sitting fully in the cup of the big u-bend cam chain bracket at the bottom of the barrels with its rubber damper in place. Thus, when I came to put the cap back on, I was satisfied that the tension I was applying by re-tightening the cap bolts was correct (with its top rubber damper in place).
Prior to all of the above, my concern was created by a picture in the same manual that appeared to show the cam tensioner sitting flush at the top of the barrels without the cap on. Hence, I was concerned about pressing down too hard on it for fear of it not being seated properly at the bottom.
Your photo looks OK to me, albeit I can't see from that angle how far above the barrels it protrudes. In may case it was about 10mm, although I didn't measure it so don't worry about (my lack of) accuracy on this.
Hope that's of some use to you.
Cheers,
D.
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Hi Drew,
If you refer to my much earlier reply, it would appear that you have come to the correct point, in that the blade does indeed stick up. As I said, I don't have the exact measurement as I don't have an engine at that stage at the moment. I ALWAYS use Honda bits (as long as they are available) but I use a wooden dowel to compress the blade via the top bracket, so that I don't put unnecessary axial load on the fairly small threads - the bolts are OK, but they are into the much softer alloy casting. The other thing I didn't say was that I also overhaul the pivoting tensioner arm if it's been damaged/jammed by a flapping chain (I wrote an article for VJMC TANSHA on doing that)
I know you had to part the crankcases apart again after missing that starter gear lockwasher so you are now very familiar with the set up.
You will now know that the front of the chain will always be in tension as the crank drags the camshaft around, but the rear will have a correctly tensioned curve in it, produced by the bend in the blade, assisted by the 2 concentric springs - it's a good enough system, as long as maintenence is carried out correctly and after you have spent all of this time and money, I'm sure you will continue to look after it. I will measure my next engine, which is nearing completion with all genuine parts - to act as a reference.
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Nice one Orcadian,
Yes indeed it's all coming back. What I admit I'm rubbish at is remembering where I read all this stuff and who from!
I think that my learning on bike building is partly based on years of general experience whereas my learning about forum usage is entirely down to this site over recent months! Hopefully readers will see past any failure on my part to acknowledge sources or link to previous discussions, etc.
Cheers,
D.
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The strange thing is the top of my cam chain blade is about 10mm below the top of the head. I'm sure the bottom end is located properly. Cam and oil pipes in now anyway. I slackened off the tensioner lock bolt and saw the chain ping taughter. So appears to be working OK. I'll test it before I sell it anyway.
Cheers.