View Full Version : Air filter search for B&S 35hp

Arny - n/a
22-Aug-08, 08:54 AM
I have a Flying Fish with a Briggs and Stratton 35hp engine and I am looking for an air filter for it. The one it has now is a cone type that just fits directly on to the intake but it is very exposed and as it points upwards it is very prone to ingesting water spray. It got so glogged up with salt last time out that it stopped the engine and so I am looking for a better solution.

I think it would be better if the air was drawn upwards into the filter to reduce the amount of water getting in. Any ideas?

I used to race karts and the airbox on a 2-stroke kart engine might do it if I can find one with the right sized connection. They are oil-soaked sponge but have a horn-shaped inlet which can be directed either up or down.

If anyone has any better ideas I would really appreciate it.


Don83000 - n/a
22-Aug-08, 11:26 AM
On ours we used a oil bath air cleaner from a series 3 Land Rover and never had any probs.

Cheers Don.

wiggy - n/a
22-Aug-08, 01:36 PM
contact keith smallwood of vortex services, either google vortex or find the link off the HCGB links page.

hes out at the mo and his computer is broken, but will be back begining of next week and i'm sure will promptly fix computer

Ian Brooks - n/a
22-Aug-08, 03:54 PM
The stock briggs 35 has a large cartridge type filter. At the cost of 5lb weight, it's thoroughly spray-proof & for good measure the intake has facilty to connect a hose from clean air. Try Ivan - I guess he must discard them when he changes to the lighter cone filter.

I was going to fit a lighter filter, but went with the standard as I ran out of time but #i think it'll stay now; It's not missed a beat all season and it has got pretty well tested. the only change I made was to turn it through 90 deg so it doesn't interrupt the thrust air.

Do you have an engine cover? How well protected are the HT coils & leads?


Arny - n/a
22-Aug-08, 05:22 PM
Thanks everyone.

Ian, yes, I have an engine cover but the HT leads etc are very exposed and get very wet... I know that won't help but how can I keep them dry when the leads are just loose?


jar2 - n/a
22-Aug-08, 06:17 PM
This is what I did with to the coils: http://www.hovercruiser.org.uk/craft-maintenance/11-scout-ma (www.hovercruiser.org.uk/craft-maintenance/11-scout-maintenance-log.html) intenance-log.html

You will also need to seal the iron core laminations as they are completely bare on the edges - they will corrode and expand the core. Sealing the plug boots to the HT lead is also a good idea (or get motorbike/ATV style sealed boots). Don't route the HT leads against any grounded metal - if the insulation gets compromised then there will be an easy path to ground (use plastic spacers or twist ties to hold it away).

Change the plugs at least once a year - not because there is anything wrong with them but because they corrode around the sealed joint between the metal and ceramic causing micro-cracks and failure.

Once you've done all that you should be able to full-bore hose the engine while it's running without any sign of a misfire.

GavinParson - n/a
22-Aug-08, 08:28 PM
I used the standard air box, vertically next to the engine, used the original intake hose and cut and extended it with a 50mm tube so the whole installation fits neatly under the engine cover. Its well out of the dirty/wet airflow so should last well.

hovmart - n/a
22-Aug-08, 08:56 PM
the standard filter has a paper filter, this is not good when it gets wet, all the k/n filter needs is a cover over the top, its the easy to rinse clean after use and takes up a lot less space

Ian Brooks - n/a
23-Aug-08, 04:13 PM
My experience with K&N's is "wet filter=dead engine", albeit this is from Rotax's, when replaced with foam type filters the problem goes away.


GavinParson - n/a
29-Aug-08, 06:29 AM
The key is to duct your intake air from a protected place,ie. under a proper cover. Leaving your filter in the potentially damp airflow to your fan or prop is just asking for trouble.

Whereas racing craft often have little protection over the engines, there is no excuse on a crusing craft.

I never had any problen with the paper filter when I used a BMW K75 and as I said, my Briggs filter is drawing from clean dry air under the under cover. Also if your craft is well designed and driven properly you should have very little spray anyway.

jar2 - n/a
29-Aug-08, 09:44 AM
There is much good advice on air filters in this thread. The only thing I would add is to use plastic frame/mesh type air filter cartridges - the ones with metal meshes tend to rust badly in a salt water environment and engines don't like breathing bits of rusty metal!

GavinParson - n/a
31-Aug-08, 01:32 PM
Here's a pic of my air filter location (minus engine cover)


garyfirth - n/a
31-Aug-08, 08:28 PM
anyone know service details

plug gap

tappet settings

ps renault 4 oil filter half price and same as bs original

chees gaz

Arny - n/a
1-Sep-08, 08:17 AM
Thanks for all the good advice given.

I will organise a sheltered intake I think similar to this pic.