No start, 01 250 trailblazer

[splicerman]

I feel like this is a common problem..
I got a swamped ride and tring to wake it up. 1st we
Replaced coil under flywheel and got good spark, carb is clean but after cranking on this bike for most of the day, just a few pops.
After reading it is common to have low compression and mine was soaked and left wet for months..we've drained the crankcase, cleaned the exhaust out..Nada... just an oily spark plug..
What should a good pressure be for the compression?
Does this have reeds or ports that require service?
Could spark timing be the issue?

Thanks in advance, Dag-n-Jr

[blueline15]

are you getting fuel with the oil?
compression should be 90+

[splicerman]

Engine feels like it has enough pressure but guage reads 75psi. Plug has mostly oil and it appears not to draw fuel thru carb as strong as I would think. Thats why I was thinking reed valves.

[Manaen]

75 is very low PSI

There are no reed valves in these engines. They work strictly off of port timing. You may also have bad main seals if it was sitting for a while. Also I suspect the cylinder is rusty and pitted along with the crank and main bearings. If water remains in an engine for a long time it will rust very quickly. I would pull the head and check the cylinder it's possible you can get by with a hone and new rings. I would also disconnect all the wiring connections and clean them and then apply dielectric grease to all the connections to eliminate any oxidation/corrosion problems.

For future reference if this happens again you should pull the drain plug on the bottom of the crankcase and crank the engine. Then get it running to full running temps to clear all the water out. Spark problems can almost always be repaired by cleaning up the wiring with WD40 (as a quick fix) and dielectric grease for a longer term fix/preventative maintenance.

[psavas]

I don't know if this helps but I just rebuilt a 1996 TB and I had a problem with it getting gas an oily black plug. I took apart/rebuilt/cleaned the whole carb and made sure my vent lines were not clogged. I than put everything back together and still couldn't get it to fire, mind you the guy I bought it from said it had not ran for over 6 years). I had great compression, spark everything could not figure out for the life of me what the heck the problem was. I decided to put the airbox back on the carb, sure as sh!t next crank it fired up the and has not stopped running to this day! I know about air/fuel ratios but I think these polaris two strokes are extremely tempremental when it comes to the "little things."

Just my $.02