Simmy's Naked Turbo Project

I had a win tonight!
With a drill and a rotary file I was able to cut right through the rings.
Then I was able to get a chisel on the ends of the rings.
Then I pounded on it with a drift, pounded some more, some more then gave up.
Doused it in penetrant and planned to let it sit some more now that I exposed the rings.
Then I realized something. The piston had moved.


below is a photo I took a month ago. 2&3 are near TDC.
At least I'm moving ahead. Just need to continue soaking and pounding.
Maybe this motor really doesn't want to be part of my Frankenstein experiment.
Too bad, it owes me now just for attempting to bring it back.

 

this was my method of holding the block with one hand and hammering the piston with the other.
#2 fought until the end



I noticed I still hadn't drilled through the oil rings.
If I went further I might have broken the piston barrier and dropped shavings to the crank.
But if I had drilled through the last ring it should have come out easier.
I was very fortunate the rubber lining on the studs stayed mostly intact.
Sometimes those things jam up the removal of the block.

 

I degreased the lower cases - they were nasty.
Polished it with some detail spray and it looks great.
No need to paint under here.
I had the clean oil pan in a box of items I started before when I planned to use 900 cases.
I'm feeling good about this motor.
I ordered a head gasket for the 891 from UK and a base gasket from Italy
The Turbo has a really nice aluminum wafer base gasket but it doesn't fit the 891 sleeves.


Below are cylinder block heights I just measured in my garage.
The standard XJ650RJC block is the 1st measurement but the motor is still together so I couldn't get an accurate reading.
the Turbo, 853 and 891 measurements were taken directly from the blocks.

 

there is exactly half a mm difference between the blocks of a 650T and the 891

 

This is awesome information!!!
Now center of wrist pin to top of crown????

 

Here's a pic instead.
I measured the top edge of the wrist pin to the glass table and the measurement is virtually same for either piston.
The 68.5 has a longer skirt but that presents no issue.

 

This is what TDC looks like with the 891 block and piston installed on the 650 Turbo crank.
Sure looks like this 772 is going to work!
I need to find the old 853 head gasket and enlarge it to fit, can't wait for the correct one on order.
Then file the head to match the bore and I can take my fluid measurement, probably tomorrow.

 

I would measure it first, at least that gets you a good start datum. Then mod the head and measure again.
Good stuff.

 

I think you’re right. If I need to raise compression that extra material might be needed

 

I put the motor together with the 31A 67 mm head gasket just because I had one on hand.
The lip at the top from the smaller gasket is very subtle, I figured this would get me in the ball park for a measurement.
As @Minimutly suggested good to have baseline.
I measured the combustion chamber to be 33 cc's
The bore x stroke is 193 cc's
So CR = (193 +33)/ 33
this give a CR of only 6.84:1

Running the numbers for 32 cc's (some inaccuracy in my eyed-up fluid measure)
CR = (193 + 32)/ 32 = 7
CR 7:1

So pretty affirmative that I need to raise the compression.
Once I get the proper head gasket it will lower this number even more.

Currently the math shows I need to shave 1.6 to 1.7 mm from the head or the block to be in the 8.0:1 to 8.2:1

Obviously I need to redo this once I get the real head gasket.
This block was already .5 mm taller so once I have some machining done, overall the motor will be physically smaller by about 1 mm.
That's good, more room between the large Turbo petcock and #1 carb hat.

 

The T marking on the ignition rotor lined up perfectly with the pointer Yamaha install in there for aligning TDC.
The screws still had the paint from the factory so no one changed anything.
I verified this anyway with a dial indicator and my TDC tool which threads into the spark plug hole.





filled to the bottom of the spark plug threads, I used cooking oil from the kitchen

 

During the fluid measurement I took yesterday I couldn't be certain I was starting with 50 cc's of fluid.
I think I did but having a senior moment doubting myself, so I redid the test with more QC monitoring of the fluid used, LOL.
Still coming up with about 7:1 CR.
This is pretty astonishing that it's this close already.
The Kawasaki GPZ750 Turbo was only 7.8:1 -and a puny 738 cc's

 

new head gasket arrived.
I expect to get some time tonight I can measure the combustion chamber one more time.

how ever much needs to be machined I think it needs to come from the bottom of the cylinder block.
The problem with this is the barrels will need to be removed from the block.
Look below you can see that there is little room to skim the head without disturbing the intake valve seat.

and it can't come from the top side of the block because the YICS ports will be machined away.
They are only 1.49 mm deep. There is a brass orifice that shouldn't be machined.

 

Weather was perfect today for a Turbo blast through the countryside.

 

Are you totally wedded to keeping the yics? Skimming the top of the block is by far the best option, as you say too much off the head takes you close to the valve seats - maybe some off both? I don't know about xj blocks but the liners I removed from a vmax needed an adaptor to tie a hydraulic puller and some boiling water to free them - and they were not just push fit, they were finish machined flush afterwards.
Alternatively, if you must machine the bottom of the block a cnc mill should manage it with just surface marks on the liners?

 

Can you get in to the port with a small end mill?
How would you remove the cylinder sleeve?
Also if we can get good measurements I am a pattern maker and could absolutely model a mockup cylinder in autodesk and get you some cut files on powermill. If you have capable machines can mill bottom off block while the sleeves are in. I would be more then happy to send you a USB with it all free of charge

 

I didn't even think of that. Awesome

 

Removing liners is not something I will attempt at home, that's some ordeal you just described @Minimutly
I've watched a Millyard video where he threw a Kawi block on the propane barbecue and they fell out.
I have a performance bike shop real close. He does this sort of stuff all day long.
If he thinks the liners should come out then that's what we'll do.
My preference is to take it out of the bottom of the block, just seems the cleanest approach.
The base gasket surface finish is much less critical also.

There is a visible difference in the 650T and 891 blocks in the section below the last cooling fin.
The 650T block actually has more space here, strange because it's the shorter block.
Both blocks have 7 fins, that just dawned on me to verify that LOL.
I'll ask him to tap the hole for the anti-ping microphone to.
That's metric taper threads and Yamaha decided to slope the surface of this boss on the 891 casting.
The block needs to be clamped in a big drill press at an angle.
He does vapour blasting so we'll see what all that costs.
That will keep everything to just 1 modified part.

I want the YICS just so I'm not adding another variable to this.
It runs really nice now.
I'm doubtful YICS does anything while under boost but I think it helps cruising around.
The purpose of more displacement is to improve the off boost response.
The response under boost is crazy stuff already with 650cc.

It looks like the YICS port could be machined in deeper so the o-ring would still fit but I'm not sure how deep those brass orifices are.
As mentioned above I would not attempt cylinder liner removal at home.
The bike shop I have close builds race bikes, he used to list on his website pricing for re-sleeving.
He's set up with a hydraulic press and all the tricks. Full machine shop.
Thanks for the offer Phoenix, but I'm expecting I can drop the block off with Jim and have something ready to paint and install.

After this will be restoration of a 650 Turbo head.
I bought a head off eBay, all in perfect condition just missing the camshafts.
All the cam caps came complete with it. All studs good.
I will likely start with it, lap the valves and new stem seals.

I think now my biggest question mark is jetting.
The 650T has 127.5 and 132.5 main jets.
This will be a WAG as to what works best and safely
To start I need big main jets to make sure it's getting lots of fuel.
A lean mixture under all that pressure will melt those pistons pretty quick I would think,
and all that debris could end up down in the turbo.
There's always possibility this could richen things, who knows??

 

You might be right about the yics not doing much on boost, and as you say off boost is where you're trying to improve - which by the way you will, massively, since not only are you going up in torque courtesy of more cubes, but the turbo will be spinning up something like one third sooner due the the increased gasses coming through it. Win win I think.

Re the turbo head, if I was suspicous of anything holding you back it would be the exhaust ports - any chance you could put a hacksaw down one of them to see how much metal there is around the cross-section of the valve guide?
If it were mine I would have the die grinder in there, but I wouldn't like to do it without knowing...

Oh, good call re pulling the sleeves yourself, it's not a home shop job unless you have some decent machinery, I will be suprised if the block top surface doesn't need a lic with the flycutter.

 

Let me see about cutting my scrap head to give you a good look.