Lowest Shim Acceptable?

andrew0853 · March 15th, 2016, 06:13 PM

So I did my valves for the first time on my ninja 250 2012.

Exhaust .203mm .229mm .203mm .279mm
Inlet .203mm .203mm 0mm 0mm

as you can see my piston two inlet lash is non existent.
So i did the math a+b-c=d
and it called for 2.6mm shim....
still no clearance, so I put the lowest shim i have in there 1.20mm
Clearance was so big i was putting feeler gauges together to measure it, turns out it was 1.143mm calling for a 2.16mm shim.
After i installed that shim clearance is .508mm
Im getting there! and it only took me 3 times to figure it out!

My questions: whats the lowest shim i can put in there?
the service manual has a table of shims to use that only range from 2.5mm-3.5mm....

also why the F are my inlet valves so tight?
Side note: i did mess with the carb synch and idle adjustment screw to get it to start and idle better.... maybe thats why they so tight while the rest are fine?
I plan on shimming them until i hit the lowest acceptable shim, then replacing the valves

P.S. i always put 91 in my bike.... or at least 89.... could this somehow be involved? i noticed im suppose to be using 87

HoneyBadgerRy · March 15th, 2016, 06:54 PM

I can't imagine any if that causing your valves to be so tight, that said, I have nothing to say.

andrew0853 · March 15th, 2016, 07:01 PM

Sorry is my first bike, so my knowledge is wanting.

Mainly i need to know if i can just keep shimming it down, or is a shim smaller than 2.5mm bad for my bike?

the bike has 26k miles on it, and the previous two valve adjustment where done by two different shops...

HoneyBadgerRy · March 15th, 2016, 07:32 PM

I believe that if the shim is out is spec that means either the valves are out of spec, or the valve seats are dissolving. I can't see what would really go wrong with shimming with a smaller shim, but again, this isn't my expertise. Someone who knows more about valves should chime in.

andrew0853 · March 23rd, 2016, 07:15 PM

Just a friendly update, have a 2.45mm shims in there now and runs like new.
throttles been sticking tho, something to do with the rubber on the handlebar.

26k miles and going strong

oh and when u turn the handle bars all the way to the left it honks the horn now lol

Mohawk · March 25th, 2016, 12:35 AM

The smallest shim you can use is dictated by the hollow it lives in in the valve retainer. Once you reach that your bucket is resting on the retainer & can not get lower.

I was surprised Kawasaki went to shim under bucket on these when they lowered the Rev limit on the next gen. It would cost them a whole new machining process & makes adjustment a pain in the ass, having to remove the cams.

This engine has been around since 1984 & the BMW S1000RR & the new Suzuki GSXR1000 both use slipper rockers like the original EX250 but with shim adjustment. Personally I prefer screw & locknut adjustment, it's simple, effective & I can do the adjustments at home, fairly simply

Glad you got yours sorted.

March 15th, 2016, 06:13 PM	#1
andrew0853 ninjette.org newbie Name: Andrew Location: California Join Date: Jun 2015 Motorcycle(s): ninja 250 Posts: 5	Lowest Shim Acceptable? So I did my valves for the first time on my ninja 250 2012. Exhaust .203mm .229mm .203mm .279mm Inlet .203mm .203mm 0mm 0mm as you can see my piston two inlet lash is non existent. So i did the math a+b-c=d and it called for 2.6mm shim.... still no clearance, so I put the lowest shim i have in there 1.20mm Clearance was so big i was putting feeler gauges together to measure it, turns out it was 1.143mm calling for a 2.16mm shim. After i installed that shim clearance is .508mm Im getting there! and it only took me 3 times to figure it out! My questions: whats the lowest shim i can put in there? the service manual has a table of shims to use that only range from 2.5mm-3.5mm.... also why the F are my inlet valves so tight? Side note: i did mess with the carb synch and idle adjustment screw to get it to start and idle better.... maybe thats why they so tight while the rest are fine? I plan on shimming them until i hit the lowest acceptable shim, then replacing the valves P.S. i always put 91 in my bike.... or at least 89.... could this somehow be involved? i noticed im suppose to be using 87 Last futzed with by andrew0853; March 15th, 2016 at 06:46 PM. Reason: Additional Information

March 15th, 2016, 06:54 PM	#2
HoneyBadgerRy ninjette.org certified postwhore Name: Ryan Location: Beaufort SC Join Date: Aug 2015 Motorcycle(s): 05 Ninja 250, 04 KTM 625 SMC, 01 Xc250 Posts: A lot. Blog Entries: 3	I can't imagine any if that causing your valves to be so tight, that said, I have nothing to say. __________________________________________________ Because Unregistered sucks at riding.

March 15th, 2016, 07:32 PM	#4
HoneyBadgerRy ninjette.org certified postwhore Name: Ryan Location: Beaufort SC Join Date: Aug 2015 Motorcycle(s): 05 Ninja 250, 04 KTM 625 SMC, 01 Xc250 Posts: A lot. Blog Entries: 3	I believe that if the shim is out is spec that means either the valves are out of spec, or the valve seats are dissolving. I can't see what would really go wrong with shimming with a smaller shim, but again, this isn't my expertise. Someone who knows more about valves should chime in. __________________________________________________ Because Unregistered sucks at riding.

March 23rd, 2016, 07:15 PM	#5
andrew0853 ninjette.org newbie Name: Andrew Location: California Join Date: Jun 2015 Motorcycle(s): ninja 250 Posts: 5	Just a friendly update, have a 2.45mm shims in there now and runs like new. throttles been sticking tho, something to do with the rubber on the handlebar. 26k miles and going strong oh and when u turn the handle bars all the way to the left it honks the horn now lol
	1 out of 1 members found this post helpful.

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March 15th, 2016, 07:01 PM	#3
andrew0853 ninjette.org newbie Name: Andrew Location: California Join Date: Jun 2015 Motorcycle(s): ninja 250 Posts: 5	Sorry is my first bike, so my knowledge is wanting. Mainly i need to know if i can just keep shimming it down, or is a shim smaller than 2.5mm bad for my bike? the bike has 26k miles on it, and the previous two valve adjustment where done by two different shops...

March 25th, 2016, 12:35 AM	#6
Mohawk ninjette.org guru Name: Chris Location: Bristol, UK Join Date: Feb 2016 Motorcycle(s): ZZR250, VFR800 Posts: 479	The smallest shim you can use is dictated by the hollow it lives in in the valve retainer. Once you reach that your bucket is resting on the retainer & can not get lower. I was surprised Kawasaki went to shim under bucket on these when they lowered the Rev limit on the next gen. It would cost them a whole new machining process & makes adjustment a pain in the ass, having to remove the cams. This engine has been around since 1984 & the BMW S1000RR & the new Suzuki GSXR1000 both use slipper rockers like the original EX250 but with shim adjustment. Personally I prefer screw & locknut adjustment, it's simple, effective & I can do the adjustments at home, fairly simply Glad you got yours sorted.