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Old 04-02-2013, 10:38 AM   #1276
motolab
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Quote:
Originally Posted by clicheche View Post
wouldn't raise the needle unless the slide is against either 'stop'??? what's a stop?
The stops are at the limits of travel, that is where the slide cannot go any lower or any higher.
Quote:
and i can't see the washer lowering the slide? how?
The vacuum above the slide compresses the spring a certain amount for a given intersection of throttle opening and rpm. Imagine this to be a constant. Now imagine your spacer between the spring and the slide.
Quote:
thanks for the exhaust advice.
You're welcome.
Quote:
the choke on the bst 40??? is there not a choke on the bst 40????
BST40 carbs have cold start enrichment circuits.

A choke is closed when an engine is cold and opened when it is warm, whereas a fuel enrichment circuit is opened when the engine is cold and closed when it is warm. A choke works by restricting the air flow, whereas an enrichment circuit works by adding extra fuel. A choke requires a fast idle cam or something akin to it (or you have to hold the throttle open manually), whereas an enrichment circuit adds a little extra air simultaneously with the extra fuel, so the fast idle is already built in.

Regards,

Derek
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Old 04-02-2013, 02:29 PM   #1277
ER70S-2
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Quote:
Originally Posted by motolab View Post
I appreciate very much that you don't take offense.

Regards,

Derek
Quote:
Originally Posted by motolab View Post
If meanings are continually perverted, then language eventually becomes such that no one can any longer be sure what others are really talking about at any given time. There are many examples of this in common usage, and I'm against every single one.

Regards,

Derek
This is why I don't take offense. Now I understand.
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Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -
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Old 04-02-2013, 03:20 PM   #1278
ER70S-2
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Quote:
Originally Posted by clicheche View Post
being new, is it poor form to deviate off of the carb when asking about the effects of modifying it? honestly not sure.
The problem with drifting off topic (although the exhaust is closely related): this thread has grown huge and it's hard to find anyting specific. Almost everything I've answered for you is already here, but how would you ever find it? I'm as quilty as you, I could have said "Hey, it's all here, read the thread."

Quote:
Originally Posted by motolab View Post
In any case, the KTM has a shorter hose to attached to the ~1/2" breather that connects to the area under the diaphragm.

Regards,

Derek
Quote:
Originally Posted by clicheche View Post
this breather you speak of, is it a pressure release thing for the carb? an exhaust thing?
Derek is speaking of the round filter, the KTM uses a shorter hose so you should be fine if you want it off the airbox. There is a large volume of air displaced in the carb as the slide moves up-n-down, it flows through the round filter. The stock filter is 3/16" thick open cell foam and not oiled, I feel it's a weak link.

Rusty Rocket clued me in to this solution:
http://www.advrider.com/forums/showp...9&postcount=82

Quote:
Originally Posted by clicheche View Post
did you make that filter? (over airbox hole)
and did you lightly filter both holes i presume?
The square yellow plastic filter is from Thunder Products. The door slides for more or less airflow, I leave mine open. The black foam you see is very coarse and filters almost nothing. So neither of the airbox openings are filtered, that's the engine airfilter's job.

Quote:
Originally Posted by clicheche View Post
why 2 holes and not one big one? easier to plug if desired?
The stock 3.4 gallon tank is just barely enough fuel range. I don't want to take the mileage hit that comes with a fully open airbox. Two holes and my 6000+ alt work well together. This may change as I just installed a 5.3 gallon Acerbis.

Quote:
Originally Posted by clicheche View Post
thanks again for the help. its staggering.

eagerly awaiting the damage i've done to the rig.
Just some increased wear, if you ride mostly pavement or solo, it won't hurt much. But riding in a dust cloud with others will be worse.
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Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -
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Old 04-04-2013, 08:20 AM   #1279
RicePt1
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Saved my butt

Thanks for the great photos and explanation. This was very helpful.
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Old 05-03-2013, 10:26 AM   #1280
Umarth
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Bluhduh help!

I rebuilt the engine of my 640 adventure this winter, mainly:
New piston and rings
New cam shaft
New rocker bearings
Re-built water pump
Re-build carburetor

The end result is somewhat underwhelming to say the least. The bike fires up absolutely no problem and idles better than ever from 1400 to 1800rpm steadily depending on where the idle screw is set. But the bike simply has no umph and engine boggs down at 1/8 from wot and up; you actually decelerate when going to wot. When not at wot, the bike runs fine but is underpowered. As is, I can get to 110kph max just takes time to get there. And going up steep hills is a problem as I can’t maintain speed. Even in dirt, launching the bike and getting the wheel to spin in 1st gear you need to rev quite a bit it before letting out the clutch. When traction is present, at no point is there any ‘fun factor’ acceleration. But between 4000 and 5000 rpm, that is where going wot kills it the most. It’s not as obvious in 1st gear, but in 3rd and above.

Another change compared to before the rebuild is the choke/enrichener. Before, when i would use it to start the bike, the idle would start at 1500rpm and steadily rise to 3k (if not more) if the choke lever was left full on. Now, it still starts up at 1500 but only rises to 2k.

So, to recap:
The carb is setup to factory settings: 45 idle jet / 152.5 main jet. I also tried 155, but that did absolutely nothing. Bike is stock.
I double checked the float height using two different methods and both indicate the float is spot on.
The needle’s clip is set to the middle position. I tried rising it one notch richer, absolutely no change.
The a/f ratio screw is 2 turns out from full in. Replaced the stock screw with the ‘extended’ one. Switched back to original one, no effect. Also tried it 3 turns out and 2 turns out; no change.
Tested it minus the air filter, no change.
The battery is new, so is the spark plug. Checked the spark and it’s a nice blue. Spark plug color is tan.
The carb diaphragm is in perfect shape.
Does not seem to have any vacuum leaks. (how could I positively test for that?)
Someone on here suggested i try the choke while at wot, result; no affect whatsoever.
Cleaned out the tiny in-line fuel filter in the carb; no effect.
Fuel is fresh and hi-octane.

Could it be the cdi? Or the spark? The engine has no trouble running right up to 7000rpm. And does not stumble as long as you don’t open the throttle fully. So, in my mind anyway, the spark seems to be doing its job.

So, anyone have an idea as to the cause of my woes?
I'm leaving for 2 years on this bike in 4 weeks and starting to loose a bit of confidence in the wisdom of going with crab based bike... but it's to late to change my mind anyway.

EDIT:
Turns out that it was the timing that was off by one tooth. Works great now.

Umarth screwed with this post 05-07-2013 at 06:20 AM
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Old 05-03-2013, 02:51 PM   #1281
dolphins13
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Quote:
Originally Posted by Umarth View Post
I rebuilt the engine of my 640 adventure this winter, mainly:
New piston and rings
New cam shaft
New rocker bearings
Re-built water pump
Re-build carburetor

The end result is somewhat underwhelming to say the least. The bike fires up absolutely no problem and idles better than ever from 1400 to 1800rpm steadily depending on where the idle screw is set. But the bike simply has no umph and engine boggs down at 1/8 from wot and up; you actually decelerate when going to wot. When not at wot, the bike runs fine but is underpowered. As is, I can get to 110kph max just takes time to get there. And going up steep hills is a problem as I can’t maintain speed. Even in dirt, launching the bike and getting the wheel to spin in 1st gear you need to rev quite a bit it before letting out the clutch. When traction is present, at no point is there any ‘fun factor’ acceleration. But between 4000 and 5000 rpm, that is where going wot kills it the most. It’s not as obvious in 1st gear, but in 3rd and above.

Another change compared to before the rebuild is the choke/enrichener. Before, when i would use it to start the bike, the idle would start at 1500rpm and steadily rise to 3k (if not more) if the choke lever was left full on. Now, it still starts up at 1500 but only rises to 2k.

So, to recap:
The carb is setup to factory settings: 45 idle jet / 152.5 main jet. I also tried 155, but that did absolutely nothing. Bike is stock.
I double checked the float height using two different methods and both indicate the float is spot on.
The needle’s clip is set to the middle position. I tried rising it one notch richer, absolutely no change.
The a/f ratio screw is 2 turns out from full in. Replaced the stock screw with the ‘extended’ one. Switched back to original one, no effect. Also tried it 3 turns out and 2 turns out; no change.
Tested it minus the air filter, no change.
The battery is new, so is the spark plug. Checked the spark and it’s a nice blue. Spark plug color is tan.
The carb diaphragm is in perfect shape.
Does not seem to have any vacuum leaks. (how could I positively test for that?)
Someone on here suggested i try the choke while at wot, result; no affect whatsoever.
Cleaned out the tiny in-line fuel filter in the carb; no effect.
Fuel is fresh and hi-octane.

Could it be the cdi? Or the spark? The engine has no trouble running right up to 7000rpm. And does not stumble as long as you don’t open the throttle fully. So, in my mind anyway, the spark seems to be doing its job.

So, anyone have an idea as to the cause of my woes?
I'm leaving for 2 years on this bike in 4 weeks and starting to loose a bit of confidence in the wisdom of going with crab based bike... but it's to late to change my mind anyway.

I had a similar problem before? My gas line was old and crimped.
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Old 05-03-2013, 06:53 PM   #1282
Umarth
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Quote:
Originally Posted by dolphins13 View Post
I had a similar problem before? My gas line was old and crimped.
Gas lines where all replaced this winter.
Crossing my fingers, but I might have found the issue: timing chain was off by one tooth. At the moment, the rocker cover gasket is curing (just corrected that snafu), will wait a day or two and then try it out.
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Old 05-04-2013, 05:35 AM   #1283
Alik
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Quote:
Originally Posted by Umarth View Post
Gas lines where all replaced this winter.
Crossing my fingers, but I might have found the issue: timing chain was off by one tooth. At the moment, the rocker cover gasket is curing (just corrected that snafu), will wait a day or two and then try it out.



Consider yourself lucky - it could have been worse than no umph...
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Old 05-06-2013, 12:00 PM   #1284
meat popsicle
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Quote:
Originally Posted by ER70S-2 View Post
...

Rusty Rocket clued me in to this solution:
http://www.advrider.com/forums/showp...9&postcount=82
...
Not sure if you saw this link from the LC4 Index:
http://www.advrider.com/forums/showthread.php?t=114485
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Old 05-06-2013, 10:32 PM   #1285
ER70S-2
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I've seen those and motolab has recommended them. But I don't like the K&N concept, since it flows more air, it also flows more dust. The K&N rates too far down the list when tested against foam filters (results available with a Google search: it's late, I don't feel llike looking for a link). IIRC inmate Blackcap was the most recent rider to have a load of dust in his carb, passed through the K&N type secondary filter. He only has 4xx posts and I'm about positive that he mentioned this in the DR650 thread. Should be easy enough to search his user ID and scan back through the DR thread. I think he's been riding in Asia through extreme dust conditions.

Here's what you don't want to find in your carb (above below the slide diaphram), and why Rusty's idea hit home with me.
Thanks to Blackcap for the photo:


This is a Q-tip I wiped just behind the secondary filter (in the 1/2" tube), somewhere around 35-40,000 miles:


And this is my carb at about the same mileage. To be fair, I ride solo, not chasing others in their dust cloud.


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Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -

ER70S-2 screwed with this post 07-19-2013 at 01:13 PM
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Old 05-06-2013, 11:05 PM   #1286
motolab
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Quote:
Originally Posted by ER70S-2 View Post
I've seen those and motolab has recommended them. But I don't like the K&N concept, since it flows more air, it also flows more dust. The K&N rates too far down the list when tested against foam filters (results available with a Google search: it's late, I don't feel llike looking for a link).
I recommend the UNI instead of the K&N.

Regards,

Derek
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Old 05-06-2013, 11:06 PM   #1287
ER70S-2
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SUZUKI DR650SE INFORMATION INDEX
Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -
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Old 05-07-2013, 03:36 PM   #1288
meat popsicle
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Along those lines: Derek,

my 03 640 with the BST40, rebuilt by me a year or so ago (with parts from you ) has acquired what may be the dreaded bog syndrome. On my last trip to the desert it would not just bog but completely kill the engine.

There has been much chatter on the CV carb bog issue and I'm wondering if you think its a venting issue or a combination of some factors... are you curious to sort it out? I'm still just a half hour south of your shop.
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Old 05-07-2013, 04:05 PM   #1289
motolab
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Quote:
Originally Posted by meat popsicle View Post
Along those lines: Derek,

my 03 640 with the BST40, rebuilt by me a year or so ago (with parts from you ) has acquired what may be the dreaded bog syndrome. On my last trip to the desert it would not just bog but completely kill the engine.

There has been much chatter on the CV carb bog issue and I'm wondering if you think its a venting issue or a combination of some factors... are you curious to sort it out? I'm still just a half hour south of your shop.
Under what circumstances (throttle position, rpm, hot vs. cold, etc) does this bog manifest? What parts were replaced during the carb rebuild (I'd look at your invoice, but can't remember details such as your real name - If you want to PM me with that, it would help).

Regards,

Derek
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Old 05-08-2013, 07:59 AM   #1290
meat popsicle
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Quote:
Originally Posted by motolab View Post
Under what circumstances (throttle position, rpm, hot vs. cold, etc) does this bog manifest? What parts were replaced during the carb rebuild (I'd look at your invoice, but can't remember details such as your real name - If you want to PM me with that, it would help).

Regards,

Derek
PM sent.

If its clear in my head... it doesn't happen when I'm on pavement, and only when I hit terrain off-road, like rock gardens, rough ground, and I think sand whoops at speed. It seems like too much shaking causes something to happen, which made me think of all the talk on "the bog".

I do remember having more difficulty at altitude or maybe when the bike is headed up or downhill. Meaning there were caveats or modifiers of the behavior. It was odd enough that I wonder if its just carb venting once again.

Although I didn't try to see if it happens when the bike is cold, it does seem to happen at any RPM or throttle position. Often the engine would die and I would have to wait a bit for it to restart, again making me think its an intermittent vacuum block unless the "hypothesized" slide flutter could cause flooding.

I'll check my carb vent tubes soon too.
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