Search

GREAT RIDES & STAYS!
Fab Ads
Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#144828 - 04/03/19 07:12 PM UK Carburetor mod experiences?
Rick Mc Offline
Junior Member
*****

Registered: 02/16/19
Posts: 50
Loc: Portsmouth, VA
My 2007 XT225 is running great since I rebuilt the carb, all new jets, 127.5 main, 42.5 pilot, 3 turns out, and most recently the Z1 mod to the exhaust. I dropped down from a 130 main in the beginning, it actually ran great but I'm at sea level and thought the 127.5 would work better at higher altitudes. The bike already had a K&N airfilter.

There is a slight hesitation when transitioning from idle and giving it throttle. I see the UK Mod described shimming the needle and enlarging the vacuum hole in the plastic diaphragm/carb top cover.

On past CV carbs like the KLR650, we would enlarge the vacuum port on the slide itself to get a snappier throttle response to help lift the front when going over obstacles.

I'd like to hear from others who have actually enlarged the vacuum hole in the diaphragm cover, or the vacuum port on the slide itself, and their opinions about the results.

Please resist from posting how the carb was designed by engineers and not to modify it, etc. The 3 turn mod, rejet, shim the needle, and enlarge the vacuum port had worked great on other bikes I have owned.

I just want to learn how the two different approaches to enlarging the vacuum port have an effect on the XT225.

Btw, this forum has been a wonderful resource helping me get this bike dirt worthy. From the knowledge base here, I've been able to really bring this bike up from something that barely ran (then wouldn't start at all), to rebuilding the carb, adjusting the valves, changed the sprockets to 15/50 (and still might go to 14/50), the inverted brake rod, Z1 exhaust mod, removing turn signals, Trakmaster II tires, etc.

Thanks!


Edited by Rick Mc (04/03/19 07:23 PM)
_________________________
--Rick
2007 XT225, K&N filter, 130/42.5, 2.7 turns, drilled vacuum port on slide to 7/64, shimmed needle, Z1 mod, 15/50 sprockets

Top
#144896 - 04/10/19 10:39 PM Re: UK Carburetor mod experiences? [Re: Rick Mc]
Rick Mc Offline
Junior Member
*****

Registered: 02/16/19
Posts: 50
Loc: Portsmouth, VA
No responses to this :-(

From the UK Mod listed here:

UK Mod

It sounds like the shim is about the same thickness as the white spacer that is already under the circlip. If so, I have one from a carb rebuild kit, and want to verify the shim thickness before I open up the carb again.
_________________________
--Rick
2007 XT225, K&N filter, 130/42.5, 2.7 turns, drilled vacuum port on slide to 7/64, shimmed needle, Z1 mod, 15/50 sprockets

Top
#144899 - 04/11/19 12:36 PM Re: UK Carburetor mod experiences? [Re: Rick Mc]
peejman Offline
Platinum Member
*****

Registered: 06/03/13
Posts: 3125
Loc: East TN USA
I've not heard of enlarging the vacuum port before this. I can see how it might help in principle.
_________________________
This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.

Top
#144901 - 04/11/19 06:35 PM Re: UK Carburetor mod experiences? [Re: Rick Mc]
Rick Mc Offline
Junior Member
*****

Registered: 02/16/19
Posts: 50
Loc: Portsmouth, VA
On further research it seems like the later models had matched vacuum holes in the plastic diaphragm/carb top cover. One person on AdvRider.com drilled the slide with good results.

And I've found other posts either here or on AdvRider.com using a shim size identical to the white needle spacer.
_________________________
--Rick
2007 XT225, K&N filter, 130/42.5, 2.7 turns, drilled vacuum port on slide to 7/64, shimmed needle, Z1 mod, 15/50 sprockets

Top
#144904 - 04/12/19 02:05 AM Re: UK Carburetor mod experiences? [Re: Rick Mc]
Rick Mc Offline
Junior Member
*****

Registered: 02/16/19
Posts: 50
Loc: Portsmouth, VA
I just pulled my carb and drilled the slideís vacuum port, only one drill bit size larger than the hole, I used a 7/64 bit.

I also drilled the vacuum port in the diaphragm cover slightly over size, again 7/64. The ďUK ModĒ called for drilling this hole larger, to 11/64, but I didnít go that far.

I shimmed the needle adding an identical white spacer to the one already under the circlip. And I swapped back to a 130 main having temporarily run a 127.5 main.

The bike fired right up and came off the choke very quickly on this warm 70 degree evening.

The throttle response improved considerably, without feeling snatchy. At a slow pace in 1st gear, a quick roll off, full throttle brought the front wheel up. The bike wouldnít do this before, even with the 15/50 sprockets. I think this will help me get the front wheel over obstacles easier. I had practiced loading the front suspension and nailing the throttle in 1st gear to clear a 4x4 during a Dirt Bike Boot Camp last weekend, but the throttle response was so sluggish it didnít work well. Now it feels like it would be easy to do.

The bike pulls well, even in 6th from very low rpmís all the way up to an indicated 74/75 which is max speed for the 15/50 sprockets. I donít believe the 130 main made much of a difference, but I put it back in there since people have said that was the stock size when the bike first came out.

So Iím pleased with the vacuum port mods.


Edited by Rick Mc (04/12/19 02:06 AM)
_________________________
--Rick
2007 XT225, K&N filter, 130/42.5, 2.7 turns, drilled vacuum port on slide to 7/64, shimmed needle, Z1 mod, 15/50 sprockets

Top
#144905 - 04/12/19 01:45 PM Re: UK Carburetor mod experiences? [Re: Rick Mc]
Az4x4 Offline
Platinum Member
*****

Registered: 08/18/08
Posts: 4163
Loc: Heber/Overgaard, AZ

Nice write up Rick. Good information. I've had my eye out for another XT225, something local, in good shape, in my price range, for a long time now. If such a bike does show up and I'm fortunate enough to snag it, I'll follow your lead and drill the vacuum port to 7/64" - if at that time you're still high on this particular carburetor mod. Thanks for the encouragement!..
_________________________
Lovin' life in Arizona's cool Mogollon Rim Mountain Country!!

Top
#144911 - 04/14/19 12:03 AM Re: UK Carburetor mod experiences? [Re: Rick Mc]
#brer15 Offline
Member L4
*****

Registered: 10/03/16
Posts: 475
Loc: Atlanta,GA
Interesting mod. I hope you can update at a later time, after a good bit of riding, and let us know if it's still working out.
_________________________
2004 XT225 purchased new in October 2004 0 miles. Current miles over 27,000.

Top
#144949 - 04/17/19 10:59 PM Re: UK Carburetor mod experiences? [Re: Rick Mc]
Rick Mc Offline
Junior Member
*****

Registered: 02/16/19
Posts: 50
Loc: Portsmouth, VA
The last 2 days Iíve been doing low speed crazy 8 drills. Riding around in tight 8 patterns at the lowest speed I can while standing. Today I adjusted the Pilot screw from 3 turns to maybe 2.5 or 2.75 turns and the bikeís idle was much smoother. I can just putt around at idle in first gear, and the bike just chugs like a tractor.

I have repeatedly tested the throttle response at low speed in first, and at the right pace, if you chop the throttle then nail it full throttle the front comes up easily. It wouldnít do this before the mod, so Iím very pleased!

The bike runs well over the full rpm range.

I think Iíll get a 14T front sprocket to improve the gearing further fo trail use.
Someone on Adventure Rider said he went from 15/50 to 14/50 and did not like it. He thought it made 2nd gear to short, and 3rd was too tall for where he rides. I looked the the Gearing Commando page, and it didnít look like it would be a problem, but Iíll get some more trail time in before I change to a 14T.
_________________________
--Rick
2007 XT225, K&N filter, 130/42.5, 2.7 turns, drilled vacuum port on slide to 7/64, shimmed needle, Z1 mod, 15/50 sprockets

Top
#144952 - Yesterday at 11:42 AM Re: UK Carburetor mod experiences? [Re: Rick Mc]
peejman Offline
Platinum Member
*****

Registered: 06/03/13
Posts: 3125
Loc: East TN USA
Cool. I do idle speed figure 8's a pretty regularly as well. On a good day I can do full lock turns at less than idle. Occasionally I can stop momentarily and not fall over. Good practice for sure.
_________________________
This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.

Top
#144957 - Yesterday at 07:34 PM Re: UK Carburetor mod experiences? [Re: Rick Mc]
Muniac Offline


Platinum Member
*****

Registered: 01/16/04
Posts: 5663
Loc: Montrose, CO
Mountain biking is another good way to cross train for trail riding. Many of those skills transfer to a powered bike. Practice is always good and it's nice to see you guys partaking. There is a safety component too. As in avoiding a crash because you practiced a skill and ride with a tad more confidence.

I wouldn't think twice about 14:50 for trail riding. It's an easy inexpensive way to test those waters. If you don't like the lower gearing the bike can easily be returned to stock gearing. I also like the lower gearing for the braking it offers when coming down technical sections of trail.
_________________________
Evolve & Simplify
Be There or Be Nowhere! A Few Adventures & Video

Top
Page 1 of 2 1 2 >

Web & Site Search
Google
 
Custom TO Customer
Specialty Resource
Fab Ads
Boardcaster Updates

Board Upgrade: Board upgrade to V7.5.8 has been completed on Tuesday Sept 2nd 2014. This should solve the missing posts problem. Enjoy the new software!

Who's Online
0 registered (), 15 Guests and 2 Spiders online.
Key: Admin, Global Mod, Mod
Shout Box

Top Posters
Reggie 11645
alexd 5915
Muniac 5663
Moto Psycho 4684
Az4x4 4163
peejman 3125
kris 2366
Paul49 1684
Doc250 1643
JerryH 1516
Forum Stats
5263 Members
38 Forums
15759 Topics
141434 Posts

Max Online: 149 @ 11/09/12 11:04 PM
Newest Members
gsmith, Andy74, SimonB, JoseXT, Vinduroman
5263 Registered Users
April
Su M Tu W Th F Sa
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30