trials and Tribulations (reed Breather and Exhaust)

Hi
Recent week long Bathurst rally found a couple of issues with my Combat.
The exhaust system is way to noisy and the engine leaks everywhere when run over 65 mph.
Brought new mufflers only to find out the down pipes are 1 1/2", hadn't noticed before.
Then turned around and had to buy new down pipes (English made), fitted the RH side only too find the pipe too low and new mufflers nowhere near the mounts, had to strap the exhaust to the frame and connect the overhead crane up and pull the exhaust up, two goes and it lined up perfectly.
The right-hand side fitted correctly.
The pipes that were on before never blued or changed colour, I now know why now as they are twice the thickness of the new pipes, that already changed colour, straw.

With the oil leaks I thought I would go the reed breather route and machined up a housing to suit the cheap mini bike reed valves.

Today was the first start, but I decided to pressure clean the bike first, when I tried to start it, it took a few kicks to start and only ran on one cylinder for a short while, by the time I checked the breather pipe in the tank there was only just a perceptible amount of air coming through the breather so.
My question here after the long winded part is this normal that the breather stops breathing rather quickly with these reed valves, my thought was that it would take a bit of time?

Went for a 15 mile run and for the first time there is no evidence of oil leaking anywhere, after sitting in the workshop for 3 hours, this a first?

We have a rally next weekend, where I should clock up 200 miles or so some at decent speed so it will be a good check.

Best Regards
Burgs

Power washers and old bikes do not mix, there is no seal on the cable entry to the points chamber, you will have water in there still. Once the reed breather is in balance little air comes out, this only takes a few seconds of running.

At a fast idling 2000 rpm the crank turns 33 times every second.

How many seconds had it been running, when you looked at the breather?

In MOST cases, a properly installed reed valve will cure almost all oil weepage. It doesn't stop case leaks from gouges and ill fit, and doesn't stop oil leaks at misfit pressure points.

ANYWHERE that the oil weeps from engine operating VAPOR pressures, it cures.

Hi
Trispark ignition so no points, most likely wet spark plug leads.

Ran no more than 30 seconds at around 1250 revs with a couple of blips to get it firing on both cylinders. thought at first that the breather was stopping engine from breathing, but it all appears ok since the run.

Grandpaul vapour leaks and leaks from the old breather, real test will be the rally next weekend. When I pulled the old breather off the hose didn't too good, so there could have been some oil leakage there as well.

All I got to see from the breather tube in the tank was a slug of oil spit out around 1 1/2" long, then nothing.

Next thing is to attack is the wet sumping but work load building up so not for a while.

Burgs

Photo of my homemade reed breather, just raw not pretty as I reckon it will get dirty anyhow.
If I cleaned it up it probably would have failed?
Kept squat to make fitting the hose on easy.
Bit of a beast to bolt up in place but time, patience and cut down allen key got me there.
Burgs

I like.
More pics please.

ETINCT I was able to upload an image using postimage this morning but can't load via url tonight? Well sorted at last, just a bit slow to load.


Burgs

That’s an impressive piece of DIY engineering there sir.

You do know that these are available off the shelf don’t you?

I think he plans to do off the shelf himself

Ahhh, ok!

Thanks for the compliment. You copied a fine design. Jim

Hi
I know these are off the shelf and I have no intention of manufacturing them as I don't have the time, I do repair work on Caterpillar transmission parts that takes up my machine time, just do little bits for my bikes when I want as I like to do so, makes a change from machining steel and cast iron .
Also not as much money in doing small jobs.

Sorry Jim for copying but made the housings slightly different to yours as you can see, made 3 off as that was the amount of aluminium I had on hand.
Went to engrave them but my D bit had a broken tip and not having good eyesight didn't notice until I half way through the first one .

Best Regards
Burgs

Burgs said:

Hi
Sorry Jim for copying but made the housings slightly different to yours as you can see, made 3 off as that was the amount of aluminium I had on hand.
Went to engrave them but my D bit had a broken tip and not having good eyesight didn't notice until I half way through the first one .

Best Regards
Burgs

Click to expand...

Not a problem. Glad it's working out for you. Jim

kommando said:

Power washers and old bikes do not mix, there is no seal on the cable entry to the points chamber, you will have water in there still.

Click to expand...

Water-cooling for the Tri-spark. Sounds pretty high-tech to me

Hi
MFB, you blokes were making me paranoid, so I had a look under the points cover and no water on, in or near my TRISPARK .

On the other side had a 70 mile run today with mixed fortunes, good one, no oil on the outside of the engine for a change, usual bad spots were the rear of the case flanges, tacho drive and mist spots around the rocker caps, so tanks Jim for ideas from your design of the breather reed valve.

Bad side while slipping along home at a good rate of knots the left hand exhaust thread let go, got a bit noisy from there.

Now have to rebuild the original Combat head that also has damaged threads, I am currently running a standard head, sort of liked the smaller ports.

Best regards
Burgs

Burgs said:

Photo of my homemade reed breather, just raw not pretty as I reckon it will get dirty anyhow.
Burgs

Click to expand...

Burgs
What is the reason for the spacer holding the reed valve off the crankcase? (looks like about 15mm thick)
The reed assembly faces outward so it can't be to make room for the reeds.
Is there a reason you can't mount the valve directly on the crankcase?
Cheers
Rob

Hi Rob
The spacer is required for a few of reasons, one you need an adaptor/spacer to marry up with the two bolt holes in the crankcases (1972 cases) and the reed valve plates which have a four bolt rectangular pattern can be adapted to suit, also need room etc to go from a round hole in the crankcase to line up with the two rectangular holes in the reed valves.
The adaptor is machined out of 10mm plate and ends up 9mm thick not a big issue the reed valve cover is about 15mm thick, need room to clear the reed valve stops and also to fit the breather outlet for the hose.
First the adaptor plate is bolted to the crankcase and then the reed valve plate and the cover plate is bolted up.

So the reason is all there, different though if you machine the case flat, drill and tap 4 bolt holes to match, but I wasn't going to remove and strip the engine down to do that.

Hope this helps, over all height is about 27mm, retaining the original hose size, in hind sight I should have fitted a 3/8 barb and replaced the breather hose instead of having the reducer in the breather line, this would have allowed me to reduce the overall height and also allowed me to be able to source a better hose.

Burgs

Yeah - thanks for the explanation Burgs!
I have the engine ('64 650ss) out of the frame at the moment so access is not an issue.
The cases are also donors (ex- Norvil- eBay) so defiling originals isn't an issue.
I've milled and drilled the rear of the cases and ported them to match the ports of the reed valve.
Got the block of alloy yesterday - now to mill it - probably not as purty as yours.
Thanks again for the explanation.
Cheers
Rob