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Author Topic: GV250 bogged down  (Read 1397 times)

echo4mic

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GV250 bogged down
« on: August 12, 2017, 12:44:54 AM »

Hello Forum,
I recently bought a 2008 GV250 from a woman in Kansas, and brought it back to Colorado.
Took it out a few times, ran great.  The 3rd time I took it out, for a 30 minute ride, about half way into the ride it bogged down terribly.  Little to no power, yet it would rev fine with the clutch in.  So I figured it was not a problem of not getting fuel.  But whenever it's in gear, clutch out and there is any load put on the engine, it just putters along like it's a 25cc, not a 250cc.   After about 5 minutes of riding like this, it picked back up and roared with power like nothing was wrong.  Oh, and while it was bogging, I'd give it full throttle then back off and it would backfire a bit. 
This has happened every time I've ridden it now... fine for a while, then (what feels like) an 80% loss of power and the engine refuses to rev up (unless the clutch is in)... then, after a bit it clears up.  Now, however, it's bogged down and hasnt cleared up... over several days of riding it just around the neighborhood.   
I've read about the CDI flat spot issue and how to "fix" that (on my CDI, with 3 plugins, it's supposedly the green w/blue strip wire)...  I've cut that wire and taped off the ends... had no effect. 

Anyone have an suggestions for what to try next? 
Since it has spark, does run (so I assume has fuel flow), I'm thinking that it must be the CDI getting in the way of the timing or something??  I suppose it could be a carb issue too... but why would it get better sometimes and then drop off again?

thanks in advance for any suggestions.
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echo4mic

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Re: GV250 bogged down
« Reply #1 on: August 13, 2017, 07:05:33 PM »

Quick update.   Both cylinders have good compression (100-120).  Both getting spark.  Fuel pump is pumping fuel (connected dummy line to the pump output and cracked the starter, fuel was pumped). 
All this leads me to suspect the carbs.  Going to pull them next weekend, give them a clean and see what that shows.
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Cloud

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Re: GV250 bogged down
« Reply #2 on: August 13, 2017, 08:10:33 PM »


Looks like you're doing all the right things.
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albertinhouston

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Re: GV250 bogged down
« Reply #3 on: August 14, 2017, 01:13:43 PM »

carb... be very careful with the air box removal. specifically the intake boots at the head
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albertinhouston

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Re: GV250 bogged down
« Reply #4 on: August 14, 2017, 05:14:22 PM »

ok so I was thinking about it.....
Yes clean the carbs. but what is causing the carbs to be dirty??
bad gas? dirty gas tank?
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echo4mic

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Re: GV250 bogged down
« Reply #5 on: August 14, 2017, 05:55:02 PM »

Thanks for the replies and suggestions everyone... 
Will be careful removing parts... looking for some how to vids, and going over the service manual to have a good understanding of the steps, etc.

Dirty carbs...  I've only had it for a month... and looks like previous owner hadnt ridden it in a while, so old gas is a possibility (I filled it, but it only needed about 1 gal).  There were also spiderwebs all up and around various places... maybe they got in there or got sucked in?  IDK.   
Fuel flows from petcock fine... and thru inline filter fine... pump seems to be pumping fine (not sure if there is a proper 'pressure test' that can be performed there or not... 
Will clean the carbs over next weekend... and probably dump the gas (give it to the lawn mower!) and get all fresh... maybe add some seafoam too.   
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albertinhouston

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Re: GV250 bogged down
« Reply #6 on: August 15, 2017, 01:04:56 AM »

If it was me.... Id....
Remove the tank.side cover and loosen the be bracket that holds the coils.....

Remove the float bowls. Take out the pilots clean them.  I run a bread tie wire through it.
 If the gas is any hint of orange pressure wash it.  I remove the cap. Petcock. Fuel gage.

I use my leave blower to blow the water out of the tank. :-)
 All could be done n 30-45 min vs. 5hours. Lol im not kidding on the 5 hours. That air box sucks.
I think i posted carb clean in the thread about 5 months ago
« Last Edit: August 16, 2017, 02:19:08 AM by albertinhouston »
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Cloud

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Re: GV250 bogged down
« Reply #7 on: August 16, 2017, 02:06:21 AM »


Is the airbox worse on the GV than the GT?
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albertinhouston

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Re: GV250 bogged down
« Reply #8 on: August 16, 2017, 02:14:41 AM »

I have found a trick for the 250 gt air box. Its a simple now.

The GV has the frame rail the prohibits the air box from moving.   
« Last Edit: August 16, 2017, 02:19:42 AM by albertinhouston »
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echo4mic

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Re: GV250 bogged down
« Reply #9 on: August 19, 2017, 05:35:11 PM »

Thank you all for your advise and comments.
Well, I think I found at least part of my problem.  When I first got the bike, I noticed quite a lot of cob webs tucked in and around... and even a fair number of tiny baby spiders crawling all over.  I took a vacuum and cleaned those out (and that was weeks ago).  I'd ridden the bike several times since then, and no problems... except this bogging down problem that would popup randomly, then mysteriously 'self heal', only to relapse again.  And the current situation - it's bogging down all the time, not getting better periodically... In fact, I havent been able to even start it all week.

Today, after removing the tank and other various parts, to get  to the carbs, I drained the carb bowls into a dish.  Drained front carb first, and noticed some 'stuff' in the fuel that was drained out (see pic).
https://drive.google.com/open?id=0Bzb_nGP4k8VNVlBsVlZSTmVyVGs

I'm not sure how spiders and bugs could get into the carbs... the air filter is pretty fine and the airbox connections seem water-tight.  But, the evidence seems to prove it.  I got crap in my carbs.
Thinking maybe it could just be a quick fix, I just sprayed some carb cleaner into the fuel intake line to the carbs and let that sit for a few minutes.  Reassembled and was able to start the engine at least (I haven't been able to start it this past week, just wouldn't turn over).   Idled good, rev'd fine.  With it just sitting there, I can idle and rev with apparent ease and consistency... like it doesn't bog down when I rev to 4k rpms... or 5k... 5k... all the way thru to 10k.   BUT, when riding it, it starts out okay, but at around 3-4k rpms, it just bogs down... I can have the throttle full open and it barely does anything... takes 30 seconds to climb past 7k rpms. 

Anyone have any other thoughts on these symptoms? On the one hand, I clearly suspect the carbs... but, then again, it revs fine (as long as your just sitting there, in Neutral)... so that tells me that it must be getting fuel, right?   So why would that be any different when in gear and moving?  I suppose if the front carb main jet is super clogged, then maybe front cyl gets enough fuel to idle... and rear cyl can rev the entire engine up (when in Neutral), but when there is any load, front cyl is starved and rear cyl can't carry the load?
Or maybe CDI?  Is there a way to test the CDI (other than just replacing it to see if that helps anything)?

So, I suppose I will need to pull the carbs completely out of the bike, fully disassemble them and clean them *thoroughly*.  I looked at removing the bowls when I had it opened up earlier, but I think the engine might be in the way of a couple of those screws... so, again, I think I'll have to pull the entire thing out of the bike to get at them.  (Once I do remove those screws, I think I'll replace them with allen head screws.
Anyone have details on how to remove that airbox?  Looks like you'd have to remove the intake manifold boots from the engine... then remove those from the carbs lower end... then maybe the carbs and airbox (together) could drop down just enough to remove them from the bike?

Also, front cylinder seems to have a bit of oil residue... and the rear cylinder does not have that at all.  I'm still seeing good compression with the front cylinder tho. Still, maybe a problem with the head gasket.  I guess the whole engine needs to be pulled to replace that, huh?  That maybe a project for this winter then.

Thanks again for your advice, it's much appreciated!

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