Mikuni 30MM carb upgrade and setup - Page 2

FastDoc · 03-07-2013, 07:58 PM

Not an expert but I would think there would be a idle mixture screw and an idle speed screw.

Weldangrind · 03-07-2013, 08:24 PM

Correct. There is a pilot mixture screw on the underside of the carb, close to the intake tube. Turn it in (gently) until it seats, counting the number of turns. Turn it back out a dissimilar amount; if it was one turn out, try 1.5 turns. The pilot mixture screw is responsible for the transition from idle to the main jet.

BTW, my guess is that you'll need to swap the stock 20 slow jet to a 25, and the 100 main to a 110.

Nicraage · 03-11-2013, 08:07 PM

Quote:

Originally Posted by Weldangrind

Correct. There is a pilot mixture screw on the underside of the carb, close to the intake tube. Turn it in (gently) until it seats, counting the number of turns. Turn it back out a dissimilar amount; if it was one turn out, try 1.5 turns. The pilot mixture screw is responsible for the transition from idle to the main jet.

BTW, my guess is that you'll need to swap the stock 20 slow jet to a 25, and the 100 main to a 110.

Thanks, I found it. It was difficult to see while hooked up. It was about 1 3/4 turns out, so I opened it about 1/4 turn more, and now I can adjust for a nice idle. I can also start it with one soft kick now (just in case my battery gets stolen). I was having to choke it even after a stall while warm, to restart it.

I'm going to take your advise on the jets. is there a model number for the jets? I've searched some threads, but unable to find it. I'm sure it's been discussed here a hundred times, so sorry.

Weldangrind · 03-12-2013, 12:27 AM

Happy to help.

The main jet is referred to as a large round: http://jetsrus.com/a_jets_by_carbure...arge_round.htm

The slow jet: http://jetsrus.com/a_jets_by_carbure...-486_pilot.htm

You'll likely need to shop somewhere else; jetsrus gets a little weird about international orders.

Nicraage · 03-13-2013, 08:49 PM

Thanks. I just placed an order. It took the APO address. It's not really shipping internationally for them, they basically ship to Miami, and then the Army Post office takes over from there.

I barely passed a Italika 150cc on the highway to work this morning at top end, so I hoping this will help a bit. :evil: Now, I'm really hell bent on mods.

Weldangrind · 03-13-2013, 11:25 PM

They wouldn't accept a Paypal order from me, because it's a "foreign address". :roll:

Nicraage · 03-16-2013, 01:49 PM

Looks like they shipped it

I couldn't find a screwdriver I could adjust the bottom screw with while the carb is mounted. Rather than wait on an order for one, I improvised.

I took a cheap screw driver and stoked it in some coals. I the used a pair of pliers to bend it (pretty easily). Works well. I'll probably make another one or two with different twists to make it easier to fine tune. (I think just one would work if it were a philips bit) :P

I don't think I could have bought anything that would be easier to get in the tight space.

Weldangrind · 03-17-2013, 12:20 AM

Classic blacksmithing! You're the man. 8)

Nicraage · 03-30-2013, 03:06 PM

Well, I recieved my jets from jets R us, (thanks for them shipping APO).

I've become very proficient with removing and reinstalling my carb 8O

I put in a pilot 25 and a main 110. Full thottle bogs down more with this jet in. I've tried all the pin clip positions, and still bogs. I'm thinking of trying a 105 or something in between, although the 100 I can't really comlain about.

Here is my question: I noticed the full throttle bog goes away if i wedge open the air intake butterfly valve a tiny bit, and it seems to give me a pretty good power increase (no matter which jet is in). I'm obviously doing this without an air filter on for testing purposes.

Are there any mods to this butterfly valve? I came up empty with searches. What if I drilled a few holes in it? any thoughts? Thanks

Weldangrind · 03-31-2013, 11:55 AM

How is the starting and idle?

edtardo · 03-31-2013, 11:58 AM

I had the same problem till I put a uni filter on

Nicraage · 03-31-2013, 01:34 PM

with either jet, I can adjust it to start great. with the larger main jet idle was fine, but riding at very light throttle in 1st or 2nd gear it was very hesitant. It's not as noticeable since i've put the main jet back to the one that came with the mikuni.

Regarding the uni filter. I've ordered one, but if I remove the air filter completely, and have an issue, it shouldn't be due to lack of proper air flow, right?

edtardo · 03-31-2013, 01:55 PM

I wouldn't think so, but these chinese machines seem to defy logic lol

Weldangrind · 03-31-2013, 03:53 PM

I guess that your engine isn't as thirsty at your elevation.

Nicraage · 04-13-2013, 03:15 PM

Quote:

Originally Posted by Weldangrind

I guess that your engine isn't as thirsty at your elevation.

The originals seem to work better. It was certainly worth the couple bucks and time it took to learn how the carb works.

03-07-2013, 07:58 PM	#16
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	Not an expert but I would think there would be a idle mixture screw and an idle speed screw. __________________ Happy to serve.
	0

03-07-2013, 08:24 PM	#17
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Correct. There is a pilot mixture screw on the underside of the carb, close to the intake tube. Turn it in (gently) until it seats, counting the number of turns. Turn it back out a dissimilar amount; if it was one turn out, try 1.5 turns. The pilot mixture screw is responsible for the transition from idle to the main jet. BTW, my guess is that you'll need to swap the stock 20 slow jet to a 25, and the 100 main to a 110. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-12-2013, 12:27 AM	#19
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Happy to help. The main jet is referred to as a large round: http://jetsrus.com/a_jets_by_carbure...arge_round.htm The slow jet: http://jetsrus.com/a_jets_by_carbure...-486_pilot.htm You'll likely need to shop somewhere else; jetsrus gets a little weird about international orders. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-13-2013, 11:25 PM	#21
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	They wouldn't accept a Paypal order from me, because it's a "foreign address". :roll: __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-17-2013, 12:20 AM	#23
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Classic blacksmithing! You're the man. 8) __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-13-2013, 08:49 PM	#20
Nicraage Join Date: Feb 2013 Posts: 27	Thanks. I just placed an order. It took the APO address. It's not really shipping internationally for them, they basically ship to Miami, and then the Army Post office takes over from there. I barely passed a Italika 150cc on the highway to work this morning at top end, so I hoping this will help a bit. :evil: Now, I'm really hell bent on mods.
	1

03-16-2013, 01:49 PM	#22
Nicraage Join Date: Feb 2013 Posts: 27	Looks like they shipped it I couldn't find a screwdriver I could adjust the bottom screw with while the carb is mounted. Rather than wait on an order for one, I improvised. I took a cheap screw driver and stoked it in some coals. I the used a pair of pliers to bend it (pretty easily). Works well. I'll probably make another one or two with different twists to make it easier to fine tune. (I think just one would work if it were a philips bit) :P I don't think I could have bought anything that would be easier to get in the tight space.
	0

03-30-2013, 03:06 PM	#24
Nicraage Join Date: Feb 2013 Posts: 27	Well, I recieved my jets from jets R us, (thanks for them shipping APO). I've become very proficient with removing and reinstalling my carb 8O I put in a pilot 25 and a main 110. Full thottle bogs down more with this jet in. I've tried all the pin clip positions, and still bogs. I'm thinking of trying a 105 or something in between, although the 100 I can't really comlain about. Here is my question: I noticed the full throttle bog goes away if i wedge open the air intake butterfly valve a tiny bit, and it seems to give me a pretty good power increase (no matter which jet is in). I'm obviously doing this without an air filter on for testing purposes. Are there any mods to this butterfly valve? I came up empty with searches. What if I drilled a few holes in it? any thoughts? Thanks
	0

03-31-2013, 11:55 AM	#25
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	How is the starting and idle? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-31-2013, 11:58 AM	#26
edtardo Join Date: Mar 2012 Location: Altoona, Fl Posts: 158	I had the same problem till I put a uni filter on
	0

03-31-2013, 01:34 PM	#27
Nicraage Join Date: Feb 2013 Posts: 27	with either jet, I can adjust it to start great. with the larger main jet idle was fine, but riding at very light throttle in 1st or 2nd gear it was very hesitant. It's not as noticeable since i've put the main jet back to the one that came with the mikuni. Regarding the uni filter. I've ordered one, but if I remove the air filter completely, and have an issue, it shouldn't be due to lack of proper air flow, right?
	0

03-31-2013, 01:55 PM	#28
edtardo Join Date: Mar 2012 Location: Altoona, Fl Posts: 158	I wouldn't think so, but these chinese machines seem to defy logic lol
	0

03-31-2013, 03:53 PM	#29
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I guess that your engine isn't as thirsty at your elevation. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0