Carb swap

[JTGS850GL]

Be sure to do a bench sync with the carbs, and a lot of the time hard starting like that can be caused by the idle screw not being screwed in far enough and as stated before in the thread, check the valves..

V

Actually it's usually they're screwed in too far. Start with the screws set at 3 turns from lightly seated. Adjust as needed. They usually end up around 2.5 turns +-.

Bad valve adjustment is more common of a problem with hard starting.

[RJordan09]

OK, more progress made, still won't stay running....

-intake boot o-rings replaced
-oil change
-oil filter changed
-confirmed all plugs are sparking
-adjusted the idle screw to 2.5 turns


...after replacing the intake o-rings, it sounds much stronger as it's trying to start. I know we're not huge Quick Start fans around here but I grabbed a bottle and the engine ROARS for like, 2 seconds after a squirt but then dies right back down. I have checked the bowls of the carbs to confirm the gas lines are working. I'm thinking this is most likely a fuel issue? The bike fires right up with the ether quick start but I'm not getting anything with the tank. Time for a petcock change? (I thought it was working fine...)

[1948man]

I think Gustov was referring to the single Idle Adjustment Screw and not to the 4 mixture screws. I think maybe he was suggesting the idle is set so low it dies.

[RJordan09]

I think Gustov was referring to the single Idle Adjustment Screw and not to the 4 mixture screws. I think maybe he was suggesting the idle is set so low it dies.

I have re-set the single idle screw in the center of the carbs to 2.5 turns. I also went through and re-checked all the seals on the airbox, as far as I can tell there are no major air leaks.

[hillsy]

I have re-set the single idle screw in the center of the carbs to 2.5 turns.

There is no pre-set adjustment for this screw - it simply gets adjusted in or out until the bike is idling at the correct RPM.

However, the individual idle mixture screws (one on each carb) are adjusted to pre-set turns.

[RJordan09]

I think my next step is here is going to be the valve adjustments

[Steve]

That should have been one of your FIRST steps, and could have been done while the carbs were in "the dip".

You did dip the carbs?

.

[RJordan09]

That should have been one of your FIRST steps, and could have been done while the carbs were in "the dip".

You did dip the carbs?

I know it, amateur hour over here but I know carbs (which were indeed dipped) and a valve adjustment is new territory so I put it off. With that being said, I have pulled the valve cover and OMG are those gaskets glued on there. This could be the first valve adjustment it's ever seen. I've already ordered new NOS gaskets. I need to go out and get a feeler gauge set, I don't currently own one. I'm going to guess that I'm looking at needing to swap out quite a few shims.

[steve murdoch]

Rich, have a look at his thread about the shim club. http://www.thegsresources.com/_forum...alve-Shim-Club
Ray does an excellent job looking after this service for the site.

[RJordan09]

Rich, have a look at his thread about the shim club. http://www.thegsresources.com/_forum...alve-Shim-Club
Ray does an excellent job looking after this service for the site.

Thanks!! What an amazing offering for the community (I'm a sucker for a donation for things like that....) I've just grabbed a feeler gauge set and it looks like everything is coming in a near 0.00 clearance. Looks like I could very well be asking Ray for a swap out on all 8 shims!

[RJordan09]

I have just finished checking all my current clearances and 7 of the 8 are coming in at 0.00-0.02mm (my feeler gauge set's smallest is 0.04mm so anything that I cannot clear with that I'm putting into the 0.00-0.02 category). The final shim clearance is RIGHT at 0.03-0.04 (my 0.04mm will clear with lots of tension)

Thinking this may be the first ever valve adjustment, is it common to see them all come in at no clearance?? Or is it more likely I am measuring something wrong? (I've thouroughly gone through all the material on BikeCliff's site and done some youtube -ing so I'm pretty confident in my measurements.

Would I still be OK to use the Service Manual's recommendations for shim adjustments? Seems to suggest simply dropping down one shim size, but will that be enough??

[JTGS850GL]

Most likely you be able to swap some of the shims to different positions so you shouldn't need all 8. Just remember to NEVER turn the crank over without a shim in every bucket or you will damage the cam lobe. Might want to pick up a "thin" test shim. Something 2.50mm or less. That way you can put that shim in and measure the needed shim on the valves that are too tight to gauge with the shims you have.

[Steve]

If it is the first valve adjustment, it is SERIOUSLY long overdue, the first one is supposed to be done at 600 miles.

Yes, it is typical for the clearances to tighten up, but not because the shims or the cams wear, it's because the valves get hammered into their seats just a little bit more.

Since this is the first time checking clearances, I will also caution you to make sure you have the cam positions correct when checking clearances. Read the Suzuki manual carefully, it is the only one that explains the procedure correctly. Check the clearances again before you install new shims, you might need something different than what you ordered.

.

[RJordan09]

If it is the first valve adjustment, it is SERIOUSLY long overdue, the first one is supposed to be done at 600 miles.

Yes, it is typical for the clearances to tighten up, but not because the shims or the cams wear, it's because the valves get hammered into their seats just a little bit more.

Since this is the first time checking clearances, I will also caution you to make sure you have the cam positions correct when checking clearances. Read the Suzuki manual carefully, it is the only one that explains the procedure correctly. Check the clearances again before you install new shims, you might need something different than what you ordered.

Thanks for the info. I did follow the service manual...this was the cam "intakes up, exhausts flat" styled measuring (to grossly over simplify).

[Steve]

I did follow the service manual...this was the cam "intakes up, exhausts flat" styled measuring (to grossly over simplify).

Sorry to burst your bubble, but that is NOT correct.

Read the FACTORY manual carefully. Start with EX1, set the cam lobe to point FORWARD. You will see that the lobe for EX2 will be pointing UP. With the cam in that position, measure BOTH, EX1 and EX2. Rotate the crank 1/2 turn, you will see that IN1 is pointing UP and IN2 is pointing REARWARD. Without moving anything, measure BOTH, IN1 and IN2. Rotate the crank another 1/2 turn, you will see that EX4 is pointing FORWARD and EX3 is pointing UP. Wiithout moving anything, measure BOTH, EX3 and EX4. Rotate the crank a final 1/2 turn, you will see that IN4 is pointing UP, IN 3 is pointing REARWARD. Again, without moving anything, measure BOTH, IN3 and IN4.

While those positions might not seem to make sense, they really do. With the lobes in those positions, neither valve is being pushed open on that side of the cam. That means the cam will not be skewed in the bearing, giving a false clearance on the other valve. Once you see that both cam lobes on that side of the cam are pointing away from the valves, it's easy to position the cam correctly.

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