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Discussion Starter #1
Hi there,

So glad I found you all, thanks in advance. So, I have a 74' CB360, and attempted to replace the points(BTW- I read the thread Bill posted re:timing). However, when I was adjusting the right point to the "F" mark, the gap drops to .3mm. I know it can safely be .3mm-.4mm, but for some reason the bike won't start...Hope this isn't too scatter-brained, been trying to figure this out for too long as I am a hopeless noob. Look forward to hearing from you.


Dan
 

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Was the bike running before you changed out the points?

Did you clean the point faces after you gapped them?, sometimes oil and grease will prevent a spark. Did you check for spark by holding a plug to the side of the engine and kicking it over?

Lastly...do you have fuel supply? i.e. fuel in tank, petcock on, no kinks in hose....
 

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hey dpb not .3 at F ,, opening at F to .3 find the high point of the cam set the points at .3mm (.012) for us metricilly challenged types and then line up the F mark and adjust the points backing plate to open the points at F lock it down and proceed from there, it will be close but check with a strobe timing light
 

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Discussion Starter #4
Firstly, thanks for the responses.
To Leethal- Yes, yes, yes, and yes.
To Jayel- When I set the gap to .3mm at the highest point(the notch on the outer sleeve?) of the cam, the points don't start to open at "F".

Also, when I push the starter button, most times it sounds like the chain gets bunched up, or something. It takes several light taps of the button to find the "sweet spot". Any ideas?
 

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Discussion Starter #5
Ok, so for those of you reading, bear with me I know this is pretty ridiculous. Here is what I'm doing:

1. Find biggest opening on left contact point, set to .350mm (using screws on contact point)
2.Turn Alternator to find biggest opening on right point, set to .350mm (using screws on contact point)
3.Turn Alt. to "LF" mark move backing plate until left point opens when marks align (I have a test light) and tighten plate bolts. Recheck
4.Turn Alt to "F" mark adjust right point (using screws on contact point) until point begins to open when marks align(using light)

After doing the above I clean points with contact cleaner, I have checked spark plugs for gas, and or oil fouling and clean them. Also, have used new plugs. I'm only getting back fire. Any insight very appreciated.
 

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AHA!.... There are TWO times on the crankshaft where the "LF" aligns during each 4-stroke cycle.... You HAVE to set the points on the COMPRESSION strokes.... If you set them on the exhaust stroke, the spark will occur while the ex valve is still slightly open, "backfiring" in the pipes..... IF you are on the compression stroke, the center of the advance (breaker) cam is 180 out..... Make sure the left side intake valve has just closed, and you should be starting into the compression stroke.... As soon as the "LF" aligns, that's the correct "time" to time
 

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Discussion Starter #7
66Sprint said:
AHA!.... There are TWO times on the crankshaft where the "LF" aligns during each 4-stroke cycle.... You HAVE to set the points on the COMPRESSION strokes.... If you set them on the exhaust stroke, the spark will occur while the ex valve is still slightly open, "backfiring" in the pipes..... IF you are on the compression stroke, the center of the advance (breaker) cam is 180 out..... Make sure the left side intake valve has just closed, and you should be starting into the compression stroke.... As soon as the "LF" aligns, that's the correct "time" to time

Ok, so I'm not sure about the breaker cam 180. Is that like at the 6 o'clock position, or 12? Also, you say "LT" marks, in the manual it says "LF"? Lastly, the intake opens, the piston goes down, when it returns to TDC that is where to align the marks (LF(?) and F) for timing?
 

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You are correct, I accidently typed LT meaning LF (I'll correct/edit that so nobody gets confused)....
LF is where the left side cylinder MUST fire (points just open)..... And, yes, the intake opens as the piston drops, and should close as the piston starts to rise.... The point should fire at "LF", JUST BEFORE the piston reaches "LT" (TDC) on THAT particular upward stroke....(the compression stroke)...
 

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66Sprint said:
AHA!.... There are TWO times on the crankshaft where the "LF" aligns during each 4-stroke cycle.... You HAVE to set the points on the COMPRESSION strokes.... If you set them on the exhaust stroke, the spark will occur while the ex valve is still slightly open, "backfiring" in the pipes..... IF you are on the compression stroke, the center of the advance (breaker) cam is 180 out..... Make sure the left side intake valve has just closed, and you should be starting into the compression stroke.... As soon as the "LF" aligns, that's the correct "time" to time
Oh jeez, this might explain my problem as well...
 

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Discussion Starter #10
Jeez. I really thought we had it there...She's still not happy. For patient, kind souls helping me in this, I thank you again in advance(or should I say retard? :lol: for your replies.
I have double, triple, and quadruple checked:

Kill switch in "Run" position
Ignition on
Have gas
Battery good (12.5v or better)
Plugs ok
Getting spark, though not great on left side, right side good
Points are new, clean, getting spark

Timing good - On compression stroke(mark on timing advance outer sleeve is pointed down, or "out 180" when intake valve closes and piston travels down, and is pointed up, or at 90 degrees when piston travels up)left point begins to open at "LF". Same for the right side except timing mark is "F".

BUT...She ain't runnin', can't even get her to idle. I'm getting backfire, maybe on the weak spark side?
help....please :?
 

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The "mark" on the advance outer is NOT the correct indicator of Compression or Exhaust stroke....Neither is pressure on your thumb on the spark-plug hole... The intake valve closure IS.... It is easy and amazingly common for the center of the advance unit (the actual breaker cam) to be installed "upside-down" (180 out) on the bob-weight plate..... This usually occurs when someone has disassembled the unit to clean and lube it and make sure it is properly operational.

IF you have spark on the left cylinder point and plug EXACTLY when LF aligns with the index during the upward stroke of the left piston that occurs immediately after the left intake valve closes, it is indeed timed correctly....

Remember, while it is a 180 degree twin, and the cylinders fire 180 degrees apart (read on the crankshaft), there is a 1/2 reduction of the camshaft speed so the points fire 90 degrees apart, and "sit" for 270 degrees before anything fires again.
The crankshaft has 540 degrees of "dead spin".....

Like this....
1 Left points fire at LF.....
2 Crank turns 180 (cam turns 90) and right points fire at F...
3 Crank rotates another 180 (total 360 crank rotation so far, so it's showing LF, but on L exhaust stroke, breaker cam lobe is now pointing directly away from left point follower with only 180 degrees of rotation of camshaft...
4 Crank turns another 180 and shows F (on R exhaust stroke)... Crank total at this point is 540 degrees, camshaft total is 270 degrees)....
5 Crank turns another 180,(totalling 720 degrees) left points align and fire again, as the breaker cam completes it's 360 degrees.....

Remember, it is a FOUR-Stroke engine.... the Crank must turn TWO complete revolutions and the camshaft one, between ignition sparks for one cylinder

IF the breaker cam (center) is upside-down (180 out), BOTH cylinders will be getting spark on their exhaust strokes, NOT on their COMPRESSION strokes

I hope this is enough information for you to remedy the situation...(and not just confuse the issue).... IF NOT, phone me and we'll step-by-step the process.... Steve (540) 427-4256 .... E-mail and we'll set up a time for the call....
 

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Dan, Please reply so we know you have this info..... Steve
 

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Discussion Starter #13
:oops: Er...hey guys. I um.....switched the wires on the points. This will give you backfire, even if it looks like you have the timing correct. Man, I thought I was losing my mind, guess I kinda did :lol:

Thanks for all the help, rest assured that I have this procedure down pat. I will now post another puzzle in the appropriate section. Steve, you are awesome, thanks dude.
 

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Secondary wires swapped? Points wired to wrong coils? Firing wrong cylinder? Rotating motor wrong direction so points open on the following cam slope, not leading cam slope?
 
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