Head gasket, valves, pistons, rings? Oh my.

I know that when checking the timing the mark on the intake ,the engine won't stay there unless you hold it with a wrench ( valve spring pressure against the cams wants the engine to move slightly from that position). With the intake cam mark held at the valve cover you should have 12 pins between the intake and exhaust gears as seen here. http://www.thumperfaq.com/yz_timing.htm . Hopefully the cam chain is OK and no crap is hiding in the basement:eek: . WR Dave

thanks, dave. i did see that page, and it all is understandable. i just don't know for sure if the cams were the exact same between WR and YZ, because if that is the case then one set-up or the other will look out of whack.

as for the downstairs, i am planning on running a full oil change after the first time i fill er back up, before i ever try to run it. (i.e. fill the oil res, cycle it through several times by turning the crank. let it settle, drain it, put in some fresh.) hopefully that will get the crap out of there.

thanks again,


OK guys,

thanks for all the help and feedback. last time i left you i was tring to figure out the timing. picking up there, here's the latest:

i chose to use the YZ timing of 12 sprocket holes between the 12oclock marks on the camshafts. i had to make a choice in the alignment of the marks on the camshaft sprockets. the best looking option was to align both of the three oclock marks at the top of the cylinder head. this meant that on both cams the 9 oclock mark was slightly higher than the head.with the 12 sprocket hole set-up, i felt that it was the best choice. i did try a few 12 and 13 hole configurations before i decided, though.

so, once that decision was made it was time to install the camshaft caps and check and correct the clearances. i had to order lifters and 5 shims in a set, assemble the unit, take the spacing measurements, pull it apart and insert the correct shims. since no shop would help me out with shims they had in stock for the mechanics, it took a while and a few fedex charges to get everything right.

at this point i also decided to use Plasigauge to check the camshaft clearance under the cap. i had never used this stuff before, but it worked just like the maual mentioned that it would. the guy at the auto parts store that sold it to me said he hadn't sold one in four years. the spacing was within tolerance (like new), and away we go.

i put the cam caps on one more time after the Plastigauge test and after figuring out what shims would yield the correct spacing. i checked the new spacing and then installed the new valve cover gasket and the cover. did the compression release lever and installed the exhaust. coolant full, oil full, tank and seat on, and it was time for the moment of truth.

one kick - hmm, seems to have good compression. kinda sounds like it wants to catch.

two kicks - yeah, stiff compression, new top end, gonna take a few to get this going.

three kicks - ok, this could be the first three of many, many kicks, especially since my girlfriend is watching me do this.

four kicks - my girlfriend is no longer watching me do this.

five kicks - VROOOM!!!!!!

pretty exciting. didn't run it too long, though, and discovered some coolant dripping out of the weep hole on the bottom of the right crank case. looks like maybe the original problem that led to all of this was blown seals on the pump and coolant mixing with the oil. fix that up and let's let er rip!!!!

more later,


Hey Jim

Know that you dropped a wad on the top end yet it would still be advisable to change out the impeller and gasket while you are in there.

actually, you are right on both counts. it was a pretty expensive proposition to use oem piston, cylinder, head assy. parts. when the engine fired and i saw the leak, i knew that i had to repair it, though. i would not have known that seal was bad unless i had the engine running, so i really don't feel as if i skipped a step.

i ended up having to take off the clutch cover and right crankcase cover, because that is where the water pump assembly sits. after all the rest of it, that wasn't a huge deal, and the parts (two seals, new impeller shaft, new bearings) were less than $50 and in stock at my dealer. again, i had not had to take any of that stuff apart during the rebuild, so i would not have known there was a problem.

with that said, i buttoned it up and went for a 25 or 30 mile 'test ride' in the mountains and all went well. i've gotta admit, the miller high life tasted pretty sweet after that ride. not having to push that bike back to the truck felt like a pretty big accomplishment.

thanks again everybody, pics or details available upon request!


Congrats! Hows the engine/ power feel compared to before it blew?

the power is at least as good as it was before, maybe better. i didn't really get after it for the first ride out, mainly kept the rpms low and didn't really get out of third gear more than two or three times. tried to break the top end in a little bit gently. it rode the same as before or better, though. the compression is certainly stiffer.

with that said, i did notice something. just twice i got to really wind it out, and it did sputter a little at the higher end. i noticed no lack of performance at all in any other setting, so i'm hoping that i can just adjust the carb a little bit (mix or maybe new jets or maybe just a good cleaning) if it becomes an issue over the next couple of rides. any ideas would be appreciated.


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