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  • 2t compression

    Can any one tell me what the recommended is in pounds per square inch on standard heads. still having fun with engine only firing on one? even though every thing is new and timed at 3/16 btdc so its back to basics.

  • #2
    2T compression

    If you have a compression gauge then why not compare one cylinder with the other that will give you some idea if its low on one cylinder, as for readings if its lower than 120lbs then you may have a problem...John p.

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    • #3
      2T issues

      thanks for the thought but it would be nice to have a figure to compare it to.Presumably Villiers must have had a ratio in psi?

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      • #4
        As John P says check the pressure of the good cylinder then thats the pressure you need on the other one. Frankly you should be able to get some idea from the resistance on the kick starter to overcome compression. Also take a plug out and put your finger over the plug hole you should be able to feel if it has compression. Unless something is drastically wrong like broken rings then it should go particularly after it has started on the other cylinder. After all you have had the engine reconditioned by VS & you say they have checked it out as ok so there must be other issues, presumably with ignition. Are you getting a good spark on the failing cylinder?

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        • #5
          2T issues

          I have a compression gauge and have a reading what I want to know is what it should be on a good day. Having replaced all the ignition components with new and on the face of it this should be perfect I am now double checking every thing. Timing, continuity, swapping coils side to side and condensers . One thing I have found was the new plug caps were not much good as the screws were set off set so they went in to the insulation and not the centre electrode, just goes to snow you cannot take anything for granted. Will keep you posted on what I find?

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          • #6
            Mike I think you will find its more likely to be those plug caps rather than anything to do with compression. I have workshop manual for the 4T but no mention of compression pressures in there, so I dont suppose the 2T manual stated it either. I dont think that was something that was ever specified. These faults are usually attributed to the simplest things.

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            • #7
              Originally posted by mikerwt View Post
              I have a compression gauge and have a reading what I want to know is what it should be on a good day. Having replaced all the ignition components with new and on the face of it this should be perfect I am now double checking every thing. Timing, continuity, swapping coils side to side and condensers . One thing I have found was the new plug caps were not much good as the screws were set off set so they went in to the insulation and not the centre electrode, just goes to snow you cannot take anything for granted. Will keep you posted on what I find?
              I would leave the plug caps off as its a poor spark at best.Use copper wire HT cable,renew the wire to the contact breaker and lead it straight to the HT coil bypassing the socket.I,ve had an internal fractured LT wire before.Try one thing at a time until you cure it

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              • #8
                2T issues

                Hi Stuart nice to hear from you.
                T have done all you suggest I can now say I have a perfect spark on both plugs double checked timing all in order. The issue know is that the left hand cylinder is not pulling the fuel through so the plan this morning is to prime the cylinder and see if it will fire on 2?Could be a big air leak but I have been most care full ( the crank has been back to V/S as I thought the centre seal was u/s but that is all good and I have tested for leaks) to make sure all surfaces are clean new gaskets so I am mystified.

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                • #9
                  Could be the LH oil seal leaking. Check that the engine sprocket distance piece part No E9310 is making contact with oil seal.

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                  • #10
                    2T issues

                    Thanks John. Spoken to V/S and they are mystified, they suggested a couple of things to check ie manifold seal and any hairline cracks but could not fault it so faced it on plate glass and refitted it but still the same.still only 1 cylinder fires if I prime the cylinder it will run perfectly until fuel is gone so I will end up taking it up to V/S to sort out as I have wasted enough time on it,I expect it to be some thing silly but I cannot see the wood for the trees.

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                    • #11
                      Proves its carburation rather than electrics, as the manifold is ok then it looks like LH oil seal. I seem to remember someone else on here had the same problem, in his case the seal had blown out because he had removed the retaining lip in casting so as to be able to change the seal without splitting crank case. This seal can only normally be fitted from inside. Also check that the seal is fitted the correct way round, lip facing inwards. If you can get it running by priming the cylinder remove the primary case filler plug to see if there is blow by.
                      Last edited by John Wakefield; 06/10/2015, 03:42 PM.

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                      • #12
                        2T issues

                        will look at that thanks for all your advice John really apreciated

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                        • #13
                          I suppose you've checked that both crankcase drain plugs are present and tight?
                          Colin Sparrow

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                          • #14
                            2T issues

                            Thank you Colin
                            first thing I checked? my next thought is to put a valve in the drain hole and see if I can put pressure in and see if I can Identify the leak?When I received the crank back from V/S I did what they suggested in filling up the crank cases with petrol which I did and there were no leaks?

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                            • #15
                              2T issues

                              Thanks to Johns persistence I have almost cured the way ward 2T in desperation I striped the clutch and remove engine sprocket (no joiner link) and then flooded the whole area with soapy water no bubbles!!!!! so after Johns prompt I removed cylinder head and timed the offending cylinder with a dial gauge so the timing was spot on reassembled and tested I cannot believe that it was so critical but it seems to be the answer still got a slight miss but that will be resolved with some "care full" adjustments, I have now ridden the greeves properly for the first time and will need to sort out handling bugs and get used to wonderfull brakes. thanks to all my readers for all the support and encouragement greatly appreciated.

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