A Good Ride Spoiled

I'm not sure getting a qualified person with appropriate measuring equipment to check the bore is going over the top.
It could be a simple case of, the bore is not perfect but good for another 30000 miles +.

Peace of mind is a fine thing and oddly enough, if someone knew no better and was told a very worn bore was fine for another 50000 miles, they would probably ride along on it with total confidence based on that.

The one good thing that could happen if Mike opts to redo the bores etc would be an average bore to ring seal next time around. This existing one was above way average when I sampled it.
Next time around chances are it won't be so damn tough to kick over!

I think I would put the funds toward an estart instead.


Glen

RoadScholar said:

Maybe. I was trying to convey the point, as gently as I could, that repairing any mechanical "system" is a balance of what you expect to get out of it. Installing a head gasket and new valve seals while addressing the valve stem to guide issue (possibly just trying the offending tight valve in the other guide) could be the best solution if the OP continues to watch the revs and the engine loading.

My experience with mechanical systems leads me to believe that half way fixes lead to half way results. I guess the word I'm dancing around is balance; similar to individuals that install high output charging systems and LED bulbs.

Up to the owner.

Best.

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Truth in that. Back in the 60s and 70s auto engines would start to get tired by 60 or 70 thousand miles. Sometimes a valve grind would be done to reinstate compression. The freshly sealed valves would be too much for the worn rings and blow by would increase dramatically along with oil consumption.
I don't think this motor is in that category.

Glen

After a light clean up the stiff Exh valve seemed to run in the guide much better.
It has almost no noticeable side to side or front to back play in the normal operating range. When I put the very end, above collet notch, in a drill chuck to rotate it seems to have a fair bit of wobble while others are nearly dead straight.
One Inlet valve has a lot of guide slop going on.
Took head to the shop recommended by local brit bike crowd FB group. They will evaluate and let me know.

PS: while out and about I went to four different auto supply shops and a Walmart today looking for blue shop towels. No luck. Seems they are now in hoarding mode ala t.p.

Further to Jim C's DIY thread repair testing video, I found this "Thread Repair Death Match":

Uh oh..... Gonna be some clogged sewers.

Tornado said:

After a light clean up the stiff Exh valve seemed to run in the guide much better.
It has almost no noticeable side to side or front to back play in the normal operating range. When I put the very end, above collet notch, in a drill chuck to rotate it seems to have a fair bit of wobble while others are nearly dead straight.
One Inlet valve has a lot of guide slop going on.
Took head to the shop recommended by local brit bike crowd FB group. They will evaluate and let me know.

PS: while out and about I went to four different auto supply shops and a Walmart today looking for blue shop towels. No luck. Seems they are now in hoarding mode ala t.p.

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Tread carefully taking that head to a machine shop
The 850 is not known for holding on to valve guides very well,cracks and loose guides are common
You need a shop that's done 850 heads before and know what's involved
Good luck with it
Cheers

I used to use those thread inserts years back and they were lifesavers.

Getting the head back this week (likely tomorrow. I actually had it back 10 days ago but they had not done the helicoil inserts for the three stud (mis-communication issue). So back it went. While I had home the new KB valves with bronze guides were extremely smooth moving. The shop did a 3 angle seat grind and bored/hones the guides and ground the stems to correct length. They stated the head did not require skimming. I fit the springs, seals, collets myself (insulators under EX springs only as per original setup).
Have received a flame ring HG and new rocker thrust washers/thackery washers.
Any tips on fitting the HG? A thread search shows lots of opinions on to coat or not.

I've fitted composite on both 750 and 850, and never needed any extra gunk.....
But, in the the words of Stephen Thingy: 'Keep Torqueing!!'

Tornado said:

Getting the head back this week (likely tomorrow. I actually had it back 10 days ago but they had not done the helicoil inserts for the three stud (mis-communication issue). So back it went. While I had home the new KB valves with bronze guides were extremely smooth moving. The shop did a 3 angle seat grind and bored/hones the guides and ground the stems to correct length. They stated the head did not require skimming. I fit the springs, seals, collets myself (insulators under EX springs only as per original setup).
Have received a flame ring HG and new rocker thrust washers/thackery washers.
Any tips on fitting the HG? A thread search shows lots of opinions on to coat or not.

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My understanding is that the flame ring gaskets are already coated, so coating them in something else is undoing this.

That said, Mick Hemmings coats them in Wellseal. And he’s probably done a few.

My method was to fit them clean and dry. By clean, I mean really clean, using gun cleaner or brake cleaner or similar.

The main thing to remember about using the flame ring gasket is to torque very frequently in the first few hundred miles. Lots posted about this already. It is amazing how much that gasket crushes. Fail to do this and a blown gasket is highly likely.

With a flame ring gasket, if things are flat, clean and correctly torqued, it will NOT leak.

A couple of tricks I have stolen with pride are to over torque a little on initial assembly, and to set the tappets loose (only during this constant re-torquing period), so you can nip the fasteners up without having to re set the tappets each time.

When I fit the springs to valves, I noted valves had oil on surfaces. I added some light machine oil to springs/seats etc. Any concerns about the guide & stem wear during "break in"?

Tornado said:

When I fit the springs to valves, I noted valves had oil on surfaces. I added some light machine oil to springs/seats etc. Any concerns about the guide & stem wear during "break in"?

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Marvel Mystery Oil in the tank for the first 500 miles. It's intended to be a top cylinder lubricant. Works for me.

maylar said:

Marvel Mystery Oil in the tank for the first 500 miles. It's intended to be a top cylinder lubricant. Works for me.

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Kibblewhite valve seals... and a few drops of quality 2- stoke oil every fill up.

For the newly helicoiled head studs, should I be using locktite to help keep them in place in head? Stainless helicoil and automotive grade 5 steel studs (3/8"-16 head side).
What about antiseize on fastner side to help keep them viable longer term?

IMHO no loctite on the helicoil end.

Anti seize on the nut end, I would definitely do.

Well, bike has been sat in the parkade since first week of October. Today I finally completed the re-install of all ancillaries (fresh oil & filter, DT headsteady & spring, single carb, tank, coils, grounds etc.) Gave it fresh 5L of gas (that's over half of the 9L HiRider tank capacity). I'd done a cold compression test a few nights ago...noted engine was much harder to kick over compression than previously, or maybe my leg was no longer in shape for it! Well left side I could manage 130psi, but when trying the right side, was having so much trouble kicking over with bike wanting to flop over (it was being supported by front wheel choke setup and didn't want ot remove it, place on center stand for this quickie test). Only manged a few good kicks giving 90 psi before I was spent. Not convinced this is max compression. So back to today: A few contact off pre-kicks after tickle to prime charge, followed by one mighty contact on kick, she fired right up and kept running, sounding really sweet. No smoking. Oil returning, bit of seep from one rocker oil line fitting, a few fuel drips off the carb bowl. Let it run only 2-3 minutes to shut down and prepare for first re-torque of head.

Inspecting the #1 center front headbolt access, doesn't seem possible to get on it with my torque wrench with the new suspensory spring setup...a major pain to unwind the tension and remove the head plates etc. Are there any short cuts folks have thought of?

Took about 2+ hrs to remove spring thingie bracket, coil, tank and do the re-torque. Got all buttoned up, tires checked (still where I last had them back in Oct), cleaned/lubed chain.
Got her fired up, again first kick after tickle. Idling pretty nice. Got suited up and took her out for first ride since Oct. Stopped after few blocks to look everything over, all seemed fine, some smoke off the head, no obvious signs of leaks so put that down to head oil film burning off. More around town riding, good power pick up, consistent sounding from pipes. Some short hills went up great. Feels more responsive than last ride. Took her to around 5k rpm briefly and felt/sounded great. Head smoke seems to have cleared. Parked up at a coffee place and found no leaks after close to an hour. First kick restart and headed home.
Will change gearbox oil and oil the SA, grease the speedo drive before further, longer test rides.

Congrats on gettingbit sorted and back on the road.

Changed out GB oil today. It was about two yrs in there, Redline 80W Shockproof, green. Put in a fresh 420ml of remaining amount in my one litre bottle. No obvious "gold" sparkles in the old stuff, but it is quite opaque. Noticeably darker than fresh.
Also pumped a bit of STP oil treatment honey into swing are zerk. Been using this since SA rebuild three yrs back. Seems like a reasonable compromise to engine oil which leaks out faster and grease which my bike had when I acquired it.

Also ga ve speedo drive some moly grease from a gun. Previously had used a marine grade bearing grease and it is a stiffer stuff than moly. Hoping moly with help get speedo needle more stable.
While doing this for first time with a proper grease gun, I found I could not release the fitting from the zerk when done. Tried all manner of angles and lever until it pulled zerk out of drive body! Still had to struggle at bench using a vice get it out of the gun end. Got it to seat back from where it came but if it disappears will have to use a bigger size I guess.
I used to use a push type hand pump which doesn't clip to the zerk. Will have go back to that if this is normal for grease gun fittings.