I stepped in it - XS750/896 build

Frenchtom

New Member
Hi Doc and thanks so much for posting this, its the exact kind of info I am looking for and the kind of work I am interested in trying.
Tom
 

Frenchtom

New Member
Its been a while but i have some more progress. I got the engine case split and the crank removed. It was not as bad as I thought but was not exactly easy either. The engine was had a fair share of crud, rust and water which I plan to thoroughly clean out. One of the crank journals had some shiny spots on it that I need to inspect closer for any damage, the rest were fine. I have not pulled the rods yet but will do that on the next update. You can see in one of the pictures all of the silicone paste that was squeezed into the engine and trapped within the oil pump pickup. I am going to test the crank for balance and see how close to perfect I can get it if its not already there.
Tom
 

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datadavid

Over 1,000 Posts
Those lines on the bearing surface are 100% caused by metal debris. I would take it to a good machinist for an expert opinion. Might stay good for the engines lifespan, might be close to failure. Hard to tell without micrometers..
 

der_nanno

Faster!
By far not a good machinist (at least not in my own opinion), but the big question is: can you feel them with your fingernail? If yes: buggered.
 

datadavid

Over 1,000 Posts
der_nanno said:
By far not a good machinist (at least not in my own opinion), but the big question is: can you feel them with your fingernail? If yes: buggered.
Thats right, any scoring and you will need regrinding. Problem with these engines is bearing shells dont come in oversizes, instead there are five sets of thicker and thinner shells in very small increments(cant recall exActly how small) but if you are lucky and crank is ground on the large side it may be possible to grind down to fit the thickest bearing shells.
Other expensive options are one-off bearing shells or plasma spraying the journal.
 

der_nanno

Faster!
A good engine refurbishing shop, should know (or have a list with dimensions) of automotive bearing shells to be converted for use on a Triple. For example from personal experience I know that Ford Cologne bearing shells can be shortened a bit and then used as oversize shells on Dnepr cranks...
 

datadavid

Over 1,000 Posts
I have a spare crank and bearing shell kit, even easier..!
der_nanno said:
A good engine refurbishing shop, should know (or have a list with dimensions) of automotive bearing shells to be converted for use on a Triple. For example from personal experience I know that Ford Cologne bearing shells can be shortened a bit and then used as oversize shells on Dnepr cranks...
 

Frenchtom

New Member
A little more progress. I got the engine stripped down quite a bit further and cleaned everything twice. I'll hit it all a third time with some disc brake cleaner. I also got the pistons and connecting rods balanced to within a half gram of each other.

I took a closer look at my crank and the scored journal. The mating bearing surface has scoring as well so I will pull the crank from my spare engine and see which one is on the best condition. If its the second crank I will be sure to pull the bearings and transfer them to the new engine. If not I'll see how much machining the first crank needs. When I put everything together I will use plasti-gauge and make sure the clearances are correct and buy new bearings accordingly.
Tom
 

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datadavid

Over 1,000 Posts
If you have the same numbers between bearing and crank on both engines bearings should be the same tolerances. I have a main bearing set where i used the black bearing set iirc, could sell you some if need be.

Skickat från min Pixel via Tapatalk
 

Frenchtom

New Member
So a bit of an update ... I got all of the old gasket material removed from all of the case surfaces and polished them up in good shape. I still need to pull the crank from my spare engine to see if it is better than my old crank. The next big thing will be blasting everything with disc brake cleaner and then picking a color for the engine paint.
Tom
 

Frenchtom

New Member
Hi Guys - I used to read old messages from folks who would go months or years between updates and think to myself - wow, those guys are unmotivated. I am now typing one year after my last update with no progress in between. That is what life with young kids, old parents and career changes will do to you. :)

I have two engines for my bike and I am trying to open up the second engine in order to remove the crank. The problem is a 33mm nut holding the clutch plate basket to the main transmission shaft. The nut is deep in side the clutch basket and there is a 3 - 1/2" long shaft sticking out through the nut. I tried using something called a plumbers socket or a faucet socket (can't remember the name) but the nut is too much for the socket to handle. The socket keeps deforming and sliding off of the nut. These sockets are nothing more than cheap sheet metal rolled into a hex shape so I am not surprised. I have tried hitting the nut with a combination of PB blaster and a propane torch but she won't budge. I can only think of two options - figure out a way to grind off/crack the nut or cut off/shorten the shaft so that a conventional socket will fit. I really do not want to ruin the shaft but I may have no choice. Any other ideas out there?
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teazer

Over 10,000 Posts
DTT BOTM WINNER
how about taking a regular socket or even better one designed for an impact wrench. Open up the center so it can slide over that shaft and weld on a nice long lever so you have a sort of deep well rind spanner.

Or buy a suitable ring spanner but I don't know if that would be deep enough.

Or get an air chisel and chisel the nut off. (sounds crude but if you are careful, the cost is one lost retaining nut)

Or smash/cut the clutch hub away and use a normal wrench. (not my favorite)
 

Frenchtom

New Member
Those are great ideas. I do have some impact sockets that I could sacrifice for the cause but I do not have a welding machine nor do I know how to weld. I tried a bit of the air chisel idea but its pretty hard keeping the chisel centered on the nut. It jumps and skips around so much I end up boogering the shaft threads.

I am leaning towards welding up an impact wrench or cutting the shaft back so that a conventional socket wrench will fit.

Thanks for the ideas!
 

Frenchtom

New Member
So I cut the shaft and got that nut removed. That allowed me to split the cases and check out the second crank. It looks like the second crank is in better shape than the crank that was in the first engine so it looks like I can avoid a machine shop visit to dress the first crank.

The next phase is some serious clean up and painting. Once that is over with I can start the re-assembly process.

It feels good being close to going in the assembly direction!
 

Frenchtom

New Member
Got all three connecting rod journals plasti-gauged and they all passed. The attached showed the smooshed out strip on conrod #3. I'll move on the gauging the crank journals over the next few days.
 

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Frenchtom

New Member
I plastigauged the main journal bearings with real good results. They all came in at 0.002" which is right in the middle of the 0.001" - 0.003" specification. I need to replace one journal bearing and one rod bearing so I will be surfing EBay this weekend.
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Frenchtom

New Member
So I am trying to figure out what connecting rod bearing size I need to order but cannot figure it out. My Haynes manual says to subtract a number stamped on the crank from a number stamped on the connecting rod. My Connecting rod is stamped 4 and the crank is stamped 2. The difference is the bearing size that I need which in my case is a #2.

The part number sold online is listed as 1J7-11656-XX or 2F3-11656-XX where XX is anything from 00 to 40. Does anyone know how to correlate the #2 calculated bearing size with the correct part number?

Thanks!
 

Frenchtom

New Member
If ever there was a reason to check a prior owner's project work, here is a textbook example. This is the upper half of my engine case where I have partially removed a crank bearing. The bearing in this location is supposed to be a thrust bearing but the prior owner used a conventional bearing. You can see where the crank rubbed the engine case from too much axial play.

I kept seeing "thrust bearing" referenced in my Clymer's manual and in an online shop manual I found. I finally double checked the engine and it had no thrust bearing installed. I even went so far as to dig through the various parts buckets I have and found no sign of the OEM version. I almost put the engine back together with the wrong bearing but seeing "thrust bearing" referenced over and over again kept nagging at me. Glad I took the extra effort to confirm what my gut was trying to tell me.
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Frenchtom

New Member
More progress - Got the cylinders painted and cleaned the head up real nice. I found some neat wire brushes on Amazon that fit rotary tools. When you spin them up the wires spread out and clean between the fins really well. One concern I have is that the manual states a 0.008" - 0.016" ring end gap and mine are measuring all at 0.014" or right near the upper limit. The manual specification is for a 750 cc engine but I have the 896 big bore kit. Would the end gaps have to be bigger on a larger diameter piston?
 

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