Discussion in 'The Garage' started by Josh, Sep 4, 2009.
Question: What do you do with the crankcase vent?
Actually, they did initially. the Standard airboxes flow much better than the Special's. Less internal noise baffling.
Also, air's a funny thing. What works on a dyno (open pod filters with no turbulence) may not translate into real world conditions, 100% of the time (on the open road at speed produces lots of turbulence behind your carbs). Also, since pod filters are typically more restrictive than the foam stock types (have to be - they're hanging out in the dirt and rain), this balances out a lot of things.
N/A engines depend on controlled properly set up air flow - the mass of that air being sucked in and set along a path has effects on how much air actually gets pulled into the piston. The head design on the XS650 is excellent, being cross flow and fairly non-restrictive, and the intake being angled to allow flow over rather than around the valves. But i'm not sure that the pod filter type won't make fuel sputter rather than atomize.
Hm. Maybe i should set up a flow bench the next time i have things apart and see if there is a difference or not between the systems.
- install a brake booster check valve in the crankcase breather line...also helps create negative crankcase pressure and serves to restrict leaking oil seals...early models have 2 lines, later models 1
- most good auto parts shops should have these valves
Here is a useful guide for cleaning and rebuilding almost any motorcycle carburetor.
Another great source of info specific to tuning the carbs on your XS650 can be found here.
A caution about Pod Filters. Not all are created equal. Some, including one particular style reportedly sold by Mike's XS and regularly listed on ebay (I think its the cone shaped pod filter) can block the vacuum port at the top of the carb inlet, creating all kinds of issues that might lead one to thinks its a jetting problem, when its a simple blockage problem created by your new pod filters. It is only the vacuum carbs that have this issue. If your running Mikuni VMs, these should then be OK.
I think Mike's XS Performance pods are OK. They are apparently identical to a K&N, but I have seen reports that the rubber deteriorates rather quickly. I am currently using the same set of K&N pod filters I bought in the late '80s. They have stayed with me through a succession of 3 XS650s over the years and I have never had an issue with them. They're worth their price.
When you remove your air box, your carbs will loose the rear support, which puts additional strain in the intake manifolds and can cause them to tear. A simple bracket to provide additional support to the carbs will reduce the strain on the manifolds.
- about the pods and the K and N filters...i have KnN's on both my XS's and will put them on my current rat-tracker project too...they are cleansable and reuseable for years
Sorry, should have been more specific: On a hot day, when the oil is smoking out, how do you avoid the (personal preference, i s'pose) cloud of oil smoke surrounding you at stops?
I was talking with someone about this last night, and i though running the line to between the pods so they suck up the smoke, but i'm not sure this would work well.
- sounds like a top end rebuild is in order
Heh. No, it doesn't happen on cooler days. I'm talking like 30C+ days, in stop and go traffic. The engine doesn't get a lot of chance to cool off, and the oil starts offgassing, and it's definitely white in colour. It's not blow by.
Unless i'm missing something?
Water cooled cylinders are 190 degrees or so........these get to 280 if not controlled...not a good scenario......and in stop and go in the heat it really can't be controlled ...and the hotter it runs the faster it heats up in traffic...........everywhere else I have found it can be controlled....230 is great.......takes some thinking though.......
for the record, I uses Mikes pods with stock jets, and so far my bike is running decent. I've not had it out on the road wide open yet, but I would HIGHLY suggest starting with your stock jetting and going from there.
- could think about mounting a remote oil filter on your front engine mount...acts as partial cooler
- a side filter
- also a deeper sump
- is oil leaking onto the cylinders?
The deeper sump will provide protection to the sump filter. It has been suggested that the sump filters come apart due to crankshaft 'windage'. An additional benefit is a small increase in engine oil capacity; Always a good thing.
I've been looking at a deeper sump made in Oz, but I like the fact that this one has cooling fins. Who sells them?
The deeper sump mod wont fit the Specials as it fouls on the side stand mount. Works on the Standards
So this is probably a really rookie question, but where can I get Xs John's carb needles? I'm going to be rebuilding my BS34 carbs for my 81 special ii, and I'm going to pod filters and possibly 2 into 1 exhaust and free flow muffler. These XS John's needles sound like my ticket, andI just can't find anywhere as to where to get them.
xs john died last summer in a car vs.car crash. (R.I.P)
he spent counless hours and miles to perfect his needles for our 34's. U might eventually find a pair here in the classifieds, but , I doubt it.
If you find adj needles on ebay they will prolly be canadians, wit a big flat spot at the top end like gordon said.
you may find xsjohn replicas, and the maker of those means well, and they may work fine, but as far as tunning those in, xsjohn was the best at settup, and talking you thru wich spacers to use. A person that merely duplicates john needles on a lathe is only copying them, and most like will be limited in tech support.
xsjohn's knowledge for these 34's will prolly never be seen again.......i miss...his.....qwirks.
I rebiult a friend's 34's, and put in canadian needles with matching jets, 140 Mj"s, one size higher pilots, he runs drilled out stock standard airboxes, drag pipes with only a bit of baffle to keep his ears from ringing, and he flogs the hell out of it. love it. It does have a flat spot in transition though.
I as well want to remove my stock airbox. My airbox (and i use that term loosely) is made up of several plastic/sheet metal pieces held in place with a lot of bits. It seems like a somewhat crude design. I want the look and performance of pod filters. When i am ready to do this mod, on my 76c model, it will be at the same time as i fit a fresh set of slide/needle Mikuni Carbs. Cash flow sucks at this point. Tax Refund please come soon. Mitch
I want to do the mod to pod instead of air boxes but my friend at work tonight told that when it rains the water will get in my carbs is this true? If so I am just to put some K&n filters in my air boxes.
yes, its a risk that can happen. you make the call.
Thought I'd ask here as I don't wanna start another thread and can't find difinitive info. Replacing stock air filters with with stock filters on my 80 do I need to " impregnate" the foam material with anything? The Haynes service book is a bit vague but I read it that you treat the filter as if I were the paper type filter and blow it out when cleaning and that's it.
So new to MC's but damn the xs is one sexy bike I wanna get to know. Baby steps
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