At wits end.... back kick when starting?

[CR500RR]

Ok, I'll try to be concise but we all know what emotion comes with the bike not starting when you want to ride.

I bought an 88' CR500 a few months ago. The details are here (http://bannedcr500riders.com/board/view ... hp?t=13971), but basically it's a mutt bike with a 94' engine and some other bits.

After I got it she ran great. It wasn't what I would call easy to start, but with proper technique (TDC, reset kicker all the way to top, use your whole body and kick) it would start cold in 5-6 kicks. Warm was 1-2.

Then one day it back kicks on me bad, hurt my foot even with a boot on and I damn near fell off the bike. It eventually started after a few more back kicks and ran great. From that point on every time I have tried to start this thing it will kick and kick with no fire and then randomly back kick on me. Every so often, it will magically start up as if nothing is wrong (and sometimes with a very easy kick) and run great. I pulled the flywheel to check the timing and Woodruff key. Both look good......

I thought "This must be me, I got kicked and am now a little gun shy. I must be pussyfooting the kicker." So I got a decomp valve installed by Roosty to help me roll this thing over faster. Same result as above. Back kicks and random starting sometimes.

In desperation I retarded the timing as far as the plate will go and got the same result as above. I reset it proper and still the same problem. So now I'm kinda stumped and am looking for help. WTF is going on with this thing? It's possessed or something!

On a side note, not my first rodeo for troubleshooting issues. I restore cars and motorcycles so I've seen a wrench or two....... maybe I'm too pissed to see this problem straight?


Thanks for any help

[Roostius_Maximus]

Remove the flywheel, check to see if the flywheel key is sheared.

[motardcr500]

If your key isn't sheared as seems likely, I have heard of a case where a bad CDI was causing that same problem,
Only have heard it once so it's not to common.
Does Honda have OHM specs for the CDI?
If so a quick check might reveal if it's good or bad.

[CR500RR]

Remove the flywheel, check to see if the flywheel key is sheared.

Key has been checked a couple times during this adventure. Not sheared, looks perfect.

[CR500RR]

If your key isn't sheared as seems likely, I have heard of a case where a bad CDI was causing that same problem,
Only have heard it once so it's not to common.
Does Honda have OHM specs for the CDI?
If so a quick check might reveal if it's good or bad.

Good idea. My service manual just arrived so I'll check the specs on the cdi.

[Kuma]

when you detailed your starting procedure it seems you left out 1 important item and if your not doing it, could explain your problem.
bring it around to TDC, THEN, go just past, bring the kicker all the way to the top. this will make sure as you are kicking it through it goes all the way through the next TDC, otherwise if you are just relying on the flywheel momentum, well that could be the results.
hope it as simple as that.

[gregrobo]

id be checking the timing also

[CR500RR]

when you detailed your starting procedure it seems you left out 1 important item and if your not doing it, could explain your problem.
bring it around to TDC, THEN, go just past, bring the kicker all the way to the top. this will make sure as you are kicking it through it goes all the way through the next TDC, otherwise if you are just relying on the flywheel momentum, well that could be the results.
hope it as simple as that.

Thanks for the reply. I start it as you described, just left out some detail in my haste. The kick definitely takes the engine all the way through the next TDC.

I decided to go back to basics and check the compression. 3 Kicks (WOT) got me 140psi, so that's looking ok.

I tried to confirm timing via a light but unfortunately my timing light will not trigger reliably off this magneto. Not sure whats going on there but I have had this issue before with this particular light. I'll try another one and see if I can make sure the CDI isn't stuck at full advance.


Lastly I'm fabbing up the adapters to pressure check the case. I've had air leaks cause hard starting before, not sure about the back kicking though...... doesn't hurt to make damn sure there are no air leaks.

[iggys-amsoil]

A side note, my very first bike, a 72 Yamaha 360 enduro did this all the time, I had to learn to turn my heel out cause it would hit the underside of the pipe. For the first three months I had a nasty looking burse their. It had a factory decompression valve but never used it.

Sorry this doesn't help.

It still seems like a timing issue.

Oh a friend of mine had a Yamaha 175 about the same yr. After putting it back together the thing actully run back words. It had something tio do with the timing plate. He wasn't sure which way it went and guessed. So he knew exactly what to fix and run fine after that.

[CR500RR]

I finally have this figured out, and I thought I would post my findings for closure. It was one of those multi dimensional issues that is such a pain in the ass to troubleshoot, particularly on an engine like this.


Problem A: The timing was pretty wacked up. It was randomly firing at the "F" or "T" mark at kicking speeds. Since "F" is around 24 degrees of advance when it happened to light the fuel off there you were in for a ride. I pulled the coil, cleaned up the frame mounting tabs, checked all the electrical connections, and put it back together. Now at kicking speeds it sparks at "T" every time. Once running the timing properly advances to "F".

Problem B: This issue relates to my starting method and the decomp I had installed. Because of the back kick issues with Problem A, I assumed that I must be kicking it wrong or I was too much of a pussy to start the damn thing reliably. So I had a Roosty decomp installed and followed "The Drill" outlined earlier in this thread exactly. For these efforts I got nothing. No start, maybe a half-hearted pop or kick on occasion.

Long story short, this CR doesn't start worth a damn with "The TDC Drill", and I cannot for the life of me start it using the decomp valve. I can however start it every time doing the following routine.

-Fuel on
-Choke on
-Roll the engine over a few times with the kicker easy
-Push the kicker until I feel compression as the piston comes up (not all the way to TDC), reset the kick lever fully
-Using my foot on the kicker, jump up high (like I'm standing on the kicker for a split second) and then come down for a full force, all-my-weight-behind-it kick

I can do this twice when it's cold and off she goes, once when hot. Not sure why this CR500 doesn't start like all the others but I'm glad it's figured out now. I'm also mystified about the decomp valve. All the stories about starting in flip-flops or by hand using one did not apply to this bike. It also doesn't work well with my method above because I'm using the engine compression to jump up high for a really fast kick. Using the decomp, the kicker isn't stiff enough to do that. Maybe there is some trick to using the decomp that I don't know..... I'll let the experts chime in.


On another note this 500 has had some engine modifications, so maybe that has something to do with it. When I pulled the reeds to check them I noticed that the intake has some port work. It's also not running a factory carb. Who knows , just glad it's running.



List of work done to solve this issue:
-Compression check (140psi)
-Engine pressure check (good, 1-2 psi over 10 minutes)
-Ignition timing check (issues, cleaned grounds and connections, fixed)
-Decomp installed
-Reeds pulled, inspected (looked good, Boyesen RAD valve reed block)

[gregrobo]

what's your jetting like and where is your air screw

[TecRider]

You keep kicking it like that and you will be scrounging around for new cases soon.
What I do is bring it to TDC, push the decomp, then kick away.

[motardcr500]

What I do is bring it to TDC, push the decomp, then kick away.

+1

[CR500RR]

what's your jetting like and where is your air screw

I have it written down and can find it for you, but the numbers will be meaningless I think. The previous owner put a Dellorto round slide on this bike. My one WOT plug chop (that was fun! ) was chocolate brown, so the main is a little rich. I'm OK with that for now. From idle to about 1/8th throttle is pretty burbley, and the pilot screw (fuel screw on this carb) is at 1/2 a turn, so I know the pilot circuit is rich. I haven't messed with it yet since I was sorting out the other issues.

[CR500RR]

You keep kicking it like that and you will be scrounging around for new cases soon.
What I do is bring it to TDC, push the decomp, then kick away.

I'm more worried about what happened earlier with the ignition issues..... some of the back kicks were pretty violent. If the cases crack because of my leg I'll be surprised, or very disappointed in Honda engineering. Either way I'm glad to be riding.


I wish my decomp worked like that!

[motardcr500]

I would swap that carb out.... I didn't realize that you were running a Dellorto...

[Kuma]

dump that delorto and either put on a PJ or PWK then you will have a wealth of information about jetting.

[Roostius_Maximus]

so its lean, still lean, always has been lean.
It'd start great if it were rich as hell or had less timing.