94 VFR RC36/2 (suspected) ignition timing issues

Hello from Belgium to all of you! Long time lurker here (even before I got a VFR), but first time poster... and I'm sorry it's a call for help.

I've had my 94 VFR for a bit over 2 years now. It's my only mode of transportation (I use it every single day and have put over 35K km, the bike is now 65K km « old »). I love it like no other bikes I've had before (nearly all of them Hondas) but it has suddenly developed a problem that I can't figure out:

• First symptom I noticed was a hard cold start. This never happened before. Where it used to start on the first push of the "start" button, it now takes 3 or 4 « pushes » before the engine starts. It does not take the throttle well at first, and I have to nurse the throttle slowly to get over an initial stumble.
• When still cold, I need to get the revs to at least 3K rpm for it to move forward without wanting to stall.
• It's now using 10l/100km when it used to be 6.5 to 7l.
• When the engine is warm, the bike feels "sluggish" and does not take revs the way it used to.Adding choke does not help.
• Finally (and more worryingly) I've recently discovered that the ignition timing is WAY off.(see details below)

All this happened at once, overnight. I came back home from work one day and noticed the idle had gone up a bit, to 1500 rpms. I lowered the idle and thought nothing of it. The next day, it was hard to start with all the symptoms I have described.

Things I've done so far; first thinking about carb issues :

1.Checked and replaced float valves (I noticed a couple were "sticky" -> no improvement

2. Cleaned idle and main jets, emulsion tube, enrichener pistons and idle mixture screws. This was done both with ultrasonic cleaner and chemical carb cleaner, followed by poking with metal jet cleaner thingy -> no improvement either

Note: I had completely cleaned and rebuilt the carbs (new o-rings everywhere, but kept the original brass elements) as soon as I got the bike, as a preventive measure after 28 years of unkown maintenance by PO's.

3. Checked for vacuum leaks around the carbs by spraying carb cleaner -> None


Turning to the FSM, I read it suggests, when poor fuel efficiency, to take a look at ignition timing.

I then:

4. Performed all the tests included in the FSM (pages 16-6 and 16-7) with a multimeter. All the components (ignition coils, pule generator, connector to the CDI) test within range.

5. Performed the check with a strobe timing light and discovered that the timing was off. At idle (+/- 1100 rpm), the "F" mark is FAR from aligning with the notch (as per the FSM), it is to the right of the notch (and even the « T » mark is to the right !)

I have bought (second hand, no NOS available AFAIK) and tested a second set of pulse generators as well as 3 different CDIs, but to no avail... Finally, thinking that some other electrical element could be interfering with the timing in some ways (shows you the extent of my knowledge in electrickery), I disconnected all fuses except the ignition, but once more, with no result.

I am now completely at my wits end. In my mind, it all points to the CDI, but I cannot believe 4 different CDIs can exhibit the exact same problem (and nothing else).

I would immensely appreciate if any of you could help me out. I love that bike like no other and really want to keep it as my daily rider. And none of my other projects are road worthy yet !

TL/DR : Honda RC 36/2 went limp +++ can’t diagnose issue and am in way over my head +++ please send help or I’m fu**ed +++


Pegleg_greg













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Compression test

 

In the last 30K km of your ownership, how many times have the valve clearances been verified?

And/Or, did you get any service records showing when, or if, the clearances were checked by the previous owner?

Tight valves don't make any noise, but they sure can do a lot of damage. Especially on exhaust.

 

Thanks a lot for your reply, Captain! All 4 cylinders show good compression and conistznt with each other (around 200 psi each).

I checked the valve clearance shortly after buying it (all well within specs at the time). But have been lazy (spoiled by my previous bike, a CB750 RC42 with hydraulic lifters) and have not checked since.

I'll get to it tomorrow, but I fear you're right and my neglect might just have cost me my bike....

 

If your compression is currently that high and consistent, I highly doubt you have a valve issue.

 

Verify the wiring at your power plug on the starter solenoid.

Unplug it and inspect closely.

I'm grasping, but you have already done a lot of verifying and changing things.

 

first signs of trouble



which may lead to this melted shit

 

Thanks to both of you for your suggestions.

I checked the starter solenoid and the plug/wiring. It's all clean as a whistle with no signs of heat or corrosion. I should mention that I also tried a known good battery without any improvement.

Please, keep the suggestions rolling! In the meantime, I'll keep on investigating the wiring harness, as I am pretty much convinced it's an electric problem (but I have been wrong before) .

Greg