Topic: hey 650 guys: cam sprocket question

[paulages]

i can't get my cam sprocket to lift up onto the cam to save my life. i'm unfamiliar with the 650 tensioner assembly (though like most 650 parts, it seems like an upgrade from the earlier sohcs). the manual mentions nothing of the cam tensioner when describing the cam installation. is there something im missing here? are the tensioner bolts supposed to be out while assembling the cam?

new replacement cam chain measured to specs. the crank will spin through when holding the cam chain upwards and taut, so the chain doesn't seem to be binding... but it really doesn't seem to have enough slack to allow the sprocket to make it up onto the camshaft. 

[scunny]

doing this tomorrow so shall let you know

[paulages]

Have you loosened the adjuster bolt on the back of the cylinders? between 2+3.

i just installed it, so i tried every combination of loose and tight, tight loose, with one eye closed.... i swear this thing was the same length, but it sure isn't acting like it.

[WFO]

After you put the head on did you loosen the cam chain tensioner lock nut and pull the tensioner up (and re tighten the nut) that may be the extra your missing.

[paulages]

After you put the head on did you loosen the cam chain tensioner lock nut and pull the tensioner up (and re tighten the nut) that may be the extra your missing.

maybe i didn't... as i understood in the literature, the bottom of the tensioner sits in the groove in the bottom case, and the middle bolt locates itself in the hole in the barrels. does pulling it up reduce the tension on the spring then? i didn't see that in the clymer's. i have the 550 and 750 honda shop manuals, but since i'm only using parts of the 650 engine i hoped the clymer's would suffice.

[WFO]

After you put the head on did you loosen the cam chain tensioner lock nut and pull the tensioner up (and re tighten the nut) that may be the extra your missing.

maybe i didn't... as i understood in the literature, the bottom of the tensioner sits in the groove in the bottom case, and the middle bolt locates itself in the hole in the barrels. does pulling it up reduce the tension on the spring then? i didn't see that in the clymer's. i have the 550 and 750 honda shop manuals, but since i'm only using parts of the 650 engine i hoped the clymer's would suffice.

I quoted my 650 manual i would assume it would give you the room to get the chain on the cam sprocket cause the next section shows the cam chain going right on over the sprocket. Heres the downloadable manual list  http://forums.sohc4.net/index.php?topic=17788.0if for some reason you can't get what you need just PM me and i will give you the info you need from mine.

[paulages]

After you put the head on did you loosen the cam chain tensioner lock nut and pull the tensioner up (and re tighten the nut) that may be the extra your missing.

maybe i didn't... as i understood in the literature, the bottom of the tensioner sits in the groove in the bottom case, and the middle bolt locates itself in the hole in the barrels. does pulling it up reduce the tension on the spring then? i didn't see that in the clymer's. i have the 550 and 750 honda shop manuals, but since i'm only using parts of the 650 engine i hoped the clymer's would suffice.

I quoted my 650 manual i would assume it would give you the room to get the chain on the cam sprocket cause the next section shows the cam chain going right on over the sprocket. Heres the downloadable manual list  http://forums.sohc4.net/index.php?topic=17788.0if for some reason you can't get what you need just PM me and i will give you the info you need from mine.

ok, found what you were referencing. i'll try it here in a little bit. i'm also going to recount the links in the chain just to make sure something isn't amiss there.

[paulages]

got it on. i had to use a long screwdriver to compress the tensioner for maximum slack, then tightened the nut down. went right on after that. good to know the tensioner works so well! now i just have to degree the cam...

[MRieck]

It makes you wonder how they did it at factory when building them. It especially makes me think about the V-45 engines and carbs. I finally developed a system that seems to work real well for that.

[paulages]

It makes you wonder how they did it at factory when building them. It especially makes me think about the V-45 engines and carbs. I finally developed a system that seems to work real well for that.

somehow i imagine you've developed lots of good systems for doing things, mike. 

by the way, is it common when degreeing a cam to find the stock TDC mark as off as i've found? i've double, triple, and octuple checked with my fingers holding a screwdriver in the plug hole and with a dial indicator in the same, and my TDC is a good 4-5 after the mark on the dyna 2000 rotor no matter what method i use.

[bwaller]

Probably best to make up a piston stop to be absolutely sure about TDC. Here's a hokey barnyard example, just brazed both ends of a plug and threaded for the bolt.

[Buber]

Actually it's much faster to use this screwdriver to lift the sprocket over the camshaft. You won't break anyhting, you are just applying tension to the said... tensioner 
It puzzled me for a while (how to get it on, when I had it off), but then I just used some plain, old brute force. Went without a hitch.

[paulages]

Actually it's much faster to use this screwdriver to lift the sprocket over the camshaft. You won't break anyhting, you are just applying tension to the said... tensioner 
It puzzled me for a while (how to get it on, when I had it off), but then I just used some plain, old brute force. Went without a hitch.

believe me, i tried. this SOB had some serious tension.

brent- i just taped an extension (welding rod) onto my dial gauge and positioned it into the plug hole. like i said though, my fingers turned out to be just as accurate feeling with a screwdriver.

[scondon]

  "True" TDC is measured by measuring piston stop in both forward and reverse direction and calculating the middle point. Don't know if the same can be found by piston height/travel max. Could be it's the same, just don't know. If you're calculating between the points when piston moves off of TDC in either direction then there may be a bit of "slop" due to primary chain slack unless you're rotating the engine around 360 degrees, in which case a screwdriver stuck down the hole will have moved on the piston crown throwing readings off a bit. Piston stops can be had pretty cheap($10?) if you don't have the means to make your own. Take this as "thinking out loud"

    That said I usually end up around 2 degrees off of "T" mark(Dyna S w/ stock advance mech and Dyna 2000)

[paulages]

  "True" TDC is measured by measuring piston stop in both forward and reverse direction and calculating the middle point. Don't know if the same can be found by piston height/travel max. Could be it's the same, just don't know. If you're calculating between the points when piston moves off of TDC in either direction then there may be a bit of "slop" due to primary chain slack unless you're rotating the engine around 360 degrees, in which case a screwdriver stuck down the hole will have moved on the piston crown throwing readings off a bit. Piston stops can be had pretty cheap($10?) if you don't have the means to make your own. Take this as "thinking out loud"

    That said I usually end up around 2 degrees off of "T" mark(Dyna S w/ stock advance mech and Dyna 2000)

i wasn't sure about that actually... glad you mention it. i did both: the point when the piston reaches the apex, and the middle point between this and when it begins to fall again. the first version put me about 4 degrees past TDC as marked on the dyna rotor, and the latter puts it even farther forward. i've not been able to find a how-to thread about cam degreeing on this site (there are plenty to be googled), so maybe i'll start another thread with pictures. i've not done it since my ASE internal combustions classes 13 years ago, so this type of help is, well...helpful.

[scondon]

 Here's a couple threads from my first time through. Don't remember what's in 'em but hopefully something useful

http://forums.sohc4.net/index.php?topic=2988.0

http://forums.sohc4.net/index.php?topic=3148.0

[paulages]

Here's a couple threads from my first time through. Don't remember what's in 'em but hopefully something useful

http://forums.sohc4.net/index.php?topic=2988.0

http://forums.sohc4.net/index.php?topic=3148.0

thanks! don't know how i didn't find those before. there are lots and lots of threads that turn up when you search "cam degree" or "cam timing."

[scondon]

I only found it 'cause I wrote/remembered the title "cam degreeing 101". Don't know if I could find it without that

[paulages]

just read through those, and it's great help. looks like i was headed down the right path- my degree wheel is bolted onto the rotor side (rotor removed), and i made a pointer out of welding wire and attached to through the starter bolt hole. i'll see if i can find a piston stop, but i'd really rather not wait if i have to order one. this project has been going WAY too long for me to be patient now.  how far off from the stock sprocket holes were you? i haven't slotted mine yet, as i'd rather do as little as necessary, and i'd like to know exactly how far to slot it.

[scondon]

 Don't know that answer as I started out with a slotted sprocket. You can practice your skills by seeing how the cam lines up when bolted in with the unslotted sprocket. Should tell you how many degrees you have to move and how much slotting is required.

[bwaller]

Just make a piston stop, break the porcelain out of a sparkplug and use that, an hour or two should get it done. Using a positive stop is the only way to be completely accurate. You don't want the cam off by even one degree so TDC must be spot-on. The TDC mark on my 550 case was off just less than two degrees.

On that engine the cam sprocket was just slightly retarded from the stock position to get that Webcam "squared".

Good luck

[paulages]

Just make a piston stop, break the porcelain out of a sparkplug and use that, an hour or two should get it done. Using a positive stop is the only way to be completely accurate. You don't want the cam off by even one degree so TDC must be spot-on. The TDC mark on my 550 case was off just less than two degrees.

On that engine the cam sprocket was just slightly retarded from the stock position to get that Webcam "squared".

Good luck

i get the idea, but i'm not exactly sure how this will be more accurate. i used a dial indicator in the spark plug hole and repeatedly got the same TDC. it is 5 degrees off from the dyna 2000 mark.

i also measured my lobe centers, and no matter how i measured- zero lash, .004" lash, on the retainer, on the adjuster nut (have any of you guys ever tried to get a dial gauge tip onto the valve retainer of a 650? it's not easy)... it's also 5 degrees off. wants to retard. before i slot it, i'll check and check and check again for TDC, but i was pretty anal with the dial gauge. movement is movement, and it was always in the same spot.

[scondon]

 If you're getting the same readings even when you remove your measurement tools from the engine and have to set them back up then I would think you're doing pretty good. I repeat a lot of steps to double check things, like insuring I get the same TDC in #4 hole as #1, etc..   Consistency is what I look for rather than trying to exactly match of all the #'s.

    You sure you didn't install the Dyna 2000 plate 5 degrees off    I'M Kidding, Paul, just kidding

[paulages]

If you're getting the same readings even when you remove your measurement tools from the engine and have to set them back up then I would think you're doing pretty good. I repeat a lot of steps to double check things, like insuring I get the same TDC in #4 hole as #1, etc..   Consistency is what I look for rather than trying to exactly match of all the #'s.

    You sure you didn't install the Dyna 2000 plate 5 degrees off    I'M Kidding, Paul, just kidding

oh man, if there was a way to make this project more complicated, believe me i would have done it. luckily i didn't have to do anything more than open up the hole for the locating roll pin in the already balanced crank and drill a big hole in the center of the rotor of my $400 dyna 2000.. 

but anyway... just to be sure, i remeasured TDC with the dial indicator in 1,2 and 4 plug holes coming up with the same exact point every time. i also came up with a 98 degree lobe center over and over again. it appears a 5 degree cam retard would give me the 104.5 megacycle calls for. is there a good reason not to measure off the top of the tappet adjuster instead of the retainer? the retainer is really hard to reach on the 650. the gap measurement is actually made between the cam and follower.

anyway, here are some pictures:
(dyna side showing it's position at TDC- it reads 2-3 but is actually at 1-4)

(degree wheel and high tech pointer)

(finding TDC throught the plug hole)

(purty looking engine  )

[scondon]

 That IS one purty looking engine   WTF is it    Kidding again, I know the answer but the pictures prove it. Man that is neat

   Trying to think of a reason not to measure off the adjuster but not familiar with the 650 top end(or 550 motors for that matter). On the 750's the adjuster and valve stem faces meet at an angle(valve fully seated) and as the valve is opened this angle diminishes until the two faces are flat against each other. This may, or may not, translate into the adjuster traveling further than the valve stem especially during the initial valve opening. This may,or may not, mean that .050 lift might be different depending on whether you measure from the adjuster or the retainer(actual valve movement).

   My guess is that it doesn't matter for your purposes. Webcam has "square" profile so you're just looking for the #'s to match, regardless of whether it's at .050 lift or .054. Sounds like you have a pretty good handle on the measuring and math so why not

   I've got the same dial caliper as you. How did you get the magnetic base to stick to the aluminum head? I cut a flat plate out of steel that can be bolted to the head at any of the valve cover bolt holes.

 Thanks for the pics