| Author | Message | ||
     Skntpig |
I tried to ask this in an existing thread but it is archived. I am in a situation that the rear cams are correct and I can lock the crank when the rear cams are pointed to the back of the bike. I think that's the compression stroke. How many degrees do I turn the motor over to get to the compression crank lock position for the front cyl? I think once I get there I can start fresh, lock the cams and line everything up using the marks on the cams and cam gears using the manual. Any tips are appreciated. http://www.badweatherbikers.com/buell/messages/290 431/733400.html?1408383890 | ||
| Rodrob |
Start at front TDC compression. Rotate 288 deg (360-72 because its a 72 deg twin) for rear TDC compression. You will find the notch in the crank for the locking tool. So maybe that was too brief. Start with no cams or tensioner pistons installed. Rotate crank to front TDC. Carefull not to bugger the timing chains. I use a screwdriver shaft to support them. Lock crank with tool. Install front cams with the lobes pointed more or less up and towards the intake side, positioning the timing chain so you can get it on the sprockets. Lock cams with tool. Install chain making sure you tension the chain against the direction of rotation, opposite the tensioner. Install tensioner piston. Remove locking tools. Rotate crank 288 deg to find rear TDC. Repeat the above. Once done, rotate crank two full turns to ensure that it all works smoothly. Did I forget anything? (Message edited by rodrob on August 18, 2014) | ||
| Skntpig |
Rear cams will lock with rear cam lock tool and crank lock if I spin them to the right spot. The issue is that I thought something dropped in the motor when I took the front cams off to replace both bad front cams. When I was turning the crank it would lock solid. I had the rear cover on the head. I had the rear shims out and the cam followers were pushed to the center and not riding on the valves. I thought they would be out of the way but the rear exhaust cam has that balancing lobe (for lack of a better term) and they were hitting. I heard the cam followers make a clank when I removed the front cams. This and the crank lock made me think I dropped something. During trying to look down the cam chain cavity the cam chain came off the cam sprocket so I lost the front timing so I can't start in the front TDC position. I'm just trying to get to a starting point again. Does it make sense that I can lock the rear at TDC compression (cams pointing back to exhaust side) and rotate 72 deg to get everything up front in position? Thanks in advance for the help. | ||
| Skntpig |
At this point I may have to just start over with no cams in. | ||
| Rodrob |
Does it make sense that I can lock the rear at TDC compression (cams pointing back to exhaust side) and rotate 72 deg to get everything up front in position? No. That will put the front at TDC between Exhaust and Intake stroke. If you turn the crank with the cam chain off the cam sprockets and you don't support the chain, it will bunch up in the lower guide and lock up the crank. Go back and start from the front. You do not want to make a mistake with the cam timing. | ||
| Skntpig |
I found out about the cam chains stopping the crank with trial and error. How do I find tdc compression on the front once the cam timing is off and cams removed? The book is so confusing. | ||
| D_adams |
Positive piston stop and a degree wheel. The interwebz is chock full of info. http://www.virdung.net/MHRcamtiming.html | ||
| Northernyankee |
Couple of questions...did you inventory all of your parts to see if you really did drop something? Also are the rears cams still timed correct? I ask this because I can't find any info in the FSM for an easy way to re-time the engine if you don't have one of the cam assemblies already timed correct. On page 3-34 complete rebuild order instructions it says that you need to find front TDC but the FSM doesn't really say how to find it. When I did my cam assemblies I did one at a time so I always had one cylinder to reference off of. I would reach out to EBR, they are usually really helpful. | ||
| Rodrob |
There is no compression stroke or any stroke in particular without the cams installed as stroke is only relative to cam timing. Thats why it's easiest to start with the front at TDC and go from there. The ECU calculates the spark based on crank position AND speed which slows down slightly on compression. It can't differentiate stroke based on crank position alone and there is no cam position sensor. The crank can only turn more that 360 deg relative to the cams. On page 3-34 complete rebuild order instructions it says that you need to find front TDC but the FSM doesn't really say how to find it IMHO the best way is with the crank locking tool. I use a long screwdriver in the spark plug hole and turn the crank until the screwdriver stops moving up. Then I screw the crank locking tool in by hand and rock the crank slightly back and forth until I feel the tool seat into the notch in the crank. Do not tighten the tool until you are sure you have it in the notch as you can lock the crank out of position. That is front TDC. Once you have the front cams installed, it becomes front TDC Compression. (Message edited by rodrob on August 19, 2014) | ||
| Northernyankee |
Good info Rob!! I would do just as Rob says, put the front cylinder at TDC and lock it, install the cams, and then move on to the rear. | ||
| Skntpig |
Rear is in time and hasn't been touched. The front cam chain slack was the reason it was locking up. | ||
| Skntpig |
Thanks Rob. I will try it with the cams out. | ||
| Northernyankee |
If you have the rears still in then just put the rear at TDC and then turn the crank 270 degrees in reverse rotation and then you should be good to go. | ||
| Skntpig |
Now there's an idea. | ||
| Skntpig |
Shouldn't it be 288 degrees? | ||
| Northernyankee |
Nope from rear TDC it would be 270 Reverse Rotation. Page 3-33 from the FSM.  (Message edited by Northernyankee on August 19, 2014) | ||
| Rodrob |
I just don't like turning the engine in reverse. Now that 270 number is interesting. I have to say I have never verified that number with a degree wheel and crank locking tool, but I will now cause 270 + 72 is only 342 deg. This is a 72 deg twin, right? Anybody actually checked this number in the manual? Does not make sense to me. But I've been wrong before. | ||
| Skntpig |
The reason I question it is I have the 2010 manual. Not sure why I ended up with that with a 2009 cr but I did. The pictures are the same but the book basically contradicts itself and calls it a 288* and also a 270* turn in the text and the following pic. I know this would be a simple operation for someone else with more experience but I don't want to make a mistake and have a grenade or have to do this operation/rotation again. I really appreciate the help and promise Sprintst I will return your locking tools soon...I hope. | ||
| Skntpig |
Was the manual written for a 90* prototype? Man I wish an annony would chime in. How is this not covered in the manual or easier to understand... I'm gonna go ride the S1 | ||
| Pmjolly |
I seem to remember a thread along these lines arguing that there was a typo in the manual concerning degrees of rotation. Someone smarter than I proved one way or another. I cannot remember if it was a typo. I just remember both sides arguing the point until one proved their point. I know no good way to search for that thread.....sorry. | ||
| Rodrob |
360 - 72 = 288, even by the new math. I any case, you can verify with a long screw driver in the spark plug hole. When it reaches it's peak, you are very close. Then finalize with the locking tool in the notch. | ||
| Skntpig |
Rob, You mentioned setting the adjustable cam sprocket by tensioning the opposite side of the cam chain tensioner (with it out) when tightening the sprocket. This seems to move it a few degrees off of the spots that the bolts and washers originally made on the sprocket. I guess if I set both the front and rear the same that would work. Any advantage to setting one forward and one back a bit? | ||
| Rodrob |
Woah! My apologies for the misunderstanding. All of this only applies if the cam sprockets have not been removed or changed!!!! If you have removed the cams from the sprockets, then you should degree the cams which is a different procedure. You might, MIGHT, be able to use the old marks made by the bolts on the sprockets, but it is not recommended. Degreeing the cams involves a dial gauge to measure a pre-detemined amount of lift at a given degree of rotation to ensure that the sprocket is correct to the cam. I don't have the numbers in front of me. I have never had to do this on an 1125R, so someone with actual experience should chime in. But what i explained IS NOT the procedure for setting the adjustable sprocket. Everything I laid out assumes that that is already done. | ||
| Nuts4mc |
360 degrees in a circle cam shafts travel at 1/2 the "speed" due to the 4 cycles it needs to complete intake, compression, power, exhaust...it takes 720 crankshaft degrees to turn a camshaft 360 degrees. the cams are DONE doing their "work" at 90, 180, 270, 360 crankshaft degrees. the angle between cylinders has to do with an engineering term named "couples" a 90 degree engine has perfect "primary" balance because the coupling forces cancel each other out......here is a video in which the author describes a "couple" when screwing in a screw... https://www.youtube.com/watch?v=-VQ0ioDCeCA bottom line 360 degrees in a crankshaft's rotation...720 crankshaft degrees in a camshaft due to the gear ratio (2:1)...the cylinder angle has nothing to do with it....you are trying to time the cams use a wooden dowel of a paper straw ( or a plastic straw from McDonalds) not a metal screw driver in the spark plug hole..it could jam and mess up spark plug threads or worse (bend a valve) to time the rear cylinder: 1) remove the valve cover so you can see the cam lobes...the book sez TDC on the compression stroke the cams are facing toward the back 2) use a dowel or straw ( or a screw driver if you are careful) and rock the crank back and forth to verify by "feel" that you are at TDC ( the cams and straw/dowel/screwdriver verify it) 3) with the crank locking tool ...locate the notch in the cranks flywheel and lock the crank at TDC. 4) attach the timing gears/sprockets to the cams (use loctite on the bolts)..there should be some "scored lines" on the sprockets that will align with the machined surface of the head (where the cover mates with the head - the scored lines should be "flat/visable" in relationship to the machined surface of the head...looking at the end of the cam atthe sprocket)...this may be difficult to do because the cams may have to engage the valve springs (this is why the cam locking tool must be used ...to lock the cams in place when you remove the sprocket from the cams flange) 5) once the cams are "tied to the crank"in the old days we would turn the engine in the opposite direction (not too far) of normal rotation to force "slack" in the timing chain...if you have manual/mechanical cam chain tensioners it is at that point you want to release the lock screw and have the spring push (or manually push the rod) into the cam chain slipper...this will take up the slack in the timing chain and the engine will be quieter and the timing will be consistent and accurate. 6) turn the crankshaft two complete turns ( in the correct rotation)to verify nothing is hitting ( pistons and valves)...if you have both valve covers off .use the dowel/straw/screw driver to verify TDC and camshaft timing ( like shown in the book) of both cylinders. hope this helps (Message edited by nuts4mc on August 19, 2014) (Message edited by nuts4mc on August 20, 2014) | ||
| Nuts4mc |
here is what the timing marks should look like:  you need to verify that the front cylinder is at TDC on the compression stroke (MOST IMPORTANT).... 1)turn the crank 270 degrees CCW 2) verify TDC of the rear cylinder with a dowel/straw/screw driver 3) lock the crank 4) time the cams ( see the pix, lock them in place with the cam locking tool) 5) bolt the sprocket on 6) assemble the cam chain tensioner 7) verify your cam timing is correct by rotation the engine a t least 2 full turns ( I would go 2 turns and then 4)...check for TDC ( with a straw/dowel/screw driver AND the position of the cams (TDC on compression stroke AND Cams (lobes) are pointing in the correct orientation ( front Cyl. point forward, Rear Cyl. point to the back) | ||
| Rodrob |
Skntpig - sorry if I freaked you out. What i said was - Install front cams with the lobes pointed more or less up and towards the intake side, positioning the timing chain so you can get it on the sprockets. Lock cams with tool. Install chain making sure you tension the chain against the direction of rotation, opposite the tensioner. Install tensioner piston. Remove locking tools. When I said "install front cams" I should have said "cam assembly". My apologies for not being clear. I did not say anything about the adjustable sprocket. I only meant that when putting the chain on the sprocket, the chain needs to be tensioned against the direction of rotation so that you do not end up a tooth or two out of time once the locking tool is removed and the tensioner is installed. The adjustable sprocket should be tight when the cam assembly is installed on the head and timed to the crank as I explained. The marks left by the bolts on the sprocket can probably by used to reassemble the sprocket and gear, but the only way to know for sure that it is precisely correct after installing a new cam shaft, is to degree the cams with a dial gauge and degree wheel. The reason is that the locking tool is not precise and the locking position might be slightly different from one cam to the next. I have degreed the cams on my 1190RS race engine where precision is critical, but not on my 1125R - yet. I will when I change the timing chains at 30K mi. I hope someone else has successfully changed out cams without re-degreeing them and could put your mind at ease. | ||
| Skntpig |
Thanks for all the help. I did the reverse 288* rotation and found the locking points. I don't have a cam or crank dial so it was just a guess. I will post up when I get it together and try the starter button. Fingers crossed. | ||
| Nuts4mc |
don't guess...use the screw driver/straw trick in the spark plug hole to verify you got the correct locking point | ||
| Skntpig |
I did. I also went back and rechecked the rear would lock in both spots too. Just a bit nervous that's all. It seems odd that the manual wouldn't walk you through this operation better. I guess they assume someone would Never remove the front cams. | ||
| Nuts4mc |
experience is a tough teacher...it gives you the test first and the lesson later...you'll do fine...don't forget to loctite the cam sprocket bolts | ||
| Skntpig |
I triple checked everything and put the front cam chain sprockets back where they appeared to be. Got it all together and crossed my fingers when I hit the starter button. Sounds and runs good. It had a little weird whistling sound before the tear down when it was cold. That is gone. I set the lash to the high side of the spec. Very happy. Thanks to everyone who helped. Hopefully this thread helps folks in the future. I think I could do this operation in the future without looking at the book. It's very daunting the first time but now after putting it back together it's really not that bad. I added the extra frame insulation from Al and changed to water wetter at the same time. I notice a 10* reduction in coolant temp. I feel less heat on the frame and more in the seat. I'm going to use the excess insulation on the bottom of the seat. |
