K&N filters and crankcase breather modification for v65

[Auris]

Hi Guzzi people,

I am new to Moto Guzzi and still don't know many of its secrets, but one thing I learned since buying my v65 (1985) is that a regular mechanic (maybe I was unlucky with mine) won't know all about guzzi's. That's why I am determined to maintain my bike by myself when possible. So far I've installed the gearbox oil breather modification. The next thing I am considering to do is to modify the crankcase breather and install k&N air filters instead of that big clunky box, even though I don't yet have full understanding how the breathing system works. I don't know if it's really possible and if it's worth it. I have seen some guzzi's with K&N filters and no big box on top of the engine.

My question one - is it worth doing such a modification? And question two - is there any documentation how to do it? And perhaps there is a crankcase breather modification kit just for that purpose for sale?

Also I would like to understand better how the original breather system works. From what I see now is that there is a split pipe going from the air filter box into the cylinders, but I don't understand whether the oil evaporates from the cylinders to the air filter box and then drips back to the crankcase, or the other way around? Also there is another outlet in the filter box just a centimeter away from the outlet where the "v" hose connects. On my bike there is a hose connected to that outlet which is probably 10 cm long and is closed with a screw at the bottom. It looks to me like it has no purpose. Should this be leading back to the crankcase? Does anyone know what that may be?

Sorry if the questions are obvious, but I am still getting to know my guzzi So any remarks or links to sources are highly appreciated.

 

[Tassie Mike]

Hi Auris, and welcome to the dark side. The small block Guzzis are about the easiest engines you will ever work on. Do yourself a huge favour- download the workshop manual for it and get a copy of Guzziology.
My advice here comes from having lived with a V50, a V65TT and now a V65NTX. YMMV.
On the small blocks, the oil vapour comes out of the rocker covers. It is collected by a tube from each rocker cover into a small box, from which there are two exits. One comes out at the top and connects eventually to the airbox. The other comes out the bottom and is supposed to return condensed oil back to the sump. This is prolly the hose you are referring to as having been closed off with a screw. If you look at the back of the sump you may see a hole on the left that is also closed with a bolt. If you don't connect the oil vapour box back to the sump, you run the risk of pressure backing up and stopping the vapour venting from the engine (see below), and your oil system will be constant loss, meaning you'll need to keep an eye on the oil level and top-up more often.
Yes, removing the stock airbox is worth doing, if for no other reason than it makes air filter maintenance sooooo much easier, thus encouraging you to do it as often as you should! You will, of course, have to invest in pod filters or similar (Unifilter, K&N, pick a brand) and may need to fiddle with the jetting. What you must do is keep the outflow from the rocker covers. If you block them, pressure will build up in your engine and every seal and gasket will seep oil till your engine seizes. As long as they are open you'll be fine. However, you should have them run into a collector of some sort (the stock one is good) otherwise you get oil all over the engine and will be running a constant loss system (see above). If you keep the stock small collector, the opening at the top will emit a bit of oil vapour, so putting a small filter on it will keep things clean and stop cockroaches getting into your motor.
Hope this helps.

 

[Auris]

Hi Auris, and welcome to the dark side. The small block Guzzis are about the easiest engines you will ever work on. Do yourself a huge favour- download the workshop manual for it and get a copy of Guzziology.
My advice here comes from having lived with a V50, a V65TT and now a V65NTX. YMMV.
On the small blocks, the oil vapour comes out of the rocker covers. It is collected by a tube from each rocker cover into a small box, from which there are two exits. One comes out at the top and connects eventually to the airbox. The other comes out the bottom and is supposed to return condensed oil back to the sump. This is prolly the hose you are referring to as having been closed off with a screw. If you look at the back of the sump you may see a hole on the left that is also closed with a bolt. If you don't connect the oil vapour box back to the sump, you run the risk of pressure backing up and stopping the vapour venting from the engine (see below), and your oil system will be constant loss, meaning you'll need to keep an eye on the oil level and top-up more often.
Yes, removing the stock airbox is worth doing, if for no other reason than it makes air filter maintenance sooooo much easier, thus encouraging you to do it as often as you should! You will, of course, have to invest in pod filters or similar (Unifilter, K&N, pick a brand) and may need to fiddle with the jetting. What you must do is keep the outflow from the rocker covers. If you block them, pressure will build up in your engine and every seal and gasket will seep oil till your engine seizes. As long as they are open you'll be fine. However, you should have them run into a collector of some sort (the stock one is good) otherwise you get oil all over the engine and will be running a constant loss system (see above). If you keep the stock small collector, the opening at the top will emit a bit of oil vapour, so putting a small filter on it will keep things clean and stop cockroaches getting into your motor.
Hope this helps.

Hi Mike, thanks for your thorough answer. It helps me a lot! I already had the same assumption about how the breathing system works but was not sure, and now you confirm what I was guessing. I already downloaded a user's manual, but I did not find detailed coverage of this topic in it. Guzziology book is a bit pricy, but probably I will get it, all guzzi people tell me I should own one. Regarding the new air filters, I will do that modification after my trip (Holland - Spain). For the breathing system, your post made me happy, because it looks like it is in place and functional on my bike. I took some pictures and that's what it looks like.

These are two outlets from the bottom of the airfilter/oil breather box:


And here the two hoses join into one:


And finally it leads to the sump. Hooray it looks like the oil breather system is not closed off!


So I am more or less confident that it's all working. What got me worried previously was an extra hose connected to an outlet very close to where the "v" shaped (rocker covers to air filter box) hose connects to the box. That little (purple) hose was installed by my mechanic and it looks to me now that it serves no purpose whatsoever, because the return (to the sump) hoses are in place. See the picture (picture taken from the right side of the bike):



I asked that question on another thread, but didn't get a definitive answer. This little outlet must have some purpose and it's something until now I don't understand what it is. But again, the breathing circle is not closed off and seemingly functional so perhaps I should just not worry about it anymore. But if you have any clues, I'd be curious to know.

Thanks again Mike for your tips!

 

[pokeyjoe]

Moto Guzzi likes to put clear tubes and plugs in the system for inspection purposes. My Aprilla had them, too. My 2012 V7 had two that would occasionally fill up with water. I could remove a small clamp (not a zip tie), pull out the plug, and drain the water out. My new V7 II has clear caps on the airbox. I think that's all you're looking at.

 

[abbienormal]

A lot of manufacturers use this setup. It is just a catch hose for oil/water at the base of the air box or catch tank. A lot of the bikes use a clear hose so you can just look at it and see if it needs drained. Normally they are long enough to hang down by the centerstand area. When there is a build up or at each tune up you just pull the plug and drain it. As John said, normally they have a light fitting clamp so the plug can be pulled out easily. That Zip Tie is not how I would do it. A good piece of hose with the appropriate plug and no clamp would be needed.

 

[bikerpaul2003]

Hi Guzzi people,

I am new to Moto Guzzi and still don't know many of its secrets, but one thing I learned since buying my v65 (1985) is that a regular mechanic (maybe I was unlucky with mine) won't know all about guzzi's. That's why I am determined to maintain my bike by myself when possible. So far I've installed the gearbox oil breather modification. The next thing I am considering to do is to modify the crankcase breather and install k&N air filters instead of that big clunky box, even though I don't yet have full understanding how the breathing system works. I don't know if it's really possible and if it's worth it. I have seen some guzzi's with K&N filters and no big box on top of the engine.

My question one - is it worth doing such a modification? And question two - is there any documentation how to do it? And perhaps there is a crankcase breather modification kit just for that purpose for sale?

Also I would like to understand better how the original breather system works. From what I see now is that there is a split pipe going from the air filter box into the cylinders, but I don't understand whether the oil evaporates from the cylinders to the air filter box and then drips back to the crankcase, or the other way around? Also there is another outlet in the filter box just a centimeter away from the outlet where the "v" hose connects. On my bike there is a hose connected to that outlet which is probably 10 cm long and is closed with a screw at the bottom. It looks to me like it has no purpose. Should this be leading back to the crankcase? Does anyone know what that may be?

Sorry if the questions are obvious, but I am still getting to know my guzzi So any remarks or links to sources are highly appreciated.

I am in a similar boat, I too have a V65, but a Florida 1989 vintage

I am converting my MG into a honed down minimalist bike and want to get rid of the airbox and put K&N or Velocity Stacks onto the carbs. My breather drain into the sump, has been blocked off and the pic you show of two pipes joining at the top, is different on mine, both breather pipes go into the top of the airbox directly.

I do have an oil leak on the bike and I am yet to determine where this is coming from. Levels in both of the gearbox and engine are ok, I have just replaced the gearbox oil and the engine oil is quite new as PO had supposedly just serviced it...

An associated question, can the inlet manifolds be swapped left to right and right to left to get different angles for the carb mounting? Looks to me on first inspection that this could be the case.

Am I likely to run into issues with the sump return feed blocked off or is it just a keep an eye on the levels?

I am just starting this project as others are coming to an end, I can post photos if people are interested as I go along.

Keep smiling and any advice you can give would be gratefully accepted.

Many thanks Paul

 

[Auris]

I am in a similar boat, I too have a V65, but a Florida 1989 vintage

I am converting my MG into a honed down minimalist bike and want to get rid of the airbox and put K&N or Velocity Stacks onto the carbs. My breather drain into the sump, has been blocked off and the pic you show of two pipes joining at the top, is different on mine, both breather pipes go into the top of the airbox directly.

I do have an oil leak on the bike and I am yet to determine where this is coming from. Levels in both of the gearbox and engine are ok, I have just replaced the gearbox oil and the engine oil is quite new as PO had supposedly just serviced it...

An associated question, can the inlet manifolds be swapped left to right and right to left to get different angles for the carb mounting? Looks to me on first inspection that this could be the case.

Am I likely to run into issues with the sump return feed blocked off or is it just a keep an eye on the levels?

I am just starting this project as others are coming to an end, I can post photos if people are interested as I go along.

Keep smiling and any advice you can give would be gratefully accepted.

Many thanks Paul

I am very interested in your progress. My wife and I are still on tour. We did around 1800 km with our old guzzi so far. We'll be back home soon and shortly after that I will start the modifications. So it would be interesting to know how it's going for you. I am particularly interested in which jets are necessary for which air filters - every one is talking about rejetting, but I haven't seen any specifics about that so far.

 

[Auris]

By the way, how easy/difficult is it to remove the factory airbox from a v65? I hope it's not necessary to split the bike...