230F stopped while riding. Starter spins too easily. No compression?

[pat22043]

I'm wondering if the collective brains of this place can give me an idea where to start my engine teardown.

I was out riding today, just playing around, second gear, mid-rev level, mid-throttle and the engine went "clank" and stopped running. When I used the electric starter, it spun fast. Too fast. I didn't hear any of the usual chuff-chuff sound that it usually makes when turning over (and not starting).

We put the bike in first and pushed it. It was easy to push. There was no chuff-chuff, and of course, it would not fire.

 

While I had no tools, and haven't even pulled the plug, I'm guessing from the sounds that it has no compression. Maybe the piston is not even going up and down.

The starter happily spins.

 

Anyone have a guess before I tear into it tomorrow?

Thanks

Pat

[DDACT]

This is exactly what happened to a buddy of mine recently while we were on a ride.  2007 CRF230.  Same exact symptoms.

 

Turned out the timing chain came off the lower sprocket.  Was probably stretched. 

 

Ended up rebuilding the whole top end.  About $750 by the time it was all done. 

 

Not overly suprising as it had been abused by previous owners (smoked, ragged plastics, etc..), but he got a good deal on it and rode it for a couple of years before it finally died.

 

Pull the spark plug and look down the hole as you hit the starter.  You can see if the piston is moving.  If it is, take the pipe and carb off and you can watch the valves.  I'd bet they're not moving. 

[teamrude]

If you have a airhose you could put it in gear and bring up to TDC. Blow air in plug hole. If coming out carb then intake valve bent or burnt bad, if out exhaust then exhaust valve is bad. If comes out crankcase breater then piston most likely. Easy and quick. Do check timing chain to be sure it is turning cam etc

[pat22043]

 if out exhaust then exhaust valve ....

 

Out the exhaust pipe. Exhaust valve clearly stuck open. Now to remove cam cover and see if the cam is rotating.

[offroad circus]

we had a 2 stroke km100 that did that once. turns out that it ate the ring on us so it wasnt worth fixing. still sitting in my freinds backyard half torn apart to this day

[pat22043]

Pulled off the seat, bodywork, tank, etc to get to the engine today. Pulled the cam cover. When the starter spins, the cam chain and cam stay fixed. Either the chain broke, or the drive sprocket on the crank broke.

[DDACT]

Pulled off the seat, bodywork, tank, etc to get to the engine today. Pulled the cam cover. When the starter spins, the cam chain and cam stay fixed. Either the chain broke, or the drive sprocket on the crank broke.

Chain may have just jumped off the lower sprocket. Thnt's what happened to my friends. Seems like you don't have to split the cases to get to the lower sprocket either. If memory serves you can just take a cover off and access it. Regardless you probably have a bent valve.

Edited August 4, 2014 by DDACT

[pat22043]

Chain may have just jumped off the lower sprocket. .... Regardless you probably have a bent valve.

 

Yes, that is what we found. Worn out cam chain (mine is a 2004 model that has been ridden a lot) jumped off the crank sprocket, bent lots of stuff, broke/trashed other. Needs everything above the base gasket.

[DDACT]

Yes, that is what we found. Worn out cam chain (mine is a 2004 model that has been ridden a lot) jumped off the crank sprocket, bent lots of stuff, broke/trashed other. Needs everything above the base gasket.

 

Bummer.  I hate to hear that.   You going to rebuild it or part it out? 

[pat22043]

Rebuild bigger, more torque, able to leap taller buildings. All new moving parts.

Should be back on the trails in two weeks or so.

[pat22043]

Frank just let me know that the engine is done. He'll be packing it up today and shipping it back either today or tomorrow. I'll have it late next week, and put it back in over the weekend. Should be great once its broken in.

[atown8605]

What was done to the motor? What cam, compression or bore size.

[pat22043]

I don't have the details of the cam, but it will be 249cc with more compression and Frank's "torque" cam.

I'll get the details with the engine when it gets back to me. 

Its probably obvious from the enginesonly.com website.

Frank said that the compression ratio is designed for pump high test, but warns that if its really hot and muggy out, it may ping a bit, and if that happens, mixing in 20% or so race gas will solve the ping. Since the 230 gets such good mileage, buying a 5 gallon can of race gas for a season is fine with me.

[DDACT]

I don't have the details of the cam, but it will be 249cc with more compression and Frank's "torque" cam.

I'll get the details with the engine when it gets back to me. 

Its probably obvious from the enginesonly.com website.

Frank said that the compression ratio is designed for pump high test, but warns that if its really hot and muggy out, it may ping a bit, and if that happens, mixing in 20% or so race gas will solve the ping. Since the 230 gets such good mileage, buying a 5 gallon can of race gas for a season is fine with me.

Are there any problems with the starter spinning a bigger cylinder and higher compression?

[adnohguy]

"Are there any problems with 12the starter spinning a bigger cylinder and higher compression?"

Nope, 10.5 compression is nothing.

Same starter motor as CRF250X

I have been running 12.5 for two years with a Shori battery with no issues at all.

I just received (2) 13-1 Piston kits with sleeves yesterday and I do not expect any issues at all, but I'm installing a custom cam grind with lobe centers 5d tighter than before for a major increase in midrange torque. Will see how it runs.

Edited August 22, 2014 by adnohguy

[adnohguy]

I don't have the details of the cam, but it will be 249cc with more compression and Frank's "torque" cam.

I'll get the details with the engine when it gets back to me.

Its probably obvious from the enginesonly.com website.

Frank said that the compression ratio is designed for pump high test, but warns that if its really hot and muggy out, it may ping a bit, and if that happens, mixing in 20% or so race gas will solve the ping. Since the 230 gets such good mileage, buying a 5 gallon can of race gas for a season is fine with me.

Std stroke? 69mm piston? 10.5 compression? Ported head? Stock carb?

[atown8605]

Please give a review after it is broken in.