korider.com | Hyosung Motorcycle Owners Forum

korider.com | Hyosung Motorcycle Owners Forum

  • October 19, 2018, 06:19:08 AM
  • Welcome, Guest
Please login or register.

Login with username, password and session length
Advanced search

News:

Welcome to Korider.com!

Pages: [1] 2

Author Topic: Getting a GT250 that was sitting for years running again.  (Read 510 times)

theorist

  • Training Wheels
  • *
  • Offline Offline
  • Posts: 9
Getting a GT250 that was sitting for years running again.
« on: August 20, 2018, 11:37:39 AM »

I just got a 2007 GT250 with 11,000 km or 7,000 miles that has been sitting for years.  It won't start.  The fuel is awfully bad.  I know I need to empty and clean the tank and carbs.  I'll also be changing the plugs, oil and filter, lubing and adjusting the chain, replacing the fuel, vacuum, and brake lines.  I may also switch from incandescent to brighter LED bulbs, replace the old and hard tires for something fresh, soft, and grippy, desnorkel the air-filter, and consider rejetting the carbs.

What else do you think I NEED to do, to get it running?

Do you have any advice on the items above? 

Are their any good videos or documentation of cleaning or rebuilding the mikuni dual carbs?  I'm not new to auto repair but I am new to working on carbs.
Logged

Register and log in and the Ads below will be gone! :D

BikeBandit.com

umop-ǝpisdn

  • Global Moderator
  • Forum Addict
  • *****
  • Offline Offline
  • Posts: 7326
Re: Getting a GT250 that was sitting for years running again.
« Reply #1 on: August 20, 2018, 02:36:43 PM »

This thread might help:

http://korider.com/index.php?topic=381.0

Likely the rubber parts will have perished. That not only includes the ones you can see, but also the ones you can't, i.e the diaphragms in the petcock and fuel pump.

Check the inlet manifolds, as they are also rubber.

Fuel + Air + Spark. It sounds easy, but in truth there's so many places it can go wrong.

What's the oil look and smell like? Any fuel smell?

Its hard to say what you will NEED. You need to have a good look around to assess that. Any rust in the tank? Filter changes will be a must. ALL of them.

I wonder why it stopped being used in the 1st place? Did it break down?
Logged
I used to be a sensitive, new age guy, but times have changed and now I am more of a caring, understanding, ninties type.

albertinhouston

  • Scraping the pegs
  • *****
  • Offline Offline
  • Posts: 837
Re: Getting a GT250 that was sitting for years running again.
« Reply #2 on: August 20, 2018, 03:33:52 PM »

************BEFORE YOU DO ANYTHING TO THE BIKE*********
hook up jumper cables turn the motor over... pure a little gas down the carbs.
BE SURE YOUR MOTOR WILL TURN OVER before you invest any $$$.

fix one problem at a time.

clean tank. once you have it cleaned. clean it one more time. lol
clean carbs. this will most likely be the reason the bike doesn't work.
BEFORE YOU PUT THE TANK BACK ON AND HOOK UP THE GAS LINES>>>>
get an empty water bottle poke a hole in the top of the lid.  push a hose it there and feed it to the pump.
once you get the carbs cleaned well enough that it runs good. It's going to take several tries to get that carb cleaned all the way.
then introduce the tank into the mix.
If you don't do it this way you will not know which is the causing you the problems.

If the motor runs good with the bottle of gas and bad with the tank then the tank is still dirty. (you will probably  need to clean the carbs again.
it's a painful process....

then you can start fixing other issues(tune up the bike)



Logged

theorist

  • Training Wheels
  • *
  • Offline Offline
  • Posts: 9
Re: Getting a GT250 that was sitting for years running again.
« Reply #3 on: August 21, 2018, 10:31:39 AM »

Thank you.  This is all excellent advice.

As a wrote this reply I saw that it got way too long.  I'll leave it in case it's useful to others trying to get their bikes starting after poor storage and trust veterans to skim or skip it if they want.

I've studied the link provided.  (I wished in vain for a wealth of videos like I found for my 2005 Ninja that I left in Massachusetts when I flew to Washington state.)  I've been reading about and watching videos about other carbs too but don't know if other non-Hyosung bikes use the same or very similar carbs.

The owner said he didn't ride much.  It seems he only rode it 200 miles after he bought it 3 years ago.  He said after a while when he couldn't start it he just left it and forgot about it.  He said he took it to a Suzuki shop after he bought it but he couldn't say what they did to it.  He asked if I intended to ride it on the highway.  When I said yes, he expressed concern because he could not get it past 70 mph and said it was very slow going from 50mph or so to 70mph maxed out.  So it was running, 2 years ago, but not well.

I turned the engine over and drained the carbs before I bought it.  It didn't show any sign of life for the first 10 minutes on jumper cables, no lights, horn, starter, nothing.  After a half hour on the jumper cables it would turn over but not start.

After getting the bike home, I removed and drained the fuel tank through the vacuum valve.  (I wish I had a vacuum pump or gauge .  I'm not sure if I tasted or just smelled gas while sucking on the vacuum tube.)  I removed the drain screws for the carbs and sprayed carb cleaner into the float bowls once an hour for a few hours.  (Do we still call them float bowls if they on on their sides?)  While relatively clear gasoline or water came out the first time, each hourly fill of carb cleaner brought out more rust colored muck.  Eventually it was still rust colored but without any water and far less muddy.

I removed the spark plugs.  Both were fouled even though showing nearly no wear and being hot CR7E plugs.  After cleaning them with carb cleaner and compressed air I connected them to the spark plug wires, grounded them, and pressed the starter button.  after a second or two, each plug gave spark. 

I removed the air filter and tried to clean it with compressed air.  It was frustrating not being able to see what the dirty side of the filter looked like, so inspired by what you shared here I used a circle saw to cut out the snorkel.  Later I found the engine runs better at times with my hand partly blocking the now larger filter air filter intake.  I've saved the 'snorkel' so that I can tape it back in if needed until I'm ready to rejet the carbs. 

After getting a compression tester with a 10M thread adapter I found that when cold the rear or top cylinder was giving 80psi and the front cylinder was only giving 45 psi of compression.  After putting a little fresh oil through each spark plug hole the rear or top cylinder gave was giving 120 psi and the front cylinder was still giving only 85 psi of compression.  Maybe the last owner couldn't get it past 70 mph because it was only running one one cylinder.  I didn't know it if had a cracked block, piston or ring damage, head or valve damage, or just misadjusted valves.  I thought of giving up but ...

I cleaned the plastic gas tank from an old push mower, connected it to the bike's carbs fuel line and perched it above the bike's air box (but not on the now drilled out snorkel.)  I put in a little clean gasoline.  I drained the carbs again.  The bike had now been on a trickle charger for a day.  I would turn but still wouldn't start.  I didn't think of putting a drop of gas into the carb air intakes or spark plug holes.  I sprayed no starter fluid into the air box for less than a second, put the air filter back, and it started up.  The longer I ran it, the better it ran, eventually firing on both cylinders.  After running it for a few minutes, getting it of choke, blipping the throttle to 2, 3, and later 4 thousand rpms, it seemed fully warmed up.  It did not want to go above 4,000 RPM.  I turned it off and checked the compression again.  I was delighted to find that it was now giving 180 to 185 psi of compression in both cylinders.  Now I know why they say to only do a compression test on a warm engine.

The next day I connected the auxiliary (push mower) gas tank to the vacuum pump, thinking that the just a foot or two of gravity was was not enough to feed the carbs beyond 4000 RPM.  Before connecting the vacuum pump to the carbs I ran some of the gasoline through the pump by turning the engine over, for about 10 separate 3-second turns of the starter with about 10 seconds of rest in between.  What came out was first a very slow flow of rust colored mud and water, then some rust colored gas, then still a slow trickle of relatively clear colored gasoline.  After connecting the vacuum pump outlet the the carbs, I started the engine relatively easily.  It didn't run too differently than before using just a foot or two of gravity to feed fuel from the auxiliary tank to the carbs.  After warming up, brief blips of full throttle would cause it to stall.  Blips of mild or mid throttle would bring it up to 4000 rpm or so.

I changed the motor oil which was surprisingly dirty after just 200 miles but maybe 3 years.  I don't remember any fuel smell coming from it, but I doubt I'd notice it after spending too much time bathed in the smell of gasoline an carb cleaner.  I may go spell the bottle I put the used oil in later.  I ran the engine again with the same limitation on the old fuel pump and on just 2 feet of gravity. 

I did see some weather cracking on the rubber intake manifolds between the carbs and the intake ports.  I worried about resulting vacuum leaks and thought of looking for a way to reseal or recondition them if replacing them is expensive.  I didn't spray anything on them while the engine was running to test if there is a vacuum leak there.

With one of the two carbs disassembled I'm really impressed.  I'm more comfortable with electronics and computers, but am impressed at how carb is a something like a very complicated mechanical calculator.  I never realized how much fuel injection simplifies things by using sensors for RPM, manifold absolute pressure, mass air flow, throttle position, intake and coolant temperatures, a high pressure fuel pump and fuel lines, and a computer to decide when and how long to open each injector.  This gives me deep respect for all the people who developed carburetors over the years.  I'll definitely reassemble the first carb before opening the second.

I haven't gotten into the gas tank yet.  I removed it and it's vacuum petcock or fuel valve, but I haven't yet removed the filler and delved inside.  I'm worried about how easy it will be to reach all corners of its inside even after removing the filler.  I don't have bunch of small nuts but did think of pouring in some carb cleaner and maybe a much of copper bb's (if I'm sure I can get them back out) and shaking it to try to clean the corners.  Without a camera I'm not sure how I'll know if the corners are clean.  If I get the bike running great I might look into some sort of sealant to stop the rust from returning.  I'll certainly used a fuel filter or two and fuel stabilizer when not riding at least once a week or a tank a month.  I don't know whether to fill the tank and stabilize the fuel or empty and oil the inside of the tank for winter storage.

I've run out of carb cleaner and want to get cheap set of little carb cleaning brushes and wires.  I've been using carb cleaner, a toothbrush, copper wire, and very fine short brass wire from a brass bristle brush.  I'd like cheap readily available replacements for the rubber pieces inside the carbs, but I'd rather pay $50 for a rebuild kit and wait for them to be delivered.  Any advice for how to keep the rubber pieces supple besides limiting their exposure to cleaners?

After I get more carb cleaner and finish cleaning the carbs, I'll try disconnecting the green (with blue stripe) wire from the brown plug going into the CDI.   Is there a good way to test the CDI? 

Will I lose much fuel efficiency from the CDI wire cut hack?  I tried unsuccessfully to remove the green wire from the brown plug so that I could more easily reverse it.  I like great handling and great fuel efficiency, but if the bike is running so poorly that I can't ride it confidently on the highway, that trumps everything else.  A smooth powerband is nice but I might be willing to put up with weak mid RPMs for the sake of efficiency.  I could use low RPM's while cruising and keep the RPMs high for performance.  I learned to do that very happily on my old Ninja 250 and in many cars.  If the bike can't make it through the mid RPMs to reach the high RPM's that's a real problem.  As the bike is now it can't even do that in neutral.  If other fixes take care of that I might try undoing the CDI wiring hack to see if it improves fuel efficiency at some cost to rideability.

It seems like there is still excessive valve chatter, but I don't know what to expect from a Hyosung 250.  I may check the valve adjustment even though most other vehicles wouldn't need an adjustment after only 7000 miles.  I was surprised to read Hyosung's service schedule.  I've always serviced my vehicles more than the manufacturer called for, but I've never replaced spark plugs and inspected valve clearance every 5,000 miles.  I'm not sure if I was more surprised by the call for an oil change every 2,500 miles or the liliputian size of the oil filter.

Once I'm done with the carbs, tank, petcock, fuel pump, and fuel lines, I'm looking forward to seeing how the bike rides.

Logged

theorist

  • Training Wheels
  • *
  • Offline Offline
  • Posts: 9
Re: Getting a GT250 that was sitting for years running again.
« Reply #4 on: August 21, 2018, 01:48:38 PM »

These aren't the best videos, but I found a couple with our Mikuni BDS26 carb (but just one) on a Yamaha Virago 250. 

https://www.youtube.com/watch?v=neaBAYm8iss
https://www.youtube.com/watch?v=V48yB3ZT8IA

I also found these detailed writeups with tons of great photos of Mikuni BDS carbs on a US or Australian Yamaha XJ600 Seca II.  They use 4 carbs that are like ours but missing the accelerator pump, jet, and circuit.

http://www.xjrider.com/viewtopic.php?t=668
http://www.xjrider.com/viewtopic.php?t=7309

Speaking of the accelerator pump and circuit on the carbs, I have a few problems.

First, while removing the first fill bowl (or the front cylinder) I found it very difficult to remove what appeared to be a short black rubber vacuum line connecting the two bowls.  In the process I broke it and found it is a fuel line with a metal core.  After replacing this, I'll remove the two float bowl covers together.  In the meantime, does anyone know a source for a replacement.  I did not even see it in the parts manual.  I'm hoping a local auto or motorcycle parts store will have a narrow fuel line that will work, even if it doesn't have a metal core, though that does seem important here.  Has anyone else broken and replaced this short pressurized fuel line?

Second, the accelerator circuit in the float bowl for the front cylinder is clogged.  It's so long and kinked that I can't get wire through it but am also afraid of packing rather than dislodging the clog.  Sprayed carb cleaner can't get through.  I'm guessing a long soak in chem dip or carb cleaner and a good cleaning nozzle tip for an air compressor may help.  Has anyone else dealt with a clogged accelerator circuit in a float bowl of their carb?

Third and probably most importantly, the accelerator pump or plunger seems to be binding.  Maybe I should say the lever for it seems to be binding.  When I turn the throttle on the carbs, where the throttle cable connects next to the front carb, a spring loaded arm connected to the throttle of the rear carb pressed a plunger for the accelerator pump.  Most, but not all of the time, this arm presses the plunger down only part way.  Friction stops it from going down fully despite the force of the spring.  A little extra force will depress the accelerator plunger or pump fully.  I have not removed the accelerator pump internally yet as I'd like to finish and reassemble the front carb before opening the float bowl for the rear carb, which houses the accelerator pump.  Lubricating the pump and the linkage with the throttle may help.  I could remove the spring loaded arm connecting the throttle with the accelerator pump plunger and wind the spring tighter, but I'm worried that another winding could bind or break. 

Has anyone here had trouble with, worked on, or found solutions with the accelerator pump and circuit for their carbs?

Thank you!
« Last Edit: August 21, 2018, 02:01:55 PM by theorist »
Logged

albertinhouston

  • Scraping the pegs
  • *****
  • Offline Offline
  • Posts: 837
Re: Getting a GT250 that was sitting for years running again.
« Reply #5 on: August 22, 2018, 02:34:29 AM »

you know im not going to read all that right.
Logged

spit051261

  • Grinding the pipes
  • *****
  • Offline Offline
  • Posts: 1158
Re: Getting a GT250 that was sitting for years running again.
« Reply #6 on: August 22, 2018, 03:23:40 AM »

Looks like the competition is back on for the longest posts ever.
Short, concise and to the point otherwise most   people won't even bother to start reading.
Logged
2010  GT650R in the best colour RED

Joss

  • Scraping the pegs
  • *****
  • Offline Offline
  • Posts: 901
    • Website
Re: Getting a GT250 that was sitting for years running again.
« Reply #7 on: August 22, 2018, 12:31:34 PM »

Has anyone here had trouble with, worked on, or found solutions with the accelerator pump and circuit for their carbs?

Thank you!

Yes in my project thread, you can take it out, clean it out then grease it.
Logged

umop-ǝpisdn

  • Global Moderator
  • Forum Addict
  • *****
  • Offline Offline
  • Posts: 7326
Re: Getting a GT250 that was sitting for years running again.
« Reply #8 on: August 23, 2018, 07:35:59 AM »

I remember someone saying that they did ultrasonic carb cleaning.
Logged
I used to be a sensitive, new age guy, but times have changed and now I am more of a caring, understanding, ninties type.

albertinhouston

  • Scraping the pegs
  • *****
  • Offline Offline
  • Posts: 837
Re: Getting a GT250 that was sitting for years running again.
« Reply #9 on: August 24, 2018, 04:39:16 PM »

not sure if you mean me...
I know there was a thread a while about carb cleaning and someone was talking about it.
but it wasn't me.
Logged

Pages: [1] 2