The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: sprint on 07.09. 2013 20:13

Title: Super Rocket Oil Loss
Post by: sprint on 07.09. 2013 20:13
A friend has a Super Rocket that has just had an engine strip and re-build. Started it up today and checked oil was returning to the tank, which it was.

Followed him for 2 to 3 miles to the petrol station and noticed it emitting oily smoke. When he pulled up at the station I noticed a trail of oil behind him and when he stopped a pool of oil emerged under the engine.

Checked his oil tank and it was nearly empty and there was no oil being returned.

Got the bike back to his place and drained the sump and whilst a fair amount came out not enough to replace what had been lost from the tank, so it seems that the oil was not being returned, or not fast enough, and so the sump was overfilling and being pumped out the breather?

Filled the tank and oil was returning again. Went for another ride and the same thing happened again. Oily smoke from the exhaust and on checking the tank most of the oil had been lost, though oil was being still being returned when inspected?

I understand that there is an anti siphoning ball in the scavenge pipe which could stick, but would it stick and then free itself again? The pump itself could be at fault but was checked during the stripdown and felt to be OK.

Any suggestion as to what the problem may be or what should be investigated would be appreciated.
Title: Re: Super Rocket Oil Loss
Post by: chaterlea25 on 07.09. 2013 20:36
Hi Sprint,
By any chance has a sump plate with a magnetic drain plug been fitted?
If the plate is fitted so as plug is near the pickup pipe the magnet can cause the ball to stick closed (been there done that!!!)
Other than that are the oil pipes clear ? some times the rubber inner can collapse or a foreign body in the return stand pipe
Was the pump stripped completely? broken drive dogs between the pump gears have been heard of !!!

HTH
John
Title: Re: Super Rocket Oil Loss
Post by: sprint on 07.09. 2013 21:08
Hi Sprint,
By any chance has a sump plate with a magnetic drain plug been fitted?
If the plate is fitted so as plug is near the pickup pipe the magnet can cause the ball to stick closed (been there done that!!!)
Other than that are the oil pipes clear ? some times the rubber inner can collapse or a foreign body in the return stand pipe
Was the pump stripped completely? broken drive dogs between the pump gears have been heard of !!!

HTH
John

Hi John

Thanks for the suggestions and advice.

Yes he does have a magnetic drain plug and it was something that was also passing through my mind. When we drained the sump I noticed that the sump plug was to the front with a fairly long bolt and extended magnet on its end. I believe that the scavenge pipe is also to the front?

I will get him to check if it is close the scavenge pipe when fitted?

There are new oil pipes fitted, but again they can be checked for any foreign bodies or obstructions? 

Not sure if the pump was completely stripped, I'll ask, but would a broken drive dog cause intermittent scavenging?
Title: Re: Super Rocket Oil Loss
Post by: muskrat on 07.09. 2013 22:20
G'day sprint. Another thing to check is the rocker feed banjo bolts. Were they replaced? It could be that the holes are too big and directing more oil there than returning to the tank.
Cheers
Title: Re: Super Rocket Oil Loss
Post by: chaterlea25 on 08.09. 2013 16:57
HI Sprint

""would a broken drive dog cause intermittent scavenging?""

YES


John
Title: Re: Super Rocket Oil Loss
Post by: sprint on 08.09. 2013 19:03
Thanks for all the replies and advice.

Hopefully the problem has been found?

On removing the sump plate it was found that the scavenge tube had not been passed through the hole in the filter but the filter mesh had been placed over the mouth of the scavenge tube so that the oil had to pass through the mesh first!!!!!!!!!!!!

I guess that with such a restriction across the scavenge tube that it simply could not return the oil fast enough and hence being dumped out of the breather?

Filter will be correctly fitted and hopefully problem solved?

Andy
Title: Re: Super Rocket Oil Loss
Post by: muskrat on 08.09. 2013 21:11
Don't ya luv it when a fix is so simple. *smile*
Cheers
Title: Re: Super Rocket Oil Loss
Post by: bikerboy on 09.09. 2013 00:50
muskrat

With regards to those rocker feed bolts, any idea what size holes should be in the banjo bolts ?
Title: Re: Super Rocket Oil Loss
Post by: muskrat on 09.09. 2013 08:21
3/64"
Cheers
Title: Re: Super Rocket Oil Loss
Post by: bikerboy on 09.09. 2013 14:55
Thank you  *smile*