I bought this '05 XT a while back in non-running condition and only 3100 miles from a local guy who said it wouldn't start again after it had been used during the previous fall riding season. Supposedly it was his girlfriend's bike. He didn't seem to be very mechanical and said he didn't want to deal with it, so he put it up for sale.
When I picked it up it was still dirty, he didn't even bother to wipe it off before showing it, and it was clear he hadn't done much recent maintenance on it. The oil was filthy, some spokes were loose, and all he had done to attempt to fix the no-spark issue was replace the plug.
xt225_purchase day_2022-03-17.jpg
After I got it, I cleaned it up, and replaced some missing hardware and a broken signal lens. Then I went through it, changed the oil and filter, rebuilt the carb, replaced a few electrical items, and determined the cause of the no-spark issue was a bad stator.
After replacing the bad part, I thought everything was done and I was going to be able to enjoy it. But it only ran for 15 miles and almost stranded me on the first test ride. I got tired of working on it so I pushed it to the back of the garage and moved on to other bikes projects since I have more than enough to keep me busy.
After it had been sitting in my garage for quite a while I decided to pull it back out and see what had caused it to lose spark again. That's when I found out the new aftermarket stator had failed on the first ride due to a defect. The manufacturer sent a warranty replacement unit and I popped it in and the bike fired right up. So, that issues is finally resolved!
And since acquiring it I've installed a few upgrades...
DMO Specialties foot pegs:
xt225_peg upgrade_2022-04-19.jpg
Acerbis Rally Pro hand guards and MZS Tuning shorty levers, and I replaced the scratched up headlight cowl and front fender:
xt225_hand guards-levers_2024-02-28.jpg
xt225_running_2024-03-20.jpg
This week I added a Precision Moto enduro rack:
XT225_PMR_Enduro rack_2024-04-02.jpg
XT225_PMR Enduro rack install_2024-04-02.jpg
Although the ignition issue is resolved, it currently has a high-idle issue after it gets warmed up. Runs fine at start up and requires choke when cold. After the choke is turned off it has a perfect idle and performs as expected. But once it gets warm after about a mile the idle starts to hang and will not drop back to normal RPMs and then engine start getting really hot with the extra revs. I've done a quick check for possible air leaks with carb cleaner, but didn't find anything. Almost seems like a cracked intake boot and it only occurs when hot.
Took the carb off and went through it again and cleaned it in the ultrasonic. Also checked the cut-out valve cover that I had replaced because it was cracked when I picked up the bike, but it was OK.
xt225_carb disassemble_2024-03-18.jpg
xt225_carb cleaned_2024-03-18.jpg
However, after everything was back together...No change. :uh what:
So, I have some more diagnostic work ahead of me to find the cause. It's practically unrideable now because it just revs out the whole time and starts to get super hot.
xt225_running_L_2024-03-20.jpg
xt225_running_R_2024-03-20.jpg
almost forgot...
During my extensive electrical troubleshooting I discovered that the main switch had an intermittent short, one of the many issues that made finding the root cause of the no-spark problem so difficult.
Disassembled the switch, cleaned it up inside, checked the contacts, applied some dielectric, and it was functioning like new again. :thumbs:
XT225_main switch repair_2024-03-05.jpg
XT225_main switch fixed_2024-03-05.jpg
That is a lot of various issues to try and find...no wonder the previous owner gave up on it. Hope you get to ride it soon :thumbs:
might be the carb diaphragm. I looked at those before i bought my xr150, neat bikes for sure. you'll get it sorted. :clint:
You probably checked the valve clearances, but I don't see it in your process above. I'd include it in your diagnostic attack
Quote from: m in sc on April 06, 2024, 07:37:42 AMmight be the carb diaphragm.
I checked the diaphragm really carefully and didn't see anything wrong with it. I can get a new genuine Mikuni one for about $75 (Yamaha wants $160), maybe I'll just fire the parts cannon at it. If it doesn't fix it I'll have a spare for my XT parts bin.
Quote from: 85RZwade on April 06, 2024, 11:51:43 AMYou probably checked the valve clearances, but I don't see it in your process above. I'd include it in your diagnostic attack
I have not checked yet but I did source the tools and gaskets in anticipation of doing it. Could a bad valve clearance cause a high idle like I have?
id say probably not, a compression check would be easy to do though. that would show one hanging up
I know this is a way different bike than the kz1100 I had very similar condition, carbs are mikuni BS34 diaphragm slide, ran well but would not settle into a normal idle.. the situation I had was a combo of leaking rubber carb mount and low speed mixture adjustment. Took quiet a few try's to correct. Lean mixture in the low speed circuit seems to be the culprit.
My carb is currently all stock with brand new genuine Mikuni jets. Below are the factory specs and what I've changed. Because these bikes are notorious for being on the lean side from the factory, it's a pretty common mod to increase the pilot one size. So, I'll be installing a #42.5 to see if that helps at all but I kind of doubt it. And on advice from another long time XT owner, the fuel screw has been changed from 2 turns out to 3, but no effect on performance or the idle issue.
2001-07 Yamaha XT225, Mikuni BST34 specs -- stock:
Main jet: #125
Pilot jet: #40 (to be increased to #42.5)
Pilot air jet 1: #70
Pilot screw: 2 turns out (increased to 3 turns out)
Needle jet: 0-1
Needle: 5DL27-1
Valve seat: 2.0
Float level: 14.1-15.1 mm (14.7mm)
A new diaphragm slide is on the way so I can see if that improves anything. I will be also be leak testing the rubber carb joint again to see if I can find any air leaks. Unlike the joints on RDs the XT part uses an O-ring between the cylinder, so I have one of those on order as well.
.... do those have that plastic housing that runs up the side of the carb body? can't see it on the pic. they are NOTORIOUS for warping and leaking air. would be on the opposite side of the cable wheel. there was a TTR225 i worked on years ago that had one that would leak like just enough to completely fuck the idle and transition circuit. IF i remember correctly, has an o-ring at either end and it screws to the side of the carb body.
Quote from: m in sc on April 17, 2024, 08:55:25 AM.... do those have that plastic housing that runs up the side of the carb body? can't see it on the pic. they are NOTORIOUS for warping and leaking air. would be on the opposite side of the cable wheel. there was a TTR225 i worked on years ago that had one that would leak like just enough to completely fuck the idle and transition circuit. IF i remember correctly, has an o-ring at either end and it screws to the side of the carb body.
Yes, it has the air cut-off valve on the side. The TTR225 and XT225 share a lot of parts including the carb. The cut-off cover was replaced with a brand new one because it had a crack in it. (The O-ring, diaphragm, and spring were reused.)
Mikuni-BST-34-carburetor-Yamaha_XT225-TTR225.jpg
When I was installing it, I was thinking that it would be an easy spot to develop a leak because of the design. Who knows, maybe I got a cover that doesn't fit well?
I'm planning a trip to Sudco to get some Mikuni parts, so I'll just add that O-ring to the list.
And when I get the bike out to do my leak testing I'll check that cover too.
Did some work on the XT today. It had been parked for a few months while I worked on other projects, but I finally decided to tackle the high-idle-after-hot issue. When I was hanging out at so-cal-sdr200's house on Friday we were talking bike projects, and he suggested it could be the diaphragm since it was the original and maybe was not allowing the slide to drop back down after raising in the bore. Since I already had the parts and it had been in my plans for a while I made the time to get it done.
Pulled the carb.
Replaced the broken OE choke cable plastic retainer nut with a nice billet one from Warp 9.
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Cleaned pilot, main, and needle jets again just to be certain they didn't get gummed up from sitting.
Replaced the diaphragm slide with a new Mikuni part. (The Mikuni part is 1/2 the price of the Yamaha one -- same part, only a different part number)
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Reassembled everything and fired it up.
After start up the bike has always idled perfectly. Once off the choke it would settle into a nice steady idle. The high idle issue used to begin after about a mile, and the idle revs would stay at 3K+. So I let it idle for a while to get it sufficiently warm before the test ride. Did a short 6 mile putt.
The high idle issue seems to be cured! :thumbs:
There's a just a hint of a little lazy drop to idle after letting off the throttle. Pretty minor, and something that should be easy to resolve with a little tweaking.
yup. that'll do it too. had to do that to both the concourses when i had them.
Not fixed after all. :bang:
Took it for a longer ride today and the revs still hang around 2-3K sometimes. Also noticed when shifting that it would over-rev each time the clutch is pulled (despite letting off throttle). The problem isn't as bad as it was before and it's not constant. I did 30 miles and it started about 4-5 miles in. The issue was tolerable, but annoying.
At least I was able to get in the longest ride I have done on the bike since I bought it. So I have that going for me.
Ha, I had a TTR225 and had similar issues. Electrical leave you stranded issue ended up being bad/stuck contacts in kill switch. Carb worked fine after cleaning but was only good to sit for a week or so with pump gas cuz it was so finicky. I def would have eventually replaced carb if I had kept it. Loved it when it was running tho
any chance your throttle cable is routed too close to head or exhaust pipe at some point? Or possibly the throttle inner wire isn't sliding freely inside outer sheath from age/use?
Quote from: RDnuTZ on August 06, 2024, 08:18:37 PMany chance your throttle cable is routed too close to head or exhaust pipe at some point? Or possibly the throttle inner wire isn't sliding freely inside outer sheath from age/use?
No, it isn't throttle cable related. It has a push-pull dual cable setup and the pulley on the side of the carb is returning all the way to the closed position at the stop while the issue is happening.
maybe a new diaphragm/slide spring is due. :umm:
Quote from: m in sc on August 07, 2024, 01:29:27 PMmaybe a new diaphragm/slide spring is due. :umm:
Possibly, I'll get one and throw it in there and see what happens. Worth a try at this point.
Also, next time I have the carb out I'm going to carefully look at the slide guide. Maybe it's binding up when getting hot? New ones are available from Mikuni for the BST34.
BST34_slide_guide.jpg
Quote from: SoCal250 on August 07, 2024, 03:30:09 PMQuote from: m in sc on August 07, 2024, 01:29:27 PMmaybe a new diaphragm/slide spring is due. :umm:
Possibly, I'll get one and throw it in there and see what happens. Worth a try at this point.
Ordered. But as seems to be the case with my luck and obtaining parts, there is a 4-week back order on the spring. :shocked:
doh.
in the meantime can you add some preload to it? for a test? like 1/4" or so.
?
I have some other parts I'll need to install soon so I may see what can be done with the OE spring while I'm waiting for it. It's a pain to take the carb out of that bike but it looks like I'm going to have to do it at least twice now. :rolleyes:
Got some parts from Moto Lab in Iowa (https://www.moto-lab.com/). A great source for Mikuni BST carb parts! Thanks so-cal-sdr200 for the recommendation!
I ordered stuff midday on a Monday and it was at my door Wednesday. Unlike some other places, everything he has on his site is in stock.
Pulled the carb today and made some changes:
-Increased the pilot from #40 to #42.5
-Shimmed the needle
-Installed an extended pilot fuel screw set. Now I won't have to pull the carb to make adjustments. :thumbs:
-Installed the missing rubber boot on the choke cable fastener on the carb.
(Left the main at the stock #125 and kept the fuel screw at 3 turns out.)
20240822_144357_resized.jpg
Inspected the slide guide and it's in good shape and shows no evidence of binding or sticking. I polished the slide edges with some fine emery cloth since the brand new part had a little bit of flashing and rough edges, and lubed the blade channels with some 2T. I have a new BST34 guide but decided against replacing it because it wasn't necessary (and I don't have the correct Torx tamper bit for the screws).
And I didn't replace the slide spring because the part is still 3 weeks out on backorder.
The first 2 items are part of a kit from ProCycle and recommended upgrades to improve performance on the XT.
No test ride yet, but maybe tomorrow if I have time.
nice. hope that cures it.
fuckin' 4 strokes... :dawg:
curious to see how it works out. good job in the extended screw. i have a 60? degree angle bit driver just for that same issue.
Attempted a test ride today but didn't even make it out of the driveway. It's worse! :bang:
Fired it up and as soon as I could turn off the choke the idle started rising. Checked the cable pulley on the carb and it was still sitting on the stop screw. Blipped the throttle a few times and no change, still hanging. Shut it off and restarted and the idle was normal again. Then it started hanging again.
I also noticed a new noise that sounds like a pulsing air/vacuum leak (kind of like tsstt-tsstt-tsstt-tsstt). It's from somewhere on the rear half of the engine but couldn't pinpoint it. It's a little difficult to hear over the exhaust noise. I sprayed carb cleaner in a few places looking for a leak and found nothing.
When blipping the throttle it now has a bad blubbering stumble that it didn't have before, but I couldn't mess with the fuel screw because it was too hot to get a hand in there, so I just put it away to deal with later. Too hot and pissed off to tinker with it any more today.
And I had to get the MB5 ready for the show tomorrow anyway.
This bike got me so frustrated that I stuffed it in the back of garage since I have too many other projects to work on. Well, after a year I decided it was time to pull it out and get back at it to see if I could resolve the issues and get it running correctly.
This thing has been so troublesome since I brought it home that it has earned the nickname of "the POS". The first year or so was spent playing whack-a-mole with various electrical issues, some of which left me stranded on the side of the road on the first few test rides. In the first 2-1/2 years I was only able to put 67 miles on it.
Over the Labor Day weekend I went through the carb again, replacing a leaking float valve and installing all new jets. The cut-off valve diaphragm and the three associated O-rings were also replaced. I also raised the float 0.75mm. After some road testing and fine tuning the jetting is now: #130 MJ, #42.5 PJ, needle shim. 3.25 turns out on the fuel screw. (Stock is #125, #40, 2 turns out.)
During my ownership, every single part of the carburetor has now been replaced except for the body, the cap, and the bowl!
20250902_144938_jets_resized.jpg
In an attempt to fix the hanging idle issue I replaced the carb manifold and O-ring. In the past I wasn't able to find any air leaks there but it sure looked suspect. It was crusty and less pliable than the new one.
20250902_134818_joint_resized.jpg
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So... after the latest wrenching attack, the POS is running perfectly now! :whoop: In the first few days of the month I've done over 160 miles, including 81 yesterday. Friday's ride was more miles than I was able to put on the bike in the entire first 3 years I've owned it!
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Sep 03 ride: 60 miles through Long Beach and the terminal area:
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Sep 05 ride: 81 miles south on PCH to Dana Point
Corona del Mar
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Dana Point Harbor
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The POS performed flawlessly. Fires right up, smooth idle, revs return to idle quickly after whacking the throttle, clean revs all the way to redline, and no hesitation. :celebrate:
Now that it runs great and is reliable, I'm going to (as my friend Darryl always says) "Ride the piss out of it! :vroom:
A 1 tooth larger front sprocket is coming next week, and sometime soon I'll put on some more street-oriented tires since it won't see dirt much.
On to the next bike project...
:whoop:
Glad you found some peace of mind with your project.
I know when I get pissed off and push stuff back for a while....I usually forget what exactly the issues were and have to start from the beginning again.
I toured the Queen Mary multiple times when I lived in SD. Seemed like it was in a constant cycle of renovation and decay. I thought I read some time ago it was going to be moved? I also remember seeing the Spruce Goose display of the Howard Hughes giant wooden sea plane that made 1 test flight and never flew again.
Quote from: busa1300 on September 07, 2025, 10:26:01 AMI know when I get pissed off and push stuff back for a while....I usually forget what exactly the issues were and have to start from the beginning again.
I create my own work invoices for my records when I service a bike. These are kept in a file for each vehicle I own. In the notes section of the invoice I notate any open issues, things to keep an eye on, or needed repairs that were not completed.
And to keep track of projects I have a large dry-erase board above my workbench on which I keep a bullet list of items that need attention for each bike (and car). Very useful so nothing slips through the cracks, and I'm not having to reinvestigate to see where I left off. :thumbs:
Last week I swapped out the OE 15T front sprocket for a 16T piece. After getting things all adjusted I discovered that because the axle had been most of the way forward already with the stock 15T piece, the new larger sprocket necessitated moving the axle all the way forward. And I discovered that there wasn't enough chain slack when it was at the forward limit.
20250910_140320_sprocket.jpg
20250910_135534_16T sprocket.jpg
So I got a new 428 O-ring chain and shortened it to 122L (stock is 120L).
20250918_145231_chain.jpg
Also flushed the brake fluid which really needed it! Thought I had done this when I brought it home, but when reviewing my service records I discovered it hadn't been done. New DOT4 and good to go. :thumbs:
20250910_150316_brake flush.jpg
And I added a RAM X-Mount for my phone on the handlebars.
Now it's time for more riding, and a test of my new top-speed capabilities! :vroom:
Whoohoo, the POS goes ZOOM!
Happy putt'n Russ.
nice. how's that 16 pull in top gear?
Quote from: m in sc on September 26, 2025, 11:29:34 AMnice. how's that 16 pull in top gear?
Dunno. The POS is living up to it's nickname. After getting it all sorted and putting a couple hundred miles on it, I parked it in the garage Sep 05, after shutting off the fuel and running it until it died. Then I put the new sprocket and chain on, but now it won't run right. :bang:
Went to go ride it Sep 23 but it won't stay running, stalls constantly, idle and up to about 1/3 throttle is erratic. Only got a hundred feet down the street before I was pushing it back. At first I thought it was just out of gas but that's not it. Slow cranks sometimes too but the battery is 12.7v.
Too pissed off to do any deep investigation or pull the carb for the 19th time. It's been pushed to the back of the garage as punishment. I've got more important things to work on.
I thought about ghost riding it into the brick wall down the street but the crappy thing won't stay running long enough or put out any decent power/speed to even get moving. Dragging it with a chain behind the truck to the dump might be a better option. :rant-1:
is the carb starving for fuel?
Had an XT225 a few years ago - swore by it, not at it! Even rode it above the timberline up Mt. Adams in WA State - never missed a beat; no idle or jetting issues, even going 8K feet higher in altitude and into the snow.
Wondering, seeing you didn't have a chance to give it a good shake-down with the old electrics, could it be a timing advance issue? A hanging electronic advance curve (I think all XT225's go from 9 degrees retarded to 31 degrees advanced) can cause wonky idle and hanging low throttle RPMs.
Being an Early American and British bike enthusiast, many bikes I've had were manual advance, and for-instance my '27 Indian could be ridden using a static partial throttle (1/8 to 1/4), and rev from a low idle to in-town speeds using only the manual-advance twistgrip. My '53 BSA does the same, but not to such a drastic extent; kinda like what you describe.
Easy to check with a timing-light and it's probably just fine, but maybe...
Warren
Finally found some time to work on the POS again after it's poor behavior on the last ride attempt.
Pulled the carb and gave it an inspection but didn't find anything that could have caused the poor running issue. I guess it will remain a mystery. (The POS is a mysterious animal.) Cleaned the jets, float valve, passages and bowl with carb cleaner and air. Reassembled and bolted it back up.
Also gave the fuel screw a tweak (+0.25) to 3.25 turns out in an attempt to alleviate a light stumble when whacking the throttle from idle.
Installed the new chain roller and inner bushing. The old chain roller was MIA and the chain had been running on the bushing.
]20251018_143714_resized.jpg
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Runs great again! :whoop: So I took it out for a short ride (10 miles). :vroom: It was a great day for it, it hit 80F at the beach today!
The 1-tooth larger front sprocket made a world of difference! It's quicker because you don't have to constantly shift, and there's no need to take off in 2nd since 1st gear is usable again. And top speed is better. Cruises effortlessly at 50mph instead of straining like it did previously.
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Looking forward to taking it out tomorrow for a longer ride.
Yesterday I took out the POS for a longer test/shakedown ride. It ran flawlessly. Ended up doing 56 miles through the beach towns and along the coast on PCH from Seal Beach down to Newport and Corona del Mar. At one point I looked down at the speedo and was shocked to see I was doing 70mph. The new front sprocket made it a new bike!
Seal Beach at Rivers End off of First St. looking South
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Corona del Mar near Lookout Point on Ocean Blvd
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Corona del Mar at Ocean Blvd & Poppy Ave looking South towards Arch Rock, which you can see in the distance
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And the highlight of the day was that during the ride I was finally able to finish my recently topped-off fuel tank and go on reserve, which I was trying to do so I could gauge mileage before having to switch over and also get MPG. After gassing up I ran the numbers...
Miles from full to RES: 146 mi
MPG: 78.45 MPG :whoop: Wow, I can't believe the mileage on this thing! I guess there's actually one thing that the POS can do well.
And with each ride it's more clear that the POS is begging for more street-oriented tires. So those are coming soon.
:clap: