[gruney1]

I have a 1985 Fourtrax 250 utility ATV, and it was running great, just went to start it and it sounds like the starter is spinning but not turning the engine over. I took the small cover off the left side, and the gears all look fine, and the starter is spinning everything fine, but the driven gear is just spinning, not the engine. I looked in my manual and see there is a one way sprag behind the alternator. Looked it up online and it is discontinued.

Are there any tricks I should know about before I take it apart? Where do I get the puller, or can I use something else to get the alternator off the crankshaft? I know on my son's Honda dirt bike we used the rear axle as a tool to remove it.

Also the kick starter doesn't work (hasn't worked since I got the ATV), so I can't even rely on that. It also seems stripped or slipping. Haven't looked into that yet.

I appreciate any advice, I will be taking the left side cover off soon, and can post up pictures when I get it apart.

Thanks,
Ken

 

[shadetree]

I have a 1985 Fourtrax 250 utility ATV, and it was running great, just went to start it and it sounds like the starter is spinning but not turning the engine over. I took the small cover off the left side, and the gears all look fine, and the starter is spinning everything fine, but the driven gear is just spinning, not the engine. I looked in my manual and see there is a one way sprag behind the alternator. Looked it up online and it is discontinued.

Are there any tricks I should know about before I take it apart? Where do I get the puller, or can I use something else to get the alternator off the crankshaft? I know on my son's Honda dirt bike we used the rear axle as a tool to remove it.

Also the kick starter doesn't work (hasn't worked since I got the ATV), so I can't even rely on that. It also seems stripped or slipping. Haven't looked into that yet.

I appreciate any advice, I will be taking the left side cover off soon, and can post up pictures when I get it apart.

Thanks,
Ken

yeah..your sprag bearings are bad on both sides...you have one on your centrifugal clutch..and one behind the flywheel..most of these will come off with some tapping with a hammer..some will be alittle harder..DO NOT HIT THE FLYWHEEL VERY HARD..OR YOU WILL DAMAGE THE MAGNETS IN IT !.. as for the centrfugal clutch..you can smack it alittle harder..and pull as your doing this..it should come off...if you cant find any sprag bearings ( one-way bearings ) for your year..they all are the same for all the years they made those trx250's..sooo..one from another year will fit it...and they only go on one side..you cannot reverse them..unlesssssss..you switch out the bearings from one carrier to the other...if you attempt this..make sure you flip them the right way..and don't damage the outter retaining spring.

 

[gruney1]

Thanks for the quick reply, I just took it apart, and before I took the cover off, the driven gear would spin freely either way. Once I got the cover off, it only spins freely counterclockwise, clockwise it turns the crank. Everything looks OK, I took some pics anyway.

Not sure what to do at this point.

 

[Helmut]

Yep, both one-way bearings are bad.

 

[Zep71]

how does the one way clutch work? what causes it to to mesh with the starter when you hit the start button?can prolonged sitting cause the clutch not to work?my kick start works fine my starter turns just like this problem gruny has but mine had been sitting for a long time before i bought it. when i got it the starter did not turn i took the starter apart used a little contact cleaner on it and now its spins.if any one could explain how the system works it would help me a great deal.

 

[Helmut]

The one-way clutch bolts to the back of the flywheel and the big gear has a hub on it that fit's inside the one-way clutch and it rides on the roller bearings of the one-way clutch.The roller bearings in the one-way clutch are not perfectly round, they're more of a cam shape. They're shaped in such a way that allows the big gear to turn freely in one direction, but lock in the other direction. So, when the starter spins, the starter turns the reduction gears which meshes with the big gear on the back of the flywheel. When the flywheel starts to turn, the roller bearings twist out and lock up and this causes the whole flywheel to turn. Once the engine starts, the engine overcomes the speed of the big gear and allows the roller bearings to turn back and this allows the big gear to turn free of the flywheel. I'm not too good at explaining this. I found a site that can explain this better than I can. The Ducati sprag bearing shown at the site I linked to below is almost exactly like the Honda bearing and it works exactly the same way. Once you read the article and understand how it works, you will know how the Honda one-way clutch works.

Sprag Bearing

ADDED: The site that I linked to shows a "fix" for your one-way bearing if it starts to slip and not catch. Looks like they're just cutting off about 1/4 inch of the spring and putting it back together. I don't have any idea if this would work or not, but it's possible. This might be a good experiment for someone to try. I can't remember if the spring on the Honda bearings hook together like the bearing on that site or not, but it might.

 

[shadetree]

looks like helmut has you ppl covered, i would like to add : if you cannot find a one-way bearing for your bike years..just get your hands on a trx300 one-way bearing from the clutch and starter side...i can't remember if they drop right in ?..even if they don't..the bearings themselves are what you need !..like helmut said..MAKE SURE YOU HAVE THEM IN THE RIGHT WAY..ON THE RIGHT SIDE !....it makes a very big difference which way..and on which side you put them..if you do have to go this route....your gonna re-use the same carriers from the trx250..your simply putting the bearings from the trx300 starter and clutch one-way bearings into the trx250's carriers..this is an easy job..AS LONG AS YOU DONT PUT THEM IN ON THE WRONG SIDE..AND YOU HAVE THE BEARINGS FACING THE RIGHT WAY !.

 

[Zep71]

any one know of a good place to buy these bearings?where would you go if you needed them?

 

[Helmut]

any one know of a good place to buy these bearings?where would you go if you needed them?

If it's for the '85-'87 Fourtrax 250, there's a good chance they've been discontinued. A Fourtrax 300 bearing might fit, but not sure. If it won't fit, you may have to do like Shadetree suggested and take the rollers out of a Fourtrax 300 bearing and put them in the 250 cage. I think you can still get the Fourtax 300 one-way bearings.

 

[shadetree]

any one know of a good place to buy these bearings?where would you go if you needed them?

If it's for the '85-'87 Fourtrax 250, there's a good chance they've been discontinued. A Fourtrax 300 bearing might fit, but not sure. If it won't fit, you may have to do like Shadetree suggested and take the rollers out of a Fourtrax 300 bearing and put them in the 250 cage. I think you can still get the Fourtax 300 one-way bearings.

yes on all the above ^^^^^..lol.

 

[rhuester]

Honda TRX250 Starter spins, motor does not engage. HELP!

New to the forum all. Saw some good "starter" advice so I though i would jump in!

I have an older TRX250 (year somewhere between an 85-87). I just got a new AGM battery and installed it. When I push the starter button, the starter just spins, motor does not engage. When I kick start it, it starts up just fine.

Any ideas?

 

[Helmut]

New to the forum all. Saw some good "starter" advice so I though i would jump in!

I have an older TRX250 (year somewhere between an 85-87). I just got a new AGM battery and installed it. When I push the starter button, the starter just spins, motor does not engage. When I kick start it, it starts up just fine.

Any ideas?

Yes, your one-way starter clutch is bad. And welcome to the forums.

 

[myslu2001]

I am looking at your 2nd pic and I was wondering, the starter gear is suppose to turn clock wise or counter wise ? Because my 85 trx 250 starts with the kick start but when I hit the starter button it dos turn but clock wise ( if I am facing it just like the picture) . I have seen on you tube a starter going the wrong way. Reason why I am asking. Sorry for the bad english .
Vous pouvez me répondre en francais aussi. Tks! merci!

 

[Deeperinthabush]

I am looking at your 2nd pic and I was wondering, the starter gear is suppose to turn clock wise or counter wise ? Because my 85 trx 250 starts with the kick start but when I hit the starter button it dos turn but clock wise ( if I am facing it just like the picture) . I have seen on you tube a starter going the wrong way. Reason why I am asking. Sorry for the bad english .
Vous pouvez me répondre en francais aussi. Tks! merci!

Welcome to da forums...:icon_ devil: The starter turns one direction whether it is cw,or ccw, which in turns the reduction gear the opposite which in turn turns the flywheel the same direction that the starter spins..the only way a starter could turn the wrong way would be an incorrectly assembled starter middle section,or someone wiring the positive,and negative battery cables backwards to the starter,and to the frame MIGHT cause it to spin backwards...

 

[myslu2001]

tks for the info. That is the reason why I was asking. I took it appart to clean it but since I am a green to mecanic I do not know if I put it back correctly.

So if you are telling me that the starter gear should go clock wise then I am ok if not then I will have to re open the starter and make some change. Now my 2nd question will be what do I have to change inside the starter for it to run counter wise