Author Topic: Triumph T100R Overheating Problems – Any Help Appreciated  (Read 9643 times)

Offline Petergj

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Triumph T100R Overheating Problems – Any Help Appreciated
« on: June 27, 2017, 11:07:41 AM »
Help needed….. I have a 1969 Triumph T100R in a Rickman frame with a single Amal 626 carb and 2 into 1 exhaust. The engine has just been re-bored to 0.020 oversize after the previous owner scuffed the pistons/bores. The engine runs well and starts very easily with the ignition timing set with a strobe, but the engine runs very hot. To ensure the carburation is OK (currently running with 190 main jet), I am about to replace the carb with a new one to be sure there are no air leaks between the throttle slide and body. I will also remove the “slip on” style silencer to see if that is increasing exhaust restriction (and retaining heat in the engine). Beyond that, I have run out of ideas!

Has anyone else experienced similar over heating issues and what was the solution? Any comments welcomed.

Thanks,

Offline Rex

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #1 on: June 27, 2017, 12:56:02 PM »
"Hot" is a relative term though. Last week was extremely hot (in the UK) so when did you try it? A very hot engine is usually a weak mixture, wrong timing, "tight" engine, inefficient oil pump, valve timing out, leaking head gasket, tight tappets, binding brakes, soft tyres, etc etc or mixtures and parts of all of it.
If the carb is the same as when it ran OK before (you have had it running OK I take it?) then that can be discounted (provided the flange isn't badly leaking) but you need to check everything you've done.
Is it down on power too?

Offline john.k

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #2 on: June 27, 2017, 01:01:51 PM »
I would suspect a new rebore pistons and rings.The motor will run hotter until the new bits wear in.If you are really worried ,lift the barrels and see whats going on.Otherwise try a bit more ignition advance.

Offline Petergj

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #3 on: June 27, 2017, 03:23:09 PM »
Thanks for your comments - I have had the bike for about a year (knowing the bores were scuffed when I bought it) and it has always run hot, hence the drastic change to replace the carb and ensure there are no leaks in the carb around the throttle slide. There is a thick heat isolator between the carb and head. All frame parts are OK (wheel bearings, brakes, etc). No lack or power and healthy return of lubricating oil to the frame (I know that is not a good indicator of adequate bottom end lubrication). I will re-check the valve timing but I am sure that was done when the re-bored barrel was fitted. Failing these checks, it looks like a full tear down.

Does anyone know if these engines are sensitive to exhaust back pressure?

Regards,

Offline chaterlea25

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #4 on: June 28, 2017, 12:03:46 AM »
Hi,
Quote
Does anyone know if these engines are sensitive to exhaust back pressure?

Short answer, no

I would remove the timing cover and check the crank oil feed seal
While its off check the valve timing

Whats the heat insulator made of? is it a soft material?
Soft insulators warp the carb flange !!! the insulators need to be made of "Tufnol" (paxolin)
Check the fuel height in the carb.

What was piston to bore clearance set at when the rebore was done?
Were the piston ring gaps checked at the same time ?

John

Offline Petergj

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #5 on: June 28, 2017, 08:47:37 AM »
There is the genuine "thick" paxolin gasket between the carb and cylinder head.

Looks like pulling the timing cover will be time well spent.

The engine has a Pazon ignition system with the timing set at 38 degrees (as per recommendations). Is it worthwhile advancing (or retarding) the timing to see if the heat generation can be reduced (there is one comment in the thread to advance the timing which I will try).

In terms of dimensional checks, the engine was rebuilt by a reputable bike restorer so I am not aware of any piston-bore and ring gap dimensions.

Appreciate the comments in the replies.

Offline Rex

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #6 on: June 28, 2017, 10:47:04 AM »
Paxolin and Tufnol are very different materials, and I should imagine you have a Tufnol item fitted.
Anyway, you really don't want to start fannying around with settings to see if it improves. If it's at 38' then it's correct so leave it and look elsewhere.
I'm still confused though....has this bike ever run right in your ownership?

Offline Petergj

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #7 on: June 28, 2017, 12:53:58 PM »
Rex, the engine was running hot when I got the bike and breathing heavily. The barrels were bored out and oversize pistons/rings fitted but the bottom end was not dis-assembled (may be a mistake with hindsight) but the condition of the crankshaft/bearings were reviewed and nothing deemed abnormal without removing the crankshaft.

Offline Rex

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #8 on: June 28, 2017, 03:20:17 PM »
So have you ascertained that the bike actually is running hot, and how was it done? Have you compared with a similar bike? Sometimes rocker box oil leaks give this impression as it stinks of hot oil when the oil runs down over the head and it gives off little wisps of smoke, too.
Needing a rebore is not in itself a reason for running hot.

Offline chaterlea25

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #9 on: June 28, 2017, 06:52:02 PM »
Hi,
Have you checked the timing with a strobe?
Also verify that the timing marks are correct (or not?)
The timing marks are not always  100% reliable
Are the correct heat range plugs fitted?

John

Offline Petergj

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #10 on: June 28, 2017, 10:36:20 PM »
The plugs are Champion N4C (when I acquired the bike, it was fitted with NGK B7ES plugs).
The timing has been set with a strobe and the timing mark checked using the slot in the flywheel accessed through the inspection plug behind the cylinder barrel.
Th engine is running Morris 20w50 oil and I will change this to Morris SAE40 at the next oil change.

The re-bore was completed due to the scuffing of the bores - I only think it is running hot based on comments from the guy who rebuilt the engine following the re-bore saying it may scuff again if I was not careful and the right hand cover feels hot (as opposed to warm). Maybe this is the way they all are and I am unduly worrying? Any drip of oil from the rocker box does  quickly burn off with a "wisp" of smoke.

Thanks for your comments.

Offline Rex

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #11 on: June 29, 2017, 09:21:29 AM »
Sounds like the bloke who rebuilt the engine was giving you some advice about oils or running in rather than dire warnings about the engine condition. Is there no-one locally you could ask about how hot the engine is?
Being air-cooled there are big variations in ambient temps....Death Valley to Alaska in winter,and the engine's are pretty tolerant of heat all things considered. How hot is the oil tank side after a fast run? Pleasantly hot or unpleasant to touch?

Offline iansoady

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #12 on: June 30, 2017, 01:14:48 PM »
I would expect the timing cover to get hot enough to make it uncomfortable to touch but not to burn your hand.

As Rex says, check the oil tank temperature - you should be able to hold your hand on it for a couple of seconds even after a hard run.

I have a digital laser thermometer gadget (like this: http://www.maplin.co.uk/p/infrared-thermometer-with-laser-targeting-n92fx but mine was cheaper) that I find very useful in a variety of situations.
Ian
1952 Norton ES2
1986 Honda XBR500
1958-ish Tre-Greeves

Offline Petergj

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #13 on: July 02, 2017, 11:37:45 PM »
Thanks again for all your comments. As planned, I changed the Amal carb for a new Amal 626 Premier this weekend and fitted with a Burden wire gauge air filter (as fitted to the original old carb). This was set up to the original T100R spec by Burden and as a result the engine is running well with a 180 jet compared to the 190 main jet I was running with the old carb (the old carb was fitted with a new 190 jet and needle/jet as part of my investigation). A plug check showed the mixture was OK (light brown colour) with the Premier carb.

Would anyone recommend running slightly richer to avoid any chance of running weak?

lansoady, the timing cover is hot and just shy of burning my hand. The oil is returned to the frame as a reservoir and the oil returned to the frame is warm and not hot. I have a digital thermometer with a probe which I will use tomorrow and get an idea of the timing case temperature (I may buy the laser thermometer you suggest when cash is available!).

Right now I am planning to double check the timing with a strobe and carefully continue to run the engine in.



Offline iansoady

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Re: Triumph T100R Overheating Problems – Any Help Appreciated
« Reply #14 on: July 03, 2017, 11:40:40 AM »
That doesn't sound excessively hot to me.
Ian
1952 Norton ES2
1986 Honda XBR500
1958-ish Tre-Greeves