TT250 carburetor? - Page 3

pcspecialist · 07-11-2016, 02:39 AM

I just got around to swapping the stock (rejetted main, shimmed needle) carb on my Hawk with a Mikuni and it is debatable if the slight improvement was worth the cost. I may have got the same results had I replaced the idle jet on the stock carb.

Ariel Red Hunter · 07-11-2016, 12:42 PM

Quote:

Originally Posted by pcspecialist

I just got around to swapping the stock (rejetted main, shimmed needle) carb on my Hawk with a Mikuni and it is debatable if the slight improvement was worth the cost. I may have got the same results had I replaced the idle jet on the stock carb.

Am happy to learn you had success re-jetting a (I presume) Keihan carb. I used to road race (I was the wrench) a Honda fitted with those carbs. Finding jets for them was almost impossible. They were un-numbered, so I had to guage the openings. I hated to do that, as I never willingly stick anything stronger than a round toothpick in a jet to unplug it. Do I think a Mikuni VM is the ultimate carburetor? No, but can I get jets for it? Yes. And the jets are all numbered, making it easy (assuming you have a bunch of jets, and yes, I know the other meaning of "Assume") to go leaner or richer in steps that are repeatable.

Jayman77 · 07-11-2016, 02:59 PM

Quote:

Originally Posted by 2LZ

A Mikuni is on the Amazon Wish List. Thanks for the recon Rojo!

Wil this Mikuni fit on the tt and do you have a link

2LZ · 07-11-2016, 04:20 PM

Quote:

Originally Posted by Jayman77

Wil this Mikuni fit on the tt and do you have a link

It should. I did a rough measure with my calipers and the intake flange mounting bolts seamed the same.

This is what I ordered. Price floats around a little. Typical Amazon.
https://www.amazon.com/MIKUNI-VM26-C...M26+%2830mm%29

Here are the jets I ordered. You'll need to pick the right ones for your elevation.
Here's some info Weldangrind has provided for direct links to jets-r-us:

http://api.viglink.com/api/click?for...-486_pilot.htm

http://api.viglink.com/api/click?for...arge_round.htm

The carb will come lean with a 100/20 setup. I went 115/30 at 3000 feet and it's a bit rich. I need to drop the pilot to a 25 I think.

Jayman77 · 07-11-2016, 04:38 PM

Quote:

Originally Posted by 2LZ

It should. I did a rough measure with my calipers and the intake flange mounting bolts seamed the same.

This is what I ordered. Price floats around a little. Typical Amazon.
https://www.amazon.com/MIKUNI-VM26-C...M26+%2830mm%29

Here are the jets I ordered. You'll need to pick the right ones for your elevation.
Here's some info Weldangrind has provided for direct links to jets-r-us:

http://api.viglink.com/api/click?for...-486_pilot.htm

http://api.viglink.com/api/click?for...arge_round.htm

The carb will come lean with a 100/20 setup. I went 115/30 at 3000 feet and it's a bit rich. I need to drop the pilot to a 25 I think.

I live 10 miles inland on pancake flat east coast less than 100 ft what would be a good setup

2LZ · 07-11-2016, 05:07 PM

Quote:

Originally Posted by Jayman77

I live 10 miles inland on pancake flat east coast less than 100 ft what would be a good setup

I'd try the stock 100/20 first, move the needle clip down one notch (to the fourth groove) and initially set the idle mixture to 2 turns out.
With your pipe, I fear this still may be lean at sea level but the clip and screw may help. I think the stock setup on the Keihin clone is a 108 if I heard correctly from rojo???

If I were you though, with pipe, at sea level, I'd order a 110 and a 112.5 main and a 22.5 and a 25 pilot and go from there. Jets are cheap.

Jayman77 · 07-11-2016, 05:16 PM

Quote:

Originally Posted by 2LZ

I'd try the stock 100/20 first, move the needle clip down one notch (to the fourth groove) and initially set the idle mixture to 2 turns out.
With your pipe, I fear this still may be lean at sea level but the clip and screw may help. I think the stock setup on the Keihin clone is a 108 if I heard correctly from rojo???

If I were you though, with pipe, at sea level, I'd order a 110 and a 112.5 main and a 22.5 and a 25 pilot and go from there. Jets are cheap.

Will start fiddling with it I have never had to jet a carb but I figure I can

rojo_grande · 07-11-2016, 05:21 PM

Quote:

Originally Posted by 2LZ

I think the stock setup on the Keihin clone is a 108 if I heard correctly from rojo???

Yep the stock jet is a Keihin 108. Mikuni jets are sized differently.

http://www.jetsrus.com/FAQs/FAQ_miku...ihin_sizes.htm

If I don't get my 3/4 to WOT hesitation/sputter issue solved, I'll be looking at swapping to a Mikuni. Set up lean at sea level might just be the ticket for my elevation. But might have to go a little richer if I swap out the exhaust too.

Rojo

2LZ · 07-11-2016, 05:31 PM

Well crap. All this talk....and I ended up just ordering one now....and a new pod filter, just in case. The carb sticks out sideways compared to the other CG motors I've had (the intake flange looks reversed) so I got a bent K&N style pod filter that will point it back into the frame. Not cheap but looks like it would work well.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

rojo_grande · 07-11-2016, 05:32 PM

Almost forgot. While scanning ebay earlier today, avoiding work, ran across a similar carb to what is on the TT, a Keihin carb with an accelerator pump.

http://www.ebay.com/itm/231591352354...%3AMEBIDX%3AIT

Any thoughts, pros, cons, to the accelerator pump?

Rojo

pcspecialist · 07-11-2016, 05:42 PM

Definitely start with the 20 first, I made the mistake of ordering 25, 30, and 35 just to cover all possibilities and I suspect the 20 that came with it would have been fine even though I am using a 25. I'm running a 115 for my main (I think, I could have the 117.5 in it). The 115 is maybe a tad too lean at my low elevation, but, fine for where I do much of my riding. No cat and modified my muffler some.

2LZ · 07-11-2016, 05:46 PM

Quote:

Originally Posted by rojo_grande

Almost forgot. While scanning ebay earlier today, avoiding work, ran across a similar carb to what is on the TT, a Keihin carb with an accelerator pump.

http://www.ebay.com/itm/231591352354...%3AMEBIDX%3AIT

Any thoughts, pros, cons, to the accelerator pump?

Rojo

Not sure about the accelerator pump units. Be curious to see....
With these small displacement motors, I've had no problems with the cable driven slides and throttle response. It's been the CV carbs that have given me the most headache of any..... Temperamental and need to be run regularly.

Ariel Red Hunter · 07-11-2016, 07:47 PM

Quote:

Originally Posted by Jayman77

I live 10 miles inland on pancake flat east coast less than 100 ft what would be a good setup

Mikuni? 115 and 20 seems to work ok. Throttle slide number is probably good for you. Be very careful to not change the float height.

Ariel Red Hunter · 07-11-2016, 07:53 PM

Quote:

Originally Posted by 2LZ

Not sure about the accelerator pump units. Be curious to see....
With these small displacement motors, I've had no problems with the cable driven slides and throttle response. It's been the CV carbs that have given me the most headache of any..... Temperamental and need to be run regularly.

I agree. Simpler is better. I once had a BMW R75 with CV carbs, soggy runner. Traded it in on a R90S, which had delOrto carbs, simple like Mikuni's, Amals, Kiehans. Ran much sharper. I don't just mean faster, sharper.

BlackBike · 07-11-2016, 10:58 PM

Quote:

Originally Posted by 2LZ

Well crap. All this talk....and I ended up just ordering one now....and a new pod filter, just in case. The carb sticks out sideways compared to the other CG motors I've had (the intake flange looks reversed) so I got a bent K&N style pod filter that will point it back into the frame. Not cheap but looks like it would work well.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

07-11-2016, 05:31 PM	#39
2LZ Join Date: Mar 2010 Location: Volcano, Ca Posts: 7,092	Well crap. All this talk....and I ended up just ordering one now....and a new pod filter, just in case. The carb sticks out sideways compared to the other CG motors I've had (the intake flange looks reversed) so I got a bent K&N style pod filter that will point it back into the frame. Not cheap but looks like it would work well. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 __________________ "Light a fire for a man, and you heat him for a day. Light a man on fire, and you heat him for the rest of his life." 2007 Suzuki DRZ400S (SM convert) 2009 Q Link XP 200 1967 BSA B25 250cc Starfire 2022 Royal Enfield Interceptor 650 2023 Royal Enfield Scram 411 1948 Royal Enfield Model G 350
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07-11-2016, 05:32 PM	#40
rojo_grande Join Date: Jun 2015 Location: Weston, CO & Sangre de Cristos Posts: 240	Almost forgot. While scanning ebay earlier today, avoiding work, ran across a similar carb to what is on the TT, a Keihin carb with an accelerator pump. http://www.ebay.com/itm/231591352354...%3AMEBIDX%3AIT Any thoughts, pros, cons, to the accelerator pump? Rojo __________________ '15 RX3 (Rojo's) '15 RX3 (marzhere's) '16 TT250
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07-11-2016, 02:39 AM	#31
pcspecialist Join Date: May 2016 Posts: 583	I just got around to swapping the stock (rejetted main, shimmed needle) carb on my Hawk with a Mikuni and it is debatable if the slight improvement was worth the cost. I may have got the same results had I replaced the idle jet on the stock carb.
	1

07-11-2016, 05:42 PM	#41
pcspecialist Join Date: May 2016 Posts: 583	Definitely start with the 20 first, I made the mistake of ordering 25, 30, and 35 just to cover all possibilities and I suspect the 20 that came with it would have been fine even though I am using a 25. I'm running a 115 for my main (I think, I could have the 117.5 in it). The 115 is maybe a tad too lean at my low elevation, but, fine for where I do much of my riding. No cat and modified my muffler some.
	1