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Still Won't Idle! I think I'm done.

  • Thread starter Thread starter UncleMike
  • Start date Start date
Though it May not be the silver bullet...that range in compression will make it hard to get your bike to balance out at an idle...:oops:


I just talked to one of the Master Certified service techs here ( Auto ) but he is a gear head to be all gear heads and has more toys than any one man should be allowed...and he stated that at the very least, you could expect to have a ROUGH idle and if were his, he would tear it down and check the ring ridge (amount of wear that the cylinder has at the very top where it meets the head), and then compare that to where the piston rings have been wearing on the cylinder itself.

My feeling is that you may have a rebuild ahead of you...
 
I just talked to one of the Master Certified service techs here ( Auto ) but he is a gear head to be all gear heads and has more toys than any one man should be allowed...and he stated that at the very least, you could expect to have a ROUGH idle and if were his, he would tear it down and check the ring ridge (amount of wear that the cylinder has at the very top where it meets the head), and then compare that to where the piston rings have been wearing on the cylinder itself.

My feeling is that you may have a rebuild ahead of you...

Fun!

Thanks for all your help, even if I did wish it had a happier ending.

~Mike
 
Fun!

Thanks for all your help, even if I did wish it had a happier ending.

~Mike

Mike...Before you tear this thing down, you may want to get additional feedback from Keith, Bwringer,and others with their specific knowledge...it never hurts to have several opinions.

Dave
 
Here's something odd,...

My Clymer manual calls for PSI somewhere between 128 and 171, with it not varying more than 28psi between cylinders. And it says that an engine overhaul wouldn't be due until one or more cylinders dropped below 100psi.
 
Mike...Before you tear this thing down, you may want to get additional feedback from Keith, Bwringer,and others with their specific knowledge...it never hurts to have several opinions.

Dave

Too late, I already went down to the garage, took a huge dump on her and set the whole mess on fire.*
 
Too late, I already went down to the garage, took a huge dump on her and set the whole mess on fire.*

Yea...I looked at the specs myself, and they stated exactly what you've said.
When you throw the Marvel oil into the mix, you can expect the numbers to climb a bit due to there being no or next to no air getting past the rings. Also, depending on how much you put in, you are displacing volume within the cylinder and that with the extra air retention will make the compression readings spike. :cry:
 
Yea...I looked at the specs myself, and they stated exactly what you've said.
When you throw the Marvel oil into the mix, you can expect the numbers to climb a bit due to there being no or next to no air getting past the rings. Also, depending on how much you put in, you are displacing volume within the cylinder and that with the extra air retention will make the compression readings spike. :cry:

So, none of my cylinders vary more than 28psi, and none are below 100psi, even though 125psi isn't great, so shouldn't this indicate something else is wrong?
 
My instinct is all this has nothing to do with rings. Your dry compression test was well within acceptable limits and should NOT be causing this kind of nastiness. Worst you could expect from that slightly-off compression is maybe some oil use and power loss, although I don't think you're anywhere close to the point where you'd have really any noticable symptoms.

Sorry to re-iterate, but you HAVE adjusted your valves, right?
 
My instinct is all this has nothing to do with rings. Your dry compression test was well within acceptable limits and should NOT be causing this kind of nastiness. Worst you could expect from that slightly-off compression is maybe some oil use and power loss, although I don't think you're anywhere close to the point where you'd have really any noticable symptoms.

Sorry to re-iterate, but you HAVE adjusted your valves, right?

I have not.
 
I think that it is still a combination of issues...I still wouldn't rule out an intake/ air leak. I know that I fought with that issue until I was ready to nuke the thing in neutral. Eventually after checking and rechecking AGAIN, and AGAIN, and AGAIN, the list of problems got so short that I was looking for a single issue.
All of them added together are making this project of yours very hard to diagnose and even harder for you to rectify. It only needs three things to run Spark...and you have that. Fuel...and you have that. And Air (compressed)...and that is where we are now.
 
I have not.

=; STOP!

Why eye aughtta... ;-)

Get those valves adjusted, ya goof! Aside from possibly fixing your compression (it did mine), misadjusted valves can cause you all kinds of headaches. I wouldn't spend another minute on this until those valves are in spec.

I put it off for a long time, too, but it's really quite easy PROVIDED you have the right tools. That means a tappet depressor so you can get the shims out, and a digital caliper so you can accurately measure them (the markings are often way off). I got the "shim tool" (tappet depressor) on eBay for $18 but they can be had retail for $25-$35 at any parts website. Digital calipers are like $10 at Harbor Freight.

DO IT!
 
=; STOP!

Why eye aughtta... ;-)

Get those valves adjusted, ya goof! Aside from possibly fixing your compression (it did mine), misadjusted valves can cause you all kinds of headaches. I wouldn't spend another minute on this until those valves are in spec.

I put it off for a long time, too, but it's really quite easy PROVIDED you have the right tools. That means a tappet depressor so you can get the shims out, and a digital caliper so you can accurately measure them (the markings are often way off). I got the "shim tool" (tappet depressor) on eBay for $18 but they can be had retail for $25-$35 at any parts website. Digital calipers are like $10 at Harbor Freight.

DO IT!

I plead innocence here. I've been doing what people tell me to do.

The good news is that as a 16v machine, it doesn't have any shims!
 
=; STOP!

Why eye aughtta... ;-)

Get those valves adjusted, ya goof! Aside from possibly fixing your compression (it did mine), misadjusted valves can cause you all kinds of headaches. I wouldn't spend another minute on this until those valves are in spec.

I put it off for a long time, too, but it's really quite easy PROVIDED you have the right tools. That means a tappet depressor so you can get the shims out, and a digital caliper so you can accurately measure them (the markings are often way off). I got the "shim tool" (tappet depressor) on eBay for $18 but they can be had retail for $25-$35 at any parts website. Digital calipers are like $10 at Harbor Freight.

DO IT!

HOLY HANNA...Yes!!! Thought that was done! That just might be THE PROBLEM... Always get additional opinions. T3rmin, you may have just saved the "Remove the arm to cure the hangnail"!!! Valves, baby, valves!! 8O :!:
 
HOLY HANNA...Yes!!! Thought that was done! That just might be THE PROBLEM... Always get additional opinions. T3rmin, you may have just saved the "Remove the arm to cure the hangnail"!!! Valves, baby, valves!! 8O :!:

Okay, okay. One more thing to tackle.

Although, I thought if you poured oil in and the psi's rose, that indicated that it wasn't valves.
 
Okay, okay. One more thing to tackle.

Although, I thought if you poured oil in and the psi's rose, that indicated that it wasn't valves.

When you poured oil in the compression raised on even the non-low cyls. And it actually raised (I think) to abnormally high levels for the non-low cyls. That means the oil is either sealing "too well" or you put too much oil in (as somebody already mentioned), and you're getting basically bogus readings.

Even if you are losing a bit of compression past the rings, you have no idea how much compression you're loosing due to too-tight valves. Get the valves in spec (which you can easily adjust), then you can do another compression check and find out the health of your rings (which you can't adjust).

Your compression and your carb sync could both be significantly off with misadjusted valves. This could easily the the cause, or at least an aggravation of the cause, of all your trouble.
 
When you poured oil in the compression raised on even the non-low cyls. And it actually raised (I think) to abnormally high levels for the non-low cyls. That means the oil is either sealing "too well" or you put too much oil in (as somebody already mentioned), and you're getting basically bogus readings.

Even if you are losing a bit of compression past the rings, you have no idea how much compression you're loosing due to too-tight valves. Get the valves in spec (which you can easily adjust), then you can do another compression check and find out the health of your rings (which you can't adjust).

Your compression and your carb sync could both be significantly off with misadjusted valves. This could easily the the cause, or at least an aggravation of the cause, of all your trouble.

I see. Time to learn something else!

Thanks, everyone!
 
Mike, I haven't been able to stick with your thread because I've been busy. I'll be busy today and this weekend too but you're getting help anyway. Just letting you know so you don't think I'm ignoring you.
I too assumed the valves were adjusted, along with a few other things.
You guys know I always say to check all the basic maintanance things first, then troubleshoot. Basics are good compression/not burning oil, valve clearances set, good fuel flow/clean-rebuilt carbs/tank/petcock, clean air filter, good spark/timing/clean electrical connectors and good plug leads, etc.
Part of the problem as pointed out earlier is that this is a long thread and I believe this thread isn't the first one about this bikes problems. So people kind of forget what's been done to fix a problem.
Your compression reads, while not balanced, are still within spec but ideally the difference shouldn't be more than 10% unless the factory manual says different. I don't believe those reads would indicate/cause your problem though. Maybe a little uneven idle but not "intake leak" symptoms.
I've taken apart a few bikes that had their valve clearances all over the place with some at less than .02mm clearance and some more than .20 mm. They weren't running well but none of them had rpm's rising significantly with engine temp. But you should adjust those valves because it's part of the basic tuning. Adjust on a stone cold engine only, overnight is best.
I'd re-check the compression with a completely warmed up engine (same temp as when the rpm's rise up) and see what the reads are then.
 
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