Finally got a nice one!

LOUD MOUSE · Post by **LOUD MOUSE** » Sun Aug 21, 2016 7:26 am

<<<At the dyno we saw that the left was leaner (too lean) compared to the correct running right cylinder>>>

Points timing and valve setting will do what you show also.

What did you do to solve the (too lean) condition? ..................lm

jensey wrote:
The cause of the bluing does indeed need to be addressed but I think it makes the bike look all the more awesome!
Agree, but find the cause. Normally the blue stops closer to the cylinder head, but at your machine it's amuch longer distance then usual...

Here, look at my CB450 :

The distance between the blue and the cylinder head on the left downpipe is longer then on the right downpipe. At the dyno we saw that the left was leaner (too lean) compared to the correct running right cylinder (left and right of the bike when you sit on it...)

jensey · Post by **jensey** » Sun Aug 21, 2016 7:56 am

Hi LM,

Just the dyno run to compare both (left and right cylinder), power is measured at rear wheel, thus rear wheel HP's. Crank is probably around 42 / 43 HP.

Blue is left, red is right.

Compression is good and equal for both, timing spot on (both cylinders).

This is a complet different carb, a constant vacuum, and what I did to resolve it was just replacing both carbs with another set. The issue was gone.

Most likely the piston of the left carb isn't responding in the same way to the vacuum then the right side.

LOUD MOUSE · Post by **LOUD MOUSE** » Sun Aug 21, 2016 8:17 am

Thanks for the chart J.
What are the lines actually showing.
2 lines red and blue which are reading What?
They seem to follow a similar curve.
Do they represent each time the exhaust valve opens?
Is this one or 2 runs?
If you have another chart after the carb replacement can you show me the difference?. ......................lm

jensey wrote:Hi LM,

Just the dyno run to compare both (left and right cylinder), power is measured at rear wheel, thus rear wheel HP's. Crank is probably around 42 / 43 HP.

Blue is left, red is right.

Compression is good and equal for both, timing spot on (both cylinders).

This is a complet different carb, a constant vacuum, and what I did to resolve it was just replacing both carbs with another set. The issue was gone.

Most likely the piston of the left carb isn't responding in the same way to the vacuum then the right side.

jensey · Post by **jensey** » Sun Aug 21, 2016 8:29 am

What are the lines actually showing ?

The chart can be split in two sections, the top charts, giving the power and torque curves, and the bottom charts, giving the air / fuel ratio as a function of the crank RPM, in this chart it's called TpM) . I focussed on the air / fuel ratio's.

In the charts two runs are combined (so the torque / power curves are merely the same), but the gas analyser which measures the air / fuel ratio is sticked to a ifferent exhaust, being left and right. The blue air / fuel ratio line is from the left cylinder, the red air / fuel ratio line is from the right cylinder.

2 lines red and blue which are reading What?

See explanation above

They seem to follow a similar curve.

Yes, they do,the power / torque curve is from the same bike, measured on the rear wheel.

Do they represent each time the exhaust valve opens?

No, nothing to do with that, see explanation above

Is this one or 2 runs?

See the answer above.

If you have another chart after the carb replacement can you show me the difference?.

No, not yet, but the plug chop showed a way better burning of both cylinders

LOUD MOUSE · Post by **LOUD MOUSE** » Sun Aug 21, 2016 8:44 am

One last question J.
How would I pic which line of the bottom chart to consider the correct one?. ....lm

jensey wrote:
What are the lines actually showing ?
The chart can be split in two sections, the top charts, giving the power and torque curves, and the bottom charts, giving the air / fuel ratio as a function of the crank RPM, in this chart it's called TpM) . I focussed on the air / fuel ratio's.

In the charts two runs are combined (so the torque / power curves are merely the same), but the gas analyser which measures the air / fuel ratio is sticked to a ifferent exhaust, being left and right. The blue air / fuel ratio line is from the left cylinder, the red air / fuel ratio line is from the right cylinder.

2 lines red and blue which are reading What?
See explanation above

They seem to follow a similar curve.
Yes, they do,the power / torque curve is from the same bike, measured on the rear wheel.

Do they represent each time the exhaust valve opens?
No, nothing to do with that, see explanation above

Is this one or 2 runs?
See the answer above.

If you have another chart after the carb replacement can you show me the difference?.

No, not yet, but the plug chop showed a way better burning of both cylinders

jas67 · Post by **jas67** » Sun Aug 21, 2016 10:29 am

@jensey, sweet Bomber!

I'll take a look at the plugs. I would say it is likely rich, as I can open the choke immediately after a cold start and take off with good power before it warms up.

I rode it 35 miles yesterday, and 25 this morning.

After buying this one, I was thinking I'd just sell the other three, but, I may have to keep one of the other three and make a rider out of it. I really enjoy riding this bike, but, with only (now) 2,711 miles on this one, I don’t want to put too many miles on it.
Given that I have so many more capable bikes, both vintage and modern, I can’t explain it, but, it is enjoyable to ride. And, of course, I love the looks. The 160’s will definitely all eventually get put up for sale. I’ve got my ’68 CL175, which, though I like it, is a actually little too small to really enjoy. The 175 makes 20 HP vs. 16 HP for the 160 (factory claimed, of course), so, I’m thinking that the 160’s are pretty much going to be display toys if I keep them. The 305 is a sweet spot for a small bike. It’s lightweight, but, the engine makes just enough power (28 HP factory claimed, probably, more like 20-23 in real life) to be a lot more useful than the 160 or 175.

jensey · Post by **jensey** » Sun Aug 21, 2016 1:51 pm

Hi LM,

The ideal air / to fuel ratio would be around 14.7 to 1. if it's higher then 14.7 to 1, for example 17 to 1 it's a lean combustion, when it's lower then 14.7 to 1, for example 10 to 1 it's a rich combustion.
In the chart you can see the red line being between 5000 to 9000 rpm around the ratio 12 (to 1). The blue line between the same rpm range is around 14 to 1.
The 14.7 to one is only theoretical, at high rpm's around 12 is good for the combustion and cooling on these older bikes, on the other hand 16 to 1 in the around 7000 rpm is just way too lean.
If I would ride this classic bike for a longer time around 7000 rpm, it would cause serious engine damage.

Between 4000 and 5000 rpm it seems even worse, the blue line is showing a way to lean mixture, not healthy. Normally the engine doesn't have to deliver much power (load) around 4000 to 5000 rpm, so it isn't that dangerous, but that changes when riding the bike with a passenger in fourth gear going up hill.

To answer your question, I rather have the red curve on both cylinders, but could be a little better when the red line stayed between 13,5 to 12.5 all the time.

@ JAS67 :

(28 HP factory claimed, probably, more like 20-23 in real life)

I think Honda didn't exaggerate, but the way they measured was completely different then nowadays. Remember, Honda showed the crank power in those days. The powerloss between crank and rear wheel are big in older machines.

Jensen