could bike need rings?

[Nevada Sixx]

I'm trying to figure out why my bultaco wont crank but once in a blue moon. The last time it ran well, my brother put regular gas in it,, then just poured some premix over in it without measuring it.
After he rode for a few minutes, it quite and never crank again except once,, and that was for a short while.
Could the rings be eat up from the bad fuel mix? Could eat up rings make a bike not crank? I have spark, and engine turns over, and i cleaned out carb real well,, but still no luck.

thanks.

 

[2stroke]

Im assuming you put fresh gas in, but how bout the plug? maybe there was too MUCH oil in the old gas, sometimes plugs can foul to the point where they will be a bitch to start,and run crappy, yet still spark enough to see when its laying on the head....Id try a NEW plug to be sure...hard to clean them ,sometimes you can get the electrodes shiny, but all the crap up inside around the insulator can still screw you up...

 

[Nevada Sixx]

i put in new plug and gas with the right fuel mix.. I also checked the silencer packing. I know it's getting fuel cause eventually, the plug will have gas on it.
Is there a way to alter timing on an old bike like that? maybe that could be it also....

 

[2stroke]

yeah..timing on older 2strokes is usually done with the stator plate behind the magneto, once broken loose, it can be rotated somewhat either way, but I dont know if that would work itself far enough out to stop running? Ive never had one move on me...so I dont know If Id try adjusting that yet...?

 

[2stroke]

oh yeah...how long did it sit since it was running last?

 

[Nevada Sixx]

othen then when i cranked a few months ago and ran for about 5 minutes,,
it has been about 10 years since it was last running,,bike looks good though for its age, its just been in the carport since about 82,, i get it out every year and wash it, and try to crank it with no luck,, so it must be the rings cause 10 years ago, the engine was rebuilt, but quite running after about an hour of riding time,,, which i believe was due to the improper fuel mix. I told my brother i'd rather just sell it and use to money to pay down on a newer honda or something.

 

[bake]

Try a compression test, maybe bro didn't put in enough oil?

 

[Nevada Sixx]

yea, it dont think he put enough in,, or maybe it didnt get mixed in with the gas in the carb fast enough,, he filled up the tank,, then pour oil into the tank.. one other idea we had today is to try and crank it without the air filter on it,, it has a k&n filter that looks more like a car filter,, maybe its not getting enough air..

 

[Jeff Gilbert]

Pull the tank & dump out all the old gas if not already done.
Pull the carb & clean it good.
Clean the air filter.
Replace the plug with new one.
Put fresh fuel in.
Try to start.
Now you know what it isn't if it still doesn't start and you've only spent about $5.

I'm sure that the gas has turned to jelly & gummed everything up if it's been 10 years since it last ran.

 

[Nevada Sixx]

or turn to wine..

i did drain the gas and clean carb, and new plug recently,, next is to check air filter and pull the cylinder.

 

[KWJams]

First off,

Do a compression test on it before you pull the head

 

[Nevada Sixx]

ok,, i did a compression test using a gauge that had a rubber end on it, we held it down in the spark plug hole as hard as we could while i tried to kick start the bike,, did we do it right???

we got a reading of only 50.. My 89 125 did 110. So i guess the old bultaco 250 didnt do very well... What does it mean when compression is that low?

 

[Nevada Sixx]

oh yea,, we also tried to start it by pulling it behind a pickup with a rope,, it didnt even try to start... :( my brother noticed that you have to get a good kick to make the plug spark....

 

[grass-digger]

50 is way low i think the next step is to take the head off and well i think you will be in for at minimum of a set of rings
if not a piston and a sleave hope it turns out ok :(

 

[Jeff Gilbert]

Originally posted by Nevada Sixx
ok,, i did a compression test using a gauge that had a rubber end on it, we held it down in the spark plug hole as hard as we could while i tried to kick start the bike,, did we do it right???

I've never used one that didn't thread in but, when you kick the bike you are suppossed to hold the throttle wfo and kick it several times.

 

[Nevada Sixx]

i didnt know that,, my compression must be sure enough low then...

 

[KWJams]

Operating requirements

An engine needs three basics to run properly:

1. Correct fuel air mixture
2. Compression
3. Spark

If one or more of these basics are missing then the engine will not run.

It is a process of elimination to determine which basic function is the problem.