2002 bajaj chetak starting issues By jhare (Read 2,016 times)

[jhare]

I have a 2002 Bajaj Chetak 150cc I'm trying to get running again and I've run into a wall, seeking your insight.  I got it for cheap from someone that said it's been sitting 5-6 months and it had started fine back then. 

Info I have collected so far:
OD reads 2200 miles
Spark:
-Compression is good at 170 psi
-valves are within spec (I had to adjust the exhaust valve, it was a bit too open)
-Verified spark by grounding spark plug to engine block and kickstarting, bright blue 
-I replaced spark plug hood with NGK resister 
-spark plug wire has good resistance (coils seem fine to me)

Air:
-Air filter and passages are clear

Fuel:
-Filled tank with fresh gas
-I cleaned the carbs and reassembled (they were pretty clean when I opened them up)
-fuel flows freely
-float height is within spec
-throttle cable is loose, it's stretched out and can't be adjusted, so there's some slack in the throttle cable

Fresh battery fully charged.

Problem: The engine will turn over but despite all my efforts it will not run.  I have sprayed starter fluid in the carb before starting the engine and then another time while starting the engine and it still won't run.  With the starter fluid the engine seems to have some ignition, but it's small and won't be long enough to make the engine run, even for a few short seconds. 

Thoughts?   

[ucwt]

Intake air leak?
My o ring on my intake was compressed so it wouldn't seal.
High temp rtv fixed mine, hope it's that easy for you.

[jhare]

Thanks, ucwt. One of the o-rings was compressed. I went ahead and changed both o-rings at the intake, but it didn't change much...

[ucwt]

Does it still have the air box on it?
Mine wouldn't run properly after I tried to make it "free flow" by mucking about with the baffles in it and it also gave me problems when the foam air cleaner got clogged.

[czmdiver]

On a 150 you will be able to pour Gas or Ether directly into the Intake Port with no manifold on and she should pop right off..  Then she will die as the fuel you introduced is used up quickly.
Good Luck

[ucwt]

Also check the enriching arm, the metal used tends to warp and not do it's job.

Look at it when articulating the throttle and see if it's making contact with the plunger sufficiently.

[jhare]

czmdiver, do you mean to bypass the carburetor? For example, remove the carb and spray ether directly into the intake port?

ucwt, good point, I had already checked the enriching arm (which I take to mean the jet needle connected to the throttle slide/valve). The jet needle would move smoothly up and down the needle jet (i.e., the jet that delivers gas from the bowl) when the throttle was articulated. One thing I'm having a hard time figuring out what is the proper amount of turns out for the idling screw (i.e., the screw that adjust the placement of the throttle slide).

Update: Doing some more research I determined the spark plug I'm using is fuel fouled, the tip is completely black. When I ground the spark plug to the engine block it still sparks bright blue. I've read that a fuel fouled spark plug will spark but may misfire, maybe leading to my problem? Any insights on this issue is much appreciated.

I'm waiting for a new iridium spark to arrive.

[ucwt]

What I'm talking about.

[cyborg]

You could be on to something,, I’ve had a few funky plugs

[jhare]

I see. The carb I'm working with doesn't have an accelerator pump (at least I don't think so). My carb is a Keihin pb20, here's an image I found:

[jhare]

Another example of my type of carb:

[cyborg]

I still think the carb has plugged up jets that you overlooked when cleaning

[jhare]

I had time to work on my scooter today, so here's my update:

I replaced the spark plug and spark plug cap, got good resistance readings all around (coil, spark plug, spark plug cap). I can't get the engine to fire by pouring gasoline or ether into the intake. The spark plug has spark verified by grounding it to the engine block. Rechecked valve clearance and it's within spec. Battery is fully charged. I swapped out the CDI with one from my other scooter (same type of scooter and same type of CDI), but no combustion.

Thoughts?

[cyborg]

Check the flywheel timing,,there's been a few issues with the key shearing and the timing is way out

[jhare]

Cybord, great insight! The woodruff key was indeed missing!!! There was some shearing on the crank rod and inside of the flywheel. Luckily I had another part laying around, popped it in, sprayed some ether in the intake and the engine fired up! I'm going to reassemble everything and take it out for a short ride. Thanks everyone for your help with this.