Valve Measurement and Adjustment 1981 Honda CB900C

This is a how to video to show you how to measure and adjust your valve shims on a Honda CB900. It is the same for most duel overhead cam motorcycles including the Honda CB750, CB900, and CB1000.

[@gregritchie1758]

I bought an old '81 CB900c and didn't have a clue. Thanks to you,..I got thru this step with flying colors and carb rebuilds thru the Honda forum. Thanx for your help.

[@IrnMaiden304]

Thank's for posting this vid, never knew it would be that easy to adjust valves for my CB750 till I seen this. thumbs up for keeping it simple also !

[@ukariah]

what year cb750?

[@IrnMaiden304]

@@ukariah 82

[@ukariah]

@@IrnMaiden304 ah, i have a 85 cb700 thats been giving me problems

[@patmclean03]

Great tutorial. I stumbled here trying to find what the clearances are suppose to be as I have a compression issue and I'm rebuilding the engine entirely after buying it recently. I have seen different tolerances floating all over different forums and such, but the manual actually states different tolerances for each of the different valves... I am going to use your tolerances, as I've seen them elsewhere as well. Thanks again. Cheers!

[@kevknudson]

Yeah, I just had my 16 year old press play and hold it for me. I just couldn't find anything like this so I made one my self. I'm glad it helped SOMEBODY

[@genesound]

Good job Kevin. Yes, .004" to .006" is good clearance for these motors to last. :)

[@superwesman]

I just insert the valve lifter holder when the valve is open, then turn the rotor until the cam lobes are pointed away from the valves - yes, you're absolutely right, you have to be careful to make sure that you don't have both sets of valves on one cylinder open but it seems easier than forcing the tool in - remember, the tool is a "valve lifter holder" which means it holds the valve lifter - it's not a "valve lifter pusher" :)

[@KevinKaysBikes]

I have been locked out of this account for years, so sorry for the delayed response. @eduki - I don't know if it is the same for a CB1100F. My bike was a 1981 CB900C, I think it is the same for the CB1000C. You need to measure ALL of them and record your values. There is a spreadsheet in an old yahoo forum for CB900C/CB1000C where you record your values and it tells you what shims to remove, move, or keep. I removed the ones I didn't need, went to the Honda dealer and they just swapped them for the ones that I needed. The spreadsheet is called __Valve_Shims_Tool_New-n-Improved.xls @GREG GERHARDT - This is a video for folks that are trying to fix their bikes. You can also measure in inches (and I am in America). I do get it. The video and sound quality is not good because I just had my son hit record while I did it. This bike was sold MANY years ago so I can't recreate it and edit. Yes, I worked in a shop with ghosts ;-)

[@vagusnerve89]

awesome vid, i've got a 1981 cb900 that i've done the valves on 3 times now

[@EricJamesVideo]

For real. I almost stopped watching, but this is exactly what I need to do with my 900F.

[@kevknudson]

@MadSmokerBBQ It is a pain to get it right. Use a new gasket only. No silicone. You need to tighten it down evenly in a "star" pattern not heavy on one. Mine leaked, then I did it again (a pain) like the book says and it works. Patience is needed here.

[@kevknudson]

@chrislee1000 No problem. That's why I recorded it!

[@JoseTorres-qj6it]

How do you do the calculation is berry inportant explain on the video

[@MadSmokerBBQ]

The cam cover gasket on my '79 CB750 leaks at the front left. What sealant & gasket do you use? I have a black rubber gasket with blue rtv silicone and it isn't sealing well.

[@Jclement552]

Love the vid. Only thing confusing is in the vid you are measuring exhaust on cylinder 4, and the engine is in the b position or 6 oclock, Your cam lob is facing up. if you do the same thing on my at pos b and at 6 oclock. my cam lobe doesnt face up?

[@rustymcmuscle]

should u replace all the shims or just the ones that need replacing

[@elliotfricker4631]

HELP !!! I stupidly removed both at the same time, I cannot get the tool to compress both buckets, it slips off one and doesn't allow room for the shim, any ideas on how I can get them both compressed evenly?!

[@eduki]

Excuse me if i´m wrong... you measure one of the shims, but then replace the other? i don´t understand...

[@SkymillionBeatz]

i have n 82 cb900c, it runs and starts right up but it seems to only rev and run right when the choke is pulled. If i let the bike warm up it will stay running and idle without the choke pulled but if i try and rev the motor it will sort of backfire as its climbing in rpms and it will sometimes climb back down in rpms slowly, any ideas?

[@zeth15943]

I know this is a old video but what size are the shims like diameter

[@MadSmokerBBQ]

Awesome demonstration thank you!

[@kevknudson]

they are all over eBay. just search for "cb900 valve shim tool" or whatever model you have

[@kevknudson]

just the ones that need replacing. it helps to take out the ones that are out of tolerance and set them aside. you may be able to reuse them. i used the fancy spreadsheet found on the cb900/1000 users website to see what I needed. i reused a couple and needed a couple.

[@fubarinwar]

I would always adhere to what the manual says. You hear all sorts of eerie things out there, like changing exhaust does not lean out the mixture or just hand tight the spark plugs... I guess who ever designed the engine knows best.

[@eduki]

Not for the CB1100F? Thanks! ;)

[@metalsmith222]

thanks for posting this vid, it was very helpful, i was pretty much clueless as to how to go about doing this. all of my valves clearance out at .004mm except one valve on the intake side of the #1 cylinder, it clears .0025 my number one wasnt firing well, thats why i went ahead and did this. is .004mm normal? the clymer says 0.08 also the one that is .0025 holding the valve open a little bit? any input would be greatly appriciated. thanks

[@tomcarro]

Do you need to have the special tool to do this?

[@kevknudson]

most people have the cheap little screwdrivers laying around and they work great. if you have the fancy magnet thing, use it.

[@metalsmith222]

thats good to hear. thanks

[@waynehauschultz4237]

Why cant i get over 6.ooo rpms on my 900custum cb 81

[@genesound]

that's in inches, in metric it's about 0.10mm to 0.15mm, considerably more than what the manual says.

[@minilandrover]

it's a lot easier to use a magnet to lift out the released shim, and avoids it popping out of the pliers and dropping down inside the cam chain passageway.. my magnet is a super high power one from a computer hard disk drive.

[@Avitiq]

Sound is camera constantly trying to focus. Chill everyone.

[@hegaredaeric]

Dude what's that at sound in your video, you got some paranormal activity going down

[@rustymcmuscle]

im on that yahoo group ill have to go check that out and thxs

[@MrRockstar1968]

Hello Kevin, thanks for the video and advice, much appreciated. I've been onto local bike shops and also searched ebay and have been having trouble trying to find a valve ajuster tool, like the one in the video clip and was wondering if you could send me details of the order number and possibly an online link of where to order one from. Thanks for your help! Stephen.

[@MrMurphc13]

www.motionpro.com/c/valve-shim-tools

[@WoodrowfollowerofYahshua]

👍🏻😀

[@kevknudson]

I agree. I don't use them anymore. They are a PITA.

[@salvox71]

Congratz

[@minilandrover]

Using a powerful computer magnet to remove the shim is not just a gimmick, shims are super hard steel and gripping them with pliers is like squeezing a bar of soap in the shower. It's just a matter of time before the thing shoots out of your grip. the danger is it dropping down into the engine!!! Not good.. so what do you do then?? strip down the engine? turn the bike upside down and shake it? no you use an extending magnet and poke about down there and hopefully get it back, step one

[@stevenbootsma]

I think i have the same problem with my 81 cb900c :(

[@sansui1968]

mesure lower part of cam bottom center of base circle on all vale in bucket cam on top engines from supras with 7mge to a old honda Ferrari what ever verey simple ,,,,,eng is not my first language

[@Teramydog]

feeler gauge dude - feeler gauge. lol

[@kevknudson]

It's not that hard, although I don't find gripping soap in the shower difficult either. I did assume the viewer has a basic understanding of life. Obviously, my bad.

[@trondyne3513]

what in god's name is that noise?

[@bosco5652]

It's called a feeler gauge and you be should be measuring them in hundreds of a millimeter. God some people just don't get it.

[@Lfig012]

buckets .....haha lol... ya avent a clu..

[@glazerguy58]

everything looks good ... except you wearing latex gloves??? Man up ... lol.