Ascot Forum

Second Generation Ascots => Tech Section => Topic started by: cdntfindanAscot on October 25, 2013, 04:54:04 am

Title: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on October 25, 2013, 04:54:04 am
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
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 25, 2013, 09:56:35 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 25, 2013, 10:02:29 am
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
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on October 25, 2013, 01:28:08 pm
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
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 25, 2013, 03:26:32 pm
....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. ;D

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 25, 2013, 05:19:56 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on October 25, 2013, 05:42:05 pm
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
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 25, 2013, 06:24:35 pm
Boy that is a great looking bike!

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

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 26, 2013, 03:10:50 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on October 26, 2013, 03:44:08 pm
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
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 26, 2013, 06:22:19 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dougie on October 28, 2013, 08:21:50 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on October 28, 2013, 08:40:15 am
cheers dougie, i guess you must be mr cormorant from the other place, with a teasing photo title but no photo  >:(
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dougie on October 29, 2013, 06:44:00 pm
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
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 30, 2013, 09:48:06 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on October 30, 2013, 10:00:37 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on October 30, 2013, 10:58:24 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dougie on October 30, 2013, 07:36:51 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on April 21, 2014, 11:17:10 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on April 21, 2014, 11:26:08 am
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on April 21, 2014, 01:32:13 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on April 21, 2014, 01:55:17 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 11, 2014, 04:32:46 pm
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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: cdntfindanAscot on July 11, 2014, 06:06:01 pm
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  :o
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 :)
Title: Re: removing the stock airbox '83 (shadow)
Post by: scottly on July 15, 2014, 10:49:01 pm


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.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 16, 2014, 10:36:47 am
The stock main jets were a #112 & #120.

The replacement jets are part of a DynoJet kit that uses their own unique jet identification numbers. The kit comes with 2 sets of jets, #118 & #122. These sizes do not correspond with Keihin or Mikuni sizing. The new jets are numbered as #124 & #126. Now I just need to get off my backside & replace the jets.

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: scottly on July 16, 2014, 11:26:01 pm
I kind of suspect the Dynojet kit assumes the stock air box with the snorkel is used, much the same as the 145 main commonly suggested for the FT?
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 17, 2014, 11:37:40 am
I kind of suspect the Dynojet kit assumes the stock air box with the snorkel is used, much the same as the 145 main commonly suggested for the FT?

You are 100% correct. I talked to the DynoJet tech a couple of times. My original airbox had a few cracks in it (dried out) so I removed it & tried the UNI filter on the end of the intake plenum. That amount of air overwhelms the carbs/engine. The DynoJet tech told me the kit is built around the OEM airbox & that there was no extra power to be had by removing the box. I don't know if I agree, but they are the ones with the dyno, not me.

My first VT Ascot had about the same mods done to it, but it had a MAC dual exhaust vs. the dual Super-Trapp exhaust that is on this bike. The first bike ran with the OEM jetting (although lean) with the after-market exhaust & a gutted airbox with the snorkle removed & a velocity stack installed. The new bike has a bigger one piece '85-'86 Shadow filter installed. I just received the larger jets the other day & hope to have the time to install them today or tomorrow. Hopefully this will straighten everything out.

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 21, 2014, 11:58:26 am
Well, I installed the new larger jets. I chose the DynoJet's #124 main jet & went through the process of accessing the carb's float bowls. All pretty straight forward. About the only really difficult part is re-installing the common intake plenum. Trying to twist it into the frame opening, then lining up the end with the airbox & the two carb boots can be frustrating. After re-assembly, the bike fired right up. I let it warm up & revved it out a couple of times. The carbs seem to be responding correctly (Finally) & the bike appears to be running great. I did not have a chance to road test it yet. Hopefully that will be resolved later on today. I will follow up on this post as soon as I have some news.

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 21, 2014, 02:51:57 pm
Guess what? Still not enough fuel at the top end! ::)

I knew I should have just gone with the larger jets to begin with. Oh well... I'm getting to be pretty quick at removing everything to gain access to the carbs.

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 26, 2014, 11:22:20 am
New larger jets are installed & they are still not enough fuel. :'( I'm getting tired of this drill. Some larger jets are on the way.

A new member joined today that has also experimented with the exhaust, airbox & jetting. He mentioned in his post that two #125 main jets are what is needed.

Do jets come with odd I.D. numbers? I thought they all ended in even numbers.

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: scottly on July 26, 2014, 10:33:22 pm
After a while on the FT, I started drilling the stock 140 main jet; it was faster than driving to the dealer and back, and I knew it would never be used again anyway, so no loss if I messed it up. As far as jet sizes, I think the Keihin jets alternate between 2 and 3 numbers per size, up to a certain point, then jump to 5 or 10 per size.
Are the VT jets interchangeable with FT jets?
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 27, 2014, 09:49:47 am
...Are the VT jets interchangeable with FT jets?

Don't know. I would tend to think so, as they both use Keihin carbs.

The DynoJet main jets are a bit taller than the Keihin jets & use a longer needle.

Where does one find accurate drill bits that are suitable for drilling jets?

Thanks
J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dibingo on July 27, 2014, 12:01:17 pm
Quote
VT500FT

Oups sorry ! I had not seen how was called your version in US.
I was thinking about the FT500.

(http://www.thumperstuff.com/ft500b.jpg)


I see that you have a difficulty finding the good jets, in France I use this : http://www.3as-racing.com/A-35000-gicleur-principal-keihin-kec.aspx#.U9UiAPkYyVI
Title: Re: removing the stock airbox '83 (shadow)
Post by: scottly on July 27, 2014, 09:13:45 pm
...Are the VT jets interchangeable with FT jets?

Don't know. I would tend to think so, as they both use Keihin carbs.

The DynoJet main jets are a bit taller than the Keihin jets & use a longer needle.

Where does one find accurate drill bits that are suitable for drilling jets?

Thanks
J.
Here is a source for metric bits in .05mm increments:
http://www.biscotoolsupply.com/metric-drill-bits-mm-drill-bits
The pilot jets I got from my local dealer were longer than the stock FT part, and had no markings other than the size. The mains were stamped AB and the size on the end.
BTW, what have you been paying for jets? My dealer charged me $4.95 plus tax for a main, and $7.64 plus tax for a pilot.
Title: Re: removing the stock airbox '83 (shadow)
Post by: scottly on July 27, 2014, 09:33:13 pm
Quote
VT500FT

Oups sorry ! I had not seen how was called your version in US.
I was thinking about the FT500.

(http://www.thumperstuff.com/ft500b.jpg)



Yes, that is the FT I was referring to. The only similarity to the VT is the rubber snorkel on the airbox. Removing it allows the motor to ingest more air, and fuel needs to be added with larger main jets. 
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dibingo on July 28, 2014, 07:44:27 am
Jets like I know :

REF : KEC
(http://img143.imageshack.us/img143/760/17gicleursprincipaux.jpg)

REF : KEP
(http://img818.imageshack.us/img818/860/1071863.jpg)

To drill jets, I think that slightly too random.

Quote
The only similarity to the VT is the rubber snorkel on the airbox. Removing it allows the motor to ingest more air, and fuel needs to be added with larger main jets.

Yes, naturally, it is necessary to grant the carburation to the new air inlet.

But of my experience, the rubber snorkel favors the work of the venturi !
I think while we bring more air, but less pressure to remove it !

On my VT500E, I left in place the original snorkel.
But I deleted the railing firewall situated after the filter box. On the version with double railing on the filter, it is useless.
My air filter is homemade with Foam of air conditioning. Works well !

I was simply inspired by various versions of VT500 of my country.
The VT500C is less powerful than the VT500E.
Honda played on the size of jets, but also the nature of the filter.
Two are possible: foam or paper.

FOAM :

(http://www.ddmototeam.com/pieces/images/10608_photo.JPE)

PAPER :

(http://www.sklepmotocyklowy.pl/pl/zdjecia/7390710.jpg)

On Transalp, everything it limps in air is similar. The snorkel is just wider and turned to the back.

(http://parapente.64.free.fr/images/Boite_a_air_G.jpg)

I think that in this idea, it's better than to delete the vorkel.

Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 28, 2014, 10:09:33 am
...BTW, what have you been paying for jets? My dealer charged me $4.95 plus tax for a main, and $7.64 plus tax for a pilot.

Thanks for the heads up on the drill kit.

As to jets, I bought the DynoJet kit for my VT & so far they have been sending me the larger jets free as warranty work.

When I bought the larger FT Ascot jets a few years back, I bought them from ThumperStuff along with a few other parts & cannot recall what they cost any longer.

The few sources of jets that I know of are:
http://www.sudco.com
http://www.jetsrus.com
http://www.pjmotorsports.com/jetting-tuning.html
You might also try ThumperStuff: http://www.thumperstuff.com/FT500.html

Good luck
J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 28, 2014, 10:15:29 am
Dibingo,

UNI filters has a nice filter for the 1985 & 1986 500cc Shadow that fits the Ascot box. It's all one piece & looks to offer much more surface area than the Ascot cages. It is part #NU-4097.

Here is a picture.

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dibingo on July 28, 2014, 01:44:01 pm
Sorry. Links of UNI filter please ?

To there my method with the foam of air conditioning, is very well. But why not ?

I ignore if I can order the UNI in France.  :-\
Title: Re: removing the stock airbox '83 (shadow)
Post by: J6G1Z on July 28, 2014, 08:51:27 pm
The link to UNI is: http://www.unifilter.com

I don't know if Amazon.com serves your area. If they do, I would check them out for pricing.

UNI offers two filters that will fit the '83-'84 Ascot. There is a foam filter that fits the original 1983 & 1984 Ascot cages. Then there is also the filter that was intended for the 1985 & 1986 500cc Shadow. Here are the UNI listings & part numbers.

1983-84  VT500 C, FT - #NU-4072   MSRP $12.95 (Original Ascot Filter)

1985-86  VT500 C    -   #NU-4097   MSRP $26.95 (Original Shadow Filter)

Here is a bit more info: http://ascot500.com/index.php?topic=290.0

J.
Title: Re: removing the stock airbox '83 (shadow)
Post by: Dibingo on July 28, 2014, 09:39:48 pm
Thanks guy !  ;)

I note it.