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Author Topic: Why Does My Honda CL200 Only Run With Very Advanced Timing?  (Read 2029 times)

Offline Classic5

  • Posts: 34
Hey All,

I'm working on a CL200 that I'm at my wit's end with. After working on it all summer and not being able to get it to run right, I've stumbled across a solution, but it seems like a dangerous one. The bike starts fine and runs better than it has before, but only if I severely advance the ignition timing. I know that this can cause problems so I'm really wanting to have it run well at factory specs if at all possible. Does anyone know why the bike is doing this?

Here is what I've done to the bike:
  • Bored out cylinders .50mm and fitted with the appropriate pistons&rings
  • Set the cam chain tensioner
  • Set the valve clearance to a loose .05 MM
  • Used a test light (not a timing light) to set the points to not only have the factory spec max clearance but to fire right at the F mark
  • Got a new "snappy" spark advance mechanism
  • Set A/F mixture screw to 5/8ths turn out +- 1/8th
  • Pulled some hair out
  • Cried a little bit.....

I haven't checked it with a timing light yet to see where it's ACTUALLY firing at, but I plan on doing that in the next few days.

Any ideas on what to check/try would be GREATLY appreciated.

Thank you!

Offline Sonreir

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Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #1 on: Oct 18, 2018, 15:30:17 »
Before doing anything else with the timing, please check compression. Low compression is a common reason for requiring advanced timing. If compression is low, we can start troubleshooting why that might be.
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Offline advCo

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Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #2 on: Oct 18, 2018, 15:31:05 »
What do you mean "severely advanced timing?" If you're saying that you set the points to the max gap and it runs, I don't see any problem with that.

Check it with a timing light as that is actually going to tell you what is going on. When the bikes running at about 3500 rpm you want to make sure the hash mark lines up in the middle of the two advance marks on the rotor.

If its way far out, then something is up with your advance mechanism either reversed or..?

Edit: Its a good idea to check compression as Sonrier stated. Considering you had the cylinders bored out I hope that you at least checked to make sure the valve seats were sealing properly.

Offline Classic5

  • Posts: 34
Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #3 on: Oct 18, 2018, 16:13:34 »
Hey Sonrier,

In addition to checking the timing with a timing light I'm planning on borrowing a gauge to see what the compression is, so thanks for that tip!

Just for my own knowledge base, do you know why the timing needs to be advanced in order for it to run when the compression is low? I would think just the opposite would be true but I'm fairly new to the art of the engine.

I'll report back once I get some more info to hopefully provide an answer to this question.

Thanks!

Offline Sonreir

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Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #4 on: Oct 18, 2018, 16:42:14 »
You need a certain amount of cylinder pressure to ensure your engine runs. That cylinder pressure is usually provided by the burning of the fuel/air mix (hot gases expand and that expansion is what provides you with usable power). The reason the spark fires before top dead center is that it takes a little while (split second, but still a consideration) for the fuel to burn inside the cylinder. This is called flame propagation. So after the spark fires, there's a small delay before cylinder pressures build. Ideally, peak cylinder pressure is at around 14° ATDC. If it comes in later than that, you're losing power.

Anyway... the point I was coming around to making is that the pressure in the cylinder that comes from the expanding gases from burning the fuel works in conjunction with the compression already provided by the rising piston. So if you start with low compression, then you're still lower than you need to be during the flame propagation period. You can get an engine with poor compression to run by advancing the timing and causing the spark to fire sooner. This gives the flame more time to propagate while the piston is still rising and creates enough total compression in the cylinder to keep the engine running.
Sparck Moto - http://www.sparckmoto.com

Audaces fortuna iuvat.

1977 Honda CJ360 - Café SOS - Stage One™, Café SOS - Stage Two™
1976 Puch Maxi - APuchalypse Now
Suzi T500 Cobra Resto

Custom Gauge Graphics
Custom Wiring Harnesses

DTT Red, White, and/or Black 360 Club - Better than those Blue guys

Offline Classic5

  • Posts: 34
Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #5 on: Oct 21, 2018, 15:55:57 »
Hey All,

I checked the pressure in each cylinder today and got 115 in both. Considering I just had the cylinders bored and put new rings and pistons in, new gaskets, made sure the valve clearance and timing is to spec,  I'm thinking it must be the valve seats themselves. Would you agree?

I was going to call up Moto Tech in OH and ship him my head to inspect/fix.

Let me know if you have any other advice!

Offline Classic5

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Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #6 on: Oct 21, 2018, 16:34:48 »
One other thing....

I finished taking the engine apart and noticed some wear marks (vertical streaks) in the fresh cylinder walls. Is that normal? Or should I be worried. The don't look like gouges, but are noticible without too much effort.

Offline teazer

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Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #7 on: Oct 21, 2018, 21:10:25 »
It takes a while for pistons and rings to bed in and for compression to come up.  When you tested compression were the carbs wide open and did you kick it over 5 -10 times until it stopped rising?

If you have the head off, if the cam is still fitted, back off the tappets and turn it over until one pair of valves are closed and then turn it upside down and pour thin oil or kerosene or gasolene into the head and see f it leaks out or weeps out of the ports.  If it does, the valves and seats need to be cut and if not, the head is fine.

When you reassemble the motor take time to be sure that teh cam is correctly timed and then that the ignition is correctly timed.

Offline Classic5

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Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #8 on: Oct 21, 2018, 23:23:07 »
Hey Teazer,

Thanks for the tip on how to check the valve seals. I'll definitely itely give those a test!

I definitely had the throttle wide open and ran the starter till the guage wouldn't climb any higher. Should I have specifically kicked it instead of using the starter?

As far as the rings seating is concerned, would you expect them to improve their seal enough to take it from 115psi up to 160 or whatever it's supposed to be? That just seemed like such a long way to go I assumed that the valves must be leaking.

Thanks!
« Last Edit: Oct 21, 2018, 23:25:02 by Classic5 »

Offline Classic5

  • Posts: 34
Re: Why Does My Honda CL200 Only Run With Very Advanced Timing?
« Reply #9 on: Oct 22, 2018, 17:44:57 »
For that matter, I can find lots of forums where people say that you need to seat the rings and that psi will go up after, but nobody ever expands on what a typical rebuild psi should be and then what it can be expected to go up to once the rings seat. Is it because there is so much variance in the process or is it something else?

Thanks!