"STICKY" or "BENT" valves?

[George]

Most of ya know I bought Mac's ex-DRZ from DMulk a couple weeks ago. After setting for most of it's life (2001 with only 1500 miles on it), it was in need of some maintenance.

First problem was a stuck float valve. Replaced the battery and fixed the carb. Took'er for a short (5 mile?) ride and parked her with fresh gas and Seafoam in the tank.

Next morning, pushed it out and started it on the drive. Sounded pretty much okay, idling at ~1200 RPM. I was grabbing jacket, boots 'n helmet when it died. Punched the start button and SPROING!!! Don't know what it was but it didn't sound good.

I've checked a bunch of stuff, including pulling the exhaust cam to check operation of the compression relief. Checked the cam timing at the same time and all looks good.

I don't have a compression gauge that fits this bike, but easy enuff to stick a plug onto the spark plug hole and feel ZERO push back.

Main tell-tale is enormous valve clearance gaps. The intakes and right exhaust are about .016, quit checking the left exhaust at a very loose .017, more than double recommended.

I'm hoping the "sticky valve" thread I found at Thumper Talk has what I need to fix the problem. Only question I have at this point, could the Seafoam have loosened up something in the combustion chamber that would have CAUSED this?

Keep in mind the bike had started just fine (really for the first time for me) only moments earlier.

Hoping for a simple solution, hate to pull the head on a nearly virgin motor.

No rush on this, I've got two weeks to my next outing. If absolutely necessary I can ride my ol' XT350 Yamaha but I bought this bike to ride, not work on.

Highest ratio of maintenance to miles of any bike I've ever owned.

Thanks in advance,

 

[bdalameda]

I am betting a stuck valve - Hopefully it did not stick when it was open enough to hit the piston and bend it. Many years ago I had an old CB450 Honda that would stick an intake valve open after it sat for a couple of months - It would loosen up after running for a couple of minutes.

 

[Dinkie Diesel]

I'd be hunting down some stuff the car dealers used to use for carbon build up. Some kind of a foam junk they squirt into the intake and it makes it's way thru and supposedly loosens the buildup. Then I'd change the oil and add a little auto trans fluid, if you can get it running again. Then change it again after a few miles.

.016 clearance isn't enough to prevent all compression or cause the inability to at least backfire, IMO.

I'm with you...pulling it apart at this stage would be like pulling good teeth.

Good Luck!

 

[George]

Thanks, guys. I got it to back fire once on ether, Jeff. 3 of the valves are at ~.016, the fourth is open more than that. With the plug in, I get just a puff at the exhaust but no pressure build up.

 

[Throttlejockey]

There has to be a valve partially open or there would have to be a hole in the piston to not have compression. I guess a ring could be stuck also.

George, was the bike stored inside? I know the valve seats could get corroded if the bike was parked with the valves in the open position. Condensation can get in and through the exhaust.

 

[CANofBUS]

Hey George, pull the exhaust header pipe so you can see the valve stem, guide, and back of the valve.
You can get a better view of the carbon build-up or, gasp, bent valve. Shine a bright LED light into the spark plug hole and look at the light through the exhaust port. If it's bent the light ring will show it. It will also aid in cleaning the stem. The bad news is exhasut valves will have less carbon build-up then the intake so you might be looking at "bent" I'm suggesting you start at the exhaust based on your post that's the one with the most clearance. If that's good, pull the intake (might want to do it anyway)
If that's all OK it's BMW's fault for using CANbus cuz it's always the CANbus

 

[tercol58]

Hey George, pull the exhaust header pipe so you can see the valve stem, guide, and back of the valve.
You can get a better view of the carbon build-up or, gasp, bent valve. Shine a bright LED light into the spark plug hole and look at the light through the exhaust port. If it's bent the light ring will show it. It will also aid in cleaning the stem. The bad news is exhasut valves will have less carbon build-up then the intake so you might be looking at "bent" I'm suggesting you start at the exhaust based on your post that's the one with the most clearance. If that's good, pull the intake (might want to do it anyway)
If that's all OK it's BMW's fault for using CANbus cuz it's always the CANbus

I have no mechanical know how but could you use one of the snakey cameras in a place like tihs

 

[CANofBUS]

I have no mechanical know how but could you use one of the snakey cameras in a place like tihs

Sure could but most don't have one. You can buy one at Lowes, Home Despot but how much will you use it. If you have one, great, but pulling an intake or exhaust will get you the same result and cost you time not money. BMW owners are frugal!!!

 

[Throttlejockey]

Doubtful it's a bent valve. If it was stuck with carbon it would probably just push it up. WD40 will eat that carbon up.

 

[BakerBoy]

George, my money is on there being a demon-possessed alien hiding in there--imagine how scared that poor little fella must feel when suddenly everything starts moving and making a terrible racket.

 

[sennister]

There are reports of some 1300s having a similar issue when running on Ethanol. Or at least that is the speculation as to why there is the carbon build up.

 

[RaYzerman]

I doubt very much Seafoam (or WD40) solvents are strong enough... naptha and isopropanol. I vote stuck valve, hope it's not bent. Pull the exhaust as CANofBUS says and have a peek. I like the ATF cleaning activity too. Hope this is an easy fix.

 

[George]

Thanks for the input guys. I'm fingers-crossed for stuck but the intake guru at Thumper Talk (Eddie Sisneros) sez bent.

Since the intake and exhaust gotta come off anyway to pull the head, I'll do all the suggested checks before proceeding farther.

 

[Throttlejockey]

Thanks for the input guys. I'm fingers-crossed for stuck but the intake guru at Thumper Talk (Eddie Sisneros) sez bent.

Since the intake and exhaust gotta come off anyway to pull the head, I'll do all the suggested checks before proceeding farther.

Hopefully Eddie is wrong, but he does know his stuff.

 

[motomac]

Damnit George, you're making me feel bad!!! That thing ran fine when I sold it!!!

 

[STraycatt]

Ah, no worries Mac, you didn't sell it to him ...

 

[Carl_T]

George, I've freed stuck valves from sitting 4 or 5 times over the years (but still a long time ago) by a few days of soaking with Marvel Mystery oil. That's if you can get to where it will soak/gravitate into the valve guide. Probably bent, but sitting occasionally sticks a valve. Worth a try if you can get the oil in the right place without a ton of disassembling. Multiple Mystery Oil applications over a three days or so. "Might" work.

 

[George]

Thanks, Carl. I can reach the exhaust and intake ports by removing appropriate parts but the guides 'n seals are at the top, don't see how to "soak' them.

I'm gonna just pull the head. Not a real problem just a PITA on a what is supposed to be my "new" bike.

Pulled the exhaust yesterday, the exhaust valve stems are rusty. Sprayed some PB Blaster in there, I'll check all that in a few minutes. Need to pull the carb. Again. <sucks!>

 

[George]

Here's the latest, folks. Pulled the head and cylinder this afternoon. Found foreign aluminum bits in the combustion chamber. expect something got sucked in first time I started it after reassembling the carb. Can't imagine what kind of small aluminum piece would have been laying loose tho.

Any suggestions?

Damage appears to be limited to one exhaust valve (bent), otherwise everything looks okay. Only one small scuff on the cylinder head where the errant valve gouged the surface.

So far, one valve and a top-end gasket set, about $75 plus my labor.

Fingers still crossed.

 

[RaYzerman]

The aluminum is a mystery, but could it be bits of the valve guide (assuming small flakes). A bent valve may have taken some metal. Anyway, hope it's not too serious and you can get ?r up and running soon.