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GS250T timing marks question

  • Thread starter Thread starter Igor
  • Start date Start date
I

Igor

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Hi everyone. I've recently replaced a valve and somehow messed the timing up as it doesn't run and sometimes pops a flame out of the exhaust. Its also popped one from the carb once. I'm trying to make sense of the timing marks as they don't match the manual. Where should i have this positioned?

The manual only has one set of markings, so im supposed to align it in the little window

T | | F


Mine has

| T | F R |

&

| T L


as you can see in the photos. Im not sure whats supposed to be in the alignment window so i can check cams are aligned

IMG_20180206_134147.jpg
 
First, welcome to the forum. I love timing issues and the vagueness in the aftermarket shop books. I would grab a copy of the Suzuki manual on BassCliff's website. I just checked the manual on there for your bike and it and talks about which T mark to use in reference to the "R" side of the advance governor.

http://members.dslextreme.com/users/bikecliff

GS250T-GS300L '82 Service Manual (91MB)

Page 3-69

 
hmmmm, looks like i have it set up correctly. I've now taken the cams off and done a rotation of the engine and re-inserted the cams. Its still not firing :confused:

maybe im not supposed to line the mark with the left line on the T?

IMG_20180206_173230.jpg
 
Your 3T mark on the intake cam looks to be way retarded; two or three teeth. Ex looks fine. Use the line beside the T to the case mark just as you have it.

Count the pin at the 2T mark as '1' and then the 20th pin should line with 3T arrow. You're probably starting beside the arrow instead of at it. With luck, the valves haven't become unfriendly to the pistons.

While you're there, by the look of the rust on your ignition advance you should be giving it some lube before it seizes...
 
Last edited:
John Park said:
Your 3T mark on the intake cam looks to be way retarded; two or three teeth. Ex looks fine. Use the line beside the T to the case mark just as you have it.

Count the pin at the 2T mark as '1' and then the 20th pin should line with 3T arrow. You're probably starting beside the arrow instead of at it. With luck, the valves haven't become unfriendly to the pistons.

While you're there, by the look of the rust on your ignition advance you should be giving it some lube before it seizes...
Click to expand...

Yeah i thought the intake looked a little off but its exactly 20 pins including the two the arrows are pointing at
 
Did you turn over the engine by hand when you first installed the cam chain to check there was no interference before you tried to run it if not and things where not correct then you may have bent valves.
Did you line up the arrow on the exhaust cam that has to be inline with the cylinder head face correctly?
On enlarging your photo it appears you have 20 pins between the arrows unless the camera angle is deceiving, and the timing mark looks ok.
Each the cams have a slot cut in the end those slots should point inwards and face each other (in the picture from the manual you posted you can see the slots and how they should look) the top of the slots should be in line with the cylinder head face that should tell you if you have things correct. Turn over the engine by hand a couple of times with no spark plugs installed there should be no interference. once you are happy it's set up ok try to start it if it will not run I would do a compression test and see what numbers you get and post them.
 
Last edited:
fastbysuzuki said:
Did you turn over the engine by hand when you first installed the cam chain to check there was no interference before you tried to run it if not and things where not correct then you may have bent valves.
Did you line up the arrow on the exhaust cam that has to be inline with the cylinder head face correctly?
On enlarging your photo it appears you have 20 pins between the arrows unless the camera angle is deceiving, and the timing mark looks ok.
Each the cams have a slot cut in the end those slots should point inwards and face each other (in the picture from the manual you posted you can see the slots and how they should look) the top of the slots should be in line with the cylinder head face that should tell you if you have things correct. Turn over the engine by hand a couple of times with no spark plugs installed there should be no interference. once you are happy it's set up ok try to start it if it will not run I would do a compression test and see what numbers you get and post them.
Click to expand...

yeah i always do a few revolutions by hand to check for interference.

The slots at the end of the cams are facing inwards, so thats fine to.

I sprayed a bit of starter fluid down the carb and it tries to fire but then nothing.

i'll do a compression test today and see what i get
 
I've just done a compression test

30 psi on right cylinder

40 psi on left
 
Yes do the compression test and post the numbers not forgetting to fully open the throttle whilst doing the test, it looks like you cam timing is ok.
 
Then you have a serious problem take out the plugs and put a good tablespoon of engine oil in each cylinder and do the compression test again, if the numbers rise you have worn cylinders/rings if they do not rise you have valve problems either way it will require striping to find the problem.
sorry to ask are your valve clearances set correctly?

just checked the manual on there for your bike and it and talks about which T mark to use in reference to the "R" side of the advance governor which I find a little confusing.
compression new is rated at 110psi
 
it was running fine before i stripped the engine to fit the new valve, so it cant be worn rings etc surely

i'll check the valve clearances again and see what happens
 
i took these when i was first stripping the engine for reference, so it ran when it was like that. I'm going to check again and cross reference

inCollage_20180207_131917924.jpg
 
i've re-adjusted the valves very slightly and slightly tweeked the cam position and im now getting 60 psi on both sides. still way off 110psi

Screenshot_20180207-143712.jpg
 
It's running! Finally! a couple of the valves clearances was slightly too tight and probably wasn't fully closing!

Tomorrows task is to try and get it to run right by playing with the carbs. idle is all over the place and it will only fire up with a little squirt of starter then it runs fine on its own

:D
 
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