Trouble with the 250, Please help!!

[schytown]

Hey guys..

I am new to this forum so I will try not to sound too much like a newbie.

I have a 2003 Kasea Skyhawk 250 ATV (Twin Carb side-by-side cylinder). The ATV contains an exact replica of the Honda Rebel engine. I am having some serious trouble with the engine.

Basically what is going on is the engine was running fine one day and it is basivally like one cyliner stopped firing, I had to ride all the way home in first gear, becasue I did not have enough torque to even get to second gear, white smoke was everywhere, and of course when I stopped the bike died instantly. The bike has maybe 70 hours on it and has not been ridden to rough, I have red lined a few times, but nothing major.

I have replaced spark plugs thinking maybe they had gone out from choke, stil exact thing, "once applying gas, it is real sketchy and upn letting off throttle, the engine dies instantly after de-revving. I do not even have enough power to take off out of first gearm now and I have no clue what it could be.

I am open to any suggestion as I bought this bike used and have had it very little time. Look forward to hearing from you guys soon...

Thanks,
Nick Schycker

[Snorebaby]

Welcome Nick. Sorry to hear your problem, but will work with ya to figure it out. I don't know alot about the 250 engines, I have a 450, but I will try to help with some typical troubleshooting.

First thing to check is that you are getting fire to both plugs. Could be a bad wire or coil. Take the plug out of the engine and put it back in the plug wire boot. Wear leather gloves when handling the wire. Try to crank the engine. You should see a spark. Best if done when it is dark or dim light. If no spark, it could be the wire or the coil. I don't know what the ohms are supposed to be for the wire or coil. I will see if I can find them and post it for you.

I don't know how the choke is set up. Also it would be a good idea to pick up a manual like Haynes or Clymers for your ATV. Alot of good info.

There should be someone else on here that can help you better than I , but it is something to do to get you started on figuring it out. Sorry I couldn't be more help right now.

Good luck and keep us posted.

[schytown]

Snorebaby...

Thanks for the quick reply, will check plugs to see if spark is reaching them and check and see if this is the problem.

Thanks,
Nick Schycker

[GearJammer]

Welcome, Nick & also sorry to hear about this........

Absolutely agree with Snorey on checking for spark first as you go thru the trouble-shooting process.

You mentioned 70 hrs. on the bike. Is this 70 hrs. since 2003 or 70 hrs. since you bought it ? Essentially, what is the actual mileage of the ATV ? General rule of thumb is approx. 500 miles for vehicle break-in. You also mentioned a few redline runs. If the ATV has gotten past the break-in period safely, a few redlines shouldn't be an issue, but if it's 70 hrs. (unknown mileage to us at this point) without having passed the normal break-in standard, redlining might then become a serious issue.

Other possibles to check & consider:

Compression readings on both cylinders. Let's hope you didn't stick a piston or drop a valve.

Clutch also comes to mind as a possible. Lack of torque, inability to get into 2nd gear. Inability now to take off in 1st. Toasted clutch ?

Please keep us posted with what you're able to determine & we'll keep trying to help you sort it out........

[schytown]

Thaks for the quick response once again....

I know for a fact that the engine was not broke-in, the engine still smelled new when it was picked up (50 hrs at time of pcik-up). I will check spark like I said, but would the engine even run if one of the pistons were sticking?? The clutch is nto the problem, becasue the engine does the same actions even in nuetral (it struggles to get going like it is not getting something, and the dies almost instantly after letting off throttle.

Thanks,
Nick Schycker

[GearJammer]

You're right.....a stuck piston could stop the show. But if the piston rings weren't yet seated, it's possible to crack rings, which would immediately result in lost compression even tho' the motor was running. Toasted valves would also have a dramatic effect on overall performance. Either broken rings or damaged valves can easily shut down the entire cylinder.

When you changed plugs, what did the original plugs look like ?

Had the oil level been up to snuff when you got the bike ?

[schytown]

When Plugs wer epulld out, they looked like bad plugs, all back and a deep flat black, like a charcole crust that had no shine what so ever. Shoud I crack the head open and take a look tomorrow??

Thanks,
Nick Schycker

[GearJammer]

Both plugs uniformly fouled/blacked ? The way you're describing 'em sounds like a rich condition, which is pretty unusual for these newer motors. Possible causes: Mal-tuned carb(s), mal-adusted valves resulting in incomplete combustion, bad rings allowing oil up into the combustion chamber & not getting burned off, coil not providing enough spark to plugs......

Before pulling the head, I'd check for spark at the plugs. If you're getting a "fat" spark at both plugs, the coil is probably O.K.

But good spark at plugs could be negated inside the cylinder if the rings or valves are preventing adequate compression to allow proper combustion. The plug could fire inside the cylinder, but there'd be no compressed mixture to fire......dead cylinder.

If the spark checks out good, I'd then check the compression readings of both cylinders. If one cylinder reads good but the other bad, then I'd try adjusting the valves to see if you can regain compression in the bad cylinder. If that doesn't work, then it's time to remove the head to see what's gone wrong inside.

Do you have seperate exhaust pipes for each cylinder ? Another thing you could check is with the ATV running, CAREFULLY touch each pipe to see if one is hot & the other cold, which could also indicate normal combustion in one cylinder but little or no combustion in the other.

Anyone else following this, please jump in with any ideas......