kickstart jammed? - Page 2 - Triumph Forum: Triumph Rat Motorcycle Forums
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post #11 of 21 (permalink) Old 10-13-2019, 05:58 PM
Supersport 400
Main Motorcycle: 1972 T100R, or a TR7RV
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I had to check the amount of valve movement when I recently re-built my T100R as the people that fitted the camshaft pinions (as I didn't have the tool at the time) unfortunately fitted the pinions on the wrong keyways, so I spent some time staring down the plug holes to watch the pistons hitting the valves and working out why the valve timing was way off. I had no-where near the amount of movement in your photo. Different engine, yes, but that looks to be way too much valve intrusion to me. Plus, you seem to be looking at the edge of the valve head - is the valve bent?

Equally, the valves in my TR7RV don't seem to intrude as far as shown in your photo. Does not look right to me.

As Don says, if the balls have come out of the pushrods and are locating on the sides of the cups you'll get this effect too. Something's not right.
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post #12 of 21 (permalink) Old 10-14-2019, 04:47 AM
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Its either a bent valve or a valve seat has come loose and is jamming the valve open = a bent valve usually

either way, you need to start stripping the bike and rebuilding.

tridentt150v,
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(Where women blow and men chunder).
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post #13 of 21 (permalink) Old 10-14-2019, 05:43 PM Thread Starter
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Firstly thanks to everyone for their thoughts and suggestions, BUT I have discovered the problem and I'd love to know how it happened! ( other than my incompetence.)
Yes its a pound coin!
So I recently had new valves and guides, a rebore and new pistons, so obviously I put the head back on.
And didn't notice a pound coin in there?? And then she ran really well for 500 miles or so till the kickstart jammed? There's no damage to the piston, valve barrel or head. There's no other way for anything to have got in there, is there?
Anyway, at the risk of being drummed out of the forum for making stuff up, that's what I found. Has anyone else found weird stuff in the engine?
Can the engine have run normally with that in there? I've partially reassembled it to check and the engine rotates smoothly so that picture of the valve being very visible seems normal and it's the same on the other side.
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post #14 of 21 (permalink) Old 10-14-2019, 11:57 PM
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Hi Ploughboy, At least the mystery is solved....

What is the white oval? Kind of looks like bottom PRT seal?? At work things falling into the motor during assembly is always a concern. Or falling into air filter housing during service & getting sucked in. If even a very small item or pebble gets stuck in valve seat the piston comes up & bends valves. Some of the Mercedes had plastic bushings break apart in intake manifold. Would smash spark plug, but 75% of time would not bend valve.

I've seen my share of small washers & nuts stuck in top of piston, but never a coin!!

My 2 year old grandson loves to hang out in the garage & "work" with Dad. He likes to "install" things in the oddest places. Have to keep an eye on him, but he loves this stuff.

Regarding bent valves, I would turn head upside down at angle & pour solvent or petrol into the combustion chamber such it fills the valve pocket. Hold head like this & look into intake port to see if liquid is leaking through. It should not leak a trace. Do same to exhaust valve. If any leaks remove valve & spin it in guide to check for obvious bend & wobbling. If ok, clean seat & recheck. If still not good, lap valves with fine compound. Look at valve & seat for non contact which will be obvious where there is no fresh lapping marks. Lap until good. Or send out for grinding.

Sometimes the piston is damaged such it pinches top ring as edge of piston is bent down. From what I see doesn't look like much piston damage. After cleaning carbon, inspect for sharp edges & burrs from the coin bouncing around. Flatten, smooth any burrs or sharp edges.

Can you post photo of head. I'd to see what coin did to head.

Are you running air filters? Could coin have falling in air filter & got sucked through carb? Coin looks to large to pass through, then by valve but I don't know.
Don
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post #15 of 21 (permalink) Old 10-15-2019, 04:59 AM
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must have been during assembly? Coin doesn't look small enough to fall in the sparkplug hole? maybe as Don said, through the inlet?
I can't see how your motor would run for miles with that coin in the combustion chamber, has to be a very recent addition.

tridentt150v,
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post #16 of 21 (permalink) Old 10-15-2019, 03:54 PM Thread Starter
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Hi Don
I checked the valve and no leaking of petrol. The picture shows a small nark near the valve head and a little carbon off the valve, no piston damage. I think you and tridentt150V are right that it can't have been in long. It must just have got in and jammed when i kickstarted her. Probably when I was adjusting the carbs. ( I'm not running air filters)
The coin is a pound coin and the silver bit is the centre of it squished out leaving that goldy ring
BTW the other picture is of the two top push rod cover tube O rings (71-1283)
One is very tatty and the other less so but not in great nick. They were new 500 miles ago- have I overtorqued or is this normal?
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post #17 of 21 (permalink) Old 10-16-2019, 12:39 AM
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Hi Ploughboy, You should buy a bunch of lottery tickets as a lucky man! Or... you used your luck up on the Triumph.

Anyway, I can't tell for sure, but looks like some nicks in head which will smooth out nicely. Same with piston at edge of valve relief.

Good you found the problem & now have a repair path. Glad you didn't bend valves or have major damage.

Regarding the PRT upper seals, that is not from over torque. The torque wrench sets the torque. The PRT seal crush is a product of the thickness of head gasket in relationship to if head or cyl have been skimmed & all that.

Saying that I've seen these red soft seals do that even with proper crush . I'm personally not a fan of them. I personally like the Viton O-rings which can come in any color but from Rabers were usually brown or black.

Push rod tube seal crush is a whole subject unto itself. Did you test crush at assembly? Even .015" is enough. I feel over .035 is getting to the max I like. More than .040" is not recommended & can cause head damage.

The official spec in Triumph Bulletin # 324 November 1969 is crush .030-.040".

Deburring tappet block sealing surface & head bore for PRT is essential to preventing leaks. I usually put a thin smear of silicon on the round O-rings. Still they often will start to seep after about 5 years.

If you have too much crush even with thinner white bottom seals, you might think about thicker head gasket. Solid copper .080" thick.

Regarding air filters, unless you have a specific race track reason to not use air filters, you are asking for trouble. No filters can wear slides, carb bore rapidly also. Where I live you won't cover 3k miles without wear out carbs & cyl bores.

I don't know how that coin got into your motor, but you'd not believe what can get sucked through a carb. Pebbles you'd be certain too heavy to suck in is not uncommon. Again I don't know the size of the coin compared to passing by valve, but small bits are thrown into air all the time by passing motorists. I've had them hit my legs often. A gas cap once. That hurt! I have factory air filters. Always surprises me how much little twigs, bits of grass & insects is in them besides the expected dirt.

Don
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post #18 of 21 (permalink) Old 10-16-2019, 02:46 AM
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Originally Posted by TR7RVMan View Post
....I don't know the size of the coin compared to passing by valve....
Here you go Don, 23mm dia, 2.8mm thick and dropping in value every day. Agree on the lottery ticket, I can't see how the engine ran with this in there and no damage as a result. Pleased at the outcome though.
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post #19 of 21 (permalink) Old 10-16-2019, 04:02 AM Thread Starter
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Thanks Don, I'm away for a couple of weeks cheering Ireland on to winning the rugby world cup so reassembly starts then. I will use the viton rings as you suggest

Success consists of going from failure to failure without loss of enthusiasm. Anon
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post #20 of 21 (permalink) Old 10-16-2019, 06:34 AM
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(Goes off to fit air filter to my TR7RV.....)
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