69 Ace 100: Getting it started

[sparkyj]

Thanks to all who are helping me sort out this non running Ace 100.
Figured I'd start a new thread based on "getting it started"

UPDATE:

Unplugged the black wire from the ignition.
So just running on direct to coil.

Coil is producing spark. Checked with meter (approx 5.5 or so) and can see spark on plug when grounded
Plug is NGL B7S, i know it is supposed to be a B8S. Don't know if that matters at this point
Gap is 24

Compression: Only have approx 80 lbs of cumulative pressure when kicking it about 8 times hard.

Squirted Starting spray in the hole. Doesn’t want to light at all.

Could replace gas, but is smells ok, pretty gassy!

But if no love at all with starting spray could this be a sign of compression?

thanks All for your comments.

[Hydraulic Jack]

80 psi is way too low. Should be more like 140 to 160. Could be the rings are stuck if it has been sitting a long time.

[sparkyj]

should i just take the head off and will there be any way to tell? Or will I need to remove the whole barrel? Also will I need new copper gaskets after that? Waiting for the manual to arrive but want to get a jump on this..

Can you soak the piston from the top through the plug hole to help loosen those rings?

[Hydraulic Jack]

You can soak the rings from the plug hole, but I wouldn't use motor oil for this. Use a tablespoon full of ATF or a good spray of penetrating oil and let it sit. Kick the motor over gently until you have the compression of the upstroke, and then put in the solvent and let it sit overnight.

You can see the rings by taking off the exhaust pipe. Because they will be compressed in the cylinder it will be hard to tell if they are stuck, but you may be able to get a tiny bit of wiggle out of them using something like brass, plastic or wood as a probe. Don't use steel tips like screw drivers because it is easy to damage the piston or a ring. What you may see is a ring that is broken, or smeared aluminum from a seizure, or a lot of carbon buildup. These would indicate the need to disassemble and either re-ring or rebuild the top end.

You can't see the rings just by removing the head, so peak in the exhaust port first. If everything is clean and tidy in there, squirt a bit of motor oil in the plug hole and re-take your compression test. If possible, do the test by pushing the bike in second gear instead of kicking. You get a better pressure rise that way. If the pressure is the same after an oil squirt, it probably needs an overhaul. If pressure goes way up, I would suspect rings and would pull the cylinder and check ring wear and piston clearance, and go from there.

[Bill2001]

A mixture of 50-50% ATF&Acetone penetrates very well. Be careful, it's also very flammable.

[olddogs]

With 80 PSI I would just go ahead and pull the head and cylinder. If you buy a head gasket so you can just look, a base gasket is just another couple bucks to look at everything. I have had 2 Hodakas come in this spring with compression issues. One had a very worn standard ring on a 40 over piston, the other was a 2 ring piston with only a worn out top ring on it. No telling what a previous owner has in store for you.

Congrats on getting spark. That's number 1 on the holy trio, fuel air spark.

[olddogs]

Whoops. Typo. 3 basic needs for a running engine. Fuel, compression, spark.

[sparkyj]

How'd you loosen the ring with the piston out? I've used Vinegar, ATF 50% with acetone, Penetrating oil, Napa Carb dunk cleaner (the newer eco stuff), metal rescue. Nothing is breaking this crud buildup on the rings. Piston looks pretty good as does the bore so my thinking if these springs can open back up i can pop it in and retest for pressure. Will apply heat next I think.

[Hydraulic Jack]

The crud in question is probably coked carbon. Try soaking the piston in straight laundry ammonia.

[sparkyj]

Ladies and gentlemen. Toaster oven. Toasted it 3 to 4 times for a few minutes and gently worked at it with a paper clip. Well i broke the top ring. But the bottom is good! So, when in doubt, have a toast!

[sparkyj]

Got the piston re ringed with a top ring and it fired right up.
First time to hear it run. I think I need to re-clean the mikuni carb. Getting it to idle requires the idle jet to be screwed all the way in.
When revving it takes a while for the idle to come back down.

After getting it started I noticed an audible rattle when pulling the clutch in. Anyone know what that suggests?

[Bullfrog]

Sounds like a worn out clutch bushing, which is fairly common.

Slow return to idle suggests (pretty strongly) that there might be an air leak. A pressure test is HIGHLY recommended. I don't know what the world is coming too, but you just can't depend on engine seals which are 40+ years old anymore. (actually, I don't think you ever could )

Cleaning carb again while paying special attention to the pilot jet and ALL pilot circuit passages is a good idea.

Ed
PS: Did I mention that a pressure test is HIGHLY recommended? (air leaks lead to seizures)

[sparkyj]

Thanks Bullfrog. How might I do a pressure test on her?
Which seals are suspect?
Are looking at a potential complete tear down here?

[Bill2001]

Do a Forum Search for "pressure test" and Google "pressure test 2-stroke" for complete information.

[olddogs]

It takes very little dirt or varnish flakes to plug up the pilot jet or passages. Start there. Make sure you use an in line fuel filter. Also could be an air leak, The pressure test will tell you. May be a base gasket but most likely a manifold to cylinder or carb to manifold air leak. Make sure top of carb is on straight and seated.

You can change the mag side crank seal by removing the flywheel and points plate assembly. The other side requires splitting the cases to change.

The rattle in the clutch is probably the bushing. They are cheap and easy to replace by removing the side cover and clutch assembly.

[sparkyj]

Thanks OldDog.
Sounds like I will need to get a list going for all of the seals, bushings and gaskets.
Any engine seals you can think of, I'll make a note.

The carb O ring may not be mating as it should. I used a very light coat of pliable form-a-gasket on the Carb spacer to barrel. maybe I'll spray some WD30 on there while its running to see if I get a change in acceleration.

Also the exhaust was a little looser when I checked today, compared to yesterday when I remounted the pipe. That might create a back pressure issue right?



A little off topic but......
As well, I have this front wheel off and the whole hub was full of grease. I think the bearing seals are shot. How do those bearings come out anyway?
I want to degrease and button up for now just so I can do a test run.