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Big trouble for my 85 GS550L

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Guest

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I've done a bonehead thing here - I've been working on my son's bike, as it wasn't running well & had zero power. Cleaned the carbs, new plugs, petcock, fuel line and it still ran like sh**.

A posting here suggested checking valve clearances - just did that using the method called out in the factory manual, all were below low limit, reset them to spec.

I also pulled the carbs to check the main jets (I'm pretty sure I mixed them up when i cleaned them) & the float height. Never got to that.

Then I had the bright (?) idea to do a compression check. I did that while the carbs were off & the engine stone cold. Here's my numbers:

1 - 135#
2 - 95#
3 - 50#
4 - 75#

What are my options now? - it appears I now own a parts bike.
 
It could just be possible that the timing chain jumped one tooth due to a bad tensioner. Or worst case, the head gasket blew. Patience. I don't think you did anything wrong. And it is not a parts bike!
 
Me thinks you need to go back & check the valve clearances again!!!!
135 psi in the one cyl means the timing is OK
 
Compression should be between 128-171 (psi) for this model. It would also indicate that the carb problem may not be all the carbs fault.

No it's not a bag of spare parts, it will be if you quit!!!!!

Best advice is to do a second compression test with a little oil down the bores to see if the compression comes up. This will tell if its rings or valves. (Sorry, can't remember if you need to warm engine first which will mean getting it running poorly!)

Once thats done then you can decide which way to go. Its does sound like a part engine rebuild on the cards.

The carb problem can be sorted by getting new main jets (at a cost) and going through the carb guides.

Do you have the time and money to do this?

Suzuki mad
 
Last edited:
Thanks for the thoughts guys - I've slept on it & think I should get the bike running & warmed up, then check the compression again.

Just thinking that because they were ALL tight when i started (PO did it incorrectly?), and the engine wasn't oiled or warm, I will most likely get different (better) numbers.

How do you check the timing??

I'm fairly sure i did the valve adjustments correctly - I'm pretty anal & followed the manual directions to the letter. I will double check though.

thanks
 
valve timing is vlearly covered int he manual

give the manual you downloaded a good read as all the questions you may ask are largely answered by it.

did you check the valve clearances per the manual or form another source?

also was the engine overnight cold?
 
145.03773773
203.052832822

psi range for the compression as per the factory manual
which sounds a bit high doesnt it considering the compression ratio is 9.8 to 1

no more than 29.007547546 difference among cylinders

minimum psi is 116.030190184

thanks to a handy kpa to psi convertor

the manual has only kpa and kg/cm2 figures
 
Yes, I had converted the metric values over to psi already. I checked/set the valve clearances EXACTLY as stated in the manual (I set all clearances to .004" (0.10mm). The engine was stone cold when i set them. As I said, every valve needed to be "gapped", the clearance was nil - .001" when I checked them before setting. i believe the PO did them wrong.

Perhaps after running the bike now (after getting the carbs tweaked & re-installed) the valves will require a little time to re-seat? This may explain the low numbers.

I am hopefull that after getting the engine warm, the re-check will yield better numbers, but I agree with you; 145 psi at the lower end of the compression spectrum does seem quite high.

I'll keep you all posted - hopefully in the next several days I'll ga et a chance to work on it again.

Please feel free to share any words o'wisdom or similar experiences!!
thanks,
 
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