honda 250 big red coasts in gear

[dustrunner]

i bought a nice 85 250es and changed the oil and filter took it out and runs very well ( had little use by old man) as i go down a hill without giving it gas it will suddenly start coasting ? if i give it a little gas it will slow back down ???? it did this before the oil change. i used 10w 40 and a new filter .. i think its a clutch issue ???

[atc007]

You'll find a trashed one way bearing and or centrifugal clutch pack.

[kb0nly]

Also check the adjustments to the clutch, i had one that someone backed off too loose that acted oddly on a downhill slope as well.

[Flyingw]

The centrifical clutch shoes need to be replaced. The one way bearing is only used for coupling the kicker to the crank. The other clutch if bad would slip while in gear and accelerating. What you are describing is worn clutch shoes.

[kb0nly]

Flyingw is correct... But make sure you try the clutch adjustment first before tearing into it further, just in case someone loosened it or incorrectly adjusted it.

[atc007]

The centrifical clutch shoes need to be replaced. The one way bearing is only used for coupling the kicker to the crank. The other clutch if bad would slip while in gear and accelerating. What you are describing is worn clutch shoes.
Absolutely Correct,,but 9 times out of 10,,this is a dirty oil engine,,make sure your kicker is solid,no slipping> I doubt it is,but could be. They generally are needing the pair around here : )

[Flyingw]

Yes very true. Oil is the life blood. If its been a while, it needs to be changed.

[Flyingw]

Its important with these engines for the purpose of clutch troubleshooting to understand what that clutch adjustment does. Installed in the clutch cover is the auto-clutch assembly. Its job is to disengage the clutch any time the shift lever is moved up or down. There is am arm thats on the right end of the shift shaft. It fits in to the auto-clutch assembly linking the shift lever to the auto-clutch. Part of the auto-clutch is an adjustable plunger and when screwed in or out (CW and CCW) will either increase or decrease the distance between the plunger and the clutch lifter on the clutch basket. If screwed CCW till resistance if felt means the adjustable plunger is touching the clutch lifter. Turning it CW moves the adjustable plunger away from the clutch lifter. The book says to adjust the clutch by turning the clutch adjustment CCW until resistance is felt then turn it CW 1/4 turn backing the adjustable plunger away from the clutch lifter by about 1/32 of an inch.

Now, putting all this together goes like this. When the shifter is in its normal or detent position, the arm on the end of the shift shaft is in its detent position. As soon as the rider lifts or pushes on the shifter to change gears, that motion moves the arm on the shifter. That turns the auto-clutch which in turn pushes on the clutch lifter on the clutch basket disengagin the clutch to change gears. Its pretty simple design and quite effective but the critical dimension in this assebly is the distance between the adjustable plunger and the clutch lifter. Too wide of a gap causes the clutch to not totally disengage before the transmission changes gears. Too close and the tranny might be riding the clutch when the shifter is moved even the slightest.

Assuming the oil in the tranny is seviceable, usually when there is a clutch problem involving the changing of engine RPMS with little enging load will be a centrifical clutch but when the engine is under load and it slips, thats usually the regular clutch. The centrifical clutch shoes are pretty robust and far out live the regular clutch plates by about 7-1. Figure many of the ES and SX motors out there are still running on their original centrifical clutch shoes so thats not bad.

The other problem with these motors is the increase of the one way bearing failures. One for the kicker and one for the starter gear train. I'm seeing more and more of these going bad but they are all OEM bearings. If you go to star it with the kicker and the kicker just wont grab or grabs intermittantly, it the one way bearing in the centrifical clutch. If you hit the start button and the starter just spins but the crank doesn't then the one way bearing behind the flywheel is bad.

I really am a fan of this motor (ES/SX) because they are very reliable motors. Basic in design but very effective. Keep the motor full of oil, adjust the valves occassionally, and keeping the fuel system clean will ensure many years of happy motoring.

[atc007]

And a clean,oiled air filter ^^^^ I' ve told A LOT of customers through the years,,they MAY outlast them. With all of the above. Simply a GREAT engine!!

[Yamaha_Rules69]

I have seen the one way bearing fail on a Honda 185 motor, and it would coast down a hill, like you are saying, but seem to "catch" again when the throttle was pushed. I tore it apart and inspected it, and the centrifical clutch shoes and drum were mint, but the one way bearing was shot. I replaced the one way bearing, and the problem was solved for me. Another way to listen for the bearing is to shut it down once warmed up, and you will hear a wrrrrrr ...... click when the engine stops. That is a tell tale sign of a bad one.

[tri again]

On a lighter note,
I changed my oil and filter.
Had to pull a side cover so the NEW oil
had to get dumped and it looked like synchro soup.

All sparkely and pretty swirley.
I actually thought of saving it since it had no time on it at all.

Rinse, repeat, when in doubt.
Get a 6 pack of neodYmium magnets and stick one the the drainplug.
These ain't like a car engine with babbit flat pressure bearings,
There really is no oil pressure per se'.
Just flow.

They are rollers that simply degrade for ever hour of usage.

In my opinion, oil changes can't be frequent enough. even if you can't change the filter.

Pour it out the fill hole every couple hrs. and refresh.

Then again, I am mildly freaked out an paranoid after my last gearbox fiasco.
For that, I apologize.

In a feeble attempt to make everyone laugh, I put a 250 es into the truck,
1st gear, shut it off.
left it in gear.

got into the truck, backed up knowing the trike was in the back and in gear.
backed the truck up, gently stepped on the brake and the trike rolled out the back of the truck and almost across the road.

so yes, they do roll even if you leave them in gear. unless there is hidden sludge

Oil can never be clean enough. with this design.

Hope everyone is having a great summer.

[kb0nly]

Oil changes are cheaper than engine rebuilds! I change my oil often on these 4 strokes. If i am not using it a lot its monthly, if i am running it a lot then it can be weekly changes. For about $8 a change its worth the effort.

[wonderboy]

The centrifical clutch shoes need to be replaced. The one way bearing is only used for coupling the kicker to the crank. The other clutch if bad would slip while in gear and accelerating. What you are describing is worn clutch shoes.

Hey Flying, I think the one-way bearing is actually not for the kicker (or at least not ONLY for the kicker). Of course, I'm not 100%, so if you are sure, chime back in, but here was my understanding of the function of the the one-way bearing (my experience was on the 200ES Big Red motor):

If you are sitting idling, the clutch shoes are retracted by the springs and the one way clutch is slipping and you are stationary. The motor is disconnected from the trans.

If you are accelerating, the engine is slinging the one-way clutch shoes outwards against the clutch bell and the engine is connected to the trans via the clutch shoe / bell connection. The one-way bearing is out of the equation at this point... it isn't doing anything.

If you are coasting (off the gas while moving), the clutch shoes would eventually retract and you would free-wheel coast (with no engine braking). This is the point of the one-way clutch, so that on deceleration, the engine still remains connected to the trans. In this case, it is the one-way bearing in its locking direction, rather than the clutch shoes grabbing on the clutch bell that is making the connection. Again, if you didn't have a one way bearing, eventually, the clutch shoes would retract once the engine slowed enough and you would freewheel.

Anyway, I admit the fact that you really know way more than I do about the SX (as evidenced by your many great SX posts), but I think in this case, the one-way is more than just the kicker coupling.

[Flyingw]

On the 85-87 ES/SX motors, the one way bearing is only for coupling the kicker to the crank. The centrifical clutch outer hub is connected directly to the crank and the center hub is connected to the tranny. When the RPMS come up, the shoes extend out locking the center hub to the outer hub.

My Army trike started out as a beat up 85 SX. When I got it the kicker would not turn the crank. it would slip 99% of the time and catch once in a while. The engine ran fine except for that problem. I removed and replaced the one way bearing and the kicker worked as its supposed to.

Whats happening to 123456q's motor is a textbook example of centrifical clutch shoes that are worn.

[dustrunner]

im supprised that the clutch shoes are worm cuz of the low miles on the trike ? ( owned by an old man from new ) can i put some sort of cleaner in the engine or just keep changine the oil cuz it looked like it may have been the original oil in it ??

[Flyingw]

I've heard of guys putting a small amount of Berrymans Chemtool carb cleaner in the oil and running it for a few minutes at idle to clean the oil system out. I think there are instructions on the can telling how to do this.

I'd say based on what you said above, before tearing into the motor its a good idea to go ahead and do a good flush on the motor first. I'm all for taking the simplest route and who knows, it very well may turn out to be crusty oil in there causing the problem so there's one way to find out. Be sure to flush and fill the differential while your at it.