DR650SE Index Topic #10- CARBURETOR/INTAKE

[badweatherbiker]

I haven't had a chance to pull it yet but should by Saturday, I'll check it out and get back with you. It's only been 200 miles since it was rejetted and the p/o couldnt remember what was in there, I am starting to get that "uh oh, I just got hoodwinkled" feeling.....

[Chill]

Originally Posted by Krusty ...

Intake-wise, what's worked for you?


-AIRBOX MODIFICATION
-AIR FILTERS
-STOCK CARBURETOR [MIKUNI BST40] MODIFICATION
-MIKUNI TM-40 [HSR-40]
-KEIHIN FCR39-MX
-FUEL INJECTION?

Mine has standard airbox, with a K&N filter. I have the stock carburetor. I had originally planned to do the airbox mod and pumper carb but have since got used to the power delivery and can ride around the low rev "hammering" now.

It seems to run well and I'm loathed to try and fix what isn't broken. I like the quietness of the standard pipe too but would like to remove the restrictor ring in the header pipe or replace the standard rusty pipe with an FMF Hi-Flo Stainless steel headpipe but I'm unsure if this will require or affect carburation changes. Or if this will give any increase in power or noise.

I doubt it will happen but if Suzuki announced 2013 DR650i I think there would be a lot of people buy them up.

[NYTrainer]

My 2004 DR came with a cut airbox, Dynojet carb kit & stock exhaust.

I replaced the stock exhaust with an FMF Q4 & powerbomb header for less weight & more power.

The stock carb set-up was great on the roads, but any off-road work quickly showed the CV carb's limitations.
I installed a Kehien 41mm, a K&N & have never looked back.
Best single mod ever!

[Kommando]

Originally Posted by Chill

Mine has standard airbox, with a K&N filter. I have the stock carburetor. I had originally planned to do the airbox mod and pumper carb but have since got used to the power delivery and can ride around the low rev "hammering" now.

It seems to run well and I'm loathed to try and fix what isn't broken. I like the quietness of the standard pipe too but would like to remove the restrictor ring in the header pipe or replace the standard rusty pipe with an FMF Hi-Flo Stainless steel headpipe but I'm unsure if this will require or affect carburation changes. Or if this will give any increase in power or noise.

I doubt it will happen but if Suzuki announced 2013 DR650i I think there would be a lot of people buy them up.

The stock exhaust isn't rusty. It's dirty. It's made out of coated stainless.

[badweatherbiker]

any ideas on how to set the float height on a stock carb?
I looked at the st bible but unless I am a tard I still don't see an actual setting for it other than a pic

[greystoke]

Originally Posted by badweatherbiker

any ideas on how to set the float height on a stock carb?
I looked at the st bible but unless I am a tard I still don't see an actual setting for it other than a pic

It's a bit of a black art to me but I seem to have done it correctly. Saw your post in the DR thread but before touching the float height check the seal on the float needle to make sure it's not worn. Search for posts by Derek (MotoLab) and read them as there's lots of technical details in his posts.

In short...
The float assembly has a little metal tang that actuates the float needle. You make small adjustments to the height by bending the tang. This affects how soon after the float starts to rise that it lifts the float needle. From my own experience the float height is very sensitive to being wrong. Too high and it floods, too low and it dies every 500m. If I remember Derek's post correctly it's 14.7mm from level. There are other posts that can describe the measuring process better than I can. Will try and find one for you

[PS: had the same issue as you with leaky petcocks too. Had to drain airbox regularly until I got it fixed. Rock bike in 3rd gear until you hit the compression stroke to make sure your valves are shut. Better to fill the airbox than cylinder]

[greystoke]

Found Dereks post

http://advrider.com/forums/showpost....postcount=1121

Using a float height measuring tool

Hold the carb in one hand and hold the base of the float cage tightly against the carb body with the index finger of the same hand. Rotate the carb so that the float tang just contacts the float needle's spring loaded plunger, but does not depress it. With the float height setting tool set to the desired height, use the other hand to drop it down over the float so the tool's posts contact the bowl gasket surface and the posts are square to the body (front to back - the tool takes care of side to side). Flip the tool to check both sides (as the float may have some twist in it). Bend the float tang until the tang on the float height setting tool just contacts the highest point on the float, but does not depress it.

Regards,

Derek

[BergDonk]

With care, ie a good eye allowing for parallax http://en.wikipedia.org/wiki/Parallax a short steel ruler available at most hardware stores will do the job http://www.justtools.com.au/prod7108.htm



Use either a metric or imperial, not a dual scale. Any dual scale measuring stick is almost useless.

[ER70S-2]

Originally Posted by badweatherbiker

Any ideas on how to set the float height on a stock carb?
I looked at the bst bible but unless I am a tard I still don't see an actual setting for it other than a pic.

Let me try to make it understandable. Note: the index finger in the pics is holding the float frame snug in the carb. It has nothing to do with the float position.

For our purposes, the float has 3 positions.
1. With the float bowl off and the float hanging straight down. It will be in a similar position to pic 1

2. Slowly rotate the carb toward upside down. Somewhere past 90*, the float will pivot toward the carb body, stopping when the tang engages the needle. This is not 'see-able', it's hidden in the plastic. This is when you want the float edge seam to be parallel to the bowl 0-ring surface; pic 2

This is where you'd measure the float height, but parallel is easier.
From the manual:
Float height: 14.7 +/- 1.0mm (0.58 +/- 0.04 in)

3. While continuing to rotate the carb completely upside down, the weight of the floats MIGHT over power the tiny spring in the needle assembly. If not, a light touch with your finger will. Pic 3

You can also see the finger holding the float frame, not touching the float itself.

Shamelessly Stolen From the BST-Bible (thanks to Laramie LC4):

Originally Posted by laramie LC4

-FLOAT HEIGTH-

- one of the other major factors that can cause problems with the BST-40 carb is an improperly set float height. this results in bogging, poor performance, and poor gas mileage.

-to set the float height you need to hold the carb inverted with the float and weight installed. you will be trying to align 2 edges to form a parallel line.



-as you slowly rotate the carb vertically, the float will drop into the bowl. when this happens you want these 2 edges to be straight.



-if yours doesn’t look straight, adjust the tab that the float weight is resting on and then try again. this can be frustrating. take your time and make sure you do it right. if not you will be doing it all over again.....

-be careful that you don’t freak out when the float drops all the way in. if you turn the carb all the way, it will sink in like this...

[sagedrifter]

The BST Bible shows the no tools method.... but I always measure mine like the manual shows.

You can pic up a Vernier Caliper pretty cheap at a Habor Freight store, maybe an auto parts place etc...

With the float installed, flip the carb over and measure from the carb to the floats bottom or the middle center of the rounded area looking at it from the side. Manual says .58" or .47mm. Gently bend the metal tab on the float needle till its right.

Its very easy to screw up, you might want to have a local show you. I've helped my neighbors before, there is probably an inmate or some other bike guy near you. Many of the screwed up carbs I've seen are float related. Guy's put in a jet kit and bump the float off and it runs lean or floods bad....

Usually the latter, some with fuel dumping on the ground...

So its... .58" from the float's bottom to the carb base where the bowl seals to. Venier Calpers work the best, you set them and lock them up to the right gap. Then use them as a story pole etc.. Then later you can measure bearings and shafts and all kinds of other good stuff. Every tool box should have the usual measuring devices anyway.

Doing it like the manual from Suzuki is fairly exact and it works every time, bike runs perfect, no guess work, no eye balling, measure it at .58" and you know its right.

[badweatherbiker]

thanks for all the help guys, got a bunch of numbers going on here though. 14.7mm .47mm, 58" lol
I have a measurer that reads 32nds or mm so am I going the 14.7 route or as Sage says .47?
I gues I am still confused

[badweatherbiker]

2. Slowly rotate the carb toward upside down. Somewhere past 90*, the float will pivot toward the carb body, stopping when the tang engages the needle. This is not 'see-able', it's hidden in the plastic. This is when you want the float edge seam to be parallel to the bowl 0-ring surface; pic 2

This is where you'd measure the float height, but parallel is easier.
From the manual:
Float height: 14.7 +/- 1.0mm (0.58 +/- 0.04 in)
-as you slowly rotate the carb vertically, the float will drop into the bowl. when this happens you want these 2 edges to be straight.



So at this point where the tang first contacts the little spring loaded pin on the needle, this is where I should take my measurement?

[badweatherbiker]

when the float drops into the bowl should the needle be seated all the way down into the chamber or half way out, I can get a parallel either way

[ER70S-2]

Originally Posted by badweatherbiker

thanks for all the help guys, got a bunch of numbers going on here though. 14.7mm .47mm, 58" lol
I have a measurer that reads 32nds or mm so am I going the 14.7 route or as Sage says .47?
I gues I am still confused

.47 is a typo; add a 1 and move the decimal one to the right = 14.7mm
14.7mm = .58" SAE

Originally Posted by badweatherbiker

So at this point where the tang first contacts the little spring loaded pin on the needle, this is where I should take my measurement?

Originally Posted by badweatherbiker

when the float drops into the bowl should the needle be seated all the way down into the chamber or half way out, I can get a parallel either way

When the tang contacts the pin on the needle AND gently seats the needle, but before the pin compresses into the needle. You want to measure the point where the needle would stop fuel flow.

[Cobain]

Made a screen for the air box to keep those pesky fishflies outta there.