Valve lash procedure after valve job

[rwcfrank]

I am having the head from my 78 2V rebuilt with a valve job and stem seals. Since this will throw off the valve lash from before the rebuild, how do I get a baseline for the shims after the work is done? Do I assemble the head and check the clearance to the bucket top and then add a shim or what? This is my first shim and bucket bike, I have purposely steered clear of them for this reason. But now its time to learn!

[musicman]

If the machinist was good, he should've taken some material off the top of the valve after he ground the head, so you shouldn't be ridiculously far off. Though I would set things up looser than usual, they'll beat in and the clearance will tighten up. I usually did a half degree of interference when I did valves, for example a 45* seat and 44.5* head, if he did that then they should settle pretty quick. And if you read around, it's a big no-no to leave the shim out, you risk damaging the cam lobes or possibly the bucket.

[rwcfrank]

Thanks musicman, my machinist is real good so I am sure he will square the valve end. Thanks for the advice.

[BassCliff]

Hi,

After the top end is completely reassembled, just use the regular valve adjustment procedure.

Valve Adjustments (8 Valve)


Thank you for your indulgence,

BassCliff

[Nessism]

Get a 2.40 checking shim (or something close) and use that to judge what shims you need. With a known shim, and measuring the clearance, figuring out what shim you need for each valve is easy.

Oh, and yes on skimming the valve ends.

[Yewtree]

Help! Broken timing chain! Desperate!

Guys..I need help badly. I just got a new job with the state of Oregon..and a damned good one..my commuter bike (85 gs700e) had a timing chain failure. I NEED this bike. It has to run. I have pulled the valve cover and removed the cams as the chain is gone...well down in the valley so low...and found four broken rockers..cams seem ok, valves depress without sticking and I dont see and witness marks on pistons...engine was at or near idle when it quit...I need any and all hands on deck! Please please please help!

[Agemax]

get a second hand engine! or its a major engine rebuild to fit a new camchain

[BassCliff]

Hi,

Guys..I need help badly. I just got a new job with the state of Oregon..and a damned good one..my commuter bike (85 gs700e) had a timing chain failure. I NEED this bike. It has to run. I have pulled the valve cover and removed the cams as the chain is gone...well down in the valley so low...and found four broken rockers..cams seem ok, valves depress without sticking and I dont see and witness marks on pistons...engine was at or near idle when it quit...I need any and all hands on deck! Please please please help!

Really? With your first post you hijack someone else's thread and demand everybody drop everything and fix your bike after a major implosion?

Everybody knows that I'm a gentle soul but sometimes I just can't stand the gall of some people. I hope this is a joke.

Click the link in my sig and you might find a repair manual. But finding a used engine to drop in your frame is probably your quickest/easiest/most cost-effective procedure.


Thank you for your indulgence,

BassCliff

[rwcfrank]

So back to my education . SHould I put the shims back in where they came from to start or use Nessism's concept of using a single shim doing all the measuring and the making adjustments? That does seem a little labor intensive if I can come close by replacing the shims where they came from before disassembly.

[BassCliff]

Hi,

Yes, replace all the shims. They don't necessarily have to go back where they came from but that's as good a place to start as any. Having a "checking shim" is a good idea, an extra one that is smaller than the rest, to use as a starting point for your measurements, and also so that you DO NOT turn the engine with any shims missing. You can score the cam lobes that way - not good.


Thank you for your indulgence,

BassCliff

[Agemax]

shimming can be a labour intensive job for a beginner but its worth the time to get it right. leave all the shims in their original place after measuring the sizes and then working out what sizes need to go where. the more "swaps" you can do the better but a spare shim is a good idea as you can pop one out, put the spare shim in so you can turn the engine over safely and swap it out with the shim it needs to replace, then carry on the sequence till you have all the correct clearances or you have determined what size shims you need to buy to complete the job

[rwcfrank]

Makes sense, thanks for all the help. Now off to get a very short haircut to prevent me from pulling any out

[Yewtree]

Sorry Basscliff....wasn't deliberate...damned mouse...I meant to start my own thread...definitely an accident...to all those I offended, apologies..dang things anyway....

[Agemax]

Sorry Basscliff....wasn't deliberate...damned mouse...I meant to start my own thread...definitely an accident...to all those I offended, apologies..dang things anyway....

haha, your mouse slipped from start new thread to reply to thread

[Nessism]

So back to my education . SHould I put the shims back in where they came from to start or use Nessism's concept of using a single shim doing all the measuring and the making adjustments? That does seem a little labor intensive if I can come close by replacing the shims where they came from before disassembly.

You are going to need a shim for each lobe just as a place holder - DO NOT rotate the cams without a shim in each bucket otherwise the cam and bucket will become damaged. What shims you use doesn't matter to start with, since you will have to systematically move that checking shim though each position on the engine and take measurements. Once that is complete you can calculate what shims are necessary and then place an order with Z1 or the Shim Club as required. I suggest getting some extra shims too just to be safe, and anticipate your next shim adjustment.