Checking valve clearance (see pic)

[Paul]

Hi I have a problem with checking my valves on the GN250 (1987), it has been off the road since 94 it does run, but badly, I'm just trying to go through a series of elimination to figure out why its sooting up and has a lack of power,

I have never done valves before, and am having a problem finding any gap whatsoever , The flywheel has the TDC mark centered in view and the book says inlet (mm) 0.03 -0.08 and ex 0.08-0.13 am using 0.05 and 0.10 feelers... so firstly am I checking in the correct place ...top of the valve and below the adjuster (see pic)

if so what next should I just undo the adjuster right out and insert the feeler, and screw down on to it then tighten the securing nut....hmm I'm stuck how to go about this?

 

[Steve]

Are you sure that TDC is the correct position for the crank? :-k

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[chuck hahn]

Yes ...you loosen the nut and back off the adjuster. Finger tighten the adjuster down to the feeler guage. Then you snug up the jam nut and recheck..because as you tighten the jam nut you can ever so slightly move the adjuster.


The TDC mark is a good indicator as to where the piston is at. But what I do is physically look at the valve and the rocker itself. I ensure the valve is all the way up and not compressed. Then I set the gaps.

 

[Agemax]

are you sure you have the right cylinder at TDC and on the compression stroke?
turn the engine and watch the L/H cylinder (No.1) inlet valve. when it opens and starts closing again, then wait for the TDC mark to come round on the crank.
then check the clearances. set them to the feelers you have, thats a nice middle of the road setting.unscrew the locknut,set the adjuster,retighten lock nut and check again.
then repeat on No.2 cylinder

 

[chuck hahn]

Thats why i said to physically look at the valve you are adjusting...to physically verify that the valve is up and not under and compression..

 

[Steve]

are you sure you have the right cylinder at TDC and on the compression stroke?
turn the engine and watch the L/H cylinder (No.1) inlet valve. when it opens and starts closing again, then wait for the TDC mark to come round on the crank.
then check the clearances. set them to the feelers you have, thats a nice middle of the road setting.unscrew the locknut,set the adjuster,retighten lock nut and check again.
then repeat on No.2 cylinder

Just one problem with that, Age. :-k

From allsuzukicycles.org,

GN 250 E 1982
Overall Length: 2,030 mm (79.9 in)
Overall Width: 840 mm (33.1 in)
Overall Height: 1,120 mm (44.1 in)
Wheelbase: 1,350 mm (53.1 in)
Dry Weight: 128 kg (281 lbs)
Engine type: Air-cooled 249 cc single cylinder SOHC, 4 valves. 22 hp / 8,500 rpm, 2.0 kg-m/ 5,500 rpm.

Yep, he said GN250, not GS250.

Hi I have a problem with checking my valves on the GN250 (1987), ...

.

 

[chuck hahn]

Also youll note that in the compression stroke, both the valves will be up.

 

[Agemax]

Just one problem with that, Age. :-k

From allsuzukicycles.org,


Yep, he said GN250, not GS250.




.

haha...OOPS
he may have grafted 2 cylinders together to make it a twin!

 

[Steve]

haha...OOPS
he may have grafted 2 cylinders together to make it a twin!

Would he then be chanelling Allen Millyard? :-k

.

 

[Agemax]

Would he then be chanelling Allen Millyard? :-k

.

it might actually be him, posting under an alias name.........

 

[Steve]

it might actually be him, posting under an alias name.........

Who would do a thing like that? :-k

.

 

[Paul]

Hey thanks, yep only a single cylinder, right now I'm thinking I'll hold off touching my GS1100, till I can master a "basic" single.... frustrating but I'm learning lots of new stuff daily.... I think I read somewhere using a drinking straw down the spark plug also works well too for determining TDC, would you agree?

OK thanks, so I'm going along the right lines

 

[Agemax]

Hey thanks, yep only a single cylinder, right now I'm thinking I'll hold off touching my GS1100, till I can master a "basic" single.... frustrating but I'm learning lots of new stuff daily.... I think I read somewhere using a drinking straw down the spark plug also works well too for determining TDC, would you agree?

OK thanks, so I'm going along the right lines

are you sure your name is Paul??????? lol

a straw may work but the TDC mark is the most accurate way (and easiest) method to use.

 

[chuck hahn]

Yes..its a poor mans feeler guage in a way.

If the cylinder is up, both valves are up, and the mark is at TDC, you can put the straw in and ever so slightly move the crank forward and back and watch the straw move up or down. When it is at the apex of the stroke it will stop comming up and pause a tad before starting to go back down. You can fiddle with it ever so gently and "feel" exactly where perfect TDC is at...make sense?

 

[Steve]

I'm thinking I'll hold off touching my GS1100, till I can master a "basic" single....

You think that's frustrating? Wait until you dig into the shims on the 1100.

It's not really all that hard, just a bit time-consuming the first time you do it.

.

 

[Paul]

AHHH the penny's dropped now .... yep I just lined up the mark without taking the covers off looking for the rocker to rise...i get it now cheers

I'll have a look again tomorrow