Bad Valves?

[MNgs500]

So lately I have been trying to rejet my bike since I got a new exhaust and intake. But lets start from the beginning when I first bought it, it ran perfect with stock exhaust and intake. Then I got the mod bug to rejet with intake and exhaust and ever since the bike has never been able to ride perfectly. Either with high idle, limited RPM or bogging. So I decided once I receive my exhaust I will have shop professional tune the carb since I have tried several times. After a week of being at the shop, they called and said that they had to do a diagnose. They said what they found is the right cylinder is dead, with the exhaust valve being burnt and tight. They said that the valve will need to be replaced. I trust them that this is whats up, but could bad jetting cause this?

Thanks,
Zach

[twocool]

You had problem, (you created problem), shop found problem.....I would trust that shop!


Burnt valve.....

Many possible causes...all due to excessive heat build up on valve and no way to dissipate the heat.

Running lean will cause valve burn...(like wrong jet)

Bad valve adjustment will cause valve burn ...(like not enough clearance, so valve stays open too long, or stays open all the time, so exhaust gas burns valve at edge)

Too open of exhaust, can give lean condition....

Rant begins now:

Why does everybody want to F*** with a perfectly good bike?  This is one reason I would be extremely cautious about ever buying a used motorcycle...guys just can't keep their stinkin hands off of stuff and f*** up everything!

Rant over..


Cookie



Cookie

So lately I have been trying to rejet my bike since I got a new exhaust and intake. But lets start from the beginning when I first bought it, it ran perfect with stock exhaust and intake. Then I got the mod bug to rejet with intake and exhaust and ever since the bike has never been able to ride perfectly. Either with high idle, limited RPM or bogging. So I decided once I receive my exhaust I will have shop professional tune the carb since I have tried several times. After a week of being at the shop, they called and said that they had to do a diagnose. They said what they found is the right cylinder is dead, with the exhaust valve being burnt and tight. They said that the valve will need to be replaced. I trust them that this is whats up, but could bad jetting cause this?

Thanks,
Zach

[The Buddha]

Being me - I call BS.
Burnt valve ... OK I call double BS.
Never seen it happen. I've seen em bent, one of my local friends managed to bend it while adjusting valves ...

OK so you get the thing back from them and do as we say. I'll bet you save a few grand.
Take off the exhaust, take off the spark plug, and turn the motor to TDC and make sure your vlave clearances are good (easy to do - they dont have to be even right for this experiment, the yjust have to be positive) and shine a bright flashlight in the exhaust port.
If you see light in the chamber via the sparkplug hole - you have a bad valve. If you dont - you're valves are good.

Do that and we'll get the next step.

I'll bet its your carb - but I'd have to diagnose your way out of it.

Cool.
Buddha.

[gsJack]

Check condition of valves with compression tests, easier than pulling exhaust.  Verify tappets have some clearance cold.  If you have good compression cold valves are not your problem, if you have good compression hot and very low compression cold then valves are too tight.

[MNgs500]

They claimed they did do a compression test. But I will do one myself, as well as the light check. I just have limited time and money now college started. I will admit it I probably screwed the bike up big time, possibly running lean and rich. I tried to follow the jetting by the book but never got it right. I will rent a compression checker after school and see. What psi would I be looking for when testing?

[AlexT]

Agreed, doing a compression test is cheap and easy. Normal is anything from 142-199psi but less than a 28psi difference between the two cylinders. Lower than that is alright, you can have a minimum of 114psi on one cylinder but still no more than 28psi difference between the two.

[twocool]

Well, maybe we don't trust that shop?  Either way, I'm with everybody else...do your own compression test...the only way to know for sure if it is valve or carbs!

Cookie

They claimed they did do a compression test. But I will do one myself, as well as the light check. I just have limited time and money now college started. I will admit it I probably screwed the bike up big time, possibly running lean and rich. I tried to follow the jetting by the book but never got it right. I will rent a compression checker after school and see. What psi would I be looking for when testing?

[The Buddha]

Compression test needs well a compression tester with the bike adapter.
You could borrow one form someone on here - I have 1 but I have to find it - and that's always hit or miss.
The light in the exhaust is more rough but it needs no equipment.

BTW you know how lean you have to run it to burn a valve Yea - not likely. It wil lrun so badly you wont want to ride it. Rich - doesn't even matter. Cant hurt it that way.

Cool.
Buddha.

[ace50]

Rant begins now:
Why does everybody want to F*** with a perfectly good bike?  This is one reason I would be extremely cautious about ever buying a used motorcycle...guys just can't keep their stinkin hands off of stuff and f*** up everything!
Rant over..
Cookie

What fun would that be???
You'd never learn anything either.
I've never left a bike alone and they all run better after I'm done with them!

[twocool]

Sure, you make some good points...but then again, there are some who "should" and some who "should not"!

A heck of a lot of the things I have learned over the years, I have learned "the hard way" by doing wrong the first time (sometimes second time, third time,  etc).

But with age and wisdom, I have also "learned" to learn from the mistakes of others!

Cookie

Rant begins now:
Why does everybody want to F*** with a perfectly good bike?  This is one reason I would be extremely cautious about ever buying a used motorcycle...guys just can't keep their stinkin hands off of stuff and f*** up everything!
Rant over..
Cookie

What fun would that be???
You'd never learn anything either.
I've never left a bike alone and they all run better after I'm done with them!

[MNgs500]

For a compression tester isnt it just a fitting that goes into the spark plug hole and you crank the engine to watch the highest pressure in the interval. I will have some time tomorrow after night class to try these out. Will let you know. Otherwise i called a guy of craigslist that works out of his garage charges $25/hr and talked to him and doesnt think its valves either but wants to look at it

[prmas]

I agree with you Cookie. I have been quietly mumbling to myself for a long time "why do people who do not know what they are doing do things that they should not do? If it aint broke, don't fix it!" We all bought a GS because it was simple and reliable. Many then do their best to throw that out the window and then grumble because they stuffed it up.  "LEAVE IT ALONE". If you want more power, buy a more powerful bike!!!

I have been a qualified motor mechanic for 43 years and one of the biggest things that I have learnt in nearly half a century is that if it is running well,  "LEAVE IT ALONE!!!!!".

My K9 is standard except for gearing and a couple of electrical accessories. I have NEVER touched the carbies, not even to adjust the idle jets, they are still sealed, or modified the intake or exhaust. It starts instantly, runs perfectly and gives great economy. What more do you want?   

Macka

[The Buddha]

For a compression tester isnt it just a fitting that goes into the spark plug hole and you crank the engine to watch the highest pressure in the interval. I will have some time tomorrow after night class to try these out. Will let you know. Otherwise i called a guy of craigslist that works out of his garage charges $25/hr and talked to him and doesnt think its valves either but wants to look at it

True - but that spark plug threads are different for a car vs a bike. The regular cheapo auto parts store issue testers are meant for cars, hence have different threads. You can take that tester and tap the fitting for the bike - which I have done on several ocassions, but right now it is awol.
Anyway go on and test it, I'll get your carbs right if you need it. I've noticed most bike mechanics of today aren't too good at carbs. You rememebr in those old old old days the car mechanics used to remobe carbs and send em off to the "carb guy" ... yea OK that will be me.

Prmas:- lots of bikes work fine while being a hair lean. If its not lean down @ that idle-2000 range you wont notice an issue in a lot of cases. You will run hotter - the chamber and exhaust will be hotter, but you wont notice it while running. The basic idea is - you jet it to run cooler. If itmakes it run better - you have a double whammy (that you have avoided LOL).

I dont think any GS is not lean as it leaves the factory. Why do I think so - because the factory manual says so. US bike = 37.5/122.5/2.5 turns/unadjustable needle. European GS = 40/125/2.5 turns/needle on clip 2 (1/2 mm higher). They pretty well know we're getting it lean. BTW yes you could have gas that would cover the difference - and US has that MTBE+achohol in the gas, while europe has less of it. That prevents the engine from knocking being that lean. However it does not help with running hotter.

If it runs great - do a plug pull @ 1/4 throttle, 1/2 throttle and 3/4 throttle. If they all turn up looking chocolatey color then you may have caught "lightining in a bottle" if not - you could probably adjust something and get away with it. Or just swap 1 jet or a washer under the needle ... either way
Oh, your bike is what year ? on the 89-00 the floats drift high, You should set it to correct level and try it. On a 01+ I notice they are a lot harder to move, however I recently pulled a set apart that had em high and looked like the bowls were never taken off. No idea, maybe it drifts higher but slower than the 89-00's.

Cool.
Buddha.

[ace50]

I agree with you Cookie. I have been quietly mumbling to myself for a long time "why do people who do not know what they are doing do things that they should not do? If it aint broke, don't fix it!" We all bought a GS because it was simple and reliable. Many then do their best to throw that out the window and then grumble because they stuffed it up.  "LEAVE IT ALONE". If you want more power, buy a more powerful bike!!!

I have been a qualified motor mechanic for 43 years and one of the biggest things that I have learnt in nearly half a century is that if it is running well,  "LEAVE IT ALONE!!!!!".
Macka

Well, I'll just completely disagree.
You never learn anything leaving something alone. I was pulling things apart and putting them back together since I was a kid. Never been to any 'school' but consider myself a pretty good mechanic, and still learning. (on my 6th bike)
This site has more newbies asking questions than any other I'm on, cause the GS is a newbie bike. Nothing wrong with that. Hopefully they're learning something they can take away with them to their next bike.
Some are better at it than others but who are you to judge.
signed,
Cranky Old Man 

[bombsquad83]

It depends on your objective.  If you want to learn, by all means, tear into those carbs.  If you really just want to ride, it's not worth it to mess with things just because you think it can be a little better.  Just don't tear into the carbs with a perfectly running bike and then complain because you screwed it up.  Post your questions and learn from others' experiences.  I'm not putting down the OP at all for messing with his bike.  It's certainly his own choice!

[ace50]

It depends in your objective.  If you want to learn, by all means, tear into those carbs.  If you really just want to ride, it's not worth it to mess with things just because you think it can be a little better.  Just don't tear into the carbs with a perfectly running bike and then complain because you screwed it up.  Post your questions and learn from others' experiences.  I'm not putting down the OP at all for messing with his bike.  It's certainly his own choice!

That's the heart of the matter. How many of you think you have a 'perfectly running bike'? It starts and goes down the road? I've been on numerous bikes where the owner though it was OK, and I thought.....DAMN, how do you put up with this!? You learn by doing. You mess it up, you can put it back, and in the process (unless you're a dumb-ass) you learn a ton about your bike.

[bombsquad83]

It depends in your objective.  If you want to learn, by all means, tear into those carbs.  If you really just want to ride, it's not worth it to mess with things just because you think it can be a little better.  Just don't tear into the carbs with a perfectly running bike and then complain because you screwed it up.  Post your questions and learn from others' experiences.  I'm not putting down the OP at all for messing with his bike.  It's certainly his own choice!

That's the heart of the matter. How many of you think you have a 'perfectly running bike'? It starts and goes down the road? I've been on numerous bikes where the owner though it was OK, and I thought.....DAMN, how do you put up with this!? You learn by doing. You mess it up, you can put it back, and in the process (unless you're a dumb-ass) you learn a ton about your bike.

But lets start from the beginning when I first bought it, it ran perfect with stock exhaust and intake. Then I got the mod bug to rejet with intake and exhaust and ever since the bike has never been able to ride perfectly.

Apparently the OP thought it was running perfect.  That's the reason I said it the way I did.

[gsJack]

Gotta agree with Macka on these, "If it ain't broke don't fix it." and "I have NEVER touched the carbies, not even to adjust the idle jets, they are still sealed"

And pertaining to carbs in particular my favorite "Don't mess with your carbs and they won't mess with you."  I've managed to go 180,000 GS500 miles and counting without uncovering the idle mix screws.

It's good we have a Buddha here along with several young carb experienced guys to help members with carb problems because bikers are gonna mess with their carbs for sure.  Known a lot of them, used to hang around uptown with a bunch of Hog riders, many spent $15-40k on their bikes and then spent more time talking about working on them than riding them.  Any one else here ever lead a Hog ride on a GS500?

[MNgs500]

Even though this shot out of topic, i agree and disagree.
1) Messing with the carbs: To many who do this which include me are mechanical skilled and like to see how the bike works. I wanted to be a mechanic for years before deciding to get into engineering. I have owned 3 cars and do all the repairs myself. I can call myself a car/bike enthusiasts because its only what i care about. I like giving it a personal touch so the exhaust was one which required rejet. This is my first bike and first carburetor I have owned so like most said its a learning piece.

2) Don't touch the carbs: This is key to someone who likes to ride. Carburetors as i learned are very touchy and require knowledge and skill to work on them. In my example doing this procedure wrong can effect other parts like burnt valves or leaned pistons. If I could start again I would have had a mechanic rejet for me.

But since I'm a person that refuses to bring bikes/cars into shops unless last resort to save money. 

[MNgs500]

http://www.harborfreight.com/quick-connect-compression-tester-95187.html

will this compression tester work??