KTM 640 Winter Project

[Low594]

Originally Posted by CSF

philosobrad - there is a write up on the filters on the 640 index page.

heres a link to the filters: http://www.amazon.com/Uni-Breather-F...=pd_sim_auto_5

If you scroll down, you see the "frequently bought together" with both filters used in the write up.

I know I just read the write up a couple of weeks ago, but cant find it! Care to post the link? Thanks!

[wrk2surf]

Originally Posted by Low594

I would look at the threads dealing with the starter sprague and starter itself. My starter shaft seal went out and the starter would fill with oil! It still worked, but it wasnt happy!

the symptoms are there...

Nice bike LOW..

I will be gettin mine cleaned up here in the next two months myself..

[Low594]

Originally Posted by wrk2surf

the symptoms are there...

Nice bike LOW..

I will be gettin mine cleaned up here in the next two months myself..

Thank you!

[juames]

Still working on rebuilding your carb? Stumbled on this in vendors, tons of cheap FCR's for sale.

http://www.advrider.com/forums/showthread.php?t=816973

[CSF]

juames - Thanks for the heads up, just looked through the thread. All of the carbs are gone... such is life. I'll eventually find one. I may take a trip to the some of the motorcycle wreckers this summer. And I'll keep an eye on kijiji and ebay...

New parts are on their way, so for now I'll have to suffer with a well sorted and rebuilt BST.

[Low594]

Originally Posted by CSF

juames - Thanks for the heads up, just looked through the thread. All of the carbs are gone... such is life. I'll eventually find one. I may take a trip to the some of the motorcycle wreckers this summer. And I'll keep an eye on kijiji and ebay...

New parts are on their way, so for now I'll have to suffer with a well sorted and rebuilt BST.

I like my BST! It works well! But I am seriously considering the FCR!

[CSF]

Originally Posted by Low594

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.

[CSF]

updates:

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.

[bmwktmbill]

CSF,
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.

bill

[Young-gun-640]

Originally Posted by bmwktmbill

CSF,
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.

bill

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

[Low594]

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.

[CSF]

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.

[Low594]

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!

[CSF]

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.

[wrk2surf]

it will all plug back into each molex.. no need for a diagram unless you are rewiring anything

airbox thread


http://www.advrider.com/forums/showthread.php?t=123569

Nice color I like my bikes white it always seems cleaner !