Six Day Won't Start

[chuck]

72 Six Day has been getting more difficult to start over the last few races. Now, I can't get it started either kick starting or push starting. The spark plug gets very wet after trying to start. If I take the plug out and kick it over in an attempt to clean fuel out of cylinder, and then put the plug back in, the bike will almost start. I'm guessing that the rings and or piston has got excessive ware and too much fuel is getting to plug. The last race it started easily was a mud race where I ran the bike at very high RPM! May have finally worn the old girl out. What do you think?

I have a PVL ignition set at 95 thousands BTDC. Getting good spark. 28mm Mikuini which I tore down and cleaned thinking that may be the problem.

Leads me to the conclusion that the rings and piston are shot. Does this make sense.

Thanks,

See you Ohio!

Chuck

[Dwight Rudder]

Very possible.  Have you done a compression check ?
Dwight

Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.

[chuck]

Dwight,

Thanks for the reply. No I haven't . I don't have the equipment. Suppose I can buy a compression guage at a car parts store? What kind of compression should it have?

thanks for the help.

Chuck

[dkwkid]

Float level? When was the last time you checked your crank seals? You can only replace the ignition side on the Sachs engine.

[firstturn]

I think Dwight and DKWKID have you on the right path.  You can make a compression tester fairly easy after you see how one is mad.  The seal behind the PVL is a easy change it it needs to be changed.  Start with taking the aircleaner off and the pipe off and see if it starts...then do a compression check and get back with us.  What I am looking for is to besure you are getting air and also making sure your pipe isn't plugged.  I hope this helps.

Ron Carbaugh

[chuck]

I already tried without the air cleaner with no luck. Didn't try taking the exhaust pipe off yet.

I checked the compression. It has 60PSI or 4.5KPA. Is that within spec?

Would a bad crank seal cause gas to get in the lower end? Does this result in low compression?

Thanks for your help.

Chuck

[chuck]

I just did a search on compression and I should be between 145 and 160psi. Wow, I'm a lot lower. Does a worn crank seal cause low compression or is it just a worn piston and ring.

If I do need to replace the crank seal do I need to split the cases or can I get to it by removing the ignition?

Thanks,

Chuck

[Dwight Rudder]

I would say that you need a bore job and piston and ring.
Dwight

Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.

[chuck]

I removed the pipe as Ron suggested and second kick she starts up. Blocked pipe was certainly the the culprit. However, I agree with Dwight that I'm due a new piston and rings.

As always this is the greatest group of vintage bike owners out there.

Thanks for all the help.

I'll see you in Ohio.

Chuck

[t20sl]

Chuck:  Don't be to hasty to tear engine apart just yet.  How did you check compression?  Throttle should be wide open when you kick it over several rapid times.  If throttle is closed compression will show way low.  Ted

[chuck]

You right. At first I had the throttle closed and getting about 60. Later tried it with the throttle open and got 90. Still lower than specs. I'm going to go ahead and tear the top end down and measure clearances.

Thanks,

Chuck

[chuck]

You right. At first I had the throttle closed and getting about 60. Later tried it with the throttle open and got 90. Still lower than specs. I'm going to go ahead and tear the top end down and measure clearances.

Thanks,

Chuck

[hrbay]

Chuck, check the pilot jet again. Look at a bright light source thru the jet to verify. May have to run a .010 wire thru to clean it out. Deburr the wire end so as to prevent scratching the surfaces in the jet.

GC

[socalmx]

If the compression is questionable, I would suggest getting it bored and a new piston. Running with a marginal bore is risky because the Sachs cylinder wears in such a way that you run a risk of snagging the ring (learned lesson the hard way). Better to be safe than sorry.

[chuck]

I cleaned the exhaust pipe out and already sent the cylinder to Forest Stahl for boring.

New piston and rings and a clean pipe and I should be ready for Ohio.

Thanks for all the help.

Chuck