Oil in 998cc air box

[GSSpyder2008]

Simple job - did mine today (thanks Ron for foam) The pipe is a bit ''non flexible'' to get the correct curve but fits fine

 

[BajaRon]

Simple job - did mine today (thanks Ron for foam) The pipe is a bit ''non flexible'' to get the correct curve but fits fine

It is a bit of a tight fit. I just trimmed each hose a little at a time until the fit was just right. Some have put a 90 in the lower hose to get a bit more room. That's fine as long as there is no low spot where the oil can collect. You do need a continuous downhill course for the oil to get all the way back to the entry/exit point on the engine.

Now you will be air-box oil free!

 

[VLADI]

Wrote on-coordinators. Thank you in advance.

 

[BajaRon]

Wrote on-coordinators. Thank you in advance.

I am not sure what you mean here. If you are saying that you attempted to contact me for a chunk of foam. I have not received anything from you either by email or PM.

If I am off base with my guess. I apologize.

 

[EKB2to3Wheelz]

Crankcase breather modification

Is the idea with this filter inserted in the crankcase vent line that the oil vapors condense out the oil and it drains back into the crankcase? Would this work if you’re going for several hours on a trip? I’d think the positive airflow from the crankcase would eventually be pushing the condensed oil up to the air box.

Very common problem with the 998 V-Twin. Some get enough oil in the air box that it wets the air filter and drips out the weep hole in the corner. 'Normal' doesn't necessarily mean it's right or should be happening. What other vehicle have you owned where you find oil in the air box? If we were to be honest. We'd simply call it what it is. A design flaw.

You basically have 3 choices. 1- You can run with a low oil level and see if this helps. Usually, it does not because it's not the oil level in the reservoir causing the issue. The crankcase vent comes off the head, not the reservoir. If you do choose to run your oil level low, check often because the 998 uses oil. 2- You can run the oil level where it is supposed to be and live with oil in the air box (Choice #1 and #2 being very similar in results). Or 3- you can fix the problem and have the best of both worlds. A full oil reservoir and no oil in your air box.

The good news is, this issue is easily and cheaply remedied. There have been several approaches. One being a 'Catch Can'. However, a true catch can removes oil from the system (albeit, not that much) and requires maintenance. I recommend a crank case breather modification. It works just as well as a catch can, is less expensive and easier to install. And, it is virtually maintenance free. It also offers the advantage of returning perfectly good oil to the engine where it belongs instead of you draining it out from a catch-can. The necessary parts (Listed below) are readily available at any auto parts store, except for the open cell foam. Which I will provide you upon request.

All you need is one of these glass fuel filters...
View attachment 175481

and 4 of these small hose clamps.
View attachment 175482

You do not use the plastic nipples as they make the assembly too long. You do not use the fuel filter element so that gets removed. Instead, you will need a small chunk of open cell foam (which I will supply at no charge if you email me). You want the foam to fill the cavity but not be compressed (kind of defeats the 'Open Cell' component of the foam if you mash it into the filter housing).

Cut the vent hose so that the hex filter ends fit into the upper and lower hose, apply the clamps and you're done! I've had mine on for over 30,000 miles and have not had to do anything to it. It still works as well as the day I installed it.

The installed assembly ends up looking like this.

View attachment 175483

 

[BajaRon]

Is the idea with this filter inserted in the crankcase vent line that the oil vapors condense out the oil and it drains back into the crankcase? Would this work if you’re going for several hours on a trip? I’d think the positive airflow from the crankcase would eventually be pushing the condensed oil up to the air box.

I've had my crankcase vent mod installed for 30k without issue. 2 trips from East Tennessee to California in hot weather. I think you'll find the mod works very well. Cured my oil in the airbox issues for good.

 

[DaniBoy]

Very common problem with the 998 V-Twin. Some get enough oil in the air box that it wets the air filter and drips out the weep hole in the corner. 'Normal' doesn't necessarily mean it's right or should be happening. What other vehicle have you owned where you find oil in the air box? If we were to be honest. We'd simply call it what it is. A design flaw.

You basically have 3 choices. 1- You can run with a low oil level and see if this helps. Usually, it does not because it's not the oil level in the reservoir causing the issue. The crankcase vent comes off the head, not the reservoir. If you do choose to run your oil level low, check often because the 998 uses oil. 2- You can run the oil level where it is supposed to be and live with oil in the air box (Choice #1 and #2 being very similar in results). Or 3- you can fix the problem and have the best of both worlds. A full oil reservoir and no oil in your air box.

The good news is, this issue is easily and cheaply remedied. There have been several approaches. One being a 'Catch Can'. However, a true catch can removes oil from the system (albeit, not that much) and requires maintenance. I recommend a crank case breather modification. It works just as well as a catch can, is less expensive and easier to install. And, it is virtually maintenance free. It also offers the advantage of returning perfectly good oil to the engine where it belongs instead of you draining it out from a catch-can. The necessary parts (Listed below) are readily available at any auto parts store, except for the open cell foam. Which I will provide you upon request.

All you need is one of these glass fuel filters...
View attachment 175481

and 4 of these small hose clamps.
View attachment 175482

You do not use the plastic nipples as they make the assembly too long. You do not use the fuel filter element so that gets removed. Instead, you will need a small chunk of open cell foam (which I will supply at no charge if you email me). You want the foam to fill the cavity but not be compressed (kind of defeats the 'Open Cell' component of the foam if you mash it into the filter housing).

Cut the vent hose so that the hex filter ends fit into the upper and lower hose, apply the clamps and you're done! I've had mine on for over 30,000 miles and have not had to do anything to it. It still works as well as the day I installed it.

The installed assembly ends up looking like this.

View attachment 175483

Thank you, Ron! Disregard my email, as this is exactly what I was looking for!

I do have a couple questions though: I’m assuming this is on the left side of the 998, where the oil filters are? Also, I’m gathering that the original hoses that are already on the bike will fit over the hex nut? If so, I’m confused about why 4 hose clamps. Seems like there’d just be one around each end to hold the hose to the nut. I’m not sure how a round hose can seal over a hex nut without leaking, but I’ll take your word for it!

 

[LongBeard]

I will be trying this

 

[BajaRon]

Thank you, Ron! Disregard my email, as this is exactly what I was looking for!

I do have a couple questions though: I’m assuming this is on the left side of the 998, where the oil filters are? Also, I’m gathering that the original hoses that are already on the bike will fit over the hex nut? If so, I’m confused about why 4 hose clamps. Seems like there’d just be one around each end to hold the hose to the nut. I’m not sure how a round hose can seal over a hex nut without leaking, but I’ll take your word for it!

This applies to all 998 V-Twin Spyders. Does not apply to the 1330 versions.

I know this is old. But I didn't see it at the time and this seems to be a reoccurring question. So, I will answer it now. With the old adage 'Better late than never'.

Yes, the vent hose in question is located on the rear cylinder on the left side of the Spyder.

The original hose is fine but will need to be cut to install the glass filter assembly.

I put clamps on all 4 ends but you can probably get away with the 2 clamps on the hex end of the glass filter.

Yes, the hose will seal against the hex. Some grind or file the hex to a more rounded shape. Better fit to the hose and easier to push the hos on over this portion of the filter.

Hope this helps!

Ron (bajaron)