K&N with added holes?

Has anyone heard of putting a few extra holes in the inside surface (3ea ¾ dia.) of the air filter housing along with a K&N? Sounds plausible as these engines like to breathe and that's what the V-Boost is all about on the VMAX.

I've seen it done by a few people. Their next questions were "what is the best way to plug holes in the air breathers". These engines are already set from the factory to run too lean in most folks opinions. Allowing more air just makes them leaner yet.

Has anyone heard of putting a few extra holes in the inside surface (3ea ¾ dia.) of the air filter housing along with a K&N? Sounds plausible as these engines like to breathe and that's what the V-Boost is all about on the VMAX.

The Vboost ties the front & rear carbs together on each side below the throttle plates. This then increases the fuel that is pulled in on the intake stroke. The same volume of air is pulled in, it just comes from two fuel sources breathing through the same air filter.

As Freebird says, it won't work. I tried it when bike was stock & ended up with duct tape over four 3/4" holes.

Gary

The Vboost ties the front & rear carbs together on each side below the throttle plates. This then increases the fuel that is pulled in on the intake stroke. The same volume of air is pulled in, it just comes from two fuel sources breathing through the same air filter.

Well all it means is if it leans it out, it gave you more airflow, then you just have to rejet to that air flow. I understand just the holes alone may not work. Just wondering if there would be any other trade off's? MPG go to Hell? Low end affected. I really think it could help righer RPM's. I'll have to think about it more!

Just re-read your post and would diagree with that it pulls in the same volume of air and just increases fuel. That wouldn't give you much at all. It pulls more of both in as that's the only way you'll get more power.

bump:detective:

What I did, an wished I had not, was to enlarge the hole as far a possible after putting the K&Ns on my bike. I ended up with a severe flat spot upon medium to hard acceleration (bogged down). I was able to 98% compensate for that by reshimming the needles on the diaphrams, I can still feel it bog down every once and a while , but it is tolerable, if I had it to do over , I would not enlarge the intakes, I suppose I coould rejet , but it is not needed right now. .

This mod is also called the RAK, Ram Air Kit mod. I've done it to my 650. The bike must be rejetted to accomodate the extra air flow. Otherwise, something like my 650 runs like it's being strangled. We started the mod at a MD, the first one I ever attended with the Houston mob. Since we couldn't get the carb screws out, I had to ride it home as is. Definitely NOT fun! Got a friend of mine who is a race mechanic to do the rejet. Cruisers are definitely not his thing but as a favor to me, he took it on. It did improve the bike's performance. Upped the "get up & go" and the mpg a bit. Only thing I have to watch out for is the local wasp population doesn't try out the inside of the air breather as their new home, something they did to my old Atlantic!

Just ordered some K&N's. The inlet hole is about Ø0.75 in area smaller than the outlet on the filter housing. I'm going to change the opening to a slightly diamond shape to get it about Ø0.75 in area bigger than the outlet, then put a course screen over the opening to keep the critters out! That's how NASCAR reduces power by adding carb restrictors! I'm sure I'll have to rejet, no biggy. And I just bet my mileage will go up slightly. Seen it plenty of times on other bikes. It's all in the jetting.

I enlarged the air holes in my 03 and I am here to tell you that it doesn't work, on a stock set up. I had to buy new air cleaner boxes to fix the problem that I created. I have found that bone stock is the way to go with these engines. Now there is no back fire or hesitation and no bogging down at full throttle.

Does this mod work? Well this seems to be a question that hasn't really been answered to its full potential as of yet. Up to this point it seems as though the responses would suggest that drilling the holes would allow more air into the engine. As others have stated this "mod" is a no-no by itself as far as performance goes, but what if the engine had a good set of slip on pipes and a full reject/carb workover to match more air and easier exhaust exit. I would bet that in the hands of the right carburetor tech/genius that this would probably be about the cheapest horsepower money could buy. What are the thoughts of others? Has anyone done a complete carburetor tune after having installed better breathing air intake and exhaust? What are the results once properly tuned?

I am really interested in knowing if this has been accomplished by anyone as I have been considering having my carburetors tuned by a highly recommended guy in Vancouver who only does carburetors. I have installed LA Choppers slip-on exhaust and was planning on doing the K&N air filter swap next service.

Increasing intake air and exhaust flow as a general rule, the increase in horsepower, if any, will occur at the upper end of the RPM range, usually at the expense of low speed response. I think if you know what you are doing and have access to a dyno and lots of time to remove and reinstall carburetors, intake air and exhaust mods on this bike Might get you 5 horsepower at peak rpm only and not through the entire powerband. The affect on your performance will be neglible IMO.

If you look at the performance chart posted in the 1/4 mile times thread in the RSTD forum, you will see that you need a large increase in horsepower to acheive a relative small gain. If you look at the 97 RSTD Vs the 2005 RSTD, these bikes have a difference of around 12hp at the rear wheel (dyno data), nearly the same torque, and very little difference in performance. Here is alink to the MCN performance data fromthat thread. http://www.mcnews.com/mcn/technical/2012JanPerfIndx.pdf

There is probably more opportunity to make the bike faster by making it lighter. As the chart bears out,its all about HP per Lb. Carbon fiber fenders anyone???

RSTDdog

I swapped out the stock air cleaner boxes and put on a matched set of hyper-chargers. Now I would do it again and yes takes a little tuning of the jets and metering rods and a set of stock Harley mufflers. I have a small flat spot that lasts around 2 seconds when stretching out 2nd the gear but put it up against a Harley with cams and open exhaust well to be kind they are close but no cigar when it comes to an all out run, I do not come in second. Also the intakes make more noise which reminds me of back in the 70's when you could hear that 750 bbl sucking wind. Understand you need to re-jet and open the exhaust (I even have a set of open Screamin Eagle mufflers for the bike but they are too loud for me) some to get the full use of the added breathing. Gas millage is still in the 43mpg range, but that depends on how much twisting you do. As with any mod until you do it you won't be sure if it is what you want. I did mine and bought a new set of filter boxes and cut them down to work as needed and the price for new ones wasn't all that much.

These bikes are setup with the carbs lean and the intake just as leaned out. Open one you should open the other and once you get it close by re-jetting and such either re-tune the carbs (sync) or get it on a dyno. the dyno will tell you more as far as how much more or less to change but like I said I would do it again and the power difference I feel makes it worth it.

I swapped out the stock air cleaner boxes and put on a matched set of hyper-chargers. Now I would do it again and yes takes a little tuning of the jets and metering rods and a set of stock Harley mufflers. I have a small flat spot that lasts around 2 seconds when stretching out 2nd the gear but put it up against a Harley with cams and open exhaust well to be kind they are close but no cigar when it comes to an all out run, I do not come in second. Also the intakes make more noise which reminds me of back in the 70's when you could hear that 750 bbl sucking wind.

Have you been up against any stock Ventures with this set up? What was the outcome? Just curious?

RSTDdog

the 96-01 standard royals has 28mm carbs on them and do suffer from restrictions. most of us who has these bikes has opened up the filter box and k&n filters to increase the power of them. our bikes only has 1 air filter on it sitting on top of the motor under the tank, and we open the stock opening to 2 1/8 ' and drill a second 2 1/8" hole thru the box and filter( which i did), some guys cut between the 2 holes and make like a foot -shaped opening as we call it "the big-foot air mod", but i don't see any differants in it( cutting out between the 2 holes. but with all said and done, you can only put a certian amout of fuel/air mixture into a certian measured area without forcing it into it. BLOWER OR TURBO CHARGER ANYONE?? i have seen on 2 royals with a blower or turbo. one had a turbo from mr turbo in tx and costed around $4k to pipe up and the guy who owns modesto customs in ca has a standard royal with a blower and side-draft carb on it, i asked him how fast he had it and he siad he had never opened it wide open but it was fast enough for him.

Have you been up against any stock Ventures with this set up? What was the outcome? Just curious?

 

RSTDdog

No I haven't but I would like to see what would happen. I'm not saying the differance is hugh but I would still like to see. I am looking at it thinking like a car. If you have 2 stock cars and on one you change, open the exhaust (remove the muffler add glass packs) and open the air cleaner there is a performance gain compared to the other car because of the unrestrictive air flow now.

These engines are already set from the factory to run too lean in most folks opinions. Allowing more air just makes them leaner yet.

I'm well aware that we go through fads in any any forum with different views coming to the fore at different times and I hesitate to doubt anything Freebird says (not least as i want to find time to ask him about discussion forum settings..) but...

The views over many years seems to have been that many VR's run too rich, surely. It's possible that some of this could be due to age and leaking o-rings around the emulsion tubes, but blackened sooty areas around the exhaust pipe ends can testify to over-rich mixtures (so if you don't have this, then an over-rich mixture might not be your problem).

Many people talked about drilling holes in the top of the airbox or keeping it slightly open, but I don't recall any great successes being reported and it didn't work for me. What seemed better for some (but not all) was replacing the throttle needle shim with a thinner one (or washers) to weaken the mid-range mixture. I did it with washers and may have a slight mpg improvement.

Part of the moral is that the only way to an ideal conclusion is to diagnose your own vehicle appropriately - I just queried whether the VR was generally set up too weak.

NB - the VR was set up differently in different markets and different years so experience in different areas may have varied.

[EDIT - I've just realised that this post in in General tech and not First Gen. How did I stray in here by mistake ???? I have no idea how Ventures other than first gens were/are jetted.]

gregg, in talking to my friend, who is a very good yamaha mechanic, all bikes in us are missed tuned to meet epa standards and some are more restricted by CA with more rules. most countries around the world don't have the strict rules we have so your bike is setup a little differant. in the old days before epa rules, you would see most cars with a cream or white colored exhaust pipe and you knew it was set right as air/fuel mixture. the only car i've seen in recent yrs with a cream colored pipes are the pontiac sst's.