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1955 T110 Cylinder Bore Question
#787089 10/15/19 1:10 am
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I have inspected the bores of my 1955 T110 iron head motor and found them to still be on their original bore, 2.795 at the bottom and 2.797 at the top. There is light scoring and a small area of corrosion that did not clean up with a few light passes of the ball hone.

My goal is to have a great running motor. Cost savings is a factor, but when it comes to expense I will err on the side of doing it right.

From what I have read the bores are still technically in spec since they are not worn .005 over the standard bore which I believe was 2.7948.

Therefore the following questions;

Is there a compelling reason to overbore? Or perhaps Sunnen hone to take out the.002 taper and maintain std. bore? Or leave as is with more ball honing?

If an overbore is the best route;

Is there any source for .010 over iron head 8.5 comp pistons? Or something close?

Or am I locked into going .020 over? if going this route what pistons would you recommend?

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Dave Swanson
1955 T110
1962 TR6SS
1965 Spitfire Hornet
1967 Bonneville
1974 Norton Commando
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Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787090 10/15/19 1:25 am
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If it was my bike, it would get .020 overbore. I personally run my pistons at 3.5 thou clearance for a quiet motor. (not recommended for those who thrash a bike during break-in)
I think Harris has pistons for it in standard CR. A lot of folks just use unit pistons and get somewhere around 7 to 1 CR maybe a little more.
Alternatively, you could look for genuine pistons from Triumph. Chances are that if you find some, they will be standard bore as all the over-sized pistons have been used up long ago.
I think the T110's run just fine with the standard CR which I think is 8.5 to 1.
If you go with the standard bore and the clearance is 6 thou or more, it's not the end of the world. You will likely have some piston slap on a cold morning, otherwise it will run OK.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787104 10/15/19 5:57 am
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First impressions to me are to bore it to quit the pock marks, but I’d want to source the pistons first,

If I couldn’t get pistons at a sensible price I’d re-ring it and keep bolting it back together. New rings, bearings, guides or what have you will still give a good motor.

Depends on how you intend to use it. It’s done 65 years on standard bore. How much work are you asking it to do?

Leaving it standard on new rings avoids some break in teething problems. You might get a bit of blow by because of the bore but that’s not a biggie. The bore in my side valve BSA is worse than that but it gets little use.


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787110 10/15/19 10:29 am
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Thank you for the replies. It will be ridden, and not abused. I would imagine the annual mileage being 500 to 1000 per year when finished. I may hone it a bit and see how it runs on the standard bore.

Last edited by Dave Swanson; 10/15/19 10:57 am.

Dave Swanson
1955 T110
1962 TR6SS
1965 Spitfire Hornet
1967 Bonneville
1974 Norton Commando
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787115 10/15/19 11:20 am
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Straighten up the bores and see what clearance you have, if its under .006 with nice straight bores, Send the pistons to Line 2 Line Coatings and have them coat the skirt,
.0025. we have done this sucessfully for years on BMWS where pistons are 500+ a set. we coat the pistons in the race engines also, and have not seen the coating come off at all..
If your bores will straighten up this will work great.

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787140 10/15/19 6:43 pm
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I've been waiting for someone to install Teflon piston skirt buttons to quiet up a noisy motor here. No joy yet.....
The last time I found a set of NOS Triumph pistons, it was from British Only, who, unfortunately, is on a sabbatical at the moment. They are cast E3000, are the stock piston for iron head T110. BTW you do understand that pistons for the alloy head T110 are a different piston....
A casual search yesterday netted no results for standard piston for iron head T110 from Harris. I did scare up the T-bird pistons but not the E3000 type.
You just might give up and use the unit pistons in the end, like I did and so many others. TT says the CR on his bike is 8:1 with them and that's ideal. Further good news is that they're cheap and plentiful.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787141 10/15/19 7:01 pm
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After what could be called an engine fire(!) a couple of years ago, I now have Thunderbird 7:1 pistons in my iron headed T110, because I couldn’t find 8.5:1 type and I thought I’d experiment with something other than the late Unit 9:1 pistons I had been using.

I should have made better notes (or any notes) but I think I measured 7.9:1 with the 1970 Bonneville pistons, using a measuring jug. Then more recently, I reckoned it was 7.5:1 after I bought a big syringe and measured oil with that. The difference could also have been down to rebores and differences between German and Taiwanese pistons.

I suspect the bike runs slightly better with Thunderbird pistons than with ones meant for the alloy head, but it’s hard to tell.


Amateur Loctite enthusiast.
Re: 1955 T110 Cylinder Bore Question
HawaiianTiger #787142 10/15/19 7:08 pm
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Originally Posted by HawaiianTiger
You just might give up and use the unit pistons in the end, like I did and so many others. TT says the CR on his bike is 8:1 with them and that's ideal. Further good news is that they're cheap and plentiful.
Cheers,
Bill


Bill, Triton Thrasher, would you happen to have the piston part number for that, 15897?


Dave Swanson
1955 T110
1962 TR6SS
1965 Spitfire Hornet
1967 Bonneville
1974 Norton Commando
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787154 10/15/19 9:01 pm
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Lower compression ratio means you can burn lousy or low-octane gas.
It works great if you don't want to try racing the bike.

For street use it's OK and the bike will still cruise at 65 MPH, and at a lower cylinder and head heat range.

Early T110s were rated at 8:1 compression and they were certainly fast enough.

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787158 10/15/19 9:47 pm
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It’ll cruise at 90 mph with the 7:1 pistons, if you can hang on and avoid the cops.

Racing is racing. You make the fastest bike you can, within the formula. Then you lose races, destroy bikes and go broke.


Amateur Loctite enthusiast.
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787179 10/16/19 12:52 am
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You HAVE raced, Thrasher.
Truer words were never spoken.

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787181 10/16/19 1:40 am
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These are on eBay right now. They look like standard pistons for iron head T110 to me. They have E3000 cast in the pic and are +.010.
ebay pistons
You just have to find rings to fit.
If you don't buy them, I will.
Cheers,
Bill

Last edited by HawaiianTiger; 10/16/19 1:41 am.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 1955 T110 Cylinder Bore Question
HawaiianTiger #787185 10/16/19 2:25 am
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Originally Posted by HawaiianTiger
These are on eBay right now. They look like standard pistons for iron head T110 to me. They have E3000 cast in the pic and are +.010.
ebay pistons
You just have to find rings to fit.
If you don't buy them, I will.
Cheers,
Bill

Snagged them! Thanks for the link Bill. I am almost certain my barrels will clean up for .010 pistons. And these are the real deal too!

Last edited by Dave Swanson; 10/16/19 5:39 pm.

Dave Swanson
1955 T110
1962 TR6SS
1965 Spitfire Hornet
1967 Bonneville
1974 Norton Commando
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787197 10/16/19 4:45 am
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HI Dave, I think you know what you need to do...

Yes you can hone it & it will run. It will be at the wear limit by time the bores are cleaned. But you say you want to actually ride it & have fun.

In the long run wouldn't it be just as well to do .020 over & be done with it. It will last you a good 30+k miles.

I know higher compression often seems desirable. But for it to work you need very special type motor build & in every case you need octane to get the advantages of higher compression.

I can't see where you'd go wrong with LF Harris 7.1 Iron head pistons. The bikes just run so well with them. Start easier. Idle a little better. You won't notice power loss. It Will run 65-70 mph effortlessly hour after hour even 110+f heat. We've crossed 8000' passes with them at 70 mph. 2 up, no problem. Actually better as they never want to ping no matter how hot or steep the hill. Also don't do that little ping on take off in very hot weather.

Maybe flat out you'll not have as much power, but in real riding just for fun you'll love it. I've been involved with 6 motors now lower compression. Not one person Ive ever heard of has regretted it. I'd still use premium fuel though. Also top tier USA fuels have "detergents" that reduce carbon build up. After several years, I've confirmed this to be absolutely true. In California Shell & Chevron have proven best.

If in very remote areas like we ride in occasionally you can only get 87 or diesel. A killer for most Triumphs.

Even the later 650 units run really well with 7.1. T140 7.4 as that's the lowest they make. We swap bikes among us. The ones that don't know it remark how well the bikes run. They are shocked.
Don


1973 Tiger 750
Re: 1955 T110 Cylinder Bore Question
TR7RVMan #787230 10/16/19 1:01 pm
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Don, yes I see the LF Harris T110 7.1 .020 pistons are available. They sound like a good option.


Dave Swanson
1955 T110
1962 TR6SS
1965 Spitfire Hornet
1967 Bonneville
1974 Norton Commando
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787244 10/16/19 6:52 pm
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I built a '55 T110 in the 90's with these pistons. I also upped the size of the valves slightly, used the stock cam and ran a 389 carb. It would run with Bonnies all day long.
What really impressed me about this bike was it's docility around town. Another thing I remember fondly about this bike was the ride. I did not upgrade to lipped seal holders on this one and used the original style felt wipers instead. The fork was so responsive over small bumps it was definitely a Cadillac ride.
This was in California where we were the lab rats for alcohol fuel at the time. It gave me fits trying to read plugs.....and bikes tended to run rich on stock settings.
Back then I had started to harden the combustion chambers on my bikes in order to continue running stock timing. It works great. Polish everything inside the combustion chamber that could act like a glow plug and cause pre-ignition, including the spark plugs.
Cheers,
Bill
PS Those pistons were a steal. They would have been over 300$ from BO.
B.

Last edited by HawaiianTiger; 10/16/19 9:23 pm.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 1955 T110 Cylinder Bore Question
triton thrasher #787267 10/16/19 11:42 pm
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Originally Posted by triton thrasher
It’ll cruise at 90 mph with the 7:1 pistons, if you can hang on and avoid the cops.

Racing is racing. You make the fastest bike you can, within the formula. Then you lose races, destroy bikes and go broke.




How very true old chap.

Re: 1955 T110 Cylinder Bore Question
HawaiianTiger #787273 10/17/19 12:24 am
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Originally Posted by HawaiianTiger

PS Those pistons were a steal. They would have been over 300$ from BO.
B.



Seconded ! That was a steal !


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project
1971 BSA A65 650 - Project
1972 Norton Commando 750 "Combat"


"Every time I listen to AC/DC, so do my neighbors"

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787428 10/18/19 7:21 pm
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Dave
I was surprised to see how many responses you received to you question on whether to re-bore your T110.
I have been doing my own machine work on British bikes for myself and customers for many years now.
I personally would never go back together with cylinder walls that looked like yours or with that much wear and taper.
I would question some of the information you have received so far.
Piston clearance really should be at .0045, preferably with less than .0002 (2/10th of one thousand) taper (not all bore jobs are top notch because the machinist is in a hurry).
Your iron head engine will run a little hotter and unless you're battling modern emissions controls, you're better of with a tad more clearance than less.
Someone suggested what I assume are polymer coatings. These are great and highly recommended, but they do not take up clearance to compensate for wear.
Their primary function is to impregnate the metal as I understand it, not act like a lubricant. The excess coating will wear off fairly fast after running in.
Further if your bores were spot on with no wear, you'd still need to both those cylinders because of the pitting and scratches on the walls. How can rings seal properly with those bores?
The pistons sold by Wassell's under the Hepolite brand are made by JCC in Taiwan. They are excellent quality. I know some on this forum have criticized them in the past, but as they say - you can't please everybody all the time.
Sam

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787435 10/18/19 9:24 pm
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When I do an engine, if it's for myself, I tighten up the clearances simply because I like quiet motors as opposed to clattery old buckets. For customers, I request my machinist to make them at least 4 thou and even up to 5. I know human nature.....when customer gets out of earshot of me, he's going to pin that throttle to the stop. I have the personal discipline to run my bikes in properly.
By the way, the book clearances for Low-Ex pistons is 3.5 thou. Triumph made their own pistons in those days and had I think better quality control than, say, Hepolite.
NOS Hepolites are to be avoided since they are now getting rare and vendors will mix pistons from different batches. That's a huge headache.
I've used JCC pistons in dozens of bikes and never had a single problem. Rings.....different story.
I can't remember anyone criticizing JCC pistons here. At least no one who has actually used them.
Sam is right about the boring. If your machinist isn't up on boring the old cylinders, he'll likely overheat it before it's done. He'll actually bore the thing in a taper. I had a friend whose TR6 kept seizing for no apparent reason. When we took it apart, only the bottom of the skirt was seized. Only one thing could explain that, taper. So, a different machinist fixed it without going to the next over bore with his hone.
Be sure to ask here about your assembly. John Healey has posted here numerous times about his technique that seems to work with the cast rings we use.
Oh, and one thing more. If you can't find +.010 rings, use +.020. Not the ideal situation but I've done it before with success.
Mind your ring end gaps, though.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787455 10/19/19 12:40 am
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Sam, The Line 2 Line coatings that i mentioned are really a good option. They are able to build up .015 total on a piston. we have taken several motors race engines back apart for inspections and measured only .001 loss of piston size. I am not saying to run anything on a bad bore, make sure the bore has no pitting and with in .0002 and you will be good!! If the pistons still have the proper taper from top to bottom, straighten the bores, coat the pistons and ride for years. I have never tried going the total .015 coating, but we have several engines that has .004 coatings and are running great

Just a thought!

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787465 10/19/19 3:40 am
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Sam. Bill, Jake, Jon, Don, thanks for all the responses. And Bill thanks for letting me in on the bargain pistons.

I found .010 rings at Klempf's. I will hold off buying the rings until I know that the overbore is a success at .010 over.

I believe I can exercise the restraint necessary to use the .0035 clearance.

And I am interested in John Healey's assembly technique. I will search.


Dave Swanson
1955 T110
1962 TR6SS
1965 Spitfire Hornet
1967 Bonneville
1974 Norton Commando
Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787650 10/20/19 11:45 pm
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Dave, I think even on a personal bike I would use atleast .004 clearance. You wont hear them at .004 . better safe then sorry especially with pistons that are not easily available!!
I wouldnt worry trying .0035 if using JCC pistons!

Re: 1955 T110 Cylinder Bore Question
Dave Swanson #787652 10/21/19 12:06 am
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I might have to agree with Jake on this one. Since it appears that you are resurrecting a basket case instead of refurbishing a running bike, you won't have a data base of settings for your particular bike to refer to. So, you wont really have any wiggle room with the lower clearances on an unknown bike. You just might get the settings a bit lean or a bit advanced and run the risk of a seizure.
Your call, but it is a bit risky.
Typically I will run a fresh rebuild for 5 minutes and check everything especially how hot the bike is running. Heat is the killer. Short hops are the insurance until you know it isn't overheating.
I get lots of cues from the bike about all this. Is in pinging like crazy? Run sluggish? Smell like burning paint? I don not hop on a fresh rebuild and run the canyons. Nope.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: 1955 T110 Cylinder Bore Question
HawaiianTiger #787656 10/21/19 1:00 am
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Agreed Bill !! Its lots more difficult to get a basketcase sorted than to freshen up the top end of a well running bike!! Go .004 or more and be safe! Get good rings!! we have had the
best luck with Goetze rings. Same MFG that BMW uses. use a 150-180 grit finish on the cyl walls. install rings dry, and lightly oil the skirts!! good luck !

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