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Old 11-20-2012, 02:13 PM   #4321
IDRIDR
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Quote:
Originally Posted by jonyfi View Post
I just got the bike back together and took it out for a ride. It's backfiring on deceleration

Can I turn the pilot mixture screw one way or the other to cease this symptom?

I put the new mixture screw in and adjusted it as the kawi repair manual spec'd
Everything with the carb is stock, air box stock, aftermarket pipe...
Turning the mix screw out (counter-clockwise) may richen the mixture enough to help with the decel popping. But that may not be the best method of setting the mix where it should be. I don't know about the KLR as mine still has a stock exhaust, but on my other bikes I've found aftermarket mufflers may pop some regardless, and a little air leak in the exhaust, such as where the header connects to the muffler and/or to the head, will result in decel popping. Find those leaks if they exist and fix them. Shouldn't hurt to give the mix screw a try, though. Don't go too far (usually no more than 3 turns out).
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Old 11-20-2012, 02:15 PM   #4322
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Quote:
Originally Posted by jonyfi View Post
Can I turn the pilot mixture screw one way or the other to cease this symptom?
I'd recommend bottoming the fuel screw (gently!), than backing it out 1.75 turns as a starting point. May help reducing backfiring on deceleration; OEM settings excessively fuel-lean, IMHO.

EDIT: Didn't intend to post redundant to IDRIDR's above; looks like we hit our SEND buttons almost at the same time.

XDragRacer screwed with this post 11-20-2012 at 09:47 PM
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Old 11-20-2012, 02:32 PM   #4323
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Quote:
Originally Posted by XDragRacer View Post
I'd recommend bottoming the fuel screw (gently!), than backing it out 1.75 turns as a starting point. May help reducing backfiring on deceleration; OEM settings excessively fuel-lean, IMHO.
OK, so after a few responses confirming that strategy as an option I will give it a try. I did do some research before reassembling and some folks suggested 2 and 1/2 turns... I thought that that was quite different than KAWI's suggested 1 and 3/8 turns...

I did 1 and 1/2

I will go to 2 turns

....and see what happens
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Old 11-20-2012, 02:33 PM   #4324
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Valve stem seals

Quote:
Originally Posted by redog1 View Post
Anyone ever replaced them without pulling the head?
. . .
Thoughts?
Thoughts:
  1. Each oil seal is under a valve retainer and surrounded by two springs.
  2. The retainer must come off to get a new seal over the stem even if you cut the old seal out.
  3. The springs have to be compressed to remove the keeper and retainer.
  4. The springs are strong.
If you made a spring compressor that DIDN'T press on the face of the valve, it would have to hold the valve stem against pretty strong pressure and not mar the stem.

So I think that you've had no responses because nobody has done it. But let this post bump your question to the current page and maybe we'll hear about someone who has done it.
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Old 11-20-2012, 02:59 PM   #4325
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I appreciate the input.

Pretty much convinced the head has to come off for the reasons you state. Really no way to compress the valve springs to get the keepers off, even if you could it's not likely you could get them reinstalled. I'll just dive into it. Now since I have to go that far, I'm thinking I might as well re-ring it. Have all winter to do it.
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Old 11-20-2012, 03:37 PM   #4326
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Quote:
Originally Posted by jonyfi View Post
OK, so after a few responses confirming that strategy as an option I will give it a try. I did do some research before reassembling and some folks suggested 2 and 1/2 turns... I thought that that was quite different than KAWI's suggested 1 and 3/8 turns...

I did 1 and 1/2

I will go to 2 turns

....and see what happens
Make sure you don't have a air leak on the downstream side of the carb. To test, hold an unlit propane torch around the intake side with the bike idling. If the idle speed changes, it's sucking in propane thru a leak. As mentioned, popping is a sign of running too lean.
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Old 11-20-2012, 03:41 PM   #4327
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Quote:
Originally Posted by HellSickle View Post
Make sure you don't have a air leak on the downstream side of the carb. To test, hold an unlit propane torch around the intake side with the bike idling. If the idle speed changes, it's sucking in propane thru a leak. As mentioned, popping is a sign of running too lean.
key word there.
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Old 11-20-2012, 06:33 PM   #4328
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Quote:
Originally Posted by redog1 View Post
Pretty much convinced the head has to come off for the reasons you state. Really no way to compress the valve springs to get the keepers off, even if you could it's not likely you could get them reinstalled. I'll just dive into it. Now since I have to go that far, I'm thinking I might as well re-ring it. Have all winter to do it.
I have no experience with doing them on a car, but I've seen/handled a valve spring compression tool that you can use while the head is still on the block for both a Honda and Mitsubishi. They were both based on C-Clamps with special fittings on them. Anyway, just saying that while it may technically be possible, I don't think you could actually get one in around the frame.
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Old 11-20-2012, 07:12 PM   #4329
jonyfi
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Quote:
Originally Posted by OKlr View Post
key word there.
UNLIT...
Ya for sure...
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Old 11-20-2012, 09:00 PM   #4330
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Quote:
Originally Posted by jonyfi View Post
OK, so after a few responses confirming that strategy as an option I will give it a try. I did do some research before reassembling and some folks suggested 2 and 1/2 turns... I thought that that was quite different than KAWI's suggested 1 and 3/8 turns...

I did 1 and 1/2

I will go to 2 turns

....and see what happens
What year is your KLR? GenII's are equipped with AIS and its sole purpose is to inject fresh air into the exhaust port to burn off excess fuel while decelerating i.e. popping is direct result. If your's is a GenI then most likely cause is exhaust leak allowing fresh air to enter the exhaust. Header flange is most common.

I set my fuel screws using an Air/Fuel meter with an O2 bung installed in the header. Most KLR's like to see just under 2 turns to just over 2 turns. Temp/elevation changes can alter the proper setting. You can set by 'ear' pretty easily. Does take a bit of practice/patience but get a feel for it and you can set it almost as accurate as a wideband A/F.

How to....install an adjustable fuel screw. Get the bike fully warm. Turn idle down below 1K rpm's. Begin turning the fuel screw in 1/4 at a time but give the bike 8-10 sec to respond to each movement. What you are looking for is when RPM's drop. Once you find that point notate the number of turns out. Now begin to open the fuel screw 1/4 turn until RPM's drop. Notate the setting then divide the two setting to arrive at your ideal setting. Be sure to return your hot idle RPM's back to at least 1200.

Side note: I've had several CVK carbs with such poor needle to needle valve sealing that even with the fuel screw closed the bike would still run. Not supposed to do that! If your bike is one then simply set it 2 turns out and call it a day.
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Old 11-20-2012, 11:49 PM   #4331
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Quote:
Originally Posted by sandalscout View Post
I have no experience with doing them on a car, but I've seen/handled a valve spring compression tool that you can use while the head is still on the block for both a Honda and Mitsubishi. They were both based on C-Clamps with special fittings on them. Anyway, just saying that while it may technically be possible, I don't think you could actually get one in around the frame.
I've done this many times on car engines. With relevant piston at TDC, screw a spark=plug threaded adapter in and compressed air is applied to hold the valves shut (normal shop air pressure).
Valve sprint compressor is not the usual G clamp style, in this case it is attached to the cylinder head eg use the rocker stud and then lever down on the spring as usual.

If you really really wanted to do the KLR you could make a shaft that replaces the cam, use that as a fulcrum to put the spring compressor lever under (eg put the shaft in the inlet side to do the exhaust springs.)
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Old 11-21-2012, 04:08 AM   #4332
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Quote:
Originally Posted by sandalscout View Post
I have no experience with doing them on a car, but I've seen/handled a valve spring compression tool that you can use while the head is still on the block for both a Honda and Mitsubishi. They were both based on C-Clamps with special fittings on them. Anyway, just saying that while it may technically be possible, I don't think you could actually get one in around the frame.
I did a tractor by stuffing clothes line in the spark plug with the piston at BDC and spinning crank to TDC or as close as you can get it to hold the valve in position. compress the spring

Some thing like this is what I used to compress the spring again it had a push rod and rocker arm over the top not OHC.



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Old 11-21-2012, 05:00 AM   #4333
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Quote:
Originally Posted by redog1 View Post
Pretty much convinced the head has to come off for the reasons you state. Really no way to compress the valve springs to get the keepers off, even if you could it's not likely you could get them reinstalled. I'll just dive into it. Now since I have to go that far, I'm thinking I might as well re-ring it. Have all winter to do it.
If the seals need replacing, there is a good chance that the valves/seat need re-facing or grinding too. Might as well do a full head clean-up job if you are going to that much trouble just for the seals
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Old 11-21-2012, 05:33 AM   #4334
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Quote:
Originally Posted by Tsotsie View Post
If the seals need replacing, there is a good chance that the valves/seat need re-facing or grinding too. Might as well do a full head clean-up job if you are going to that much trouble just for the seals
+1. If it's worth doing it's worth doing it correctly.
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Old 11-21-2012, 06:45 AM   #4335
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Quote:
Originally Posted by Danger4u2 View Post
+1. If it's worth doing it's worth doing it correctly.

I (unfortunately) had the head off my '08 twice when I had it. Sounds/seems like a daunting task at first, but its not so bad. Just takes time, and an extra $38 or so for a head gasket.

Beyond what's involved with a valve adjustment and the Doo, its pretty much just pulling the carb, the exhaust header, coolant hose, and the bolts holding the head to the cylinder, and taking care not to drop the cam chain into the case. And of course proper torque when re-installing.
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