classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: thunderace1 on June 13, 2010, 10:11:50 PM
-
Dear All,
New to this forum, but could do with some help (from far more experienced owners) with my oif 1972 t120rv and its non starting!
I have tried everything using my limited knowledge but no joy. The problem is that the bike just will not fire up and I cant see why (it has sparx electronic ignition fitted). I have replaced the battery (runs at > 12.6v), new plugs, checked earth (same voltage), static timing okay, carbs cleaned and checked, fuel in tank!, engine turns over okay etc. etc but no joy. Looking at the book one thing it says to check is the voltage between the -ve terminals of the ignition coils and earth (when the ignition is on) and I get no reading. Does my electronic ignition wiring affect this or do I have some problem with coils etc? How can I safely check that there are sparks at the spark plugs and is there anything else obvious that I have missed?
Thanks for the help ::)
-
Thunderace, Does it need a choke??? Look at my post Step2534
-
Dear step2534.
The bike has new concentric mk1 amal carbs with choke fitted. I have checked float levels, cleaned them thoroughly and replaced the slides with brass ones, checked balancing and cables etc. I might be wrong (and probably am!) but I feel that my problems are electrical rather than carb related.
Best regards
Thunderace
-
Looking at the book one thing it says to check is the voltage between the -ve terminals of the ignition coils and earth (when the ignition is on) and I get no reading. Does my electronic ignition wiring affect this or do I have some problem with coils etc?
Yes, that test probably won't work with the Sparx electronic ignition, also the two 6V ignition coils should now be wired in series for the electronic ignition.
How can I safely check that there are sparks at the spark plugs and is there anything else obvious that I have missed?
Remove the spark plugs, refit them to the plug caps, and then rest the plugs on the cylinder head. If you switch the ignition on, and turn the engine over with the kickstart, both plugs should be seen to spark together once for each crankshaft revolution.
-
Dear L.A.B.
Good to have your advice on this , yours is a name I recognise from the classicbike.net site.
I will try your suggestion re checking the spark plugs tomorrow.
Best regards
Thunderace (my 'modern' bike!)
-
Are you sure you have set the Sparx ignition timing correctly?
A common mistake is to set electronic ignition timing using the wrong timing mark on the alternator rotor so the firing point ends up 180 degrees out.
-
On another tack, when I fitted two new Amals the pilot jets were blocked with swarf. I know that Amal (or whoever makes them these days) were supposed to be addressing the QC problems, but maybe it's worth checking them anyway?
Squirt some neat juice into the pots and see if it fires.
-
Dear All,
Further to the responses I have tried testing the spark plugs as LAB said and they didnt work! One of the end of the cable connecting the two coils had come off, attaching it I now have spark plugs working so thanks for that advice. However the bike still wouldnt start and so I tried to clean out the carbs, they seem okay but still no joy on starting. I had ordered another sparx kit for my t140e (which is my next project) and I even tried swapping over to the new coils and starting unit but still no joy. I think that the battery is okay, spark plugs now okay, carbs okay, the engine physically turns okay on the kick start but it refuses to fire up - anything else I could try or I have missed. Next stop for me is to sell the damn thing on ebay!!!
-
can you tell us what work has been done since the bike last run i.e has it had a rebuild
things to check are
ignition timing Does the sparx ignition give a spark on both cylinders at the same time? if not try swapping over ht leads
next I would try fuel simplest would be to squirt some fuel into the cylinders either through carb air intake or through the plug holes be careful use only a little to minimize risk
can you feel the compression on kick start if not check the valve clearance if these are ok you could do a compression test
if compression is ok check valve timing although if the bike has run since these have been changed/ reset as in a rebuild then it is unlikely to be the cause
is the engine turning over on the kickstart? the clutch could be slipping enough to stop it turning past compression but allowing it to turn with the plugs out (not very likely but still a possibility)
hope this gives you somewhere to start
Yosemite
-
Dear yosemite,
Thanks for your detailed suggestions.
When the bike was running previously it was running very rich (and was difficult to start then as well) and I had only done about 1000 miles on it. When I bought it the bile had been in a scrap yard since 1978!; needless to say it took a complete rebuild, a couple of years of my life and more money that I would ever admit to my wife! My current work was to take the head off and clean the chambers and valves etc of the carbon deposits and thoroughly clean the carbs, rockerboxes etc.
I will check that the spark plugs fire together, I think that the sparx kit fires both spark plugs each time.
I will also try your suggestion re squirting fuel
I have a compression guage and so I will look at this, previously I seem to remember that it was about 100
I did redo the value clearances when refitting the rocker boxes but I will have a look again
The engine does turn over on kickstart but I do have to free the clutch plates before I try and kick start it
Busy day tomorrow!
Regards Thunderace
-
I will check that the spark plugs fire together, I think that the sparx kit fires both spark plugs each time.
Don't bother checking, as it is a wasted spark system so both plugs fire together.
-
Thanks l.a,b never used a sparx ignition unit before so I wasnt sure
If everything checks out ok a couple of other things to check, check that the throttle cables arent holding the new carbs open as this can make starting nearly impossible also check that theengine is not flooding (are the plugs wet with fuel)
yosemite
-
Taking the rocker covers off I discovered that the tappets have become undone (or have become loose) damaging the threads on the rocker arms and the tappets themselves and letting the pushrods come off. I am sure that my tappet gaps were correct and locked in place. Anyway new tappets and tapped rocker arms (5/16 CEI if anybody is interested, it also means that my t120 has unf,unc,cei,ba,metric and whitworth bolts etc!).
I have now put the rocker boxes back on with new gaskets and ensuring that the pushrods are on correctly (leaving off the carbs and rocker covers). The problem now is that there is compression on the left side but virtually no compression on the timing side even though everything seems in place. Any suggestions as to what might cause the loss of compression on the right side of the engine only?
I seem to spend far too much time in the garage than on the road!
-
I discovered that the tappets have become undone (or have become loose) damaging the threads on the rocker arms and the tappets themselves and letting the pushrods come off. I am sure that my tappet gaps were correct and locked in place.
To avoid confusion, I think what you are referring to as "tappets" are in fact the rocker adjuster screws? As the tappets (or cam followers) are located within the tappet blocks at the lower ends of the pushrods.
Anyway new tappets and tapped rocker arms (5/16 CEI if anybody is interested, it also means that my t120 has unf,unc,cei,ba,metric and whitworth bolts etc!).
Triumph begun a major change-over from British Standard to Unified (UNF, UNC etc.) threads from the 1968 model year, however, they didn't get around to changing the rocker adjuster threads to Unified until 1978 apparently, and there shouldn't really be any "metric bolts" as standard, and certainly very few-if any, Whitworth threads by 1972. And don't forget the fuel tap threads-which are BSP.
-
Dear LAB,
Yes you are right I do mean the rocker adjuster screws.
With the different threads it does seem to me (first time that I have done anything like this) that whatever was lying around in the factory at the time went on to the bike! The metric bit is that one crankshaft main bearing is imperial and one is metric, the whitworth bolt is the centre 9th cylinder head bolt on my model.
Any thoughts on why one side of the engine has little compression and what I can do to check any potential problems?
Thanks
-
My ninth bolt was BSCY like all the rest, although it did have a reduced hex if I remember correctly.
Why do you think it's a coarse thread like Whitworth?
-
With the different threads it does seem to me (first time that I have done anything like this) that whatever was lying around in the factory at the time went on to the bike!
No, not really, it's just that a greater variety of thread forms were used by British manufacturers at that time (not just motorcycle manufacturers) and with the adoption of metric thread forms it can seem a bit odd to some people to find so many different types of threads used.
The metric bit is that one crankshaft main bearing is imperial and one is metric,
Well, metric bearings were not that uncommon on British bikes of the period (Norton Commandos etc.), and your Triumph's wheel bearings are metric too.
the whitworth bolt is the centre 9th cylinder head bolt on my model.
I can't find any data on that thread although I think the other head bolts were still cycle thread at that time?
Any thoughts on why one side of the engine has little compression and what I can do to check any potential problems?
It's difficult to say based on what we know, but it's got to be something to do with the valves or rings, so I can only suggest you check the obvious things such as a broken ring, leaking head gasket or valve not sealing properly?
-
if you do a compression test with a tester you can usually eliminate ring/piston problems by putting a small amount of oil into the plug hole of the problem cylinder. turning the engine over a couple of times to spread the oil around and redoing the compression test
If the problems are rings/pistons then the oil should seal them and the compression rise significantly if it does not then suspect valves, or head gasket
-
Thanks for the comments.
Taking the engine apart again, with just the cylinder head on (no rocker boxes) there is very good compression on both sides of the engine which I think means the head gasket and rings are okay. Fit the rocker boxes on and I lose compression on the timing side so I think that the valves are my problem?
So taking the cylinder head off etc I might get certain other work done, any thoughts on the following?
- any point having the cylinder head skimmed?
- my copper gasket is only 1000 miles old, anneal or replace?
- my t120 has push in exhausts, the t140 shop does a push in exhaust seal kit any one tried one of these?
Thanks
-
- any point having the cylinder head skimmed?
Is it warped? If not, then I'd say no.
- my copper gasket is only 1000 miles old, anneal or replace?
Copper gaskets can be re-used a number of times if they are re-annealed first, (personally, I prefer composite head gaskets).
- my t120 has push in exhausts, the t140 shop does a push in exhaust seal kit any one tried one of these?
Unless they are causing problems I'd suggest you leave them as they are. Use ordinary silicone sealant to seal the pipe to head joints.
-
Dear LAB,
Thanks for your comments again.
Thunderace
-
Taking the engine apart again, with just the cylinder head on (no rocker boxes) there is very good compression on both sides of the engine which I think means the head gasket and rings are okay. Fit the rocker boxes on and I lose compression on the timing side so I think that the valves are my problem?
Not to me they're not. I would say it's the valve(s) being held open by the rockers is why there's no compression. Does the "no compression" cylinder change sides as you turn the engine over? Do the valves (all four) operate as you turn the engine over?
-
it definately sounds like something is sopping a valve from closing do you know if the compression "comes back" if you take the rocker boxes off again?
you could try taking one off at a time to check wether its exhaust or inlet
then its just a case of checkig everythig is moving freely on the side with the problems ( assuming that the rocker clearances are ok)
if the compression doesnt reappear then suspect a valve problem
hope you get it sorted
yosemite
-
I've come across rockers being held open by contact with the rockerbox. Had to dremel the area for clearance. Had us stumped for half a day until we figgered it out.
-
Hello,
That is a good point from rogerwilco.I take it your cam is OK and opens and closes like the lobe should?Does the valve guide have too much play,valve sticking in guide?Are the valves really closed at firing?Pushrod bent?Maybe your shop could do a pressure loss test in the faulty cylinder thru the sparkplug hole?Is a ring broke?
Are all the rings put on right in the bad cylinder?Tell us how you come along please.
Good Luck
huron
-
Yebbut Huron, if he removes the rocker box and there's compression, it can't then be rings, sticky valves or valve guides, can it? ::)
-
You make no mention of HOW you adjusted the rockers. The fact that the pushrods came adrift suggests to me that the engine may not have been rotated to the correct position while adjusting each one. So that the gaps were wildly out. The lack of compression could be for the same reason.
Re-check the valve clearances following the instructions in the manual. Each inlet valve clearance should be adjusted while the inlet valve on the opposite cylinder is fully open and the same for the exhaust valves.
Jim.
-
Dear All,
Thanks for all the comments.
£200 later and a lot of time it seems that the problem(s) might have been solved as the bike started properly yesterday. Some of the valves were sticking in the valve guides (hence I was loosing compression when the rocker boxes went on the cylinder head) and so to finally resolve that problem I have bought new valves and guides (from TMS) and had them professionally fitted and values seats done (at T&L here in Bedford). From LAB’s comments about timing I have rechecked this and it appears that the rotor mark seen through the timing hole was set against TDC rather than BTDC (checked this against Lunmad videos on Youtube – I think that these are very good). I now also have new rocker adjusting screws that use Allen keys (much easier than using the BA spanner type) and I have used loctite on the threads to assist keeping them in place. As far as setting the gaps I have now done by using the manual, seeing Lunmads video and also looking at Hughie Hancock’s videos so I am reasonably sure that they are correct. When the weather is good I will get in MOT’d and get it out on the road where it should be!
Next my 1978 t140e which is half complete.
Talking of which I obtained this as a box of bits and I am starting to work on the brake system. With the lockheed callipers I am looking to replace the pistons etc and give them a complete overhaul. The book says not to undo the bolts that hold the two sides together but since the callipers are not connected to anything and I cant get the rusted pistons to move, how else can the callipers be overhauled? I do not really want to get new ones and would prefer to overhaul as much as possible of the original bike
-
The book says not to undo the bolts that hold the two sides together but since the callipers are not connected to anything and I cant get the rusted pistons to move, how else can the callipers be overhauled?
There doesn't appear to be any real reason why the calipers cannot be split and rebuilt successfully, and I've heard of others who have done it without problems although the internal gallery seals were never listed as a spare part, but they are available apparently, as I have it on good authority there is a Ford Transit caliper seal kit which uses identical size pistons to the Triumph Lockheed caliper, and one Transit kit contains all the seals necessary to rebuild two Triumph calipers, including gallery O-ring seals.
-
Hi
not sure if splitting calipers will help in getting rusty pistons out of the calipers
you could try using an airline to force pistuns out or if this doesnt work you could reconnect the calipers to a master cylinder and pump out the pistons one at a time
then clean up replace parts as neccessary then work on opposite piston
-
Hello,
The 3rd step I know of is a grease fitting made to fit the brake line on the caliper coming from your hand pump on your handlebars.
If you do this with air pressure please put a piece of wood so between the brake pads so the parts and the fluid dont fly around.
If you have tried already with your own front brake pump cylinder that might blow its seal out?At any rate be careful that the pistons
and the fluid dont fly around far.
If you have the wheel out, did you try to push the piston back a bit with a C clamp?
Hope you get them out
huron
-
Dear all,
Thanks for the comments on the brakes.
I have now have both calipers apart, all seal removed and the pistons out. The calipers have been off the bike for years (perhaps even decades) and there is no fluid in them. I found an article in Classic bike where they removed rusty pistons by drilling holes in them, using a tap and then a bolt to push them out. Works a treat although the pistons are hard to drill and they were rusted to hell. It seems that Tricor (and TMS) do a complete caiper seal kit and stainless pistons and so its only money... (if I dont spend it the wife will!).
Thanks again
-
[
£200 later and a lot of time it seems that the problem(s) might have been solved as the bike started properly yesterday. Some of the valves were sticking in the valve guides (hence I was loosing compression when the rocker boxes went on the cylinder head) and so to finally resolve that problem I have bought new valves and guides (from TMS) and had them professionally fitted and values seats done (at T&L here in Bedford).
With respect, they saw you coming. Sticky valves don't happen with worn guides, so there's a good chance that your guides were perfectly useable. A good clean with solvent on a Q-tip (valves and guides) then a valve lap would likely have been all that was needed. A morning's work and 200 quid saved.....