Should I do a CV Carb slide drill mod?

dh · 10-29-2016, 12:18 PM

I ordered a jet kit for my XF250 that came with a drill bit and instructions to enlarge the hole in the carb slide. The carburetor is a Teikei MV30, nearly identical to the one used on the Zongshen Sierra 200 and Yamaha TW200 models(MV28 I believe).

Has anyone done this and if so what was your experience? I have read that this is a popular mod on Harley CV carbs, but haven't seen much about this topic here. Thanks!

Update: After looking at a few KLR forums on this mod I drilled the slide and cut the needle spring a tad. I also put in a bigger pilot jet that came in the kit.

The bike still starts up ok, and idles ok. I do notice quicker throttle response and more power around the 3k-4k rpm range.

Weldangrind · 10-30-2016, 12:20 PM

Thanks for sharing that mod. I have a similar carb on my TW, and I'll be looking for performance enhancements like that. What size did you drill it out to?

dh · 10-30-2016, 11:12 PM

Weld, I used a 1/32" bit to do this mod. I have also cut the needle spring about 1/16".

There was no noticeable change in throttle response after cutting the spring.

2LZ · 10-31-2016, 02:46 PM

Glad to hear it worked. I've done that mod on many HD's and it seems to work fairly well, but HD's rev so slowly anyway. I'm not a big CV carb fan to begin with, but you can do things to make the respond more briskly. My '09 XP200 actually came with a real Mikuni CV. There are some mods for that one as well. It's hard to beat a cable tugging on a slide for response, over vacuum pulling the slide up. My Q Link revs more quickly now but still not a quickly as my CG motors.

Petro2020 · 11-11-2016, 03:28 PM

Anyone know how to remove the screws to the carburetor or can provide a product that can clean the carb without taking it out (XP200) that has been sitting for 18 months with gas...guessing it is clogged.

Thanks!

BlackBike · 11-11-2016, 06:02 PM

You could try this type https://www.walmart.com/ip/17491945?...&wl13=&veh=sem

Just needs to get in there to the Jets. Too Long and may melt seals nothing sure thing but will help melt the varnished fuel if you don't want to take apart. But for 18 months? Good luck

2LZ · 11-14-2016, 01:27 PM

Quote:

Originally Posted by Petro2020

Anyone know how to remove the screws to the carburetor or can provide a product that can clean the carb without taking it out (XP200) that has been sitting for 18 months with gas...guessing it is clogged.

Thanks!

The float bowl screws? Do yourself a favor and get some small vise grips, lock them on the screw heads and twist to break them loose. You'll probably just strip them with a screwdriver.

The dang CV carb on these are so temperamental to sitting. The pilot jets clog up quickly. My Mikuni CV on my Q Link is real bad about sitting and even if I don't ride it for months, I start it and get it hot at least once every couple weeks just to keep it ungunked.

Once you can access the float bowl screws and get them broke loose for the first time, the only saving grace is you don't have to remove the carb thereafter to access the float bowl. Just remove the throttle cables, loosen the intake and air filter clamps and spin it sideways with the bottom of the carb pointing out the right side of the bike. Makes for easier cleaning down the road.

OUTERLIMITS · 11-14-2016, 02:14 PM

It's ok to leave gas in the tank for many months, but make sure to run the carb dry with the engine idling and drain the float bowl if your carb has a drain screw if the bike is going to sit for anything more than a few days. With the tiny pilot jets these small bikes have, they will clog in no time. I also don't use gas from the tank if it has sat for a month or more.

jimwildman · 11-15-2016, 09:39 AM

Quote:

Originally Posted by OUTERLIMITS

It's ok to leave gas in the tank for many months, but make sure to run the carb dry with the engine idling and drain the float bowl if your carb has a drain screw if the bike is going to sit for anything more than a few days. With the tiny pilot jets these small bikes have, they will clog in no time. I also don't use gas from the tank if it has sat for a month or more.

Add stabilizer, Turn off the petcock, Start it up cold, by the time it warms up at all it will have used up all the gas in the bowl.. Let her sit till spring..

Dump the gas from thr tank and run it in your lawn mower.. put new gas in the bike turn on the petcock and fire it up.. I like to leave fuel in a metal tank, to prevent rust. even if it goes bad.. A plastic tank should be emptied out for long term storage.

Azhule · 11-15-2016, 10:02 AM

Should be a good start to your gasoline storage woes

most "Stabilizer" products claim 12 to 24 months of stabilized fuel

http://www.schaefferoil.com/neutra-fuel-stabilizer.html

https://www.goldeagle.com/product/sta-bil-360-marine

http://www.starbrite.com/startron

10-29-2016, 12:18 PM	#1
dh Join Date: Jun 2014 Location: NW Arkansas Posts: 453	Should I do a CV Carb slide drill mod? I ordered a jet kit for my XF250 that came with a drill bit and instructions to enlarge the hole in the carb slide. The carburetor is a Teikei MV30, nearly identical to the one used on the Zongshen Sierra 200 and Yamaha TW200 models(MV28 I believe). Has anyone done this and if so what was your experience? I have read that this is a popular mod on Harley CV carbs, but haven't seen much about this topic here. Thanks! Update: After looking at a few KLR forums on this mod I drilled the slide and cut the needle spring a tad. I also put in a bigger pilot jet that came in the kit. The bike still starts up ok, and idles ok. I do notice quicker throttle response and more power around the 3k-4k rpm range. __________________ 2013 SSR XF-250 Last edited by dh; 10-29-2016 at 03:10 PM. Reason: Update
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10-30-2016, 12:20 PM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Thanks for sharing that mod. I have a similar carb on my TW, and I'll be looking for performance enhancements like that. What size did you drill it out to? __________________ 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
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10-30-2016, 11:12 PM	#3
dh Join Date: Jun 2014 Location: NW Arkansas Posts: 453	Weld, I used a 1/32" bit to do this mod. I have also cut the needle spring about 1/16". There was no noticeable change in throttle response after cutting the spring. __________________ 2013 SSR XF-250
	0

10-31-2016, 02:46 PM	#4
2LZ Join Date: Mar 2010 Location: Volcano, Ca Posts: 7,094	Glad to hear it worked. I've done that mod on many HD's and it seems to work fairly well, but HD's rev so slowly anyway. I'm not a big CV carb fan to begin with, but you can do things to make the respond more briskly. My '09 XP200 actually came with a real Mikuni CV. There are some mods for that one as well. It's hard to beat a cable tugging on a slide for response, over vacuum pulling the slide up. My Q Link revs more quickly now but still not a quickly as my CG motors. __________________ "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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11-11-2016, 03:28 PM	#5
Petro2020 Join Date: Nov 2016 Posts: 1	XP200 Can't Remove Screws to Carburetor Anyone know how to remove the screws to the carburetor or can provide a product that can clean the carb without taking it out (XP200) that has been sitting for 18 months with gas...guessing it is clogged. Thanks!
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11-11-2016, 06:02 PM	#6
BlackBike Join Date: Feb 2016 Location: George West, Texas Posts: 4,097	You could try this type https://www.walmart.com/ip/17491945?...&wl13=&veh=sem Just needs to get in there to the Jets. Too Long and may melt seals nothing sure thing but will help melt the varnished fuel if you don't want to take apart. But for 18 months? Good luck __________________ ***************************************** 2015 Bashan"Blaze" BS250GY-31 (DB-07K-250) GONE 2017 Suzuki V Strom 650 XT "We are all born ignorant, but one must work hard to remain stupid." ~Benjamin Franklin~
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11-14-2016, 02:14 PM	#8
OUTERLIMITS Join Date: Oct 2015 Posts: 75	It's ok to leave gas in the tank for many months, but make sure to run the carb dry with the engine idling and drain the float bowl if your carb has a drain screw if the bike is going to sit for anything more than a few days. With the tiny pilot jets these small bikes have, they will clog in no time. I also don't use gas from the tank if it has sat for a month or more.
	0

11-15-2016, 10:02 AM	#10
Azhule Join Date: Dec 2015 Location: CO Posts: 1,525	Should be a good start to your gasoline storage woes most "Stabilizer" products claim 12 to 24 months of stabilized fuel http://www.schaefferoil.com/neutra-fuel-stabilizer.html https://www.goldeagle.com/product/sta-bil-360-marine http://www.starbrite.com/startron __________________ "Think as you like... but this self proclaimed Professor is always right" - Buckshot "You never know what someone is hiding beneath their smile..." - NinjaTom - R.I.P.
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