TEC HH100 engine won't start

[Dan693 510]

Just finished the rebuild on my 1970 Raider 10. I started it last night and it seemed to run pretty good for a few minutes but I had to leave the choke on to keep it running. I figured that was because I hadn't made the final adj to the carb.

After a few minutes it shut off like turning off a light switch and now wont fire a shot. I replaced all wiring, fuel lines, and rebuilt the carb during the rebuild.

 

I confused because it seems to have good spark but even with starting fluid in the plug hole it still wont fire.

 

Things tried......

The gas is from my can is maybe 2 months old at most. Also tried starting fluid. No fire. Gonna get new gas anyway.

Removed carb again and blew out with compressed air. It seems fine but maybe I messed up the rebuild.

Disconnected kill switch wire....no change. 

 

I was excited to take a test ride on my first WH after a ton of work......but as of now it's just a big red boat anchor.

 

Any help with starting the troubleshooting process would be greatly appreciated.

[N3PUY 1,031]

If it has good spark (at the right time) try a new spark plug.

[pfrederi 17,708]

If it won't at least pop with spraying carb cleaner (or starter fluid) in the carb you have a spark issue.  Do you have a plug tester??   Like N3puy says first try a new plug...and don't use a Champion. Try an autolite 356  (I have had too many champions that wouldnot fire under compression )

[Dan693 510]

The plug is brand new.....it is a Champion J8C which is what the guy looked up and said it was the one I needed for the HH100.

 

You may be right though.....I have spark but even with starting fluid it won't fire ????.......it almost has to be a bad plug.

[N3PUY 1,031]

If that motor has electronic ignition ..... was the flywheel off and not tightened enough?   Could change spark timing.

[Dan693 510]

The old guy that bought it new in 70 started it when I bought it so I decided to leave the engine alone......except for the carb. Seems like it has good compression and the old oil wasn't too dirty when I changed it.

 

Thanks for the ideas!....feel free to keep them coming.

[N3PUY 1,031]

I would take the screen off the flywheel and remove the flywheel nut.  Make sure the key slots are still aligned.  A loose flywheel will run for a while but starting and stopping will finally sheer the key.  Take a look and eliminate that possibility.    It takes 3 things for a motor to run.....  compression, fuel and spark at the correct time.     

 

[pfrederi 17,708]

Nepuy has a good idea...sort of like the soft fly wheel  key used in smaller Techys it can be deformed but not shear leading to bad timing.  Also how do you know you have spark??  Laying the plug on the block and seeing it spark could still be a problem as some plugs will not fire under compression. 

 

The elephant in the room is the electronic ignition..but lets resolve cheaper issues first

 

[Dan693 510]

Thanks to everyone for the help. New spark plug didn't change anything. It still won't fire a shot.

Executive decision....I've decided to pull the motor, throw it on the bench and go through it. Maybe a rebuild but I'll see.

 

The flywheel key wasn't easy to see if it had sheared or partially sheared but since it has good spark, compression, and starting fluid I think it has to be something with the timing so I'm just gonna take the motor apart and check everything. A little disappointed that it wont run but its just a side project to keep me out of the bar so I'll just hafta be patient and go through the engine.

 

If I end up doing a full rebuild (which it seems like I always do) I have a couple of questions for you old timers with experience.... 

 

Does it make sense to replace the Walbro carb with an aftermarket one? The idea of a brand new card sounds good I think.

 

Does it make sense to increase the displacement by boring it out? What does that do to the valving?  Is there a good source for parts to do that?

 

Dan

[pfrederi 17,708]

You say you have good spark...exactly how are sure of that..spark plug tester, laying it on the block????

[Dan693 510]

Attached is a pic of the third sparkplug. All had a visually strong spark from my past experience with lots of engines. Best I could do without an extra set of hands. I also checked the resistance with my tester.....zero Ohms on each plug.....any ideas?

[pfrederi 17,708]

I assume the head bolts were in when you tried firing her up with starter fluid.  The transistorized ignition system in the techy is different i have to look to see if it can be seriously miss timed

 

[N3PUY 1,031]

40 minutes ago, Dan693 said:

The flywheel key wasn't easy to see if it had sheared or partially sheared but since it has good spark, compression, and starting fluid I think it has to be something with the timing so I'm just gonna take the motor apart and check everything.

So is the key "sheared or partially sheared"?  Or you didn't look?   You're probably correct that  "I think it has to be something with the timing".  Looking inside the motor will only show you valve timing and you said it has good compression.  So no need to check valve timing.  It was a simple failure with no noise or grinding.  Look for a simple fix.    SPARK TIMING!

[pfrederi 17,708]

 

The air gap and the flywheel key are about the only things that can change timing, assuming the trigger pins work.  This system is very similar to the breakerless Kohler system of the same era.  Check your air gap and the spark test.