L.A.B. may know bore size decision to make

Put down the mic's, back away slowly from the cylinder.... :lol:

Ive been in the recon industry long enough now to smell bullshit, what arn't you telling us hobotsis, what size is stamped on the top of the pistons ,what size is on the box,

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Oh shoot lighten up, I'm don't enjoy asking for handling holding and not being difficult on purpose. New factoids are being found daily to both confuse and then resolve the dilemma. I applogize for entangling innocents with my fettering.

Simplified as I now understand what's going on - to confuse us all... Please I beg to be put down and called names, if it helps me learn by IDing my errors here.

1. Didn't expect much weird after mostly good operation for most a year.
When smoking developed to point of gasket blow by assumed that...
2. Trixie had been honed prior so ass-sumed too much bore removed on finding too big of ring gaps.
3. Taiwan .040" stamped pistons/ring set from Baxter's I ass-umed to be correct in all components, especially after most a year fine.
4. Initial clean up hone done by an exiting machinist, there fore no final bore measures to go by, so gritted teeth - put it together, then fooled smoke free most a year.
5. RH smoke free ring was the one Wes picked to check and find ~.025" gap, we only measured close enough to know it was over twice too much.
6. I just thought the other night to check compressed ring OD. I used same ring as in #5 as it was at hand off the piston, to find it 2.882", ie: on the smaller size of 40 over rings going by Ken's list. Still ass-umming correct parts sent, thought big gap must mean Trixie bores too big .
6. Got Trixie's barrel back with 2.910" bores, which later I learned here are .005" less than full .040" ID.
7. Rechecked RH ring but broke it last pm squeezing with fingers so no big deal a bad ring anyway, so got the L top smoker ring off and found small vice grips laying in my living room shop would hold it w/o skewed force to snap, To get new surprise with only 2.85x" OD. Huh?, Put in bore to measure its gap to find it half way between 0.025 and .026", ie: a slightly bigger gap than the RH ring.
The only thing that re-solved my dilemma is the accident of a broken ring handling so checked the other one. Is this my initial error to ass-umed both top rings are for same size over bore, ugh.
8. BINGO. Smoke and gasket failure on side of smallest OD ring, ie: wrong mix of top rings supplied.
9. Calculations say pistons clearance is .004" and just now found I could slide .004" and piston into bores with some resistance but piston jammed with .005" blade. So both calc's and direct measure agree, Trixies pistons and bores are fine.
10. DomiRacer has ring sets so no need to pester anyone on this further, will pick of the pieces on Trixie's 4.4th rebuild post where piston photo's are.

Good. It does sound like a new set of +.040" rings will solve your problem (we all hope!). Be sure and check the end gap. With a 2.910" bore, they should be a little tight out of the box.

Ken

Wes says he's sure his jugs are worn to an over size 40 over so asked Rich Stone near Baxter's cycle what rings to get, told DomiRacer and been essentially smokeless a couple years now. Implies a bit of file to fit in Trixies case, I hope. Manual says .010" top ring and .008" 2nd ring but I've read if 2nd gap is ~20-25% bigger it vents pressure between rings for better top ring sealing. Any thoughts on that in Norton?

Right finally cut through the crap,return the pistons and ask for a replacement set,they are incorrectly machined and not fit for the job they were intended for, who knows why they arn't the right size, they could have been droped , have the incorrect taper or cam machined on them, not worth the hassel, that said a +0.040 ring set should solve the issue. what brand are they?

Ole Splatt you will love this update, remembering you stuck you own noise in hobot fettering feces and its left me feeling like an old woman with hot flashes and mood swings. DomiRacer was a prompt delivery of rings for ~$30.

Ring gap at top of bore where rings reverse direction seated with an upside down piston crown:
light colored 1st ring = .010,
dark colored 2nd ring .012".
thickness .062"
closed OD 2.865" . . . . . . . huh !!!??? . . . . = BBISS "Blank Brit Iron Starting State", again.

How can these rings close up to smaller OD than the over gap rings yet give almost correct gap out the box. !!!???
Does not compute.
What is significance of the two differing surface colors, one appears gun blued dark the other lighter gray gun metal?
Ring stack in box had lighter ring on top of darker one on top of the oil set. Hot rod articles say current practice is make 2nd ring gap 20-25% larger than 1st ring to vent trapped pressure so top seals better. This implies lighter ring is top one?

Oh yeah, another weird thing, on initial install the wrist pins slipped in pistons w/o much force, so used that method to install pistons. They were pretty tight to back out a week ago even heated hot to touch by handy hair drier. I needed my wood dowel drift 'lightly' tapped on to move them with Wes backing up the impact off rod shells. If I ever took Trixie to red line it was by accidental instants only entering hwy with following traffic or such. Is it expected to get wrist pins tighter with normal operation? May install via wrist pin method again if Wes will come over or can talk wife into being extra hands for the rod rap back up.

Oven cleaner is working as I type. Under side of smoker L piston show light tea colored hint of oil burn while R piston is clean as day installed. R piston top only had carbon cake on ~1/3rd its crown while smoker L full coverage 1/16" thick.

Chrome top ring is it, never wasted my time to measure closed ring diameter, more than likely not even round, so what size is printed on the ring box,or have you had to gap them, as for 2nd ring gap don't get to carried away with all the crap you read, probably does make a difference but you will never notice it

Alas- no numbers on the box that directly relates to any measures, just hand written parts numbers. Wes remarked his set came in different boxes with a brand name, mine just plain yellar no names. Wes came over and reminded me these ring are Norton re-pro's and the manual had reference on which way to place the gaps while mentioning the second "tapered" ring. This would be the dark one with an inside edge camber we place upward. We found AE stamped on the lighter ring which only tonight it dawned on me was chrome, unpolished. We faced this ring AE side up. I attempted to measure the bores and got 2.912", ie: .002" more than machinist wrote and .003 less than full 40 over. Untouched top gap .010 and 2nd .012". Close enough for this shade tree, ie: 100% better than twice the prior gap out the boxes. Barrel used up my very last drop of hard squeezed Hylomar and is now snugged down to show a bead around to set up then nip till it hurts tomorrow am and finish up to ride most of Saturday, finally.

Wes is hot to trot over a museum well preserved '74 Triumph 750 with 40 miles showing on odometer. Has a sign for $3500, and told points ignition put back in after 'reversed battery blew the electronic one'. Told first/2nd kicker starter but then would not start it nor let Wes and told "come back Saturday - might be better". Attitude was strange as if bike was not really their interest and stifled any questions about it. So Wes is double piqued to keep pressing until its a go deal or obvious the funny business. Its in Eureka Springs a fabulous Victorian Alp's 1910 limestone fairly land and there's a Triumph rally going on so cool bikes and riders on top of the regular bunches. Rally is based at the Hub, a suburb of the real deal Lit'l Abner's Dog Patch USA.

Hope the dry rings seal up before I hit end of my drive way. They'll get a bit of pre seal on warm up with re-torque first though.

Seems strange that out of the box rings fit,sort of suggests your measuring is off. Ever stop to think, actually I don't think you do much of that,that he wrote the piston size on the box

Oh well splat it takes all kinds to make Norton's go around so doing the best i can with what I got. It helps my sanity to have Wes witness my funny business and thank goodness helps me know who to pay heed too. Anywho this current untouched ring set fits like the manual says so only hours before back in the flow exposing my self to strange women and wild does on a real Combat.

splatt said:

Seems strange that out of the box rings fit,sort of suggests your measuring is off. Ever stop to think, actually I don't think you do much of that,that he wrote the piston size on the box

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I have to say, measuring pistons and bores and such with a caliper is ok for general ID but for true sizing an inside mic for the bore is best and outside for pistons. A telescoping guage will to for bore but feel is still transfered.

pvisseriii said:

splatt said:

Seems strange that out of the box rings fit,sort of suggests your measuring is off. Ever stop to think, actually I don't think you do much of that,that he wrote the piston size on the box

Click to expand...

I have to say, measuring pistons and bores and such with a caliper is ok for general ID but for true sizing an inside mic for the bore is best and outside for pistons. A telescoping guage will to for bore but feel is still transfered.

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To many turners these days only use digital calipers, quick fast and approximatly accurate,I have always used an inside mic and measured off that with external mic, if forced to use tele gauges alway check 2 or 3 times

I told machinist I needed to closet .00x" bore measures and find he did within .002". Knife edge analog dial ID calipers is plenty accurate enough, IF, the bores are not worn barrel shaped and Trixie's were not. We started Trixie today and she did not even puff out smoke once, so rings sealed up dry before even full oil pressure hit. Stayed smokeless on a couple warms up of 100 yrd and back. Gives a Ripping Response sound on throttle blips now too. Did not get to ride off d/t delays of a newly sticking tickler flood and the air box boots about a year old fell apart and no way to get to civilization w/o crossing THE Sea of Grit. My fault of course for thinking I could enjoy Norton hobby like Charlie Brown getting the foot ball jerked away, again. A hidden decay tear was found in L air boot under side likely cause of the mild scoring seen. Last time air boots off was last fall before Texas trip, fine then.

Who Sir? ME Sir? No Sir! Its you sir who can't keep up with the flow. I'm told everything I eat turns to shit but so what I've an intact Combat again, see ya.

Have a good ride, Steve.

Thanks for the blessing pviss, I'm working up nerve to actually get beyond driveway and back. Done with the ring saga so story picks back up on last page here. Recent news of a fella going under semi wheels so Safe Journeys hobot
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Last update for anyone keeping track. Saturday night got smokeless oil tight wonder going a 100 yd and back and warmed enough for Sunday's re-torque then a start up for Blank Brit Iron Staring State ***** as much smoke and rough running as before the tear down !!!!????, hm, I'd knocked off a coil wire brushing off the oxidized head stains from oven cleaner a bad idea I'll not do again, ugh. Put wire back and had a wonderful ride up/dn Wes's Mt. road and his wilder creek bed steep drive way. Then headed out and side tripped to 82 yr couple who invited up to their son's new home site so followed them across gravel bed creek crossing that half way sunk me to meet their son on dirt bike, who took short cut up pasture slope so I followed but too slow on street tires to have traction so slowly spun out on LH side, then both of us plus locked front slide back 50 yd to gravel path. Had me a fling on to Mt dome pasture but too crated by gopher hole to go over 25 mph or keep butt in seat. Just needed a standard correct 40 over ring set to solve. Then a 50 mile joy ride on secondary no traffic twisties and home before dark and not once damn deer encounter.