Topic: Camshaft Questions

[Lazerviking]

Putting together the top end of my 77 cb750k engine and upon inspecting my camshaft it looks as though there are some flat spots on the lobes, one that's particularly bad is the on the intake lobe of cylinder #3 which has some pitting. I've ran it by a few friends and the general consensus is that I need to replace it. Sigh.

At this point I'm a bit lost as to how the different components of new camshafts do(valve lift, duration, etc.). I don't think I need anything too fancy but if I'm going to spend $200+ bucks on this I'd like to get as much bang for my buck as possible.

Where is a good/reputable place to purchase a new camshaft?
What specs am I looking for in a camshaft if I'm planning on doing long rides in my bike(like 200-300 miles a day)?
If I have flat spots on my lobes does that mean my rocker arms may be damaged too?
Any particular camshaft that you'd recommend that wouldn't require any additional parts being replaced, ie; valve springs.

[MCRider]

Good used cams can be had for less. Mostly any "K" cam prior to yours should be fine, maybe a little better.

OCICBW

[PeWe]

Why not an improvement making the bike more fun and usable?
Moderat cam like WebCam 41  "Broad power range for street or touring. Bolts in to stock engines."

[Lazerviking]

I was thinking getting a non-stock camshaft could add to my bikes performance but I'm a little unsure of how big of a difference an improved camshaft will make. I'd prefer not spending a whole lot of $ but I'd rather put the right camshaft for my bike in right now while its opened up.

[Jerry Rxman Griffin aka MuthaF'er]

Cams $200 - $300 new. Will make a NICE difference. Not a big investment.

Consider using F2/F3 springs since they are stronger than the K springs (except K8) if you can find a REAL set (don't they all look alike?!) for cheap or spend some more $$ and buy some heavy duty springs. The springs are insurance against valve float and total engine destruction.

What to buy? APE 370, Megaycycle 125-65, Webcam 61A, Dynoman DP117khd maybe. I'd limit it to these vs the higher performance since your engine is not built. I think these cams will improve your mid-range and some top end, not just serious top end at the expense of rpms below 7000.

Anyone else have some suggestions?

[BPellerine]

0n the cheap side how about a good 77 /78 f cam be easy and reliable.bill

[Lazerviking]

Thanks for the cam suggestions Jerry, I have a webcam41a available for a good price. Any thoughts on that cam?

[Old Scrambler]

Good choice on the 41a.............I have one in an F0 motor. It needs good stock components all around in the cam-tower..........a K&N air-filter in the box and almost any 4-1 or 4-2 header system will work (prefer reverse megaphone muffler). The hardest amount of tension on the motor is when you let the motor idle............especially below 1200 rpms.   

Anything more aggressive?...........take Jerry's advice on the heavier springs.

[Jerry Rxman Griffin aka MuthaF'er]

Just don't go overboard in a stock engine. You'd need to keep it above 7000rpm for the benefit. Next thing you know you'll be spending multiple thousands like some of us, huh Dennis?!

Dennis, wish I had heavier springs with my STOCK F cam  Wouldn't have floated the valve when I missed second. But then I'd never been on the forum and never would've met you and all the guys either 

[PeWe]

Low idle is not that good anyway, oil pressure up to the cam might suffer. Stable idle around 1400-1600rpm is OK for me, 2000rpm when warming up to ensure oil where needed.

[Old Scrambler]

PeWe.........I like your thinking.............I really took notice of how much pressure is exerted on the rockers by the steep ramps on a performance cam...........It makes me consider that the rocker shafts (pins); the rocker centers (holes) and the cam-tower races for the pins may wear with irregular results. Another good reason to change the oil and filter on a regular basis.

Jerry.............I'm still learning as I go.................but getting convinced that bee-hive design springs keep better contact with the seats and retainers......while having less pressure at the point where the rocker begins to climb the cam-lobe............all leading to less chance of valve-float.

[garyS-NJ]

Valve float only happens at high rpms...  i ran the #$%* out of my F3 (&every other motor). & didn't kill anything all that fast.  Most folks don't ride that hard.  Light valve train gets high rpms and high rpms are where big cams come on and high spring tensions are required there and that puts loads on everything.  It's just a decision on how much you want to spend and how often you want to rebuild. Stock is most reliable and a mild cam lift increase goes with mild flow increase and mild increase in service intervals.

[Lazerviking]

Welp, I went with the dynoman dp117khd camshaft and threw in some some hp valve springs on top of it. Just put the top end together tonight and I think everything is looking good. My only question is about adjusting valve clearance. At first I began adjusting the clearance to stock specs and quickly realized that wasn't right when I began turning the crankshaft to adjust the next valves and it got stuck and would not rotate further. I went back through all my notes and realized I needed to adjust the clearance to 0.040mm all around. The only thing I noticed is that amount of clearance leaves a lot of free play when the rocker arms are not engaged by the lobes.

Will this cause any problems? Or Noise? Or is that normal?

Any other comments or suggestions are welcome.

[Jerry Rxman Griffin aka MuthaF'er]

Got stuck? Valve hitting piston probably. The extra free play means the valves are not opening as much and are clearing the pistons now. I'm hoping you are degreeing that cam then you will check the clearance of the valves and pistons.

[Lazerviking]

Got stuck? Valve hitting piston probably. The extra free play means the valves are not opening as much and are clearing the pistons now. I'm hoping you are degreeing that cam then you will check the clearance of the valves and pistons.

Okay, I'm having a lot of difficulty finding information on degreeing my cam. Is there a good thread that would help me wrap my mind around this procedure? I've found a pdf on the dynoman website that kind of just confuses me and also says I need a handful of specific tools that I do not have.
So many learning curves to this project. 

[Bodi]

You need a dial gauge and a way to attach it to the head to measure the valvestem drop (ie valve lift). And a degree wheel. Mount the degree wheel under the alternator rotor nut with a pointer (bent bit of wire hanger on a case screw, usually) pointing at 0 deg when 1 and 4 are at TDC. You can use the ignition "T" markings or use a dial gauge through a spark plug hole to find exact TDC.
Your cam specs at 0.020" lift with tappets set tight (no clearance). If you measure an intake valve, it should open 37 deg before TDC (0.20 stem drop) and on closing get back to .020 at 65 deg past BDC. Assuming this is not exactly right (it never seems to be) shoot for the centre - the intake valve should hit 0.020 on closing at 28 degrees more after BDC than it opens before TDC. You will need a slotted cam sprocket to adjust this...
Then check an exhaust valve to confirm the opening and closing are also in spec.
If the engine is binding up, it's very likely a valve is hitting a piston. This is, as you may suspect, a bad idea. Possibly the cam is a tooth or more out of time? Counting on tappet clearance to solve piston/valve interference is not a good plan.

[Jerry Rxman Griffin aka MuthaF'er]

I understand your mental dilemma. This scared the #$%* outta me too. Too complex/complicated it seemed after reading all the instructional gobbledy gook. After I did it it was a '#$%*, why did that need to SEEM so complicated?!' moment. HOWEVER you need to do this if you're using a high performance cam. I lucked out my first time when I just slapped that Yoshimura Daytona cam in and aligned it like the stocker. No valves hitting pistons but it probably would have run that much better had I done it the RIGHT WAY!

Get that degree wheel Bodi says from Dynoman, APE, etc. A piece of coathanger is what I used for a pointer. Bent a loop and stuck it under a 6mm bolt. At TDC the pointer should be bent to read '0' on the degree wheel. I got a dial gauge and a magnetic base from Harbor Freight. I used a 3" L shaped metal corner shelf brace from Lowes to mount the magnetic stand on. I attached it to the top of the head using one of the valve cover holes and a 6mm bolt. Put the stand on the brace and the dial indicator on the stand. Position it as close as possible parallel to the valve stem above the spring keeper and it's 'pointer' touching the keeper to measure the lift of the valve. When the valve starts to open that is zero on your dial gauge which should correspond to 37 degrees BTDC on the degree wheel. You should have the lash set correctly at this point. You'll rotate the cam shaft slotted sprocket to make the adjustment of the cam to crank to obtain the beginning opening at 37 BTDC. ETC. ETC. ETC. Lock down the 2 bolts in the cam sprocket then rotate it 2 turns and recheck everything. If not on the money do it again. You only have to do this on one cylinder! 

Use this, Bodi's explanation and the instructions you have and just play with all this until it starts to sink in to your way of thinking. I'd bet that Dynoman's instructions are Webcam's? If not go to their site also to study. Do NOT get in a hurry. This is probably the most complicated procedure you'll have to do BUT when you get it and look back you'll probably say 'that was a pain in the ass' AND 'that was really much easier now that I see WTF I'm doing'.

Bodi says to use the degree wheel on the alternator rotor. I used the points shaft on the other end. Either will do, just depends on the hole size in the wheel. What you are attempting to do is to set the timing of the cam with the crank so the cam opens the valves the correct amount at the right time so that the valves don't kiss the piston and you get the most performance from your engine.

Lot easier the second time   

[PeWe]

It take some training to time the cam. I found out that the play in valve train had a big effect on the result when measure the degrees on the wheel.
0 lash means that you will tighten the valve adj screw until you can see the dial gauge needle move just a little.

Do not forget to adjust the cam chain tensioner before timing, cam chain tightened as it should when running the engine.

[Old Scrambler]

The process should look something like this.............http://api.viglink.com/api/click?format=go&jsonp=vglnk_14151111940389&key=05c870975166525eee12fc837803917a&libId=73df61e3-5073-46d1-9413-95ae8ae34da0&loc=http%3A%2F%2Fforums.sohc4.net%2Findex.php%3Ftopic%3D135473.75&v=1&out=http%3A%2F%2Fs928.photobucket.com%2Fuser%2Fddweinhold%2Fmedia%2FCB750%2520Classic%2520Bonneville%2520Racer%2F2014750bike009.jpg.html&ref=http%3A%2F%2Fforums.sohc4.net%2Findex.php%3Ftopic%3D135473.100&title=Classic%20Bonneville%20Racer&txt=

Be sure to rotate the motor forwards when finding the 'T'-mark. That will keep tension on the internal chains and get you closest to TDC. Three or more hands (arms) and multiple brain-waves do wonders to make this process happen.

[MCRider]

Got stuck? Valve hitting piston probably. The extra free play means the valves are not opening as much and are clearing the pistons now. I'm hoping you are degreeing that cam then you will check the clearance of the valves and pistons.

Okay, I'm having a lot of difficulty finding information on degreeing my cam. Is there a good thread that would help me wrap my mind around this procedure? I've found a pdf on the dynoman website that kind of just confuses me and also says I need a handful of specific tools that I do not have.
So many learning curves to this project. 

Bodi and Jerry give good procedures. I put a WebCam 41 in mine. Even though it says drop in, on the first try valves hit pistons. PRobably becuase they were higher dome Arias pistons and the phrase "dropin" no longer applied. Mike R redid my top end, valves and guides etc. I timed the cam. Seat of the pants man it runs good now!
WebCam had a good PRocedures printout. Others do to. Relax and work it out. Worth it.

Back in my teen age years I had a Triumph Bonneville I put a road race cam in (Big mistake, should have gone flat track torque cam for street) Anywayt, ran like crap. Finally found a shop who timed the cam and it screamed. Too much RPM for street, but taught me a lesson I then relearned 40+ years later.

[PeWe]

In the end time cam with actual valve lash. 0 lash to see the cam data.

True TDC is very important to check as well. There is a procedure for that with piston stopper. My adv unit has a rather big lash that affect the TDC and align T and F marks. Adv unit to the maximum counterclockwise direction give correct TDC in my engine. To the other direction the mark in case must be moved 3mm to the right. I have made extra mark just for sure.

[Lazerviking]

I understand your mental dilemma. This scared the #$%* outta me too. Too complex/complicated it seemed after reading all the instructional gobbledy gook. After I did it it was a '#$%*, why did that need to SEEM so complicated?!' moment. HOWEVER you need to do this if you're using a high performance cam. I lucked out my first time when I just slapped that Yoshimura Daytona cam in and aligned it like the stocker. No valves hitting pistons but it probably would have run that much better had I done it the RIGHT WAY!

Get that degree wheel Bodi says from Dynoman, APE, etc. A piece of coathanger is what I used for a pointer. Bent a loop and stuck it under a 6mm bolt. At TDC the pointer should be bent to read '0' on the degree wheel. I got a dial gauge and a magnetic base from Harbor Freight. I used a 3" L shaped metal corner shelf brace from Lowes to mount the magnetic stand on. I attached it to the top of the head using one of the valve cover holes and a 6mm bolt. Put the stand on the brace and the dial indicator on the stand. Position it as close as possible parallel to the valve stem above the spring keeper and it's 'pointer' touching the keeper to measure the lift of the valve. When the valve starts to open that is zero on your dial gauge which should correspond to 37 degrees BTDC on the degree wheel. You should have the lash set correctly at this point. You'll rotate the cam shaft slotted sprocket to make the adjustment of the cam to crank to obtain the beginning opening at 37 BTDC. ETC. ETC. ETC. Lock down the 2 bolts in the cam sprocket then rotate it 2 turns and recheck everything. If not on the money do it again. You only have to do this on one cylinder! 

Use this, Bodi's explanation and the instructions you have and just play with all this until it starts to sink in to your way of thinking. I'd bet that Dynoman's instructions are Webcam's? If not go to their site also to study. Do NOT get in a hurry. This is probably the most complicated procedure you'll have to do BUT when you get it and look back you'll probably say 'that was a pain in the ass' AND 'that was really much easier now that I see WTF I'm doing'.

Bodi says to use the degree wheel on the alternator rotor. I used the points shaft on the other end. Either will do, just depends on the hole size in the wheel. What you are attempting to do is to set the timing of the cam with the crank so the cam opens the valves the correct amount at the right time so that the valves don't kiss the piston and you get the most performance from your engine.

Lot easier the second time 

This explanation is definitely a step in the direction of me understanding Degreeing. Thanks again Jerry!

Looks like I'm going to have to just jump into this and pound my head against the wall until I have that "eureka" moment.

I am wondering why a new hp cam made for this specific engine would have the timing notch marks on the end, like the stock cam, if you end up having to degree the cam yourself thus making those marks obsolete?

[Lazerviking]

It take some training to time the cam. I found out that the play in valve train had a big effect on the result when measure the degrees on the wheel.
0 lash means that you will tighten the valve adj screw until you can see the dial gauge needle move just a little.

Do not forget to adjust the cam chain tensioner before timing, cam chain tightened as it should when running the engine.

Thanks for the tips PeWe, putting them into my notebook!

[Lazerviking]

The process should look something like this.............http://api.viglink.com/api/click?format=go&jsonp=vglnk_14151111940389&key=05c870975166525eee12fc837803917a&libId=73df61e3-5073-46d1-9413-95ae8ae34da0&loc=http%3A%2F%2Fforums.sohc4.net%2Findex.php%3Ftopic%3D135473.75&v=1&out=http%3A%2F%2Fs928.photobucket.com%2Fuser%2Fddweinhold%2Fmedia%2FCB750%2520Classic%2520Bonneville%2520Racer%2F2014750bike009.jpg.html&ref=http%3A%2F%2Fforums.sohc4.net%2Findex.php%3Ftopic%3D135473.100&title=Classic%20Bonneville%20Racer&txt=

Be sure to rotate the motor forwards when finding the 'T'-mark. That will keep tension on the internal chains and get you closest to TDC. Three or more hands (arms) and multiple brain-waves do wonders to make this process happen.

The photos and advice are supremely appreciated! Really gives me a better idea of how this procedure is done.

[Lazerviking]

Got stuck? Valve hitting piston probably. The extra free play means the valves are not opening as much and are clearing the pistons now. I'm hoping you are degreeing that cam then you will check the clearance of the valves and pistons.

Okay, I'm having a lot of difficulty finding information on degreeing my cam. Is there a good thread that would help me wrap my mind around this procedure? I've found a pdf on the dynoman website that kind of just confuses me and also says I need a handful of specific tools that I do not have.
So many learning curves to this project. 

Bodi and Jerry give good procedures. I put a WebCam 41 in mine. Even though it says drop in, on the first try valves hit pistons. PRobably becuase they were higher dome Arias pistons and the phrase "dropin" no longer applied. Mike R redid my top end, valves and guides etc. I timed the cam. Seat of the pants man it runs good now!
WebCam had a good PRocedures printout. Others do to. Relax and work it out. Worth it.

Back in my teen age years I had a Triumph Bonneville I put a road race cam in (Big mistake, should have gone flat track torque cam for street) Anywayt, ran like crap. Finally found a shop who timed the cam and it screamed. Too much RPM for street, but taught me a lesson I then relearned 40+ years later.

I'm slowly wrapping my mind around this process, thanks for the advice and the support. Rebuilding an engine has really made me understand the importance of patience.

[Jerry Rxman Griffin aka MuthaF'er]

If you aren't a patient information sponge it will get more expensive real fast and very time consuming.

[DH]

I understand your mental dilemma. This scared the #$%* outta me too. Too complex/complicated it seemed after reading all the instructional gobbledy gook. After I did it it was a '#$%*, why did that need to SEEM so complicated?!' moment. HOWEVER you need to do this if you're using a high performance cam. I lucked out my first time when I just slapped that Yoshimura Daytona cam in and aligned it like the stocker. No valves hitting pistons but it probably would have run that much better had I done it the RIGHT WAY!

Get that degree wheel Bodi says from Dynoman, APE, etc. A piece of coathanger is what I used for a pointer. Bent a loop and stuck it under a 6mm bolt. At TDC the pointer should be bent to read '0' on the degree wheel. I got a dial gauge and a magnetic base from Harbor Freight. I used a 3" L shaped metal corner shelf brace from Lowes to mount the magnetic stand on. I attached it to the top of the head using one of the valve cover holes and a 6mm bolt. Put the stand on the brace and the dial indicator on the stand. Position it as close as possible parallel to the valve stem above the spring keeper and it's 'pointer' touching the keeper to measure the lift of the valve. When the valve starts to open that is zero on your dial gauge which should correspond to 37 degrees BTDC on the degree wheel. You should have the lash set correctly at this point. You'll rotate the cam shaft slotted sprocket to make the adjustment of the cam to crank to obtain the beginning opening at 37 BTDC. ETC. ETC. ETC. Lock down the 2 bolts in the cam sprocket then rotate it 2 turns and recheck everything. If not on the money do it again. You only have to do this on one cylinder! 

Use this, Bodi's explanation and the instructions you have and just play with all this until it starts to sink in to your way of thinking. I'd bet that Dynoman's instructions are Webcam's? If not go to their site also to study. Do NOT get in a hurry. This is probably the most complicated procedure you'll have to do BUT when you get it and look back you'll probably say 'that was a pain in the ass' AND 'that was really much easier now that I see WTF I'm doing'.

Bodi says to use the degree wheel on the alternator rotor. I used the points shaft on the other end. Either will do, just depends on the hole size in the wheel. What you are attempting to do is to set the timing of the cam with the crank so the cam opens the valves the correct amount at the right time so that the valves don't kiss the piston and you get the most performance from your engine.

Lot easier the second time 

This explanation is definitely a step in the direction of me understanding Degreeing. Thanks again Jerry!

Looks like I'm going to have to just jump into this and pound my head against the wall until I have that "eureka" moment.

I am wondering why a new hp cam made for this specific engine would have the timing notch marks on the end, like the stock cam, if you end up having to degree the cam yourself thus making those marks obsolete?





The factory markings indicate the point at which the piston is at tdc and the valves should be closed for cylinder #1.
It's the starting point for installation. If the cam is installed a tooth off one way or the other, the mis match of the
marks will be glaringly obvious. Once you do the actual adjustment to "time" the lift events of the valves according to the
cam manufacturer's specifications, you may notice that the factory timing marks are still fairly close. A few degrees difference
in when valve events occur can make a BIG difference in the way the engine behaves.

[PeWe]

I timed a cam for first time last year. Earlier head lifts during the 80's I mounted the cam sprocket according to marks my local tuner had done in sprocket and cam. No timing needed.

The timing process took rather long time when I double checked the result to be very sure about the correct procedure. I think my new pistons broke in manually during this process. It's much easier now when I have timed some times the last year.

The photos below show timing since I have mounted the restored head. Check cam sprocket bolts, if it is close to cam holder head.
Next time without removing the carbs.
Tank off
Frame kit off (I had no coils in first session, did it later without removing the coils.)
Head cover off
Free access to cam. Change cam is easy.

This need carbs off:
Remove head, cylinder, pistons or whatever needed without draining the oil

[Lazerviking]

Alrighty, so I'm feeling a little more confident in this procedure and I ended up biting the bullet and purchasing a proform universal degreeing kit that should be here midweek. I'm sure I'll have more questions when I get into it but right now I'm wondering what other components will need to be adapted because of the hp cam I'm installing. Such as my carbs? I've been told I'll need to jet my carbs to get the proper fuel mixture. Is there anything else that will need some attention because of my cam?

[70CB750]

Great illustration PeWe!

Only thing, I would use the alternator side nut to turn the engine to make sure I dont bend the little bolt on the right side.