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**sixtysix** · 08-12-2003, 05:31 PM

I bet they moved the valves, shims and everthing, I would guess some of your valves are not seated right since you have bad compression, you need to try a leakdown test and see what it says. Or just shim the valves back to the proper width and see. The valves shim clearance should always tighten with wear, as the valve and seat wear.

**Snow** · 08-12-2003, 08:20 PM

I dove in and pulled the head tonight to take a look at the cylinder bores and see if the pistons were still being held in tight. I was expecting to see bad scoring or at least some grooving, neither of which I had the misfortune of seeing.

When I stuck my finger in and felt the bore, it felt like a thin film of oil, but then I rub my index and middle fingers together and felt nothing.... is that how it's supposed to be? There was no glaze that I could see, the cylinders looked pretty much like they did when I put the kit together about 1000 miles ago. Also, the pistons were in tight as the day I put them in brand new.

Now here's the question which I am going to sleep on and decide tommorow sometime - I have another motor, which is known good except for 3rd gear and I actually had it in my bike for well over a year with no smoking or any other top end related problems. We pulled the motor to put my original (current) one in and havent touched it since (about 6 months ago?), so I figure the valves and seals and shims and cams are all in the right places. Do you think I can get away with just replacing the head gasket and putting my 78 heads on my 79 motor? I know they will physically fit just fine, so that's not an issue in my mind.

**fusionking** · 08-12-2003, 09:25 PM

Seriously, what could it hurt as long as you did it right? You just might ride it forever!!!!!!!!!

**Snow** · 08-13-2003, 06:23 AM

Basically what I'm asking is if the rings were toasted, wouldn't I see some evidence in the bores? If I don't have to pull the jugs off, hone 'em, and put in new rings, I will be a much happier person.

**sixtysix** · 08-13-2003, 06:34 AM

At a 1000 miles I have to wonder if it is even broken in yet? Have you hammered it a bunch? (easy low variable RPM runs for first 500 or so then, mix in some some quick full throttle runs after that.) Did you use convetional oil or synthetic? I would put the other head from the 79 on it and then put some nice fresh dino oil in it and go hammer the snot out of it for the next 1000 miles then see how the motor preforms. Just my opinion.

**xssiveone** · 08-13-2003, 07:13 AM

Got to agree with Gary on this one, I think it's just aproaching the break in point where the rings are starting to seat into the cylinder walls.

Rather then pulling your head, why not do a valve clearance adjustment on it and see what happens. It's only about an hours work, and might just save you a bunch of work pulling the head.

**Snow** · 08-13-2003, 07:33 AM

I tried measuring the clearance and all seemed to be close to spec on the exhaust side, but then the intake side I couldnt even fit my .102mm feeler in, wouldn't budge in there at all.

I've already got the head off and now am trying to find a replacement head gasket (cometic C8046) that I can get relatively fast. I went ahead and ordered a new cam chain from partsnmore, figured I don't need to be in here again later.

What dino juice would be best to run? Someone mentioned running a flat weight oil? I prefer running castrol, but I'll run anything you gurus say I should to break it in.

**uk1.1s** · 08-13-2003, 09:42 AM

Valve clearance closing

Snow

Not sure if the others posting here have explained the valve closing yet or not - just speed read down and it didn't look like it

I thought over time the valve clearance would widen, not tighten...what's going on here ?

On shimmed valves - clearances will tighten when the valve heads start to wear into the seats (often on exhaust sides where valves / seats may burn out) - but possible on the inlet side too. Or a shim has settled for some reason (like dirt below it - but less likely due to the forces applied whilst the engine is running.

This means that the valve seat in the head either need replacing (it's a hardened steel ring insert) or maybe just a bigger shim will do for now.

Having said all this my old KZ 1000 has just one shim that always gives trouble - you can measure / remeasure for ever, re-shim and it always seems out. So maybe some weird valve shim rule applies where at least one has to make no sense to the owner - just to drive him mad.

Have fun.

**Snow** · 08-13-2003, 02:10 PM

Well, after talking with my Local shop about getting a cometic replacement head-gasket and being told it would be around $55 and would take two weeks....I called Pro-Flo again (where I got the Wiseco kit in the first place) and they will have it it me in half the time for just under $45 including Florida sales tax.

Now I have to sit on my hands and make sure I wait for all my parts to come in before reassembling my baby.

I suppose I should check the clearance on the head I'm about to install so I can order any necessary shims while I'm at it.

**TopCatGr58** · 08-13-2003, 09:37 PM

Hey there Snow,

Instead of tearing into your other engine, since you've got this one already apart, I'd stay with this one. Did you do your own head reconditioning/lapping? If so, then since you've run 1000 miles on it, you might want to relap the intake valves just to ensure a good seal, since the clearances were too close, they were probably not sealing as completely as they should, and that could have been a big part of your compression problems? And they may have gotten a bit burnt, carboned up now!?

Then, after relapping them put "1" cam in, the intake, snug the bearing caps but don't actually fully torque them,(use lots of assembly lube!!!) then rotate the cam a few turns and check your clearances, then pull the cam, calculate your shim requirements and get your replacement shims, and then put them in, then replace the intake cam again, rotate a few turns, then recheck the clearances, should be good then, then pull the cam, and you're ready to reinstall.

Like Gary said, until an engine is broken in, it WILL burn oil until the rings are fully seated. A guy on the Yahoo list didn't take this into consideration when he did his big bore, ran it till it went dry, fried his new engine cause he didn't check his oil levels often. They usually recommend a single weight oil, like 30 weight, until the engine is broken in, then you can switch to your favorite multi-range oil. Castrol makes a single weight, too!

Once you have your engine together and torqued down, you can do a bench compression test just to see if they are close. I did on mine when I first rebuilt it....found 1 cylinder at 0....had bent a valve and didn't realize it, had to tear it back down and fix the valve, but because I hadn't fired up the engine, was able to reuse the head gasket.....per the high performance motorcycle machine shops recommendation!!

T.C. Big Bore veteran!

**Snow** · 08-30-2003, 07:15 PM

Well, I finally got the bike back together today...took alllllll day :/

But anyhew, being my first cam chain replacement and timing setting solo, I was very afraid that I would totaly screw something up. But I didn't, even got to test ride a couple times.

Compression is either 120 all the way across or 210 all the way across, depending on how ya do it. 210 is if I leave the other spark plugs attached and go WOT, 120 is if I just turn the starter over and no throttle.

I am going to throw new plugs in tommorow as the ones I ran were *severely* fouled.

**ratbyk** · 08-30-2003, 10:40 PM

Compression

If you are getting compression readings of 210 I would strongly suggest that you only put premium fuel in that bike. Also recheck your timing and make sure it is not advanced anything over stock settings.
With readings of 210 you are approaching 12 to 1 compression and will loose a piston or two or three to detination in a heart beat under WOT with any kind of load at lower RPM.
Todays fuel will not support that kind of compression ratio without the latest ECM available on the new motors.
Ken/Sooke
78E Ratbyk

**Snow** · 08-31-2003, 07:24 AM

I think I may have done the test wrong or something, should I just pull all of the plugs before doing the test and then use WOT? Is there a procedure listed in the clymers manual that I managed to miss?

After doing a seach on the forums, I found this quote from Sixtysix that confirms that I did it wrong this time:

According to the manual the compression test sould be done on a warmed up engine, throttle open, spark plugs removed. If the test was done that way then 145-155 is 'good compression'. I am not looking at the manual right now so this is from memory but I beleive that the allowable spead is 15% from highest to lowest. 15% of 155 is 23psi so I would say that you were OK. BUT I have known list members that have run their bikes at well over this 15% figure (me included) with no ill effects. I beleive that running an engine with a large compression spread gives it an unbalanced feeling and puts uneven stresses on certain engine bearings, so longevity would be compromised.

**TopCatGr58** · 08-31-2003, 09:14 AM

Hey there Snow,

Yeah, like you found, you should pull all the plugs, makes it easier for the starter to turn the motor, have WOT, and then run the test. After my rebuild with my Big Bore, I got 175-185 range after breakin. I run Premium exclusively due to the increased comps you get with those pistons. Congrats on getting all back together safely and running. Watch your plugs. I was also running 4-1 pipes and Indy filters, was running too lean even though there were no performance symptoms, the plugs were pristine white! Went up 3 jet sizes before started showing some color. Didn't want to run too lean and burn holes in my new pistons!!!! Enjoy!!!

T.C.

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