Infant to the Cycleworld

Greetings
I am about as Green as they come to this Hobby, mind you no license yet. But I am excited and determined to conquer this at the tender age of half a buck, especially since I purchased an XJ550Maxim (82) in the fall of 2013 and to know that I have found such a site that is populated with a bunch of individuals that are knowledgeable makes it a heck of a lot easier.The bike (cosmetically) is in great condition and it has 12k miles on it. I just recently changed the Petcock filter and ordered a rebuilt kit for that as well, the tank shows no rust and didn't feel the need to rebuild the petcock at this moment. I removed the carbs for cleaning (will tackle this at a later date) and replaced the intake boots which were cracked. I know I have quite a ways to go before it's road worthy, but I am on my way. At this moment I would like to ask a few questions regarding the compression test, should i remove all of the plugs and can I have the battery charging from my car (car is off) while doing so and yes I should unplug the TCI before the test.

 

unplug the TCI.

you can jump from the car battery as long as the cars not running.

(but you can easily do the test from a fully charged battery on the bike itself.)

take all the plugs out.

if the carbs are installed; remember to hold the throttle all the way open while you run the starter and do the tests.


hope this answers your questions.

 

Thanks for the quick response, not sure whether the battery by itself will be enough to complete the test, now if the carbs are off do i still need to open up the choke and hold the throttle wide open?

 

I know I am also new here, but this is what i know. If the carbs are off, then no cables will be hooked up. So opening the choke and holding the throttle open will do nothing. You just dont want any air restriction, so if carbs are off then you are good to go. There is a thread somewhere on the site i will look and post.

 

You want to have your valves in spec also before you sync your carbs. You will want to replace your brake lines too before going out riding. Once you get these things taken care of you should be good to go.

 

This might be a lot of information (as the title states.) But a lot of information.

http://xjbikes.com/Forums/viewtopic/t=27544.html

 

Thanks again to all, I will post my results tomorrow for comments😃

 

A quick note about the "choke:"

It isn't. The "choke" on our bikes doesn't choke anything; the choke lever operates enriching plungers on the carbs that lift up and dump extra fuel into the intake tract.

If the valve clearances are tight (and many of them likely will be since they have probably been ignored) you might get some "scary" compression test results. If that happens, get the valves in spec and re-test.

 

Greetings All, I attempted the compression test on Saturday but unfortunately the current battery did not have enough juice to get through the first cylinder, so I had to spring for a charger, and affter letting it charge all night I woke up and found a fully charged battery, yes!

Now, keep in mind that the bike has not run in over 2-3 months and post September it was just run up and down my street (not registered) and in addition the gas tank is currently off and so are the carbs (cleaning).

I don't want to get discouraged here but "BigFitz" was correct with "Scary", I expected higher readings myself to say the least but what do i know.

Cylinder 1 = 50
Cylinder 2 = 60
Cylinder 3 = 50
Cylinder 4 = 50

After a teaspoon of oil (not me) I received the following readings

Cylinder 1 = 60
Cylinder 2 = 70
Cylinder 3 = 60
Cylinder 4 = 60

The good thing is that they are all within the same proximity. I will definitely check my valve clearances once I order the tool, should I be concerned at this point?

 

Greetings All, I had some time today to check my valve clearances and everything went ok with the removal (cover) process following BigFitz instructions (lobe pointing upwards 90 degree) but i could not get the feeler gauge in between the shim and the lobe thingy due to tightness. Not sure how to proceed at this point?

 

I am having this trouble with a KZ650 I bought super cheap as a parts bike b/c the PO said it had a hole in a piston. I was going to part it out, but when I got it home and did a quick compression test it was low on all
4 cylinders. A wet test made no difference. I heard some compressed air coming out of the carb and took the valve cover off to check the valve clearance. Almost all the valves had zero clearance.

I am no expert, but what I have done is order 4 of thinnest available
shims and will put them in under one cam at a time to test the clearance.
Unlike the XJ I have to take the cams off to get to the shim that is under the bucket.I will likely take the head off and check the valves and look for the "hole in the piston"

You would only need one thin shim. Just an idea. Other more experienced people may have a better answer.

Kevin

 

assume that the clearance is zero and change shims accordingly then recheck the clearances.

CN

 

Spartacus,
Welcome, you will get all the information and help you need here. Stick with it and you will have one sweet bike. It's hard to beat an XJ, great looks, reliability, handling, and performance.

 

I really appreciate the feedback and I will proceed based on zero clearance as per CN

 

Given the compression is low. Is it not likely the clearance is "less than zero"
By that I mean the valve is in an open position. True zero clearance would be when the valve is closed and there is no clearance between the shim and the
cam. My thought is shims are not inexpensive, so why not invest in one very thin shim and get the exact clearances you need. Again I am not a mechanic and am just thinking it though and asking the question.

 

You may want to check your valves and replace shims as needed. Here is a video on how to do it:

https://www.youtube.com/watch?v=V3gxT57eoDE

make sure that you write down what's in there and get them to spec.

http://i307.photobucket.com/albums/nn31 ... 3d56ad.jpg

If you want to swap shims instead of buying them, you can send Hogfiddles a PM and he runs a shim pool.

I hope this info helps.

 

Feeling a bit bummed out today, after getting the shims required (from Len/Chacal, btw excellent service/support and thanks again) to put the valves in spec (based on prior readings and the shim chart recommendation), i couldn't get the feeler gauge through (tight). I put the valve cover back on and did a comp test and got even more discouraged based on the readings:

1 = 70
2 = 70
3 = 70
4 = 0

 

Strange. If you can't get the feeler gauge in and it's the smallest size and the shim is fully seated, they are way too tight. How about giving us some more detailed info, like I'm sure you gave Len. Give us your Intake and Exhaust for each cylinder, gap (which sounds like 0), the original shim size, and the new shim size. so, for example:

I .011 was 255 now 245
E .016 was 260 now 250

Let's see what you're actually dealing with. I keep a book with that info so when I check clearances I know what shim is there without removing it.

 

Hey Kilt, here are the clearances prior too


E1 .006 = was 270 now 260
E2 .005 = was 265 now 250
E3 .005 = was 270 now 255
E4 .005 = was 270 now 255

I1 .005 = was 275 now 265
I2 .005 = was 265 now 255
I3 .005 = was 275 now 265
I4 .005 = was 270 now 260

The readings were taken prior to replacing shims

 

For starters, if you've got eight dead tight valves running compression tests is a waste of time.

A valve that is so tight you can't get a feeler under it will generally require either two or three sizes smaller of a shim; sometimes four (exhaust valves.)

 

Now I'm confused. (See quotes above.) Were they all "dead" tight, as described by you in your post from Saturday; or were they showing the clearances listed above (which, if in imperial or "inch" measurements are close?)

I ask because .005" = .12mm, which would be in spec for an intake valve. Then if you replaced the installed shim with one two sizes smaller, you'd be looking at .22mm, or .008" which is horribly wide, not so tight a feeler wouldn't fit.

Something totally doesn't make sense.