cam advice needed

[Kbecker3]

I got a new gasket for the cylinder cover (you can see where oil was seapling out) and figured I would replace that. While I was in there I figured may as well check the valve clearances. When I poped the cover off the exhaust cam kind of looked like it had some wear..

I wasn?t sure if they should look like that or not, but looking at the rocker arms it looks like that would be how they should wear. But typicly I thought cams really shouldn?t see much wear.

The ones above cylinder?s 2&3 I can actually run my finger across and feel some wear. I can?t feel much of anything on the outer two. Its an ?81 Suzuki GS750L tscc engine.

My guess was the PO may have run low on oil (not sure what would cause this) should i just check clearances and bolt it back up, or look for a replacement? any advice would be greatly apreciated.
Thanks!
-Keith

 

[Kbecker3]

here's the other picture.

 

[posplayr]

Doesn't look unusual to me

Doesn't look unusual to me

I have a 1981 GS750EX daily rider (see the one in blue) that has 58K miles on the clock but has been well cared for and good compression (155-170 psi). I know there has been clutch work done and possibly some top end work as the compression is virtually OEM stock.

I just pulled the valve cover on it last nite to try and fix some oil leaks (my dress work pants are starting to get pretty oily on the pant leg). The culprits are probably the tach drive or the cylinder head bolt o-rings. I only pulled one of the o-rings last nite and it was actually pretty soft so someone has changed it before. Possibly when the head was off (or not).

Here is about the worst of the exhaust lobes on my GS750. There is some pitting near the top of lobe on the front side. The bike runs fine and even though there are pits the lobes run off the high spots not the ow spots so you can get away with alot more damage than what you might think. My parts bike with only 29K miles that had been sitting since 1986 (a 1980 GS750E even though I posted it as an L as I was a little confused at the time) has worse cams, See the pictures in the link below.

On top of that, my GS1100E although it had a good exhaust cam lobes, there was pretty bad pitting on the intake side and it ran like a bat out of hell (getting up graded to new webcams and APE springs and oem followers).

Bottom line is it depends what you are going to do with the bike. If you bought it for $500 and are trying to get it into some basic transportation just make sure that you have some high metal to run on and that the lift is not to worn off . That assumes the pitting is similar to what I show I would not even bother to pull the cam (you need a better close up pic of the worst cam posted for a better appraisal from the board). If you are rebuilding then you might look for a GS750/GS1100 set of replacements. If you go whole hog then get new cams but you are now looking at cash approaching a good percentage of the the value of the bike.

I know this comments about leaving a pitted cam in the engine might raise some eyebrows, and there are others with more experience but out of 3 bikes i have now pulled apart two running well and the 3rd a 29K miles parts bike all had some sort of cam pitting and it did not seem to effect the way they ran.

While you are in there I would make sure that your oil leaks are solved. Check/replace those front o-rings and probably the tach drive seals (not shown). See a picture of the socket wrench on top of the left side o-ring bolt with the engine still in the bike. You might need a mirror to see down into there to clean the surface but it is assessable.

Here are some questions i was posting about the 1980 parts bike.

http://www.thegsresources.com/_forum/showthread.php?t=118248

Posplayr

 

[Kbecker3]

took a close-up of the worst looking one.

 

[Kbecker3]

this one was a close runner up.

 

[Kbecker3]

just an over view

 

[posplayr]

Looks like that one might have gotten hot

Looks like that one might have gotten hot

Humm, most of mine have been pitted near the top of the lobe, that looks like something got in there or it got a little hot. Well the damage has been done and unless you are looking at a show bike I would live with it. Keep an eye on it when you adjust valves.
It would be nice to drop the pan (this does require dropping the exhaust) , I would pull the pan, clean the screen on the oil pickup (I had a bunch of old gasket material that had fallen and got lodged in the screen on my GS1100E), look for any metal bits in the pan and with fresh oil and filter let it go at that. I used Casteroil 10-W40 but later swicth to some Mobil 1 which allowed the trans to shift quiet a bit better.
If you do drop the exhaust you can do a much better job of detailing the engine without removal.
The only other thing (related to possible engine contamination) to do would be to look at the oil pump to see if there had been any damage but that requires pulling the clutch which I would not go out of my way to do.
It could be some one ran it too long on the side stand. You want to be careful about running the bike too long on there. With the bike at an angle the oil pickup in the sump may not be submerged.
I found for my old GS750 that a good parts bike can ge a great investment. I got a complete non running 1980 GS750E that the PO could not sell except for the $250 I gave him. It was relatively low highway miles at 29K so exhaust, disks, starter clutch etc and other stuff is really pretty nice much better than mine.

It cleaned up pretty nice as shown in this link.

http://www.thegsresources.com/_forum/showthread.php?t=118663

Posplayr

 

[Guest]

I have a set of 1100 cams that would drop right in in great shape if you would like them. PM me.

 

[t3rmin]

I have a couple slightly funky lobes myself. Runs great.

 

[Kbecker3]

brought the cams to work yesterday and mic'd them up and they are well within the service limit still so they are going back in the bike \\/. I ordered new gaskets (including new oil pan, and head gaskets) i dropped the oil pan, there was some sludge in there. kind of glad that i am doing this. 2 of my cylinders look like they are running hot.. can i just adjust the carbs, or would that require a sync? also is there anything else i should do while i have the exhaust off, i checked the sump looked clean. how should i go about checking the oil passages up to the top end? compressed air?

here is a pic of the oil pan...

 

[Kbecker3]

here is why i think the carbs need adjusting.. any help on this would be greatly appreciated. thanks!

 

[Nessism]

here is why i think the carbs need adjusting.. any help on this would be greatly appreciated. thanks!

There are only two adjustments on the stock carbs; sync and pilot mixture screws. Both are relatively minor adjustments and will not cause damage inside the engine.

While the engine is apart it's a good idea to rebuild the carbs to make sure they are clean and the o-rings are fresh. If you have non-stock exhaust or air filter, all bets are off and you will need to rejet.

 

[Kbecker3]

as far as i know it should all be stock. stock carbs, stock exhaust, stock air filter/box. just put a new seal on it re-fiberglassed a small hole that was worn in it. (air box)

so i should just have to adjust the pilot mixture screws?

 

[Kcwiro]

my exhaust cam looked exactly the same as yours but I had ~40K+ I went an dreplaced the cam.. cost me $250... then I burned up the head because I did not keep a close enough eye on oil... expensive mistake... I am using old ones I got from my replacement head.. they have marks but nothing I would worry about purrs like a kitten... when it is together that is =P in pieces atm for cleanup =P

those funny marks just show up on exhaust since the rockers have that funn groove on them. No idea why but...sometimes if it ain't broke don't fix it :-D

Oil leaks definately get them solved... nothing ruins a cleanign job that a leak that got missed...

Good luck

 

[Nessism]

as far as i know it should all be stock. stock carbs, stock exhaust, stock air filter/box. just put a new seal on it re-fiberglassed a small hole that was worn in it. (air box)

so i should just have to adjust the pilot mixture screws?

As I said, pilot mixture screw is relatively minor adjustment - effects idle and mixture at low throttle openings. It will not cause the coloring evident in the combustion chamber photos you show. Regarding that, it's hard to tell but it looks like #4 is okay, #3 is lean (cooking the exhaust valves), #1 and #2 look rich but could be oil residue - is the engine burning oil?

 

[Guest]

Looks like some oil in there. Change the valve stem seals and how are the rings?

 

[tkent02]

Other adjustments...
Also if the floats are all out of whack it will lead to different fuel mixtures in the different cylinders. Worth a look, someone may have messed with it at some time. Is it a coincidence that the order rich to lean is the same as the relative position when the bike is on the side stand? Could it have run for a long time on the stand?
Maybe it was parked forever on the stand and somehow gunked up the float valves?
Not sure.
I guess I would go through the whole carb procedure, from cleaning, to orings, to plug chops, then you will know.

 

[Kbecker3]

as far as i remember it was running great as of fall. i just took it all apart to replace the valve cover gasket (it was seeping oil, not bad, but just didn't like the oil mess) and check clearances. while i was at it i fixed that hole in the airbox and replaced the seal on the lid, since there wasn't much left. when i pulled the valve cover i saw those cams, and wanted to check every thing out. So i pulled the head since i had the cams out, head gasket was also seeping some and there is only 12 more nuts to take off to pull the head, plus it is easier to clean now with the exhaust off.

so far it looks like oil should be getting up there to the cam fine havn't blasted air through the passages yet, but probably will this weekend.

i just noticed it was looking like the 2 cylinders were running hot when i pulled the head. all last year I never noticed it burning any oil, it never smoked, it ran great. oil level stayed constant. (probably should have done a compression test, but i thought it ran great, so didn't do that (also didn't think i would find a cam that would look scored)

if i adjust those carbs should it go back to having a good burn if everything else is fine?

 

[Nessism]

Just go through the carbs completely and be done with it. Replace the various o-rings, verify the float level, set the pilot screws to a consistent level, and make sure everything is spotlessly clean. Sync after you get the engine back together and final set the pilots to the highest idle method.

Regarding the head, replacing the valve stem oil seals is standard pratice since you already have the head off.

Good luck.

 

[robertob]

Yeah, hard to tell but it sure looks as if it's pumping oil.

What was the compression before?

As others have said, you have no reason not to pull the springs out and check the valve stems, lap the valves and replace the valve stem seals.

You should also replace the base gasket if you disturb the head nuts like you've done.