Diagnosis.

[dirt dame 559]

Yeah, I know, I don't disagree with you. But I don't think the RFS is an interference motor, no? And if I'm wrong, the penalty will be poor performance, not more damage.

If by that, you mean that the valves don't move far enough down to come in contact with the piston crown at any time, I don't know. If they do however, you could have a damaged valve and low or no compression....so you could end up with no performance in that case.

I know that when Jeff threw the cam chain on his newer style motor 530, they were amazed at the repair shop that he didn't destroy the valve train.

[kellymac530 0]

guys you can do a quick easy valve check without pulling the head....put gasoline or some other solvent into the intake track and mark it to watch for leak down...same in the exhaust tract...

there a few ways to do this....the motor is out of the bike right?

drain all fluids, pull the plug, fill the cylinder with fuel, re-install the plug, turn the motor upside down over night....look in the intake and exhaust tract for fuel leaking thru the valve seat...a little moisture weeping thru i dont think would be an issue.

now if it is wet anywhere you have a problem...and if it leaks as soon as you flip it over...you have really had an interference issue.

another way you could do it is simply pull your plug...blow air into the cylinder to make sure it is dry, then put liquid {i would NOT use water because you are talking about bare metal parts...rust}

into the intake tract{i would tilt the motor forward} let it sit for a while like over night, try to blow air into the spark plug, if moisture come out the plug hole, OR if you see bubbles in the liquid you have a leak...repeat for exhaust side just tilting the motor backwards

to sum up...liquid transfer = "BAD"...no liquid transfer = "GOOD"

[Spaugh 1]

the tensioner is most likely fine. they aren't very sophisticated. you should be able to see if it's working with your hands.

we want to make this painless so you must be like water and go with the flow. be like the Fonz. take the flywheel off and look at the damage. depending on how fast you were moving and your karma, it will vary. figure out what is broken before thinking about what parts to replace.

the motor didn't come out of a toyota corolla. its interference.

the head takes 5 minutes to remove. at 250 hrs your ring gap is out of spec. your kw valves are good for another 250+ assuming they didn't make love to your piston. the bike will still run for a while, but it ain't a Honda. I would at least throw a new set of rings at it while I had it apart. you should have a metal head gasket on there that is reusable, and the only extra parts you will need is a set of rings and a base gasket. learn to do a top end, you will thank yourself once its done and you still have your retirement $ in the bank. Splitting cases is a good place to draw the line.

I am free friday night if you want to have a beer and play motor detective.

[paulmbowers 236]

the tensioner is most likely fine. they aren't very sophisticated. you should be able to see if it's working with your hands.

we want to make this painless so you must be like water and go with the flow. be like the Fonz. take the flywheel off and look at the damage. depending on how fast you were moving and your karma, it will vary. figure out what is broken before thinking about what parts to replace.

the motor didn't come out of a toyota corolla. its interference.

the head takes 5 minutes to remove. at 250 hrs your ring gap is out of spec. your kw valves are good for another 250+ assuming they didn't make love to your piston. the bike will still run for a while, but it ain't a Honda. I would at least throw a new set of rings at it while I had it apart. you should have a metal head gasket on there that is reusable, and the only extra parts you will need is a set of rings and a base gasket. learn to do a top end, you will thank yourself once its done and you still have your retirement $ in the bank. Splitting cases is a good place to draw the line.

I am free friday night if you want to have a beer and play motor detective.

Well...it is a factory 540 kit. So no simple rings, these. Base gasket's different, too. I'll pull the flywheel and go from there. I'd not invest a new top end with the suspicions I have about the bottom end. i don't mind investing the time and energy to get the timing chain going, but getting carried away I'm not.

Should be easy enough to check the valves by pressurizing the cylinder via the spark plug hole. The cam is out, so all valves should be closed and sealed, right? If I juice the cylinder and it just blasts out, I'll know something's up. But I gotta get the chain out first to see if it got bunched up at the bottom and broke anything else down there.

One thing I learned is a new respect for getting stranded.

Thanks, everybody.

[paulmbowers 236]

Update:

I pulled off the flywheel and found the timing chain all snarled up in there. It fractured the chain guide, tension rail and the guard under the timing sprocket, and broke two of the bolts holding those pieces on. One of the bolts had enough meat left I could unscrew it, the other will require a bit of extractive surgery, but shouldn't be a problem. The good news it I was able to find all the broken pieces of the timing chain and the adjuster, and the crank turns freely and with normal compression.

I've ordered all the bits and pieces to fix this mishap, and will do that. Maybe it will fix the marbley sound in the process- we can always hope, no?

Thanks again everybody for the encouragement.

[tntmo 887]

Here's an old trick to remove valve spring keepers and springs without removing the head.

1. Remove spark plug

2. Put motor at or about BDC

3. Slowly feed some parachute cord into the spark plug hole, several feet should do it. Leave plenty out of the spark plug hole.

4. Turn motor to TDC. The cord will push up against the head and valves, keeping them in place. You can also change out valve stem seals using this method.

Best of luck on your repair, I think you'll end up with a good running motor without spending too much.

[paulmbowers 236]

Here's an old trick to remove valve spring keepers and springs without removing the head.

1. Remove spark plug

2. Put motor at or about BDC

3. Slowly feed some parachute cord into the spark plug hole, several feet should do it. Leave plenty out of the spark plug hole.

4. Turn motor to TDC. The cord will push up against the head and valves, keeping them in place. You can also change out valve stem seals using this method.

Best of luck on your repair, I think you'll end up with a good running motor without spending too much.

Never heard of that, and damn clever. Thanks!

[kellymac530 0]

now that was farmer enginuity tntmo...i love that...

fakey...offer still stands if you wanna ride before your parts come in...

[paulmbowers 236]

and in other news:

Rod/crank is bad. Probably the cause of the marbley sound. There's some normal side-to-side slop, but there's also up-and-down slop. I can grab the piston and pull up and down on the connecting rod and feel tick-tick-tick without the rod moving.

Off to intensive care. Now- stroker or not?...hmmm.

[TrophyHunter 15]

Go big or go home. Sorry to hear it wasn't as easy as originally thought.....

[paulmbowers 236]

And now I just might take some of you up on your generous lend programs. It will be a few weeks offline, but I'm certain I'll return with a roar.

[bikeslut 1]

why stroke it ?

Were you lacking for power before? Don't you want the most reliable engine you can get (other than being a KTM, I mean)?

That thing dug trenches in asphalt... do you WANT more, or do you need more? I would say for dirt, you had all you need.

but I ride a 250... what do I know?

[paulmbowers 236]

why stroke it ?

Greed and the lust for power.

Duh.

[Crawdaddy 96]

I ride a 250... what do I know?

All there is to know.....

[bikeslut 1]

oh I understand... I'm the one that had to replace my FZR1000 with my ZX-11... a Balckbird would've been next, then a Hyabusa... but seriously... I NEVER used everything those bikes had (although I MAY have seen the speedo go past 150 one time.... on a track)... I get the "faster" appeal

To each his own, I guess... if you need more cc's to be faster than me, you go ahead and spend your money...

good luck with your bike... feels good to at least have a plan, huh? That's the good thing about a bike as nice as yours... if the engine were to blow on one of my bikes, I'd scrap it and start over... or get a 290 kit on the WR

[dirt dame 559]

why stroke it ?

Greed and the lust for power.

Duh.

Be careful what you wish for....

[kellymac530 0]

when you comin up to pick my bike up?

i figure if you blow it, maybe i will get a free 570 kit or a stroker

jk...i will keep your fancy glasses as colateral

oh wait you might need those to ride....

[Spaugh 1]

[tlking6 0]

I'm replacing (among other things) the guides, chain etc. Should I also replace the tensioner? It looks fine, and is not old. It's also $35.

Oh- who has a cam chain tool? BS?

Hey Paul,

I have the KTM cam chain tool and the fly wheel puller. Let me know if you want to borrow them.

[paulmbowers 236]

Got my motor back yesterday. It was ready some time ago, but I've been, well otherwise occupied. I'll start installing next week.

[bikeslut 1]

I was going to ask, but didn't want to pick an black scab... let us know when you are ready to break it in... as opposed to break it

[Uncle Champ 116]

Hey guys I know this is after the fact but I have a tool that is basically a drilled out spark plug with an air fitting, you put it in the hole attach the air line it holds up the valves and also checks for leaks in the valve train, if all is cool you can change parts and the valves stay up with no worries.

who'd a thunk it?

[PastaPilot 17]

Paul, Now that all is said and done, what did you decide to do with the rebuild?

Parts replaced, power adders?

[paulmbowers 236]

It's built very similar to the previous, but not an aftermarket rod. Factory 540, new Kibblewhite valves, new factory cam, and a whole buncha new parts like timing chain, adjusters, etc New main bearings, even though the others were within spec. No stroke, no super-big bore. I had the carb bored to 41mm and rejetted, plus I added a filter to the carb vents, the lack of which may have hastened the demise of the piston/cyl in the previous motor.

[paulmbowers 236]

IT LIVES!

Rode it around the 'hood today with a quick (and I mean FAST) run on the freeway. The new EXC gearing (and the motor) seems to change the weight balance- the front end seems to be much lighter....