Valve Adjustment Intervals/Trouble shooting running issue 82 gs850gl

[aclaytonb]

IIRC, the early 80's CB750's were every 5000km.

[cowboyup3371]

IIRC, the early 80's CB750's were every 5000k.

5 million miles or 5000 kilometers? If 5 million miles than that's pretty impressive



Or probably 5,000 miles?

[aclaytonb]

Five-hundred-millions kilometers.

Nah. Think it was every 3k miles (5k km-ish) because I remember thinking, "Holy hell thats way too much work... ." Now I know better.

Edit: FSM says 4k miles.... i lose again.

[LAB3]

Here's my 1/50 of a dollar. Every bike has it's quirks, ALL OF THEM! Some bikes are less of a P.I.T.A. than others, that's why they tend to hold their value better. It doesn't matter which brand or model you get, sooner or later SOMETHING will be tough to do, get parts for or be expensive for a relatively minor fix. I'm not the one that makes the rules, this is just how it is.

[Grimly]

I religiously checked my shims every 4000 miles or so, but the type of running I was doing (long straight motorways all day long, and not accelerating hard, even in towns) meant that almost invariably there would be no need for shim changes, so I extended the intervals to 8000 miles. That worked out fine for a few years.
When my pattern of useage changed, I still wasn't thrashing the bike but the long straight roads had gone. Checking at 4000 miles again, showed that virtually nothing had changed, and maybe the odd shim would be needed next time.
Since the long ten-year layoff of the bike, and most especially in the past two years, I've been using the engine much harder than ever before, and it's been willing and able to freely rev its guts out without negative effect. However, in the space of two years, all the inlets have closed up, and a couple of exhausts, too.
Conclusion; if you don't give harsh acceleration you can get away with 8000 mile checks, but you have to ascertain this for yourself, don't just take my word for it. Every bike is different, as is everyone's treatment of their bike. My occasional thrashing might be someone else's normal riding.

[chanceafrica]

The manual seems a bit unclear or im missing something. It says check one and teo at the same time and 3 and four at the same time.it says intake can only be checked if the lobe is up or towards the rear and exhaist can only be checked if the lobe is foward or up. Will the lobes only line up in this manner in one position? So if one exhaust is up and two exhaust is foward, this is this is the correct position. But if one exhaust is pointed to the rear but number two lobe is pointed up, that is the wrong position, because i cant check them at the same time. Its confusing.
Does that make sense?

the manual doesnt specify which cam on which cylinder should be pointing where, but gives an orientation that will only work in one position.

****

[Nessism]

The manual seems a bit unclear or im missing something. It says check one and teo at the same time and 3 and four at the same time.it says intake can only be checked if the lobe is up or towards the rear and exhaist can only be checked if the lobe is foward or up. Will the lobes only line up in this manner in one position? So if one exhaust is up and two exhaust is foward, this is this is the correct position. But if one exhaust is pointed to the rear but number two lobe is pointed up, that is the wrong position, because i cant check them at the same time. Its confusing.
Does that make sense?

the manual doesnt specify which cam on which cylinder should be pointing where, but gives an orientation that will only work in one position.

****

Found this using the search function...

Point 1E forward at the gasket surface, then measure 1E and 2E.
Point 4E forward at the gasket surface, then measure 3E and 4E.

Point 1I at 90* to the valve, then measure 1I and 2I.
Point 4I at 90* to the valve, and measure 3I and 4I.

Again, key element is to have two adjacent valves on the base circle at the same time.

[chanceafrica]

Basically it only works in pairs, with the rule that exhaust lobes can only face forward or up and intake can only face rear or up. As long as there is a pair following these rules( either one and two or three and four) then its right. I had a 2.55 in one of my tappets and it measured .09 gap. I swapped it to a 2.60 and now its .02. So i could have shims that are off or feelers that are off, im i ok to put the 2.55 back in with the .09 gap? Because its close to spec and will wear in? (.03-.08)

[chanceafrica]

And yes i did a full crank rotation to squeeze any oil skewing my reading

[chanceafrica]

Ok i jist read the valve tutorial and it said .09 was ok. Anyways thanks. I know it seems obvious. Im just looking at this on my phone at the shop and its hard to navigate the links

[chanceafrica]

I do want to add that it seems silly to be checking hundredths of a mm with precision tools , while just visually placing the lobes where it looks like its in the correct position

[Steve]

I do want to add that it seems silly to be checking hundredths of a mm with precision tools , while just visually placing the lobes where it looks like its in the correct position

It may seem silly, until you look at ALL the numbers.

Yes, you are checking in hundredths of a mm. The allowable range is FIVE hundredths, but the minimum clearance is only THREE hundredths above zero. Accuracy is not just important, it's CRITICAL.

The reason that the cam position is not specified, for example, as xx degrees Before (or After) Top Dead Center (TDC) or Bottom Dead Center (BDC) is that there is actually quite a range where neither cam lobe is pushing on its respective valve. The approximate center of that range is when one lobe on that side of the cam is pointing UP, the other one is pointing AWAY from the center of the engine (could be forward or rearward, depending on whether it's the exhaust or intake cam, respectively).

You say that "the manual doesnt specify which cam on which cylinder should be pointing where". On the contrary, it is very specific. As Nessism pointed out, the Suzuki manual tells you to point the lobe of Exhaust #1 (E1) at the front edge of the head. In that position, E2 will be pointing UP, measure BOTH, E1 and E2 clearances. Rotate the crank 180°, you will find that the lobes are set to measure I1 and I2. Rotate the crank another 180°, you will find that E3 and E4 are ready. Rotate the crank a final 180°, I3 and I4 are ready to be checked. It really can't get much easier.

.

[chanceafrica]

I did the valve adjustment and its still running poorly. Maybe a little better but something just aint right. 2 or 3 shims i adjusted were just slightly larger than spec (.09) . I cleaned the air cleaner and oiled it. Im gonna check out my intake boots next as well as the exhaust. Theres a piece that came off a while back that i assumed was just an aesthetic piece. Where the header meets the exhaust. The bike sounds "throaty" ....deeper than usual. The exhaust pops alot when decelerating. Sounds like a lean condition and or exhaust leak? All 4 cylinders are firing. I dont recall ever cleaning the carbs, its never needed it. I wouldnt assume my issue is carb related just yet. What do you think?

It may seem silly, until you look at ALL the numbers.

Yes, you are checking in hundredths of a mm. The allowable range is FIVE hundredths, but the minimum clearance is only THREE hundredths above zero. Accuracy is not just important, it's CRITICAL.

The reason that the cam position is not specified, for example, as xx degrees Before (or After) Top Dead Center (TDC) or Bottom Dead Center (BDC) is that there is actually quite a range where neither cam lobe is pushing on its respective valve. The approximate center of that range is when one lobe on that side of the cam is pointing UP, the other one is pointing AWAY from the center of the engine (could be forward or rearward, depending on whether it's the exhaust or intake cam, respectively).

You say that "the manual doesnt specify which cam on which cylinder should be pointing where". On the contrary, it is very specific. As Nessism pointed out, the Suzuki manual tells you to point the lobe of Exhaust #1 (E1) at the front edge of the head. In that position, E2 will be pointing UP, measure BOTH, E1 and E2 clearances. Rotate the crank 180°, you will find that the lobes are set to measure I1 and I2. Rotate the crank another 180°, you will find that E3 and E4 are ready. Rotate the crank a final 180°, I3 and I4 are ready to be checked. It really can't get much easier.

.

I do want to add that it seems silly to be checking hundredths of a mm with precision tools , while just visually placing the lobes where it looks like its in the correct position

[chanceafrica]

It was an exhaust leak. That was my secondary issue. My 4-2 cross section is rotted out a bit. Def needed the valve adjustment too though.

I did the valve adjustment and its still running poorly. Maybe a little better but something just aint right. 2 or 3 shims i adjusted were just slightly larger than spec (.09) . I cleaned the air cleaner and oiled it. Im gonna check out my intake boots next as well as the exhaust. Theres a piece that came off a while back that i assumed was just an aesthetic piece. Where the header meets the exhaust. The bike sounds "throaty" ....deeper than usual. The exhaust pops alot when decelerating. Sounds like a lean condition and or exhaust leak? All 4 cylinders are firing. I dont recall ever cleaning the carbs, its never needed it. I wouldnt assume my issue is carb related just yet. What do you think?

[Steve]

It was an exhaust leak. That was my secondary issue. My 4-2 cross section is rotted out a bit. Def needed the valve adjustment too though.

Either that is a typo or you have a very unique exhaust configuration.

Most bikes with crossovers were between 2 and 3.

.