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Old 05-01-2012, 05:54 AM   #6886
moterbiker
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Quote:
Originally Posted by Maliwal View Post
So I've got a '92 Xt 225 Serow and I just replaced the stock carb with a knock-off Mikuni VM-32 (I believe). First step (after the modifications to make the damn thing fit and function!) was to up the stock (for the new carb) 120 main jet with a 130. Fired up first crack and idles so beautifully it's hard to describe. Off the line she's got more power than before, so much so that I accidentally blasted across the first intersection from the house with one wheel on the ground

But after first gear the problems start. Past about half throttle the bike chokes and stumbles. I can short-shift and slowly work her up to sixty downhill (easy) and fifty or so uphill. And I mean a 1-2% grade at most. Each gear I go up it seems to have less power and throttle range.

After finding the problems I thought: Ok, not enough fuel under load. Larger main jet! I worked up slowly to a 145 MJ (Yeah, I know. Way huge.) Problem got better with 135 and 140 but then worse with 145. She just can't burn THAT much, I guess. I guessed timing (poorly-timed spark firing after up-stroke, not a problem at low RPMs, but more and more pronounced with higher RPMs). Pulled flywheel and checked upper and lower sprockets (upper is cracked horribly and needs to be replaced, but that's $77 I don't have right now ) chain tension was good, timing marks seemed right. Possibly very slightly advanced on the upper sprocket, but there's no way it skipped a tooth. If anything, chain stretch, but to my (un)professional eye, not enough to cause the issues I'm noticing.

So long story short, I've not a damn clue what else could be wrong with it. It seems like a lack of fuel (or too much air?).

Any ideas folks? I'm missing great riding weather here! Missed the last month waiting for the carb, which has been absolutely beautiful here in So. California.

Thanks in advance,

Mal
What does your plug look like? I am wondering if the problem is the opposite, too large of a jet.
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Old 05-01-2012, 06:06 AM   #6887
GlennR
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Does anyone have rear rack laying around they would like to get rid of? PM or email sandjoh@gmail.com Thanks

If you have two of them in that pile I need one too.
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Old 05-01-2012, 06:37 AM   #6888
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Quote:
Originally Posted by Maliwal View Post

Any ideas folks? I'm missing great riding weather here! Missed the last month waiting for the carb, which has been absolutely beautiful here in So. California.

Thanks in advance,

Mal
Isn't carb tuning fun?

What are the other settings? Like needle (is it adjustable), airbox setup, etc.
The 140 sounds to rich for a "stock" carb.
Did you check the float setting? -- It can make things act wierd if out of adjustment too far.

Sometimes a drastic change can point you in the right direction. Like removing the snorkel or even opening up the airbox at the side cover -- by removing it but then taping off a large portion of the opening. If it gets better at least you know you were too rich. And if it's already open you can tape it up a bit. Not a permanent fix but can be helpful sometimes in troubleshooting. Once you know the direction you need to go you can start fine tuning the jets and needle. But the float setting has to be right first.

Good Luck!!!

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Old 05-01-2012, 09:47 AM   #6889
TTRPaul
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carb

Concerning the new carb problem. I suspect to large a jet or possible needle/diaphram problem. Let us know what you find out. Also if the upper timing gear is as you say I would be replacing both gears and chain before severe damage occurs. This is just my opinion based on past experiences, no hard facts to back it up though.
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Old 05-01-2012, 10:10 AM   #6890
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Quote:
Originally Posted by moterbiker View Post
What does your plug look like? I am wondering if the problem is the opposite, too large of a jet.
Plug was pretty fouled when I pulled it (toasted about 4 threads up too, cooked pretty thoroughly. But this may have been because I ran it for about 500 miles on full choke to get it home from my last trip... Not sure, really. As for the MJ being too large, I considered that and ran the 120 main jet. The problem was worse than with any of the other jets. I checked the plug after running all the way to 145 MJ, so I may have toasted it doing that alone.

Quote:
Originally Posted by Rumlover View Post
Isn't carb tuning fun?

What are the other settings? Like needle (is it adjustable), airbox setup, etc.
The 140 sounds to rich for a "stock" carb.
Did you check the float setting? -- It can make things act wierd if out of adjustment too far.

Sometimes a drastic change can point you in the right direction. Like removing the snorkel or even opening up the airbox at the side cover -- by removing it but then taping off a large portion of the opening. If it gets better at least you know you were too rich. And if it's already open you can tape it up a bit. Not a permanent fix but can be helpful sometimes in troubleshooting. Once you know the direction you need to go you can start fine tuning the jets and needle. But the float setting has to be right first.

Good Luck!!!
Oh yeah, it's proving to be an absolute blast! Considering everything else that's happened with this beast, I keep telling myself: First bike, it's a learning experience. And that's for damn sure! I can now do a carb removal, clean, and re-install in under 10 minutes, including removal of jets and diaphragms and clearing of passages. Lots and lots of practice!

I eye-balled the floats and they seemed to be set properly, the needle would open after about 3-4 mm of float drop. However, I'm new to this stuff so honestly I just said "Meh, looks like it works. Better to not screw with it." Could it be that the float bowl isn't refilling fast enough? Makes sense to me, since the problem is only under load (when more fuel i being burned).

I have yet to play with the air box, but during these tests it was opened slightly (only have the bottom screw and the top of the airbox cover is being held closed by gorilla tape, but the tape had slid in the heat, leaving the top of the airbox cracked about 2-3mm.

I have no idea about adjusting the needle. I assume you mean through the use of shims under the needle stop, but I don't have any shims (bought the jets individually, not as a set) nor know exactly how to tune the carb for their use, if that makes sense. It also seems to make sense that the needle could need to be shimmed, causing an increase in fuel flow from the main jet at lower internal pressure, resulting in a richer fuel mixture. Yes?

Quote:
Originally Posted by TTRPaul View Post
Concerning the new carb problem. I suspect to large a jet or possible needle/diaphram problem. Let us know what you find out. Also if the upper timing gear is as you say I would be replacing both gears and chain before severe damage occurs. This is just my opinion based on past experiences, no hard facts to back it up though.
I will try to play with it some more this evening, I'm thinking I'll drop it back to the 130 MJ and try shimming the needle (pretty sure I know what to do; it's not complicated).

I would absolutely love to replace the gears and the chain, it was pretty alarming to see cracks run straight through the upper one. However, all told, those three parts total something like $250, and as of two weeks ago, I have no job. So that's sort of not really a possibility. The only reason I'm still even considering riding this thing is because the upper sprocket isn't solid plastic. I stuck a magnet to it all over, and found that it has a ferrous core. It's just covered in plastic. Why? Hell if I know. But the metal innards (I really, really hope) will keep it intact for now.

Thanks folks, your input is greatly appreciated! I'll be sure to let y'all know how it turns out. If all else fails, anyone interested in the charred remains of a Serow?

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Old 05-01-2012, 11:16 AM   #6891
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Quote:
Originally Posted by Maliwal View Post
I have no idea about adjusting the needle. I assume you mean through the use of shims under the needle stop, but I don't have any shims (bought the jets individually, not as a set) nor know exactly how to tune the carb for their use, if that makes sense. It also seems to make sense that the needle could need to be shimmed, causing an increase in fuel flow from the main jet at lower internal pressure, resulting in a richer fuel mixture. Yes?

I will try to play with it some more this evening, I'm thinking I'll drop it back to the 130 MJ and try shimming the needle (pretty sure I know what to do; it's not complicated).
Some carbs have an adjustable needle with several slots cut into it and a clip that can be moved from one slot to another to raise or lower the needle in the slide. Very small increments, they (slots) are virtually right on top of each other.
If it is a non adjustable one then shimming is about all that can be done. I would suggest one or two thin washers to shim it, maybe .02" to .04" overall.
Dropping back to a 130mj and shimming the needle seems like as good as place as any to start.

Good luck

Edit: one last note, shimming it will make it richer in the midrange (you knew that) so keep that in mind. My experience (at a higher elevation then you) is that they can be fairly sensitive to the whole air box opening thing. So keep that in mind when trying to balance the air fuel ratio. With this being an after market carb it is all kind of a guess. Keep us posted.

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Old 05-01-2012, 01:21 PM   #6892
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2008 XT250 oil drain plug seized

I've not kept up with this thread, but just had an experience I thought I'd put out there...

The oil drain plug was seized (I tightened to torque spec last time) and the head of the bolt stripped off. Frustrating. After the head was rounded and the socket just spun, I used both vice grips and a pipe wrench, but the metal just shaved off, seemed incredibly soft.

I packed a 1/2" size socket with JB Weld and secured it up against the rounded bolt head by using a bottle jack from below, although, I suppose duct tape might work too. I left it for a couple of days until I could get back to the project and the seized bolt just spun right off as if it were in butter.

btw, the Yamaha dealer didn't seem surprised that I had seized oil drain plug and they had a replacement bolt in stock. They wanted about $100 (and the hassle of transporting the bike over there) to weld something on to the bolt to remove it.

Instead, the JB Weld worked great!

Also, the next time I do this, I think I'll try to initially loosen the bolt with the crankcase stone cold. I know the manual says warm the engine first, but on loosening the bolt just now, it didn't seem as tight as what I fought with the other day (when everything was hot.) I don't know, just a thought. Maybe the PB penetrator just had more time to work, I don't know. But if the aluminum crankcase expanded from the heat, that means the circumference of the bolt hole would be just a little bit tighter. No?
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Old 05-01-2012, 01:29 PM   #6893
Tom S
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Quote:
Originally Posted by airborndad View Post
?? This ??
kamperbob.com/xt225tires
from Kamperbob
Thanks, Airborn. That’s not the one I was looking for, but some good info anyway.
I found what I was looking for & it wasn’t even in this thread. Sorry for wasting your time.
‘Gunnerbuck’s observations here on various dual sport tires may be useful.
http://www.advrider.com/forums/showp...postcount=2662
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Old 05-01-2012, 03:14 PM   #6894
Reposado1800
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Quote:
Originally Posted by Maliwal View Post
So I've got a '92 Xt 225 Serow and I just replaced the stock carb with a knock-off Mikuni VM-32 (I believe). First step (after the modifications to make the damn thing fit and function!) was to up the stock (for the new carb) 120 main jet with a 130. Fired up first crack and idles so beautifully it's hard to describe. Off the line she's got more power than before, so much so that I accidentally blasted across the first intersection from the house with one wheel on the ground

But after first gear the problems start. Past about half throttle the bike chokes and stumbles. I can short-shift and slowly work her up to sixty downhill (easy) and fifty or so uphill. And I mean a 1-2% grade at most. Each gear I go up it seems to have less power and throttle range.

After finding the problems I thought: Ok, not enough fuel under load. Larger main jet! I worked up slowly to a 145 MJ (Yeah, I know. Way huge.) Problem got better with 135 and 140 but then worse with 145. She just can't burn THAT much, I guess. I guessed timing (poorly-timed spark firing after up-stroke, not a problem at low RPMs, but more and more pronounced with higher RPMs). Pulled flywheel and checked upper and lower sprockets (upper is cracked horribly and needs to be replaced, but that's $77 I don't have right now [click to show pic]

) chain tension was good, timing marks seemed right. Possibly very slightly advanced on the upper sprocket, but there's no way it skipped a tooth. If anything, chain stretch, but to my (un)professional eye, not enough to cause the issues I'm noticing.

So long story short, I've not a damn clue what else could be wrong with it. It seems like a lack of fuel (or too much air?).

Any ideas folks? I'm missing great riding weather here! Missed the last month waiting for the carb, which has been absolutely beautiful here in So. California.

Thanks in advance,

Mal
Put in a 125 main jet. It will run better.
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Old 05-01-2012, 04:41 PM   #6895
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Quote:
Originally Posted by justacommuternow View Post
The oil drain plug was seized (I tightened to torque spec last time) and the head of the bolt stripped off.
There shouldn't be much pressure on the threads of a stripped off head. The head is what provides the fastening.

If you find yourself in this position again, first try to just back out the bolt with needle nose pliers if you can get a grip on it. If that doesn't work, drill a small hole in the bolt, tap in an ez out, and extract.
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Old 05-01-2012, 05:16 PM   #6896
Tom S
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I missed this post & thought he nuked it after I got the email notification.
Quote:
Originally Posted by justacommuternow View Post
... if the aluminum crankcase expanded from the heat, that means the circumference of the bolt hole would be just a little bit tighter. No?
No, the hole will get a little bit larger.
Quote:
Originally Posted by mk4 View Post
...If you find yourself in this position again, first try to just back out the bolt with needle nose pliers if you can get a grip on it.
If you can’t get it loose with vice grips you sure as hell ain’t gonna get it loose with needle nose pliers. That would never even be my choice for something like a stuck bolt.
It often helps to tap the bolt before trying to loosen it. You might even try to tap it around with a hammer & a punch before trying to loosen it with a wrench, vice grips, or whatever. Those little impacts from the tapping help a lot sometimes.
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Old 05-01-2012, 07:27 PM   #6897
Maliwal
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Carb Issues

Well, tried shimming the needle in conjunction with adjusting the fuel mixture, but no dice. She ran a little different each time, but nothing I did really seemed to make much of a difference. Parked her back in the shed for the night. Tomorrow I'm going to try swapping the needles from the old and new carbs. They have a very different shape and who knows.

I'm fresh out of ideas once more
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Old 05-01-2012, 07:38 PM   #6898
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Quote:
Originally Posted by .JimC View Post
So I tried your idea - and the front fender just flops all over the place. The aluminum mount I made is reasonably stiff but the fender itself has no strength and when only supported from 2 holes it just flops around in the breeze. What did you do to stiffen it?
I mounted the fender as close as possible to the wheel. I used the 10mm bolts that held the fender onto the fork originally, to mount the fender to the 4" piece of 1/2" square aluminum. I tapped the 4" piece where the 10mm bolts mount, and the main mounting piece/bracket is threaded to accept the allen bolts that the 4" piece fits over. All the allen bolts have nylock nuts on the other end, including the ones that attach the brace to the fork leg. I just used stuff I had in the basement.( I noticed someone on xt225.com had mounted a small Harley fender, looked better,but I don't think it extended down as much.)
I haven't switched mine back to the original position yet as it persists to be 46 degrees and raining here
I just returned from a 400km ride with no shaking whatsoever.
It looks real ugly, but works great. I mean really, I love these bikes, but damn they're fugly!
I say just stick with it, and it'll work. It's a great mod if you live in rainy areas.
(My guess is you must be in the Pacific Northwet.)
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Old 05-02-2012, 03:23 AM   #6899
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Originally Posted by woofer2609 View Post
I mounted the fender as close as possible to the wheel. I used the 10mm bolts that held the fender onto the fork originally, to mount the fender to the 4" piece of 1/2" square aluminum. I tapped the 4" piece where the 10mm bolts mount, and the main mounting piece/bracket is threaded to accept the allen bolts that the 4" piece fits over. All the allen bolts have nylock nuts on the other end, including the ones that attach the brace to the fork leg. I just used stuff I had in the basement.( I noticed someone on xt225.com had mounted a small Harley fender, looked better,but I don't think it extended down as much.)
I haven't switched mine back to the original position yet as it persists to be 46 degrees and raining here
I just returned from a 400km ride with no shaking whatsoever.
It looks real ugly, but works great. I mean really, I love these bikes, but damn they're fugly!
I say just stick with it, and it'll work. It's a great mod if you live in rainy areas.
(My guess is you must be in the Pacific Northwet.)
Mine's too loose to even try riding it. I think my alum stock isn't as stiff - I did use the hardware you described, but the c-channel just twists easier than the 1/2" square stock. I'll fab up a new mount in the next couple of days and try again. I brazed together a 2-piece mount - much tougher to get it properly aligned than bending 1/2" stock!

I'm not in the nortwet - but I do need a shorter (front to back) front fender. 2nd choice is to just cut the fender.
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Old 05-02-2012, 10:19 AM   #6900
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Anyone running a Pelican 1450 as a top case with the TCI quick release system?

Hey Everyone,

I scoured the thread, but couldn't find much on anyone using one of the smaller-sized Pelican cases as a top case on their XT (except for the photos from GauloisUSA, thanks!)

I have the TCI Borrego rack and was curious if anyone was using their Borrego rack with TCI's "Top Box Hard Case Adapter kit" and a Pelican or other brand of dry case. Here's a photo (courtesy of TCI's website) of the quick release plate:



I really like the idea of having a waterproof, lockable top case (that also locks to the rack) that is quick release for the times I want to take the case inside with me, or to take it off for trail riding etc. Thanks in advance for any info on this setup!
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