4 cycling mystery solved!

Bikeguy Joe · #1 09-11-2009, 10:29 AM

I have been reading a lot of posts lately about engines that four stroke a lot, some all thew time. I have a bike here I built a while back, and have been unable to sell it due to the fact I couldn't get it to ever break into a clean 2 cycle.

I changed the stock plug and wire, tried every setting on the needle, soldered and re-drilled the jet to the proper size, ect.ect.

If I put the "C" clip on the top notch, it would STILL 4 cycle and have very little power, if I moved it down it would get more power on each lower setting, but the 4 cycling was still there, no better, no worse.

Finally, today, I said "I guess I'll just go run this one hard and see if it's a ring sealing issue, break-in problem, ect, I'll either cure it or kill it." (I was just a bit frustrated, having run this bike for 20 miles or more and still running badly with everything I'd tried.

I was doing my "pre-flight inspection" and noticed the throttle cable was a little loose. The adjuster at the top of the carb is all the way out, so I looked at the throttle assembly. Apperently, I overlooked a shoddy fit where the cable housing goes into a sleeve and into the throttle housing. I used my aircraft cable swaging tool to squeeze the sleeve down tighter, and pulled the slack out of the cable before doing so.

THIS WHOLE TIME, THE ENGINE WAS 4 CYCLING BECAUSE THE CABLE WAS ONLY PULLING THE THROTTLE 3/4 OPEN AT BEST!!!!! I never got a good carb setting due to an overly large jet to begin with, and then the throttle not opening all the way meant I never really had a shot at setting the carb right.....

Yeah, I feel stupid being the "Godfather of motorized bicycles" and all to have let such a simple, tiny problem cause me so much grief.

I'm gonna go ride.

**BarelyAWake** · #2 09-11-2009, 10:57 AM

orly? o_O

*runs off to check bike*

actually, my 4 strokin probs seem to be behind me - but it can't hurt to check this lol

Venice Motor Bikes · #3 09-11-2009, 11:51 AM

That's something for everyone to think about! Great detective work Holmes!

aquarianmonkey · #4 10-12-2009, 11:42 PM

I have checked all of that on my bike. It will only 2 cycle when I climb hills. I was told that these engines only 2 cycle when they are under heavy load ? It would be nice to have 2 cycle all the time. I wish S&S would build a carb for these. They do wonders for old Shovles LOL

flybytaco · #5 10-20-2009, 06:48 PM

mine 4 cycled only at top end everywhere else she was mint. I have a box of jets from all the streetbikes i've done and they are the same type of jet but were way too fat as they were for big bikes. I soldered and used a ss wire that is in my snapon electrical terminal removal kit. it has 3 sizes so I used them to make the hole int the jet. stuck it through and heated the jet fed the solder and pulled out the wire after it cooled I made the hole barley smaller than the stock jet and problem solved.plug chop was beautiful bike revs from dead slow to full revs cleanly no 4 stroking at all anywhere anymore.

silverbear · #6 10-20-2009, 08:14 PM

Thanks for posting, this is all good to know.
SB

bandito · #7 10-20-2009, 11:13 PM

When a 2 stroke motor 4 strokes what is it doing. Dont call me stupid I already feel that way by not knowing please. I know what dieseling is on a gas motor!

flybytaco · #8 10-21-2009, 12:08 AM

Quote:

Originally Posted by bandito

When a 2 stroke motor 4 strokes what is it doing. Dont call me stupid I already feel that way by not knowing please. I know what dieseling is on a gas motor!

It putter puuters istead of a clean rev.. runing too fat

bandito · #9 10-21-2009, 12:21 AM

So when my 4 stroke putters is it 2 strokin? lol thanks fly.

**BarelyAWake** · #10 10-21-2009, 03:04 AM

Firing every other stroke, usually a sign of a too rich mix - most HTs will 4stroke until broken in, even then most continue to do it when they're not under load and/or cold.

Drove me bat**** insane tryin' to figure out what was "wrong" with my motor fer the first coupla hundred miles