Quantcast
Jump to content

  • Join Today, It's Simple and FREE!

    As a member, you can post in our forums, upload your photos and videos, use and contribute to our downloads, create your own member page, add your ATV events, and even start your own ATV club to host your own club forum and gallery.  Registration is fast and you can even login with social network accounts to sync your profiles and content.

hunterchub

Suzuki LTF250 Quadrunner diagnosis please

Recommended Posts

Chasing problems.

ATV is acting choked. Smells of gas. Black spark plug.

Idles fine. Soon as I hit gas it wants to choke out.

What I have done:

1. New fuel pump

2. Rebuilt carb

3. New throttle cable

4. Emptied gas

5. Checked pit cock

6. fresh non ethanol fuel

7. New NGK spark plug

Did all this and still dogs out when I hit the throttle. Idles fine.

Its worse when it get warmed up. Wont do hills very well.

Finally check the compression.

Cold it was 80 psi

Warm it was 100 psi

Book says range between 146 and 199 psi

Limit says 114 psi

Range seemed high to me. But I am probably wrong.

The ATV has had a hard life on the farm. Never did a valve adjustment.

Always changed the oil.

Is it time for a rebuild? Any recommendations.

I would say the ATV is valued at $1000 when running.

Your thoughts? Thanks. Scott

Share this post


Link to post
Share on other sites


You been wrenching a lot. Definitely adjust the valves. If you have one sticking open a bit it will effect your compression. Do you have a pet cock with a vacuum line on it?

Share this post


Link to post
Share on other sites

Hi. I have a similar problem with my 94 LT-4WD. Tried most things listed above, and next plan to take the head off and check the valves & rings. Also mine puffs black smoke when starting, which leads me to believe that I am getting oil in the bore when left for a while.

Not much help I know, but wanted to let you know that you are not alone :-)

Cheers.

C

Share this post


Link to post
Share on other sites

Tim ANC.

I do have a vacuum line on my petcock. It is clear as all the vacuum lines are clear.

Thanks.

Share this post


Link to post
Share on other sites


my issue was blocked petcock (slowed it down) and vapor lock as gas cap was blocked. it would run 30 seconds then quit running. cleaned both and runs fine now. did rebuild carb beforehand - final adjust was to make throttle needle go further out. move it one notch.

Share this post


Link to post
Share on other sites

Excellent. I had a tank venting problem on an old LT230. Would run for a bit then just sputter. After a while start back up again. Rebuilt the carb, changed the pet cock and in general banged my head on it. Vent wasnt big enough on the tank cap. Good idea on the needle jet adjustment too. I still recommend a valve adjustment if its never been done.

Share this post


Link to post
Share on other sites

yes- my kids lt160 needs valve adjust as it runs hot but runs well- gotta do it

Share this post


Link to post
Share on other sites

Oil will drip out the fwd cap, put a rag over the exhaust pipe. Since, I dont have a feeler gage that fits in there well, I cut a strip of aluminum out of a beer can. Beer can walls are .005 inch thick. I assume you have a manual for this.

Share this post


Link to post
Share on other sites


Thanks Tim. Yes I have a manual (downloaded off internet). Pictures are kindof poor. I have considered getting a Clymer (if available) or another book that may be appropriate.

Share this post


Link to post
Share on other sites

Hi Hunterchub.

Did you get to the bottom of this?

I thought I had a breaktrough last weekend - I was checking the vacuum and breather pipes to the carb, and noticed that the fuel pump vacuum pipe was a little loose at the carb end. So trimmed it back to improve the fit in case it was leaking. The quad started great after that, and ran better than it had for a long time.

However, I just used it and although it did start great (better / easier than it ever has) and ran well, after about 10 minutes of use it started losing power and back firing again :-|

It seems that I cured one of 2 problems, and when the engine gets warm the main problem comes back to haunt me!

I am wondering if I could have a sticky valve, which is either jamming open when the engine heats up.... the engine heating is a red herring, and I just have a sticky valve??

I will try to get hold of a compression tester and check when cold/warm, but can anyone please suggest any other possible causes of power loss when engine gets warm.

Thanks

C

Share this post


Link to post
Share on other sites

Hi,

I think I just found out why my LT-4WDX was starting well and loosing power / faltering when it got warm....

It seems to have not been when the engine warmed up, but after a period of time! Let me explain;

Having checked the fuel pump and valve clearnces I decided to buy a service kit and give carb a complete ovelhaul. When I removed the fuel needle valve housing I discovered a wad of fine fibre type crud backed up against the mesh which covers the bottom end of the valve housing.

It seems that while this wasnt causing a complete block, it was restricting the fuel flow to the bowl. And when the engine was demanding more fuel there was enough surplus in the valve for a short while, but after 5-10 minutes of work the restiction in the fuel supply meant that the carb could not deliver enough fuel in the mixture for more than about 10 min hard use at a time..... but on tick over it would run and run!

Anyway, carb has now had a good clean and been treated to new jets..... and crud removed. Tomorrow the quad is going to get some serious use, so fingers crossed.

Hope this helps someone out there.

Cheers

J

Share this post


Link to post
Share on other sites


I looked at it under a microscope once it dried out.... and it seems that the 'wad' was a mixture of various small/fine hair-like fibers and a whole lot of dust.

I can only guess that as the carb had not been serviced since I got the ATV .... and probably not for a long time before (maybe never since new in '95), and that in a previous life the quad was a farm vehicle. That the fibers may have been a mixture of fine animal hair and hey / grass, and that the dust /fiber wad had gradually built up over a very long period of time.

Anyhow, I used it yesterday pulling a harrow for a couple of hours and it behaved very well - started well and had plenty of torque. So it seems that the carb service & most likely the removal of fuel restriction cured it.

Cheers

J

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Similar Topics

    • By Freezeman
      I came across an odd temporary fix for a 1985 yamaha 80 ATV.  It has no spark, yet if I warm the CDI unit up a bit with a heat gun or hair dryer then it fires right up and runs fine until shut off then it returns to no spark until warmed up again. Partzilla shows $217 for a new CDI  
      It's sort of nuts how I found out the fix to warm it up. My old shop TV requires my heat gun warm up around the transformer area every day before it will turn on too.  
    • By Mike Iadonixi
      Hi my son has a 2000 Polaris trail boss 325 it has no lights will not start unless pulled or i jump it the battery is good there is a new starter switch on it too any suggestions thank you for any help
    • By dirtybear00
      Hi guys I am new here. Not new to ATV s. I have a 2000 Yamaha big bear foot shift with no spark Looking for manual to down load any tips on where to find one or links be great thanks from Canada  
    • By Brad Leeson
      What's going on party people? First, thank you for allowing me the opportunity to be here. I recently purchased a 2005 yrs 450 and have yet to run the bike at full throttle. The bike fires up, idles, seems like everything runs fine except a little popping when you let off the throttle or until you hit 5th gear. It runs strong; no bogging or sluggishness until you hit 4th gear and open it up. Then it begins to act like it's out of gas or the about to be out. I can pull over and sit for 5-10 min and it runs strong again until you open the throttle. I have the carb off the bike to clean and wrote down a list of factory and what I found installed. I also listed other key factors and hope someone can help and explain. I'm new to the scene and have no prior mechanical experience but my theory is worst case scenario I have to take it to the shop anyway so why not learn. I actually enjoy it. Lol. Thanks a million. Hope to get back on the trails soon. 

    • By Bud03420
      I just got this bike and not getting any spark I know nothing about it so before I spend any money on it I like to see if it fires dose it have to have a battery to complete a circut and spark cause it dosent have one
  • Similar Tagged Content

    • By Jers
      I need to know what I have and what tire really go on it, Mine has 24x11x10 on the back and 22x8x10 on the front and I need new tire but I don't think are the right size. Also I can't find the model number listed but it looks like a 250 quadrunner 2wd and I think it is a 1987 maybe, can anyone help me, also I it has a rich running sound and I put a carb diap in it and cleaned the carb. is there a jet needing replaced?
    • By Steve1266
      I went out to ride my quad today. When I started it up it ran for a minute, then died. Since then it will turn over but won't start. I've check the spark plug and get great fire. I have had this quad for about 6 months, and very new to breaking it down. But need help. Thanks
    • By evlsnke
      loud clicking, snapping noise under load when accelerating.
    • By thesandmanisme
      Hey, does anyone have a pdf for service manual on an LT230? Having some issues.
  • Recently Browsing   0 members

    No registered users viewing this page.


×
×
  • Create New...