Topic: so i don't end up doing something wrong, i'll ask first, checking the horse shoe

[Redline it]

cb400f 76, i took off the valve cover and to verify if the cam chain tensioner is functioning, i loosened the rear cam chain guide bolts, and i was gonna loosen the adjuster bolt/lock nut and then the push rod cover bolt. if that's in the ballpark, do i remove the rear guide bolts or just leave it loose as pushing on it the tensioner guide is moving, but how to check the horse shoe? push down on the push rod with a small round  pin or bolt to see if the tensioner is moving? thanks in advance, i've looked all over and can't find the thread. i'll look some more meanwhile. 

[bryanj]

There is no real way of checking if the tensioner is working properly, but from many workshop years i would say 95% are not due to loose chain burring the pivot points.

[Redline it]

There is no real way of checking if the tensioner is working properly, but from many workshop years i would say 95% are not due to loose chain burring the pivot points.

thanks, i was just checking to see if it was seized, the horseshoe,  i had the rear top guide bolts loose and so i went ahead and loosened lock nut and bolt that holds the push bar in place and watching down the chain at the bottom, and as soon as the push bar lost its grip, the back guide shot out with quite a bit of force and it moved quite a bit. original owner didn't do too much for maintenance that i can see. 10000miles. i'm trying to find out what has to be done to the chain tension for a static setting. i had it close to tdc 1/4 #1cylinder when i loosened it.

[Tim2005]

It's great that it moved, the horseshoe could well be ok. Next you need to push it back down with a longish thin rod
 To do that it is best to take the cam out, to give better access. Also, is your engine in the frame still? That makes it trickier but not impossible
 

[Redline it]

It's great that it moved, the horseshoe could well be ok. Next you need to push it back down with a longish thin rod
 To do that it is best to take the cam out, to give better access. Also, is your engine in the frame still? That makes it trickier but not impossible

motor is on the floor, take the cam out??? you mean push it back from the rear chain guide, down the hole andpush on the horse shoe. couldn't i take the front spring/pushrod cap off? or does the chain fall off the crank shaft gear? it doesn't matter where the chain goes as long as the links don't increase or shorten.

[Redline it]

It's great that it moved, the horseshoe could well be ok. Next you need to push it back down with a longish thin rod
 To do that it is best to take the cam out, to give better access. Also, is your engine in the frame still? That makes it trickier but not impossible
 

motor is on the floor, take the cam out??? you mean push it back from the rear chain guide, down the hole andpush on the horse shoe. couldn't i take the front spring/pushrod cap off? never mind about the cam falling off question, lol

[Redline it]

so by loosening the tension setting bolt with the cam set on #1 cyl tdc, the horseshoe will travel too far? and has to be set back? back to what target? to compress the pushrod spring, and then lock it in with the tension setter bolt? does the motor have to be running to loosen the bolt? i'll wait to find out before i do anything else. lol i thought i knew this stuff, apparently i'm lost. it's getting to be a regular place.

[Redline it]

i'm not sure i'm doing this right, replying to the comments, the extremely valuable comments. but i'm not sure if i have to remove the cam and poke the horseshoe lever, it's not stuck by any means, i loosened the lock bolt on the front and simply pushing down on the tensioner slipper i can push it pretty far, it's under slight spring pressure, but moves as slick as silk. and i might be catching on to why some have to push the bottom horseshoe, because it's stiff and wont move easy or smoothly? it's like when you take the head or and cylinders off. you just hang the chain, and when you put it back together i don't remember preloading that slipper. but put it over the cam gear and line up the marks to the case, as long as it's timed right, valve timing, then all you gotta do is put it together, set the cam. start it and loosen the lock bolt and it finds it spot? i'm all ears. 

[Tim2005]

Yes, cam out. As the motor is out this is easy- once the vam is out you can see when the slider is bending and the horseshoe is moving. Aim to push the horseshoe back against its spring then lock it in place with the tensioner bolt

[Redline it]

so unless its going to throw the chain, i pushed down on the tensioner slipper with a rod from the top until the the slipper was well below the mating surface and snugged up the lock bolt. done deal. now just put it together adjust valves and see if it's close to where it should be stuff it in the frame and gas it up, by about a month away and i have a good feeling that even though it's painful to look at, it's gonna be a tight 10,459 miles. the only thing off is it's got corrosion on the tops of the motor surfaces, some things are pitted, the cam bearings are looking new. no oval wear. all stock parts are there.

[newday777]

Yes, cam out. As the motor is out this is easy- once the vam is out you can see when the slider is bending and the horseshoe is moving. Aim to push the horseshoe back against its spring then lock it in place with the tensioner bolt

Maybe you should be including why and clarify what is the proper position and adjustment. (I for one, don't know the 400 motors) that would probably help take out confusion from short answers. 😉

[bryanj]

If you can get the bolts back in and locate the blade propely just tighten the top tensioner down, as too adjustment with the cam cover off you leave the adjuster clamp loose and use a spanner on a cam sprocket bolt to hold the cam rotating to rear of engine so all slack is at rear run then whilst holding nip up the clamp bolt then locknut.
With cam cover on you get all the slack at the rear by putting weight on the kickstart till engine is just about to turn OR remove generator cover and rotate the crank forward. DO NOT use a spanner on either of the nuts on the points side

[Tim2005]

So you haven't pushed the horseshoe back against the spring?

[robvangulik]

The question was"how to check the horseshoe" and it is functional, so why is the further dismantling necessary?

[Redline it]

So you haven't pushed the horseshoe back against the spring?

yes, i'm thinking i did i see the bottom in bright light. and i never removed the lock nut/bolt. and if that's the one bryanj is talking about being able to get back in, i'm thinking if things were worn out,chain and gears that the tensioner would push far enough the spings would be so far out that the push bar is too far past. maybe, anyway i used a screwdriver and pushed the back tensioner slider top down close to 2 inches past the cover sealing surface and then tightened the lock nut/bolt and the slider had just enough spring in it to push the top of the slider close to the cover surface and when the bolted slider holder was tightened it had a bit of spring load on it. it's not loose. i didn't turn the sprocket back to gain more slack, i was figuring that as long as the bolt/nut on front was in already, that soon as i get it started the auto tensioner should do it's thing, but it'll only take a second to to it over and i'll get all the slack in the backside before i push it down again. this is the most free tensioner i've ever seen, it's defianately under the spring pressure of the pushbar. when i was pushing the slider down as soon as the bow hits the chain then it's pushing the horseshoe back around. there's only a smidgen of slack in the front side. i could take an image or short vid of it doing it's thing. only i doubt it could see the horseshoe down around the chains, i'd need three arms to get light in there. the pictures and instructions on pushing the pushbar in from the bottom looks easy, but all in all, the moment i loosen the lockbolt while its running at 1200 rpm should override any discrepancies of that slack, as long as it functions it'll move to where it should be. i've owned 2 400f's 76 since early 80, 1 was part (i thought) and this new project and another motor, i've never used the automatic tensioner or it didn't move, not that i can remember, of course it falls out of the usable margin of maybe 30 minutes of memory. i'll send back the results in a bit. thanks you guys.

[bryanj]

PLEASE DONT TRY TENSIONING IT WITH ENGINE RUNNING it simply dont work as unless engine is super smooth, which i have NEVER seen, even fresh out of crate, the chain will be varying in tension and adjuster moving about.
There is not enough room for the tensioner horse to move to let the pushrod fall out.
Tension it using the kickstart as i described, thats worked on all the fours for over 40 years and was shown me by a Honda UK travelling technician

[Redline it]

There is no real way of checking if the tensioner is working properly, but from many workshop years i would say 95% are not due to loose chain burring the pivot points.

this single statement holds a lot of power in that i paid over a mint fee for this 400f i just picked up. i don't know what i was thinking, except that the owners (2) did absolutely minimal maintenance, it looks like it sat at the bottom of a lake for 30 yrs, only on the outside, yet it's what it was, leaving the showroom floor condition on the inside, surprisingly, solid in between the 1 and 5%, and its coming out to be more like a 3 or lower. i was starting to get worried about the tension(er), about it being precisely exact on installation, even with nearly no slack on the front side of the chain, i was gonna re adj where the push bar lock bolt  was set at, but didn't because as long as the pushrod spring and horseshoe is working well, and the cam, chain and gears and bearings are in good shape you don't have to be accurate on assembly nor where the crank and cam are related together. before the rockers are assembled up to initial start up. it matters none, only to get it close about the chain tension. other than if the push bar has gone too far into the lower case, i dont' know if it even can. only after the rockers are put on, you'll have to time the 2 shafts of course, then the ignition. that's the beauty of japans brilliant design of automatic chain tension. soon as it starts and rpm is 1200and the lock bolt is loosened, the slack, tension and lock bolt position on the pushbar will change and find its place to be lock nutted-gently, so it doesn't create a divot, in the pushbar, or broken off.

you can see if it's moving by watching the tensioner slipper while you loosen the locknutted bolt, the slipper will become more bowed into the chain. that'll at least let you know it's not seized. working and working properly i know to 2 different things. 

[Redline it]

The question was"how to check the horseshoe" and it is functional, so why is the further dismantling necessary?

, that is exactly right, in all aspects. i have always had problems in people not understanding what i'm saying. so then i go on with a lot of details and it usually adds to more misunderstanding. but hey, you nailed it.

[Redline it]

PLEASE DONT TRY TENSIONING IT WITH ENGINE RUNNING it simply dont work as unless engine is super smooth, which i have NEVER seen, even fresh out of crate, the chain will be varying in tension and adjuster moving about.
There is not enough room for the tensioner horse to move to let the pushrod fall out.
Tension it using the kickstart as i described, thats worked on all the fours for over 40 years and was shown me by a Honda UK travelling technician

i'm banking on it running super smooth, and i'm gonna let the tensioner adjust it. we'll see what it does, if it doesn't work, i'll go for the technique of your rotating the generator forward method, thanks for the inside info. i haven't seen over 4 motors, but 2 of them have run pretty well just running them as hard as if they were in factory production race bikes, in my mind. over 40 yr of  it, i know your experience is far more than i have. although i can tell you some history of the crazy things i've done to these motors only to know how much they can take and keep running and running, hard. they're gonna outlast me. this will be #3 and the last one that one that i work on. an xr650r 2000 is taking more of my interest lately. even though my ability i noticed last week at kennedy meadows, is teaming up with my memory.  i envy the people who are going to pillage this place.

[bryanj]

Here in UK due to the learner laws in the 70's a lot of CB 250 G5 and CJ 250 were sold and they have the identical cam chain system.
As normal with "learner" bikes they were horribly neglected, even under warantee period and so came apart frequently, also the 400 was a very low seat height and as such a lot were sold to ladies, now i dont want to sound mysogenistic but again most did not worry about servicing until it didnt work properly, yes there are many fastidious lady riders who really look after their bikes, i can only comment on what came through the workshop door!.
Yes a recently rebuilt a 400 that had done less than 20,000 and been passed down from father to son, only reason for rebuild was bad storage and that horse shoe was perfect.
Over 40 years of working in Honda dealers and privately i can honestly count on one hand those horseshoes that were reusable

[Tim2005]

I'm with you there Bryan, adjusting while running is not at all reliable, I've found the method you describe is by far the best way to do them.