Rec'd as per braigasen.com
(Main jet, Pilot jet, Needle jet, needle, slide)
BMW R100 / Mikuni VM34: 230, 40, P4, 6DH4, 2.0
BMW R75/5, R100 / Mikuni VM32: 200, 35, P2, 6DH3,2.5 (Stan Smith at Rocky Point Cycle)
BMW R100 / Mikuni TM38: 230, 22.5, no NJ listed , 6DP4, no slide listed
Cleaning a Mikuni Flat Side
Re: Cleaning a Mikuni Flat Side
I wrote all the steps down & some may (or may not) be interested.
MAKE SURE THE PETCOCKS ARE OFF
Use only hand tools – most screws, etc. are soft brass & easily stripped.
Disconnect the fuel line from the carb.
Remove the two screws from the top of the carb & remove the slide/spring/needle mechanism. You can let it hang from the throttle cable. Nothing flies apart. Inspect slide & needle. These parts usually stay clean.
Loosen the hose clamps on both sides of the carb & remove intake tubes. This will free the carb from the bike. Hold the carb level.
Remove the float bowl drain bolt. Do this over a big funnel into a gas can as any fuel in the float bowl will stream out.
Take the carb to a comfortable, well lit work area. Use a low (2”-3”) walled cardboard box for your work surface. Have two glass or metal containers for parts holders. One bowl gets the metal pieces, one gets the plastic pieces.
I removed things in the following order – put the metal bits in one bowl & plastic bits & rubber bits in bowl two.
A) Float bowl & gasket.
B) Floats – they drop right out.
C) Float arm pin – a few taps with a small punch.
D) Float arm – lifts off.
E) Main jet – screws out - nut driver.
F) Main jet ring - plastic
G) Pilot jet – screws out - flat/narrow screwdriver
H) Needle jet – tap this out of the carb from the bottom – use a soft (wooden or plastic) object to tap it out – I used a 1/4” plastic dowl – the needle jet comes out in the venturi area.
I) Remove screw from the needle valve plate – be careful here – both of mine were very tight & the screws are soft brass – they'll strip easily. I used a phillips bit & a 8” ratchet for extra torque. Press down hard on that screw head. A rubber band bewteen the screw head & the phillips head may help by preventing slipage.
J) Remove needle valve plate.
K) Remove needle valve retaining clip – its tiny.
L) Remove needle valve & o ring.
M) Screw Idle stop screw & Pilot air screw in all the way CAREFULLY COUNTING TURNS. WRITE DOWN TURNS FOR EACH.
N) Remove the Idle Stop screw/spring & the Pilot air screw/spring. Small washers here.
Clean all metal parts with carb cleaner – use safety glasses – I shot carb cleaner once & it came back at me & stung my eyes. 20 minutes of water washing in the eyes. Use an old toothbrush, Q-tips, etc as necessary. Get all the varnished old gas off of all surfaces – this may require soaking in carb cleaner. Use the long plastic tube on the carb cleaner. Shoot the cleaner thru the jets & all carb passages (little holes). Use canned air & shoot the air through all the jets & passages. Make sure the you can see daylight thru the jets. The pilot jet may need a thin wire (I used the wire from a garbage bag tie) thru it a few times to clear it.
To remove varnish from the plastic bits (floats, etc) I used vinegar, alcohol & elbow grease – no carb cleaner on these.
Inspect o rings & gaskets & replace as necessary
Reassemble in reverse order- do not over tighten the jets - they'll strip. Only tricky part is reinstalling the needle jet - you do this from the top. I used a pick-up tool & lowered it into the hole at the bottom of the venturi. look down that hole first with a flashlight & you'll see it will only go in one way. Once its aligned, press it into the hole. It may require a tap with the dowl to seat properly.
A few notes:
Some (Bill @ rockypointcycle) recommend replacing the pilot jet. I didn't & mine runs fine. YMMV.
First carb took 1.5 hours, second one took 45 minutes even though it was dirtier. I got more confident & went much faster.
If idle isn't right, don't be surprised. Your old idle screw setting was with a dirty carb – use all in & back out 1.5 turns & adjust from there.
If you lose any of the little bits you can order most from: http://www.psep2.biz
Download & refer to the Mikuni diagram (this should be #1): http://www.iwt.com.au/TMdrawing.htm
Hopefully I got things in the right order & used the correct terminology & didn't lead anyone astray .
MAKE SURE THE PETCOCKS ARE OFF
Use only hand tools – most screws, etc. are soft brass & easily stripped.
Disconnect the fuel line from the carb.
Remove the two screws from the top of the carb & remove the slide/spring/needle mechanism. You can let it hang from the throttle cable. Nothing flies apart. Inspect slide & needle. These parts usually stay clean.
Loosen the hose clamps on both sides of the carb & remove intake tubes. This will free the carb from the bike. Hold the carb level.
Remove the float bowl drain bolt. Do this over a big funnel into a gas can as any fuel in the float bowl will stream out.
Take the carb to a comfortable, well lit work area. Use a low (2”-3”) walled cardboard box for your work surface. Have two glass or metal containers for parts holders. One bowl gets the metal pieces, one gets the plastic pieces.
I removed things in the following order – put the metal bits in one bowl & plastic bits & rubber bits in bowl two.
A) Float bowl & gasket.
B) Floats – they drop right out.
C) Float arm pin – a few taps with a small punch.
D) Float arm – lifts off.
E) Main jet – screws out - nut driver.
F) Main jet ring - plastic
G) Pilot jet – screws out - flat/narrow screwdriver
H) Needle jet – tap this out of the carb from the bottom – use a soft (wooden or plastic) object to tap it out – I used a 1/4” plastic dowl – the needle jet comes out in the venturi area.
I) Remove screw from the needle valve plate – be careful here – both of mine were very tight & the screws are soft brass – they'll strip easily. I used a phillips bit & a 8” ratchet for extra torque. Press down hard on that screw head. A rubber band bewteen the screw head & the phillips head may help by preventing slipage.
J) Remove needle valve plate.
K) Remove needle valve retaining clip – its tiny.
L) Remove needle valve & o ring.
M) Screw Idle stop screw & Pilot air screw in all the way CAREFULLY COUNTING TURNS. WRITE DOWN TURNS FOR EACH.
N) Remove the Idle Stop screw/spring & the Pilot air screw/spring. Small washers here.
Clean all metal parts with carb cleaner – use safety glasses – I shot carb cleaner once & it came back at me & stung my eyes. 20 minutes of water washing in the eyes. Use an old toothbrush, Q-tips, etc as necessary. Get all the varnished old gas off of all surfaces – this may require soaking in carb cleaner. Use the long plastic tube on the carb cleaner. Shoot the cleaner thru the jets & all carb passages (little holes). Use canned air & shoot the air through all the jets & passages. Make sure the you can see daylight thru the jets. The pilot jet may need a thin wire (I used the wire from a garbage bag tie) thru it a few times to clear it.
To remove varnish from the plastic bits (floats, etc) I used vinegar, alcohol & elbow grease – no carb cleaner on these.
Inspect o rings & gaskets & replace as necessary
Reassemble in reverse order- do not over tighten the jets - they'll strip. Only tricky part is reinstalling the needle jet - you do this from the top. I used a pick-up tool & lowered it into the hole at the bottom of the venturi. look down that hole first with a flashlight & you'll see it will only go in one way. Once its aligned, press it into the hole. It may require a tap with the dowl to seat properly.
A few notes:
Some (Bill @ rockypointcycle) recommend replacing the pilot jet. I didn't & mine runs fine. YMMV.
First carb took 1.5 hours, second one took 45 minutes even though it was dirtier. I got more confident & went much faster.
If idle isn't right, don't be surprised. Your old idle screw setting was with a dirty carb – use all in & back out 1.5 turns & adjust from there.
If you lose any of the little bits you can order most from: http://www.psep2.biz
Download & refer to the Mikuni diagram (this should be #1): http://www.iwt.com.au/TMdrawing.htm
Hopefully I got things in the right order & used the correct terminology & didn't lead anyone astray .
-
Major Softie
- Posts: 8900
- Joined: Tue Aug 03, 2010 1:46 pm
Re: Cleaning a Mikuni Flat Side
Very kind of you to go to all the trouble.
Hope they're running great now.
Hope they're running great now.
MS - out
Re: Cleaning a Mikuni Flat Side
plus 1 on wearing safety goggles. You'll find the carb cleaner coming right back atcha. Don't ask me how I know that.