Forum

[Connie 60]

The more I read and ponder I am becoming more and more suspicious of my pistons and rings. I can see the new high volume pump working like a champion on cold start up. It pumps that hard that a good stream shoots from both holes at the top of the return tube until it clears the cases and becomes intermittent. This flow is coming from the cases and not the timing chest as well because I had only just fitted the pump and replaced the cover. This gives me some confidence that the scavenge lines are ok.
Apart from reinstating the crank breather to help out I wonder if it is simply that that much blowby is getting by that it is forcing the oil out the breather before it can be scavenged adequately. Could this be possible and that there is actually nothing wrong with the scavenge system? When the the bike is on the work table and I pull the motor over by hand with the kickstart I can hear a fair bit of leakage going past the rings. How much is normal though? Its all very subjective.

[Bullet Whisperer]

You don't want any leakage past the piston rings - certainly none that you can hear !! I bet your engine oil turns black very quickly too. You have excessive blowby, without a doubt. Cheers, Paul.

[Norm]

I have a feeling I mentioned that several days ago

[Connie 60]

You sure did Norm but with new rings and pistons how hard can it be? I am sure I got the rings in order but but maybe I botched it or the shop didnt get the clearances right. I reckon I might go out another size and start again. Any sugestions on supplier with due respect to hosts of course but I am concerned about the Indian parts in the twins now from whatI have read.

[Barnes]

Hi mike. Dave hollyman imports and supplies the JE pistons I have mentioned. If the conny runs the same bore dimensions as the super meteor then the standard interceptor pistons that he gets fits a +.40 bore on the conny. Ed

[Norm]

Mike I put an Inter together a while back new pistons and rings and it smokes and went through lots of oil, it is pulled down again at the moment waiting on another set of rings to see if that will slow it up. Also fitted stem seals to see if that will help

[Connie 60]

Thanks guys I shall lift the barrels and check out the clearances before going any futher. A hone and different rings would be a start in the right direction but I fear the bores will be maxed out for this set of pistons which are only at 10 thou so plenty of meat left yet.
Cheers Mike

[Norm]

Mike what are you saying here are they +10 pistons or do they have 10 thou clearance. If piston clearance is within spec, a light hone to clear any glazing of the bores and a new set of rings and you are good to go again. No point in boring if there is no bore scoring

[Mark M]

Mike, OBB (Bob Murdoch) on the lnterceptor site described how he cured oil burning on an SM by using car rings from a Morris (?) but sizes only go to +40 for our use. Piston lands need widening but this is not difficult. Check it out! REgards, Mark

[Bullet Whisperer]

I will share a little secret - with 70mm bores as standard, piston rings for a 'unit' 250 Matchless G2 and the AJS equivalent [model 8?] will go where any 70 mm bore and oversize Enfield engine piston rings will go, and so far, at least, I think most piston rings available for these machines are NOS Hepolite items, not shoddy reproductions. Cheers, Paul.