removing the stock airbox '83 (shadow)

[cdntfindanAscot]

Morning Gents,
I have posted the same question on the Shadow forum, but seeing as they share an engine with the Ascot thought I'd try here too in the hope that they're pretty much the same...

Pretty much what it says in the title. Has anyone successfully removed the stock air filter box etc and replaced it with a pod/ K&N/ Uni type filter?
I know these are a bit fussy when it comes to air and fuel intake but I'd like to lose the box on mine and it would be most helpful if I have a good starting point.

So can anyone out there say 'yes! you need filter X, jet Y and air screw out Z turns and away you go'?

I know its hoping for a miracle but you never know
cheers

[J6G1Z]

I didn't remove my airbox on my VT500FT, but I modified it as much as I thought possible. I removed all the internal screens & replaced the filter with a K&N filter. (I don't run or recommend K&N filters any longer due to fine dust passing through to the clean side) I then cut off the rubber intake snorkle & replaced it with a small aluminum velocity stack that just fit into the opening.

I ran the MAC dual exhaust & had a Bike Shop tune the bike by placing sniffers up each pipe. I seem to recall that they went up on the main jet 2 sizes, but I'm not 100% sure on that one.

Check out the bike below. Unfortunately I don't have any info on the bike other than the picture.

Good luck
J.

[J6G1Z]

It has been a while since I've worked on an VT500FT, but I seem to recall a large common plenum running under the fuel tank from the carbs to the airbox. I think that I would look into keeping that plenum & remove the airbox. Then locate a large UNI type of oiled foam filter that would go around the end of that plenum inlet. Just food for thought.

Whatever you end up doing. Please make a post that shows what you did.

Good luck
J.

PS. Another resource you might try is the FT500 Ascot owners group on Yahoo.
http://groups.yahoo.com/neo/groups/ascotvt500enthusiasts/conversations/messages

[cdntfindanAscot]

cheers J
You are correct, there is a plenum/ big rubber sock that goes from the carbs to the airbox and the hope was to attach a filter to that.
now to Physics 101
I am guessing that if i just remove the box and strap on a pod filter, the air flow speed, if different, (probably greater) would be what causes any upset?
does it make sense that if i take a stock air filter, make my own 'container' and have an inlet of the same size as the stock box it should work?
I know that the length of the inlet manifold (carb to cylinder) has an effect on performance but will air inlet length have an effect?
or is the air pressure/flow the same regardless of box size?
my brain hurts now, think i need a lie down
cheers
nev

[J6G1Z]

....my brain hurts now, think i need a lie down
cheers
nev

Huh....  My head hurts also. I will have to think about this over a nap.

J.

[J6G1Z]

So... I've been thinking about your last post & I'm trying to determine what you are attempting to achieve.

Usually you modify the air intake & the exhaust outlet to allow a larger volume of air to be pumped through the engine as easily as possible. Then you add more fuel & that creates more power. Usually you start with modifying the exhaust to allow the engine to exhale easier & reduce pumping losses. Then you move over to the intake side.

If you build another airbox that has the same size holes in it... I'm thinking you might as well leave the factory box in place. The factory usually does a pretty good job on engineering the airbox & exhaust. The OEM components most likely provide the highest level of performance at the stock sound levels on the exhaust & the most weather protection on the intake. Now if you don't care how loud the exhaust is, than you can find more performance. If you don't care about hearing the carbs sucking air & don't ride in the water, etc, then you can find more flow on that end. More airflow + more fuel = more power & most likely a bit of a drop in MPG. Hopefully you build enough power that you need less throttle input to achieve the same speeds & maybe your MPG numbers break even.

It's all about what trade-offs you are willing to live with.

Well... I hope my ramblings make some form of sense & are helpful.

Good luck
J.

[cdntfindanAscot]

So... I've been thinking about your last post & I'm trying to determine what you are attempting to achieve.

...

Its purely cosmetic. not trying to gain an extra hp or two just trying to get a stripped down bare bones look. (this kind of style... http://thebikeshed.cc/2013/10/24/redmax-trumpet-tracker/  )(only a cheaper shed build  )
If I can lose the air box then i will swap out and hide the battery etc under the seat hump

[J6G1Z]

Boy that is a great looking bike!

There is nothing as appealing to the eye like a Street Tracker done right.

J.

[J6G1Z]

Hey there Nev,

Check out this bike.
http://groups.yahoo.com/neo/groups/ascotvt500enthusiasts/photos/albums/439561376/lightbox/1394657667

There are two pictures of it, unfortunately I don't have any info on it.

J.

[cdntfindanAscot]

cheers J
looks like it has been done then, although the filter on that bike looks like its still in the wrapper, hope it worked 
nev

[J6G1Z]

Probably kept the wrapper on the filter throughout the build to keep it clean.

That's one cool looking custom Ascot! Wish the owner would post up some of the details & specs on the bike.

J.

[Dougie]

I used a pipercross filter over the plenum tube. This combined with the 2 headers merging into a 50mm single pipe allowed it to rev out much better.

The Pipercross filter was listed for a old model Mini.

Can't seem to get the link to work, reporting error.

[cdntfindanAscot]

cheers dougie, i guess you must be mr cormorant from the other place, with a teasing photo title but no photo 

[Dougie]

cheers dougie, i guess you must be mr cormorant from the other place, with a teasing photo title but no photo 

Thanks for that , have deleted the folder without any content.

There is another folder named Pipercross Airfilter, not great pics mind you

[J6G1Z]

cheers dougie, i guess you must be mr cormorant from the other place, with a teasing photo title but no photo 

Thanks for that , have deleted the folder without any content.

There is another folder named Pipercross Airfilter, not great pics mind you 

Please post up the pics or a link to the folder. I'd like to see what you have done.

Thanks
J.

[cdntfindanAscot]

see if this works
http://groups.yahoo.com/neo/groups/ascotvt500enthusiasts/photos/albums/1484252250

and theres a brief conversation from this post...
http://groups.yahoo.com/neo/groups/ascotvt500enthusiasts/conversations/messages/28069
and on for a few more clicks.

[J6G1Z]

There we go. I think that's the way that I would go. I much prefer the oiled foam filters over the K&N type. I used to run K&N's in all of my vehicles until I found a very fine dust on the clean side of the air-box, or carb opening. If you really want to use a screen & gauze filter like the K&N, try the AFE Proguard 7.  http://afepower.com/technology_detail.php?tech_id=6   They use seven layers of filtering media between the screens. I have one of these filters in two of my vehicles & have never found any dust downstream of the filter.

Please post up any pics of your intake & exhaust modifications. There is not very much documentation on modifying the VT's.

Thanks
J.

[Dougie]

Glad you found it.

The most important thing is it sits in still air largely drawing  air from where  the airbox used to sit, behind the sidepanels.

[J6G1Z]

Are there any updates on this post?

I'm about to remove the air-box on my VT500 Ascot & attach a large UNI oiled foam filter on the end of the common intake plenum that attaches to the carbs & runs under the tank.

One of the P/O's modified the exhaust to a true dual exhaust & also modified the air-box by adding some air inlets on the removeable plate that you use to service the filter. I found the foam filter has about a 1" hole rotted through it, so it is no longer filtering the air properly. The bike needs some jetting work as it has a bit of a dead spot around the 1/2 to 3/4 throttle range. It acts like it wants to cut out & chokes a bit, then picks up RPM. Plus it is very cold blooded during the first start of the day. I'm thinking that it is probably running on the lean side & needs to be fattened up some. The dual exhaust has had some sample taps installed in the head pipes a few inches away from the head. I'm assuming they were installed to allow EGT probes to be installed for tuning purposes. I would really like to locate the P/O that performed these mods to find out the extent of the jetting changes (if any) were performed. I will post some pics of the exhaust below.

So... Has anyone worked over their carbs to perform properly after changing the exhaust & filter? What all did you do?

Thank you
J.

[cdntfindanAscot]

I haven't been brave enough yet but the subject was mentioned on a facebook post a few days ago
https://www.facebook.com/hondavt500/posts/598737126885770?stream_ref=10
(in case the link does not work fb page name is Honda VT500 and the post is on the 25th march)
Probably not the answer you are looking for but seems it can be done but lots of messing about and patience required.

[J6G1Z]

I just ordered a Dynojet carb kit to see how that works out. I've always wanted to try one of these kits. I just don't know if it will be rich enough for the filter & exhaust modifications.

Thanks for that link. I didn't know about that group. I'll have to check it out some more.

Here is one post that I think is worthy of saving.

The plenum is the key- multiple CV carbs like to breathe 'common', 'calm' air, so a K&N on the tail end (or inside the OE box) could work well. Briefly; I have K&N type mesh filters, each mounted on a 6" long swept-back 50mmsilicone hose. Mains are #130 front, #135 rear. Needles shimmed up 2mm & slides drilled to 3.2mm, pilots are both #40.....

Thanks
J.

[J6G1Z]

Just in case anyone else is interested...

You need a filter with a 3" I.D. to fit the intake plenum where it attaches to the airbox.

I picked up a UNI model #UP-6300AST. It's a 2 stage pod with a 3" I.D. inlet & 6" long. It also has a 15 degree angle on it.

It fits the plenum opening perfectly. I have not removed that air-box to see how well it fits into that area yet, but I don't expect any problems with fit. I may need to fabricate some brackets/braces to hold the coolant recovery tank in place. That remains to be determined.

Thanks
J.

[J6G1Z]

Well I tried this experiment & the results were not great.

I removed the complete air-box assembly along with the oil seperator & the coolant recovery tank. I found that my coolant recovery tank was dry rotted enough to have a hole right above the current coolant level. Any higher & it leaks. Not good! For now I'm using a tall prescription bottle as a temporary coolant recovery tank. It's working.

Once I removed all those parts & cleaned up the area in the center of the bike, I removed & inspected the air intake plenum. I found several areas where the sealant around the carb boots had rotted away & was potentially letting dirt inside. I cleaned up the plenum inside & out, then I re-sealed the carb boots with some black RTV. I ordered a large UNI filter & installed it onto the end of the plenum. There is plenty of room now & the side panels fit like normal. It is a great looking modification, but unfortunately the bike doesn't care for it one bit. I believe that it is just too much air for the carbs to handle. I installed the DynoJet kit with the richest jets & it still wasn't enough. I think that someone who is real sharp on jetting CV type carbs might be able to make it work, but I don't have that type of experience.

I re-installed my air-box after modifying it some http://ascot500.com/index.php?topic=291.0   and now the bike runs much better. I still have a bad spot after 5.5K RPM, but I just received the next two steps richer jets to dial it in with.

If anyone has anything to add to this post,  please do.


J.

[cdntfindanAscot]

I did try some basic messing about without any success so I am back to stock at the moment. 

For anyone experimenting, this is what I tried. (save you the time trying it out  )
experiment 1.
I removed the whole airbox and clamped the OE filter to the plenum  - thinking it would be the same volume/ rate of air flow as stock. and the result was a resounding 'No!'  - I could not open the throttle more than fraction before it bogged down. I deduced from this that the filter does not slow or reduce airflow in any way. So it must be down to the air 'intake' hose size .
experiment 2.
removed the intake bit (snorkel?) of the stock airbox and connected that to the plenum, (no filter). The result this time?  slightly better than air filter only but still completely unrideable again bogging down as soon as the throttle is opened.
My final deduction being that the volume of stored air in the stock box also plays a big part in the engine running correctly 
My next sometime in the future experiment will be measuring the internal volume of the stock airbox and making another different shaped one (shallow, oblong to run directly under seat pan, with oe intake snorkel on one end and the plenum on the other) and see if that works. If it does then there is plenty of filter material available loose to then fit in said box.
It will probably be a while before I get round to this though, I am making the most of the nice riding weather

[scottly]

I re-installed my air-box after modifying it some http://ascot500.com/index.php?topic=291.0   and now the bike runs much better. I still have a bad spot after 5.5K RPM, but I just received the next two steps richer jets to dial it in with.

If anyone has anything to add to this post,  please do.



J.

Sounds like the snorkel is indeed a major restriction.  ;)What size main jets were stock, what size jets have you tried, and what size jets did you just receive? My experience with the FT CV carb is that it's 90% a main jet issue when you allow the motor to breathe.