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Discussion in 'Thumpers' started by CSF, Oct 13, 2012.
I like my BST! It works well! But I am seriously considering the FCR!
Yea, I'm not sure if I'm ready to make the switch. I might try to put the FCR from my SXF 250 on for a few days and actually see what all the fuss is about. I like the idea of the TM40 as well, for a new one that's ready to install the price is much more reasonable... anyway, I have a few other items on my "farkle wish list" to get to before a carb upgrade.
Got my rebuilt mono-shock back with the new orange spring all loaded in, it looks great. I didn't take a picture of this, but they put a new valve on the cartridge, so it should be way easier to recharge next time. Nice...
I got a little excited and started putting the rear end back together, feels good to see it taking shape:
I'm still waiting for my carb parts to show up, so I moved on to some air box mods. There was no inner side cover on the air box and the snorkel was falling off and won't sit properly in the top hole any more, I think that rubber is shot. The side cover had a rough hole hacked into it with some screen (I think from a screen door) pop riveted into it. There was lots of muck and debris in the air box, so I really wasn't happy with the state of the air box. When I took the bike out for a hour or so test ride I found the current side cover let in lots of water and junk in to the air box, for me an open side cover just isn't going to work. The air filter looks like a mud filter... Anyway you get the idea. I know air box mods are a hotly contested topic in the 640 world, but since for now I'm sticking with the BST and I intend to ride the bike mostly off road I'm going to open up the top of the box and rework the side to be open but less vulnerable to water and dirt getting in.
Trimming out the side cover to accept a new piece of aluminium:
New aluminum insert being trimmed out:
Test fitting the new slug:
I'll drill some small neat holes near the bottom off the slug to let the air box breath, but an new inner air box cover will be going in behind the side cover. I'll drill some holes closer to the top of the inner cover to prevent water getting into the air box and I'll back up those holes with some fine screen. That should keep the junk out.
I'm going to make a aluminum cover for the top of the air box as well, it will have two openings that will be backed up with some fine screen to keep junk out. Here is the start off that:
Thats it for tonight, I'll throw up some more pics soon.
Having been down the 'fine screen " route on other motorcycles I can relate from experience that the air flow will be affected in ways you may not anticipate.
Air is like water and when you run water through a screen...like your kitchen sink spout, it gets weird. Guess I think it's a flow thing, maybe it's a speed thing.
Screen is restrictive in my experience in a way air filters are not.
Screens, holes and baffles are not the same.
Why? Not sure, may work for you OK and I will be wrong.
Hi Bill, I'm confused now.... I may be misunderstanding what people are talking about when they say they are doing "the airbox mods"... I was under the impression that the go is not to replace the filter with a screen but rather just to replace the solid plastic side panel with a screen to allow more air into the airbox which then gets filtered by the nicely oiled air filter, am I correct?
From what you said above, it sounds like you're saying that the side panel is hollowed out as CSF has done, a screen put in the side panel as the only means of filtering the air and then no actual air-filter used to filter the air once inside the airbox... if this is the case then I'm with you, I wouldn't be doing that :huh
Sandrails use a prefilter sock, think they call them OuterWears or somesuch. I've thought about buying one for the fabric. Seems better than screen since it is designed for airflow, but I wouldn't assume jetting & airflow won't be affected.
Well experience is experience, and experience is king. Thanks for the input, I'll leave the screens off for now and see how It works first. If I still find I'm getting lots of junk in my air box I try some screen. I think the way I'm setting up my holes I'm minimizing the ability of water and junk getting in.
Any way, I'm breaking all kinds of bike modding rules here, changing lots of things in one shot instead of one at a time to see how each affects the various systems. So things are going to be tricky enough to set up correctly in the end without a tough to solve problem like weird air flow from screens...
Just to clear up any confusion - I will in no way be removing the foam filter. Thats essential equipment in my books.
Good to hear about the filter! Yea, I tend to break that rule quite often myself! It'll be fine, just won't knowwhich thing netted which result. That and always figure you will have to retune the carb!
Uhgh,,, winter. I'm not a fan of it. So I guess that maybe makes me unpatriotic, being a Canadian. But, it gives me time to work on the bike ...
The view from my garage this morning, I didn't even try to go to work:
I kept working on the air box with the "no fine filters" suggestion in my head, I think I'll add a screen to the top to keep the larger pieces of junk out of my air box, but I'm pretty happy with my hand built cover:
Its certainly not perfect but as my friend keeps saying "you're building a dirt bike, it'll get beat to s@#t the first time you really ride it, no need to make it pretty".
Speaking of not pretty, here is the inner side cover:
I tried everything to make those holes smooth. The plastic just wouldn't cooperate. Everything I tried ended up messy and unacceptable. So for now this will stay as is, I may at some point make another aluminum slug and cut the plastic out, but for now I'll leave it as is and see how it works...
I move on to fitting the exhaust I bought, it wasn't easy but its much lighter the the stock piece:
also, heres a little "preview" of the finished product, I got really excited to see the bike like this:
I have a seat concepts seat on the way, but I thew the old one on anyway:
The tank and fairing still need another coat of paint and a good clear coat but, i'm liking the overall look...
I did however run into my first real problem. The electrical. F#@k! I wish I had taken good pictures when I took it all apart. Its a mess and I really don't know how to put it back together. Electronics are probably the thing I'm least comfortable with, I would really appreciate if anyone could post some detailed pics of their wire loom...? please! I have a diagram, but its of little help. Any real world photos or help would be greatly appreciated.
it will all plug back into each molex.. no need for a diagram unless you are rewiring anything
Nice color I like my bikes white it always seems cleaner !
I'm doing a HID kit and adding an extra horn and a few other accessories but thats it... still there are a bunch of connecters that don't seem to match up. I connected all of the Molex's that I could and hooked up the battery (i think its dead) and all I got from the dash was a neutral light... is it weird there there are a bunch or connecters that don't match up?
Also I went through the air box thread more then a few times... Thats where I came up with my air box mods... if you have better data on air box mods I'd be happy to use it...
seriously though - I really need some pics of you electrical connections...
I have the same year as you so let me know what you need pics of and I can snap them for you no problem!
Bike is looking nice CSF!
Don't forget, there are quite a few connectors that are not used under the dash of an Adventure.
Sorry I can't help you with photo's of the electrical as my bike has been changed to the Enduro set up.
Thanks! I'm pretty happy with the way its all coming along.
I'd really appreciate a few pics of the right side, around the carb and the side of the air box where the CDI is... any pics unused molex connectors would be also be appreciated too.
There is an old debate about the airbox and the BST40 diaphram carb that stems from from some dyno work done at the Sommers KTM dealership in Austria. They opened the airbox on the side an installed a rectangular screen and left the snorkel in place. They rejetted or re-needled, can't remember and got some extra horsepower on the dyno.
Someone got the idea to remove the snorkle and cut the snorkle hole bigger to accomplish the same thing. This had the advantage of keeping the ingress of water at a higher level and also dust is forced to enter at the seat level.
When more open mufflers were used some of us reasoned that more 'air' was needed from the intake end of things.
What I am saying is if you remove the snorkle and cut the hole bigger, don't block the opening with fine screen because you will restrict the flow of air into the airbox.
With the airbox closed on the sides and open on the top(enlarged hole, no snorkle, no screen) the system runs fairly clean even in heavy dust. Whe you pull the foam filter to clean it you will find dirt on the top but it will be clean on the bottom.
If you are far from home you can remove the filter and wash it clean with gas from the tank. It will dry quickly in the sun. Knock off anything loose after it dries and oil it with engine oil.
The engine will run nicely and thank you especially if you have a bunch of pavement to cover crusing back to the crib.
I have installed an 39mm FCR on my 2005 640A and also a Air Fuel Ratio meter. The bike was running rich across the board and I couldn't correct it easily, so as part of the tuning process I rode the bike without the side of the filter.
No observable difference in the AFR at all. This is with the snorkel removed and a Staintune muffler.
I also know this is controversial on this board to mention opening the airbox has no affect.
But put me on the fence regarding "opening the airbox".
I've clipped all of my connecters back together and charged up my battery. I tested the battery and it seems to be giving me 12volts. I went over everything again and can't see that I've missed any connections other then the fuel level sensor and rear brake switch. I get nothing at the dash except a neutral light. The head lights won't fire, no horn, signals or anything that would indicate life in the system. Am I missing something? Any suggestions?
Did you check inside the ignition keyswitch? It is not uncommon for the soldered terminals to break off inside the switches base cup causing a certain # of electrical woes...