Pulling head on YZF750---

Post by **FZRDude** » Sat Jul 29, 2006 11:57 am

Thanks go to dfrois for the articles...

exupturbo · Post by **exupturbo** » Sun Jul 30, 2006 5:41 am

Good articals but there are more on the subject, the front cover of the magazine I mentioned had a YZF750 and a FZR750 on the front cover both wheelying next to each other and I think the riders were touching crash helmets whilst on the back wheel. The YZF had a 1000cc conversion and the FZR had the 911, the test riders prefered the 911 engine. I through away all my bike and car mags when I moved house

Mark

dfrois · Post by **dfrois** » Sun Jul 30, 2006 9:23 am

No thanks needed. I learned a lot when lurking around here before rebuilding the 400, so It's only fair that I try to give something back. As for the YZF/FZR mag, I am REALLY sorry I don't have that one...should be a good read!

I`ll send the other ones today or tomorrow if I can.

DF

KontoBoy · Post by **KontoBoy** » Thu Aug 03, 2006 4:32 pm

Interesteing reads. I'll have to figure out how to translate the French.

I didn't know why I didn't think of it earlier but we have a great library in town that might have the article--Library of Congress. When I get back in town I'll check it out.

Kontoboy

P.S. I found a road that will give Deal's Gap a run--55 miles and over 600 curves. A little inaccesible and lots of traffic though. Hana Highway.

instigator · Post by **instigator** » Tue Aug 22, 2006 6:39 am

Hi Kontoboy.

Don't want to start a new topic but a quick question - When taking the head off the yzf750, did you have any trouble taking it off once the head bolts were taken out? I've taken the head bolts out and cam shafts but the thing is still sticking on some how. It wiggles in place and lifts up a small part but obviously something is catching.

The part that the cam lobe on the cam shaft pushed down upon. Those silver bucket type covers - are they supposed to come off? All of them? I can't see anything else that is casusing an obstruction.

KontoBoy · Post by **KontoBoy** » Tue Aug 22, 2006 11:25 am

Sorry I've been a stranger here--I was on vacation a couple weeks, and last week got my daughter off to school and went to the AMA races at VIR. I'll get back to work on the bike very soon.

You did take the intake manifolds off and the coolant tubes/thermostat housing off didn't you? As I recall there are a couple bolts on the coolant tubes that go into the case.

After I removed the cams and head bolts I just rapped it with a rubber mallet a bit to break the gasket seal, and then it pulled right off. Make sure all the head nuts are off--they tend to stay in their sockets and feel loose but aren't off completely.

As I recall there are also several collars in place between the head and cylinder block that may cause it to stick.

The buckets stays in place--no need to remove them unless you are doing valve work.

Kontoboy

Post by **FZRDude** » Tue Aug 22, 2006 11:26 am

Instigator,

Those silver buckets hold the shims in place, DO NOT take them out/off until you are ready/need to.

instigator · Post by **instigator** » Tue Aug 22, 2006 11:52 am

Hadn't taken the buckets out but it was my only idea that was making the head stay in place. The intake manifolds, no, but then they aren't attached to the cylinder head so I can't see how they would stop the cylinder head coming off.

The cylinder head will rise about 0.8cm but then stop abruptly. All bolts and what not have been taken out so I don't know whats stopping it from coming out. I will assume it is these collars that you speak of Konto - will try again tonight and let you know how I get on.

Cheers

creed12r · Post by **creed12r** » Tue Aug 22, 2006 12:13 pm

Sometimes the cylinder head nuts (the captive ones under thecams) feel like they are fully loosened but, they are still attached by a couple of threads, first check they are all fully undone then, lift the head up as far as it will go,

The gasket may be stuck to the head and the barrels, stopping it from lifting.

The head bolts may be slightly splayed out and catching the threads as you lift it.

Lastly the cam chain tensioner guide catches on the inside of the head as you lift it, you need to push the guide away through the tensioner hole as you lift it.

Chris

instigator · Post by **instigator** » Tue Aug 22, 2006 2:53 pm

Hi

I'm not sure on all of the terminology used to do with top ends (or bottom ends for that matter!) but here are two pictures I've just taken:

Inlets are taken off as per picture. What have to be taken off exactly? I'm a bit puzzled as to why it's not coming off. (the gap between the two and the gasket you see - they are supposed to come off just like that, yes? I.e seperate fairly easily?)

Creed - Cylinder head nuts are fully loosened and removed (the ones with allen key fixing) Gasket is not stuck, moves arounf freely now. Head bolts? The cam chain tensioner, not sure how that would catch on anything really but it doesn't seem to get in the way as we try and lift it off.

Clues?

instigator · Post by **instigator** » Tue Aug 22, 2006 2:55 pm

If the bolts on the frame have to be removed, then surely the engine will drop?

As for the large nut in the 2nd picture, closest to the camera (there is 4 of them, 2 on each side). Do they have to be released? I have released 3 of them but access is very tight and to be honest, not sure how you can undo the 4th without dropping the engine!

ExupElvis · Post by **ExupElvis** » Tue Aug 22, 2006 3:05 pm

Dood! That's the wrong piece!
Your trying to pull the tappet/cam carrier with the cylinder head still in place - that doesn't work!
The oily exposed accorn nut in the bottom corner of the pic is one of the cylinder head nuts.
There's 4 of those (one at each corner), and eight more below the cam main journals that will need a long 6mm allen wrench to get at.
You will be able to see the four along side the cam chain cavity if you look in at an angle - carefully.
Stop with the cam box removal though, that can cause damage to the valve stems if it's horsed around as it sits now.

instigator · Post by **instigator** » Tue Aug 22, 2006 4:01 pm

So the engine DOES need dropped then....grrr....see, I figured this but the bloody service manual didn't really specify it.

3 of the 4 main nuts round the side have been released but the last can't be done anyway so engine has to be dropped for that.

ExupElvis · Post by **ExupElvis** » Tue Aug 22, 2006 4:23 pm

I've heard the cylinder head can be removed without dropping the engine - re-installing may be a different matter altogether.
I've never tried to do it that way.
Depending on which manual your working out of - yes some of them are very poorly writen, including the factory book IMHO. (The cylinder head re-torque pattern is in there, but it's very easy to confuse it with the cam main cap pattern {which is different}, and same with the torque specs).
Much easier to drop the engine for that job, and not much more work either.
Good luck with that, it's the stuff we all learn at some point or another.

creed12r · Post by **creed12r** » Tue Aug 22, 2006 11:42 pm

LOL, best of luck.

Chris

exupturbo · Post by **exupturbo** » Wed Aug 23, 2006 5:00 pm

You can get the head and barrels off with the engine in the bike but it is a pain in the A**, the part you have undone is the cam carrier and will NOT come off without removing all the valves and springs. To get the head and barrels off you will have to undo and remove all the engine mounting bolts apart from the lower rear one as well as unhooking the chain whilst supporting the engine with a trolley jack, now you can drop the front of the engine in the frame and remove the head and barrels. To be honest it is a LOT eaiser just to pull the whole lot out and work on the engine on the work bench

Mark

KontoBoy · Post by **KontoBoy** » Wed Aug 30, 2006 10:26 pm

I finally got the YZF1000 head last week. Time to get back into it.

I took the lead from Mark and measured the 750's compression chamber with oil and a syringe.

Here's What I got.

Top of piston to top of block. 4.5cc
Cylinder head: 13.5cc
Stock gasket: .0035 in

Using the Bowling and Grippo calculator

http://www.bgsoflex.com/auto.html

I get a compression ratio of 11.0:1. OK, it not the 11.5 factory spec but close.

Keeping the same 13.5 cc head volume, same thickness but 77mm gasket, and 77mm 1040 bore with the 750's 46mm stroke, I get a compression ratio of 12.2. A little high, but not too bad.

Now add a base gasket or two to raise the deck and drop the compression ratio. A .0035 increase drops compression .2 cc to 12.0. Or just leave an some extra on the cylinder block.

But that's a problem. The YZF 750 block is 8.1 cm high, the 1000 block 9.7.

I can't take enough off the 1000 block without taking away the gasket mating surfaces and cutting into the cam tensioner opening.

Crommie's post was right on. You just can't cut enough to get the compression ratio where it needs to be.

That leave's resleeving and boring the 750 block. I'll check into it but there may be structural issues here too. The 1000 block has some extra material around the sleeve, and the YZF sleeves have a relief cut into them not present on the 1000.

I looked at sleeves last month and they were running $70-80 each (x4) plus installation, no longer a cheap option.

I did email Dutchman Racing regarding a big bore kit they advertise. No one's home, no phone listed. Guess they don't need the business.

So right now I plan on slapping a new head gasket on and putting it back together. The ring gaps are still in spec, and since it's not burning oil I'm going to leave the valve seals alone to. I suspect I'll be in there again sometime, but I may still make it back to the track this year if I take a minimalist approach.

Damn, and I was getting excited.

Kontoboy

P.S. Anyone want a 1000 cylinder block? It needs a .5 bore. $100 plus shipping (what I paid).

ExupElvis · Post by **ExupElvis** » Fri Sep 01, 2006 12:01 am

Konto - how did you account for the piston dome volume?
I think I might be seeing a small problem in the first pic. ????

KontoBoy · Post by **KontoBoy** » Fri Sep 01, 2006 1:45 pm

Piston dome--damn it didn't occur to me until you mentioned it. I need to subtract out the volume of the piston dome that protrudes from the oil.

Maybe that is where I lost that .5 in compression.

I guess I could leave the oil in, drop the pistion a known height into the cylinder, then add measured oil until the dome is covered. Then calculate the volume it should have taken to fill the added depth if the dome wasn't there, subtract with the amount of oil I actually added to determine the dome volume. That then gets subtracted it from my previous CC calculation.

That's a lot of work, and unfortunately I don't see how it could change the deck height enough to use the YZF1000 block.

Kontoboy

ExupElvis · Post by **ExupElvis** » Fri Sep 01, 2006 2:41 pm

I agree on the cc calculation approach you mentioned - It's one i've used as well.......I was going to offer that same proceedure but then thought maybe I ought to ask first........
And no, it won't make much difference if the major castings don't fit well together.

That mixing and matching of different engine parts can get pretty tricky, but it can offer an education too.
Just a painfull one.
Good Luck on that.

EXUP Worldwide

Pulling head on YZF750---

taking head off

cam case