missing cyl. at idle

[prometheus578]

Well, I pulled the carbs off and did a compression test. When my friend did his test, #3 cyl. was really low. My test showed approx 140psi on 1-2-3, and approx 20psi on #4.

Your testing method was loopy, but it doesn't matter. happens some times. Depending on how strong the battery is, compression readings can get lower and lower as the battery drains. Also, if there's grit around the spark plug hole, the O ring doesn't seal properly, and there goes your compression reading.
No matter.
The valves that you think have NO clearance, just need to go thinner a size or two. Put in a thinner shim, recheck and readjust as needed. Double check several times. Do the shims, crank it over (BY HAND) to make sure they're all seated properly and check them all again.
Easy work... just takes time.

[tomeriker]

verry strang

ok. here goes

I redid my compression test with same results. ( #4 very low)
I adjusted the shims, now the clearances are fine, but #4 still low.
I stop for the day and go back the next day. #4 is back up but #2 is low.
There is a miss still in the engine. all plugs are good and good spark. My compression problem that started in cyl. #3 has moved to #4 and then #2. This isn't possible so I'm going to say my compression guage is faulty.

The bike doesn't smoke so I will assume the rings are good and that my problem has to be carbs. SOOOO, I will go back to the plan of taking the carbs from my running bike and put them on the problem child..
I will keep you all informed.... thanks

[audijunky]

Did you follow the instructions in the tech tips for doing the compression check. As Prom said I think the method you used may be giving you these bad readings.?

[fredintoon]

methodology

Hi Tomeriker,
the carbs must be wide open to get good compression test numbers. If you are pulling the carbs anyway, take 'em off then do the compression test. That beats holding the twistgrip open which only opens the butterflies and you hafta hope the slides lift. Pull all four plugs when you do the test and crank the motor ten turns to get a good reading.
Fred Hill, S'toon.
BTW, try a leakdown test too.
F.

[tomeriker]

testing method

yea, when I did my testing the carbs were off the bike. all the plugs were removed and the battery was charged and I cranked at least 10 times each.. I didn't read the tech article but maybe I should find it and read it, because obviously I am doing something wrong.

But for all who said it was carbs.... YOU WERE RIGHT...

I took the carbs off my other bike and BAM! The bike is alive and runs rather well. SOOOOO, back to the drawing board.

I think I will just take them to a professional about an hour away and let him do them right.. At least now I know I'm not a carb mechanic.

On the bright side, my valves are shimmed correctly and I have the possibility of having a second XS.

My friend that bought the new bike wrecked it and had to go to the hospital, but was treated and released. Apparently a lady pulled out in front of him and he had to ditch the bike. Talk about bad luck. He only had the bike for 4 days?

[skids]

Yeah, we all have to ride as if we are invisible. I hope he is OK.

[tomeriker]

audijunkie

A little off topic.. but.. I noticed audijunkies avatar. A bobbed XS. That looks really cool.

I have been debating over doing that with the 2nd XS I have since its not in all that great of shape. I noticed a chain drive conversion also. You guys are doing some pretty cool stuff.

[audijunky]

Hey Tomeriker.
Thanks for the compliments. Got the information on "how to" from Pggg and Xschop. Great bunch of guys. If you want some more info and background there are two threads in the other bike discussion area named "chain drive 25 pics" and "chaindrive continued". Covers Pggg's conversion as well as mine and some of Chops. Chop also has a thread in the XS11,XJ11 discussion area titled "begging new mod, need help" it also has some useful info. Good luck on the chop if you decide to do so.

[audijunky]

Also I have a photosite with a bunch of pics of my rebuild/chop
heres the linkhttp://sfranklin8.photosite.com/album1/

[audijunky]

Forgot to add that XSchop says he'll be manufacturing a front sprocket housing for a chain drive conversion. So keep an eye out for that.