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Bike is not respondng to throttle, popping, performing poorly

  • Thread starter Thread starter djg42
  • Start date Start date
D

djg42

Guest
Hello,
I was riding the other day and my bike was running fine. All of the sudden, when I pulled the throttle it wasn't responding properly and was backfiring. On the way home it was sometimes running ok, and sometimes I could barley move.
When I got home I took the carbs apart and everything seemed fine, the jets seem clear and the diaphragms are both fine. Fuel flow from the tank was good. Both float bowls are filling up with gas fine. Both intake boots are good( there are a couple of cracks but they dont go all the way through, and I put some grease over it to see if it would make a difference-which it didnt)
it idles fine and when in neutral it responds to throttle and revs normally.

I know i need a new cam shaft tensioner because mine jiggles around. I have tried re-setting it and it doesnt help. My bike was running good so I thought i could ride until i got the new one. I am expecting the new cam saft tensioner anyday in the mail.

What does this sound like? What can I check? Could the bad cam shaft tensioner have messed something up? thanks in adance for the help!!
DG
1980 GS450
 
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Sounds like you have the air/fuel ratio concept covered, so it is 'unlikely' that air and fuel are the problem. You mention that the cam chain tensioner is on the fritz and that you have a new one on the way. Good idea as that "can" cause a valve timing issue that "MAY" lead to the problems that you are having. Too much slop in the cam chain will cause the cams to be somewhat out of sync and without going into the long story, may indeed be the problem.

I would also check the plug wires and the boots. Usually an "on again...off again" problem is NOT mechanical ie. cam chain, and is more likely to be the ignition and its' related pieces. Verify that the plug wires are tight in the coils, that the caps are clean and tight to the wires AND that the plugs are fresh. Check the grounds to the coils (frame mounting points) and get the bike running IN THE DARK, AS IN NO LIGHT. Mist the wires with Windex or equal and see if you can detect a misplaced spark signal (blue arc to ground) ect.

Please report back... :-k
 
Thanks dave! Im still waiting for the tensioner to get here, but i did all the electric testing you recommended and it seems to be fine.
I also did a compression test which was good. Ill uodate when i get the new tensioner on. Thanks agian for your help!!!
DG
 
If the tensioner is not working and if its running bad it might have already skipped a tooth on the chain, just tightening up the chain in the now wrong timed position wont fix it.

Not saying thats your problem but if it is you need to pull the valve cover and remove the cams and start the timing procedure from there.
 
well i put the new tesnioner in and there was no improvement. O know i need to order the gasket and remove the cylinder head but i dont know what to do once im in there. any advice would be greatly appreciated. Thanks!
DG
 
Afore you pull head, concider these:
- Dont need to pull head to check the cam chain timeing, just the cam cover (and engine case cover).

- You say the intake boots are old and cracked but not leaking.
If the intake boots are old and cracked, then I wonder what condition the intake boots orings are in. Do you know if they have been changed anytime in last decade or so?
Although you havent stated the classic symptom of bad intake boot orings, I understand they can cause all sorts of symptoms that people make lots of other adjustments to compensate for.

>>later note:
Oh, now I see you have a 450. I dont have any experince with 450 (nor any 2 cyclinder GS), but would quess they have orings in intake boots.

.
 
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Thanks! Unfortunately, The intake boot O-Rings are new. I can check to see if the cam chain is off with out removing the head?(Im clueless about this!)
 
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Remove just the cam cover from the cyclinder head to see cams and cam chain.

Do not need to remove cyclinder head.

WHere in general are you located?
(maybe add that to your profile so it shows up on all posts)
 
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We all thank AlphaSport for their good microfische

We all thank AlphaSport for their good microfische

Cam cover, aslo called cyclinder head cover.
It (item #1) bolts to the cyclinder head, and covers the cams.
(you may need new gasket if you take off the cover)
14.gif










Cyclinder head (Item #1).
Has the cams (not shown)
Bolts to the cyclinder block.
16.gif
 
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Thanks guys!
I checked the coils and there good. I had a new battery sitting around which i tried too.
I guess ill have to take the valve cover off(thanks for clearing that up redman!)
I ordered the gasket which will hopefuly come soon.
 
i just got my gasket in the mail and im going to dive in and take off the cyclinder head cover. How do I remove the silver end caps? My manual has a square end cap with screws holding it in place but my bike has a different kind, theyre round and have no visible screws. Thanks!
DG

downsize3-3.jpg
 
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djg42 said:
i just got my gasket in the mail and im going to dive in and take off the cyclinder head cover. How do I remove the silver end caps? My manual has a square end cap with screws holding it in place but my bike has a different kind, theyre round and have no visible screws. Thanks!
DG

downsize3-3.jpg
Click to expand...
I had to stand on my head to look at your pic. :rolleyes:
 
I have the cylinder head cover off, and know im realizing i have no idea what im looking for. Im not sure how I check to see if the cam chain jumped a tooth
 
Hi,

Set the #1 piston to TDC. Then there are timing marks (numbers) on the intake and exhaust cam sprockets. There is supposed to be a certain number of links between the sprockets. Sorry I don't have the numbers in my head (18? 20?) but it's in your manual.

EDIT: Sorry, I just noticed that you have a 450. Setting TDC might be a little different for your bike than in the link provided (Thanks Mr. bwringer!). Check your manual.


Thank you for your indulgence,

BassCliff
 
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thanks!
I rotate the crank so its to TDC and then the front sprocket marking "2" points to the 1st chain link,and the rear sprocket marking "3" should point to the 18th chain link. But How do I determine which part of the chain is 18?
DG
downsize4-2.jpg


2010-09-04_004750_GS450camtiming.jpg
 
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ahh i see, like this
when i checked it seem fine, but the chain did jump around when I was rotating the crank shaft so Im still hoping this was the source of my problems.
camchain1.jpg
 
That chain looks very loose between the cams, something does not look right there. :eek:
I am sure the chain should be taught between the cams, I am sure something has moved.
 
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