Author Topic: 1914 2 3/4 engine problems  (Read 892 times)

0 Members and 1 Guest are viewing this topic.

Offline veikko1

  • Full Member
  • **
  • Join Date: Nov 2014
  • Posts: 29
  • Location: Finland
1914 2 3/4 engine problems
« on: 12 Jan 2018 at 18:55 »
I am thinking this engines breathing system. There are ball and spring in crankshaft timing end, but after that, any valves to outside? Other question is piston pin ends. I have a good pair iron pistons, but there haven`t any grooves to circlips. I have also new solid pins, maybe some bronze caps must doing? Any measures??
Regards veikko1
 

Offline Chris

  • Master Member
  • ****
  • Join Date: Jun 2004
  • Posts: 494
  • Location: Kent, UK.
Re: 1914 2 3/4 engine problems
« Reply #1 on: 13 Jan 2018 at 08:19 »
Hi
The original arrangement on 2.3/4 engines where cast iron pistons and solid gudgeon pins were used was a copper disc each side of the gudgeon pin. These were good for many miles until wear of the barrels and of the copper discs became sufficient to permit a disc to slip down between the piston and the bore. The result of this occurring is that the gudgeon pin moves to one side and the dreaded "tramlines" appear down the cylinder wall. Normally the wear between cast iron pistons and cast iron barrels is very low and the clearances are also low compared with alloy pistons in an iron bore so it is an extreme case where this problem occurs. A more frequent case is where during assembly a copper disc falls out without it being realised when the piston is being manipulated into the bore. Loss of compression and tramlines will be created in a very small mileage.
Chris.

Offline veikko1

  • Full Member
  • **
  • Join Date: Nov 2014
  • Posts: 29
  • Location: Finland
Re: 1914 2 3/4 engine problems
« Reply #2 on: 14 Jan 2018 at 21:03 »
Hello Chris
Many thanks your answer. I ordered new gudgeon pins from Cox and Turner, England, and them are solid type. Maybe we can do copper disk so tight, that it can`t fallen at assembly time? Would you, or someone else known this engines breathing system. Not any, from timing side? I am thinking, that must come some pressures from crankshaft end ball valves?
Regards Veikko

Offline eddie

  • Master Member
  • ****
  • Join Date: Mar 2006
  • Posts: 1237
  • Location: Hampshire, UK
Re: 1914 2 3/4 engine problems
« Reply #3 on: 15 Jan 2018 at 07:35 »
Hello Veikko1,
                      As you say, the crankcase breathes through the valve in the crankshaft into the timing chest. In the floor of the timing chest (towards the back of the bike) there should be a pipe fitting to allow the pressure to escape. This fitting usually has a short stand pipe on the inside (to retain some oil), and a copper pipe on the outside that routes the vapour to the left hand side of the bike, so that it lubricates the primary chain.

  Hope this helps,
                            Regards,
                                         Eddie.

Offline veikko1

  • Full Member
  • **
  • Join Date: Nov 2014
  • Posts: 29
  • Location: Finland
Re: 1914 2 3/4 engine problems
« Reply #4 on: 16 Jan 2018 at 20:44 »
Thanks Eddie. I have looking pictures of your TT-model, and thinking, what is this pipe. Now I can doing something similar to my bike.
Regards Veikko