Valve shim adjustment on 85 Maxim-X 700

Ok, long story short...

Still can't get her going. Poor compression seems to be the culprit. Nothing's been done since my last post for lack of money.

Now that other bills are paid, I'm going to break down and have a leakdown test done by the dealer at my next paycheck. I'm almost positive they'll tell me a valve adjustment is in order. At that point I plan to take the bike back and do it myself... with a little help from my friends!

So who's done it? It's a 5 valve, dual overhead cam, shim-under-bucket design. It looks as though the cams will have to come out? Seems like an ordeal having to take the cams in and out to adjust the shims each time. I've heard of a shim-swap through the mail program... are there shims for my bike in this program? Should I just buy the complete head (9600 miles) off ebay for $250 and be done with it?

I need the low down.

Thanks in advance

Jon

 

I went through that. There are a few posts relating to my experience on this forum. Do a search, and see what you find.

Bottomline:
There is no shim pool for our bikes. X's only share shims with FZ bikes of the 80s.
I have about 5 shims in my garage.
It is a pain only if you let the clearance get down to zero.
Do not pay a dealer to do a leakdown test.
If it has set for a while, compression will be VERY low until it runs.
I would do the shim job instead of buy the head. You don't know if a new head will solve your compression problem.
Also, it needs to run again before you do the valve job - this is to knock carbon off of the valves, which can affect clearances.

Please give more information:
How many miles on bike. When was last clearance job done? How long since it last ran? What are the current clearances? Does the new head come with valves, or is it only the very top head? I can't remember the names, but our top heads come in two parts! One with the camshafts, and one with the valves and springs.

 

Richard,
Thanks for the quick response.

My bike is new to me, bought as is with 26000 miles. I've never seen it run, PO said 5 years ago it became harder and harder to start so he just put it away. Thought it would be a quick carb clean and go.

Don't know the maintanance history, thought the bike looks great and everything works. Except for the whole "engine" part...

Haven't taken clearences yet. Willing to bet they're at zero.

Tried pop-starting it with no luck.

Can't get her running before valve job, can't do valve job without getting her running...chicken or the egg, it seems!

Why shouldn't I pay for a leakdown test? Thought it would focus my efforts for not much money.

The head is complete:
http://cgi.ebay.com/B246-85-Yamaha-XJ70 ... dZViewItem

Thanks

 

Well... here is my thoughts on the leakdown...

If it doesn't run without a leakdown, what is a leakdown going to do for you except tell you: you need to rebuild something expensive!

Also, I built my own leakdown tester with an air compressor. It didn't tell me anything other than get me worried before I got the thing running. It told me the intake valves were leaking significantly. However, that was to be expected with zero clearances and carbon on the valves.

So, for me, all it did was get me worried.

What I think is cool about your situation is that it is EXACTLY the same as mine about 6 months ago.

My bike sat for 5 years, and two of the cylinders had about 40psi compression. however, it runs GREAT now! With compression back up to spec too.

My brother and I did our carbs. Are you sure you got the idle circuits sufficiently? on our carbs, the idle circuit has 3 legs. So, if you spray cleaner in one side, it is exiting two, potentially masking a problem. You need to spray in the air side and block the fuel side, so that it only exits in the throat. Then you need to spray in the fuel side and block the air side so it only exits in the throat. Also - there is two exits in the throat. One is a one-hole exit, and one is a three hole exit. So, you need to block those individually also!

In other words, the carbs are incredibly complicated. It took two cleaning sessions on mine to get them working correcltly.

 

I started a new line so that I can point out the most important thing:

get the bike running! I had several people tell me to quit fooling around with details, and get the thing running!

This is because compression comes back up, and you can't really do and valve work, or any carb tuning until you get the thing running!

You really need to be liberal with starter spray in the air box to get it firing. Be sure you have the air filter in place though. it will run rough if at all without the air filter. Also - make REALLY sure you have a good battery to start the thing with. You may want to jump it to a car, because that is critical.

So, that should be priority number one! Once you get it running, things will be much easier!

PS: Did you do a benchtop synch on the carbs? I found that for the initial firing, I had to play with the idle speed adjuster quite a bit to get it running.

 

Sorry, one more line. I forgot to mention that 26,000 miles is just about right for your first valve adjustment. So - you should expect that they will at least be measurable. So, another reason not to worry about clearances.

Mine went to 34,000 with no adjustment, and that is why I had problems.

Other things: Change the oil before you fire it up, mine had broken down severely. After I ran it for 5 minutes, I changed it again, and more crap came out. I think that is really important. You really should change out all of the fluids, I did, and I am glad that I did.

 

Richard

Reading your posts was fun and informative. They gave me hope and inspiration, so thanks!!! You're right, our problems are/were near identical.

So in the end, did you use the ground shims or get new ones?

Thanks for the tip on the idle circuits.. though I figured that one out during the rebuild and took the majority of the time getting them clean. My carbs are whistle clean, I assure you.

Wish I could get the thing running, but even with starter fluid I get nothing. Got a single sputter once while pop starting it, but thats it. If it was a carb issue I know I could at least get a sputter with the starting fluid.

Guess it's time to check the clearances and see what I'm dealing with. Problem is, with carbon build-up I can't trust them.

Once back in my youth I got an a scooter engine started by spinning it the crank directlly with a drill/socket combo. (spins much faster than the starter will) I may resort to it again. Bad idea I know, but hey, I havn't matured all that much and I think it would work.

 

Yes, I did the benchtop synch (by eye).

Yes, changed the oil first thing.

Played with the idle speed screw but probably did more harm than good. Can you give me a ballpark setting?

 

What about your battery?

I only used the ground shims after I got it running. Then I only ran it with the ground shims for about 5 minutes. This was because I only needed to be able to measure the clearances, and running with ground shims is bad for the lifters. After I did that, I ordered new shims (which came from japan), and waited TWO months to receive them!

What I would suggest doing is running the idle speed to zero, and then crank it slowly open while spraying starter fluid and cranking the bike. I remember it took us a couple of hours to get it to run more than a couple of seconds. I would do this with the choke off so that you aren't putting too much fuel in.

Also - it didn't take too long to get a pop letting us know that it was firing. Then it was about 30 minutes of popping and playing with the idle before it ran for about two seconds. The whole time we were using starter fluid. I think the trick is to heat up the cylinders and let the rings expand - or unfreeze. This helps compression, and will help it run.

One thing about our bikes is that they are incredibly sensitive to fuel mixture at idle when cold. In the morning, the choke is so sensitive that 1/8" of lever travel is literally the difference between not starting at all and running rpms up to 4-5K! I think this is generic to X's because I talked to another X owner that told me his does the same thing.

But, once you get it warmed up, it seems that idle mixture is not important to get it running. So - warm it up with starter fluid, and then tune it (synch and idle speed will do the most good).

I am suspecting your battery. If your battery is good, do you know if your coils/spark plugs are good? AKA: do you have a good spark? Good spark can be deceiving on our bikes because it may look good, but not be good enough to spark the mixture when cold.

 

I think we went through two cans of starter fluid! :lol:

 

One other thing you may want to try is to spray some sort of oil in the cylinders. This can help make up for bad compression. I believe that mine increased to 60 after I put some motor oil in there. Maybe if you spray a fog into the intake nipples while cranking, it could help seal any valves too.

In fact, this may have been what caused mine to fire, and I didn't even know it.

I think I sprayed Seafoam from a spray can in both the intake and directly in the cylinder and let it sit for a while. This was in addition to the motor oil.

 

Brand new battery. I have a nice fat spark on all my brand new plugs (when grounded to the block).

I have been jumping the bike to crank it because it will wear out the battery quickly otherwise.

I really liked "What I would suggest doing is running the idle speed to zero, and then crank it slowly open while spraying starter fluid and cranking the bike." Maybe I could dance a lttle jig too! Ha! how many hands do you have?

Quick question that's been in the back of my mind... sitting on the bike, are the cylinders numbered 1-4 left to right, or right to left? Just don't trust that PO...

Thanks so much
-jon

 

I will admit that it was easier with two people. I would suggest doing what your two hands allow. The starter fluid has to go through the air filter, so it is not critical that you spray and crank at the exact same time anyway. At least not in my experience.

Cylinder 1 is far left if you are sitting on the bike. Numbered from left to right, so next to the right is 2, and so on. Did you not get a manual with the bike?

Just keep at it, I am sure that you can get it firing soon.

Maybe you should look at other obvious things - is the bike in neutral on the centerstand? Kickstand up? Both coils firing? Spark plug caps not grounding out? Caps all the way on the plugs? Gas in the carbs (this requires you to put the petcock in prime)?

It seems to me that the simple things always bite me! You are looking for a big problem like a burnt valve, when there really is no gas in the carb! :lol: (This happened to me).

 

"Maybe you should look at other obvious things - is the bike in neutral on the centerstand? Kickstand up? Both coils firing? Spark plug caps not grounding out? Caps all the way on the plugs? Gas in the carbs (this requires you to put the petcock in prime)?"

Yes, all done.