Hitchcocks Forum

Hi All,

I am an expat now living for the last year in NZ. I have just done a two day trip from Christchurch to Hastings from the south island to the north island. Lost my air filter on the first day and bike (350 RE classic), bike ran and drove great for the journey until near the end. I stopped for petrol and noticedots of oily mess over the full stand. I did not seem to have compression, but bike started and i got home. I got the bike to start at home, but no compression. Please what could this be?

Cheers

Mike

They do that from time to time

First check the valve clearances

Decompressor stuck open maybe? I think this because you said you lost the air filter. Could equally be something stuck in a valve. Flying a kite.

Another thought - Did the 'low compression' occur shortly after stopping for petrol - you may have received rubbish fuel. Old 'blown' petrol might feel like low comp, what does the kick start feel like? Oily mess is normal, only dots! that's clean (and could be from the chain), check gaskets later. Check fuel flow, blocked filters, jets.

Sticking decomp is common (if you take it to bits just be sure you don't drop the valve in the engine - easily done)

You should hear the decomp "wheezing" into the exhaust port if it is stuck)

Also check valve clearances but that shouldn't happen all of a sudden. Did it have compression when it had cooed down?

Having said all that, my 350 has occasionally lost compression and has mysteriously got it back again.

If the air filter dropped off it was the cone type on the back of the carb? Shouldn't make any difference as they are pretty free flowing. Probably a good idea to replace it though.

My thought on the lost air filter is foreign object down the hole holding the decomp open when you re-started, not enough to wheeze. Bugs and beetles going in whilst the engine is running get ground up but when the decomp is used they can get stuck if a bit of grit gets in there.

But like I said, flying kites, throwing ideas up; what happened before it went wrong, lost the air filter and fill up. Trace the problem back to the point it went pear shaped.

Hi All,

Many thanks for all of your help and advice. I will check it out, but just worried about the amount of oily mess.

Cheers

Mike G

Hi All,

Many thanks for all of your help and advice. I will check it out, but just worried about the amount of oily mess.

Cheers

Mike G

As so often happens people only answer half the question with the obvious answer. Lost air filter, would cause lean running, oil blowing out, crankcase pressure probably caused by piston damage/seized rings due to running too lean.