Valve guide seals sob story - need advice

[Jay Estes]

Just did a top-side rebuild. It was a bike flooded in Harvey, only 9Kmi, generally great shape - except for the flood and sitting 10+ yrs.

Started the bike tonight for first time (in maybe more than 10yrs) and ran great, smooth, everything firing, but tons of smoke. Smoke didn't clear after first minute or two, and it just continued to smoke. Shut it down, scratched heads with friends, and after thinking thru causes found out that we stupidly left the valve guide seals OUT of the rebuild (rookies doing first rebuild screw stuff up ya know?). Ive done the requisite self-flogging, and had the beers to get me over it, so time to fix the muther.

We need to pull the engine to get this fixed right - not a terrible thing, but a PITA. (I did read thru the replace them in the bike procedure, but I'm not really ready for that level of tedium)

Simple question/worry is this: Can valve guide seals really allow that much oil down the valve guides when the seal is not on? The valve stems were were tight in their guides, and you could literally pull suction when removing the valve stem from the guide. We decided no need to have them checked since the bike was low-miles. We honed the cylinders which had no scoring whatsoever, and put in new rings. Bike kicks hard and seems to have sufficient compression.

Advice? Is it possible that the valve guide seals are the sole source of the oil being burned? Would you expect alot of smoke without them? Thanks for any advice or experience in this area.

 

[Jay Estes]

Update: It doesn't really smoke at all at idle. Bike idles really clean end even. When you give it some throttle tho, smoke comes. Is that to be expected with missing valve guide seals?

Here is a video of a start to idle and then watch what happens when you hit the throttle.

 

[TwoManyXS1Bs]

Hey, Jay. Yup, it's pulling oil thru the intake guides. When the engine is revved, then the throttle is dropped, intake manifold vacuum skyrockets. This vacuum (up to 14psi) pulls the oil thru the guide. Doesn't take much to turn it into a mosquito fogger.

Gotta have them guide seals...

 

[xjwmx]

I have seen some things on here about removing the springs with the engine in the bike. Involving stuffing rope in the plug hole to keep the valve from falling in.

 

[Jay Estes]

Yes, Thanks for both thoughts.

I read thru the procedures for replacing them in the bike, but frankly - we can pull the engine fix this and put it back in about 4 hrs, so I'm not crazy about all the fiddliness of trying to keep the valves held up and making special tools to compress the spring etc. I'd rather just go in the correct way - it's not all that bad to pull the engine.

 

[Paul Sutton]

I had to remove the valves approximately 20 miles after a rebuild. It was not as bad as I expected. Sure it cost me 1 - 2 hours to pull the engine but it did not cost me anything but time. I assume you will be lifting the head right off:

1. Do not rush this job, even if it takes longer than you wish. Even spread it over two or three evenings so you can check and double check all measurements.
   
2. You do not need to split the cam chain. You will find instructions on the forum how to do this by removing the cam bearings then threading the cam shaft out. Make sure the tensionor is slacked right off.
   
3. The head gasket can be used again as long as it comes off clean and goes back on free from oil and dirt and the metal surfaces are clean.
4. When you remove the valve keepers and springs give the seals a good oil. Carefully push them on and you should feel a very definite click when they are in place.
5. When putting the cam chain back on it may feel as if the chain is too short. There is a trick to it. With the cam in place and the bearings on one side, align the cam notch/dot and TDC mark correctly. Do not try to lift the chain over the top of the cam sprocket - it just will not fit. The problem is the chain stops the cam sprocket dropping down low effort into that central cavity. Using both hands stretch the chain horizontally at the 3 and 9 o'clock positions. Place the chain onto the 3 and 9 o'clock positions of the sprocket and the sprocket will drop down a little further allowing you to pass the chain completely over the rest of the sprocket. Now check that the TDC and notch/dot are still aligned correctly.
6. It may require a little extra force to thread the other set of bearings on, but nothing excessive.

At this point you can complete the rebuild as you have already done - Good Luck.

 

[Jay Estes]

Great advice thanks. We did the top-end rebuild without ever cutting the chain, and remaking it. We were albe to remove the bearings both ends, position the cam lobes carefully, remove the chain tensioner fully, in order to just barely get the cam sprocket just under the chain. Extra hands are helpful to lift the chain in several places over the sprocket as it barely, barely fits (you also have to ensure the sprockets down low are fully engaged, they can become disengaged when you loosen the chain tensioner. Once the cam/with sprocket is out, you should not let the chain drop down into the engine (fortunately, I have no experience there). How do I know? Missed the proper timing by one cog first time round. You've really got to be careful with that one - it amounted to something like 40deg rotation on the crank (timing marks).

I do very much appreciate you taking the time to write it up here though. It's a very useful bit of help. -J

 

[xjwmx]

Yes, Thanks for both thoughts.

I read thru the procedures for replacing them in the bike, but frankly - we can pull the engine fix this and put it back in about 4 hrs, so I'm not crazy about all the fiddliness of trying to keep the valves held up and making special tools to compress the spring etc. I'd rather just go in the correct way - it's not all that bad to pull the engine.

I don't blame you if it takes all that. Regarding timing, the easy way is line up the timing marks and then ask yourself if the cam sprocket was one notch to either the left or right on the chain would the mark on the sprocket be more vertical?

 

[Paul Sutton]

Xjwmx's comment is just so true. When you check the cam/TDC position things do not always look perfectly vertical, even with a new chain. Mine looked slightly off vertical but when I considered shifting the chain one tooth either way it would have been just too far out. Very handy tip xjwmx!

 

[xjwmx]

I did it an even easier way, actually. When you think it's vertical, brace your hand on something and put your finger on one cam sprocket tooth and then turn the crank until your finger is on the next tooth. Takes the guesswork out

 

[5twins]

Also keep in mind that once you apply the tensioner to the cam chain, it will roll the cam backwards a little. As the chain wears and stretches over time, this will keep happening more, one of the reasons the chains need replacing from time to time.