Topic: 3rd Gear Issue has me stumped

[Deltarider]

I wonder what the sparkplugs gap is. You weren't tempted to set it too wide, were you?

[pamcopete]

akabek,

It's not necessary to remove the caps from the wires or the wires from the coils to check for continuity. Just measure the resistance from one cap to the other on each coil. Typical resistance with 5K caps would be about 25K Ohms which includes the 5K + 5K = 10K and about 15K for the coil itself. If it was clutch slippage, the revs would go up at the point of slippage.

I was not going to remove the caps.  I did not want to remove the wires from the coils.  If I can measure from the coil to the end of the cap that would be easy enough the next time I remove the tank. 

I am going to play around a bit more with the jetting.  What I may do is remove the pods and try straight stacks and see how that works.  When I took the video I had to switch to reserve.  It is a long shot but maybe I was experiencing fuel starvation which is what it felt like.  I may empty out my tank and refill it with fresh fuel.

It's not necessary to remove the tank to measure from one spark plug cap to the other. Just pull the caps off of the spark plugs. 1 - 3 and 2 - 4 and measure from one to the other. That measurement will include both caps and the coil in series for a total of about 25K oHms.

[akabek]

I wonder what the sparkplugs gap is. You weren't tempted to set it too wide, were you?

I just put new Denso plugs in and I believe the gap is 0.025

[akabek]

It's not necessary to remove the tank to measure from one spark plug cap to the other. Just pull the caps off of the spark plugs. 1 - 3 and 2 - 4 and measure from one to the other. That measurement will include both caps and the coil in series for a total of about 25K oHms.
[/quote]

Well that makes is much easier.  I will check today.

[akabek]

It's not necessary to remove the tank to measure from one spark plug cap to the other. Just pull the caps off of the spark plugs. 1 - 3 and 2 - 4 and measure from one to the other. That measurement will include both caps and the coil in series for a total of about 25K oHms.
[/quote]

I just pulled the caps off of the spark plugs and 1 - 3 was 23.1 ohms and 2 - 4 was 24 ohms.

[pamcopete]

akabek,

OK. That was easy. Do you like the turbulence theory?

[akabek]

akabek,

OK. That was easy. Do you like the turbulence theory?

I have no doubt there is turbulence but before I put the pods on and I was running stacks with the same jetting I had no problem.  I don't think turbulence is effecting the stuttering I am experiencing.  I may empty out my fuel tank and fill it with fresh fuel.  Maybe I was starving the carb of fuel while my tank was transiting to reserve.  We will find out soon.

[akabek]

I removed my fuel lines with filters and replaced them with straight clear fuel lines.  My tank was filled up with premium gas and replaced my pods filter with open stacks.  The result is I have the same hesitation but only in 3rd gear.  I am not sure where to go next??  Any suggestions?

If 3rd gear in the tranny was the problem how can I diagnose it?  Whether I am accelerating slow of fast the hesitation is there.  I will post a new video of today's ride.

[akabek]

I have a 1975 CB550 with about 200KM on it this season without issue.  Over the last week I have been adjusting my carb jetting and in the last two days I noticed if I accelerate hard the bike sometimes experiences sudden hesitate 4-5 times until it red lines.  My chain tension and timing both check out.  The hesitations feel like fuel starvation but when I experienced that last year the bike would stop accelerating at a certain point.  In this case the bike reaches the red line with 4-5 jolts along the way.

Below is some info on my bike setup

Dynoman DP592 SV pistons 10.5:1
Pamco electronic ignition, coils, wires
Ported & decked head, valve job
CB650 cam
MAC 4-1 header with Cone Engineering muffler
Keihin CR26 carbs, stacks and ITG socks

The reason I am adjusting my jetting is the bike accelerated from 0 to red line is strong but while cruising below 5000 RPM the bike bogs if I snap the throttle open.

Any thoughts why the bike is hesitating during hard acceleration?

[seanbarney41]

dude...it sounds like your bike runs great, so great, in fact, that the power has uncovered some weaknesses in the clutch/transmission...leaning strongly towards the transmission, if it was the clutch it would be more prevalent in all gears, worse the higher...from your video, I am really not sure why everyone else is thinking this is carbs or ignition.  I had a 750 that did that, but it was second gear, I never fixed it, was cheaper/easier to find a different motor

[pamcopete]

akabek,

I listened more carefully this time and what you call a hesitation, sounds to me like a brief surge in RPM, which would be the clutch slipping. Why only in third gear? Probably that is when there is enough torque to cause it. Try skipping third gear and see if it shows up in fourth, or shift early into second. Any combination like that to cause the same high torque that is there in third. Have you ever changed the clutch or know that it was changed by a PO? You could also simply adjust the clutch a little more critically to ensure it is engaging completely. What kind of oil are you using and when was it changed? Change the oil anyway. Use Motorcycle oil, non synthetic. Hold the clutch lever with a tie wrap when draining to get all the oil off of the clutch plates. Leave it that way over night.

Of course, seanbarney41 could be right and the third gear dogs are rounded off. But it could also just be a loose adjustment or poor adjustment of the shifter.

[akabek]

I have a gut feeling the issue is in the tranny so I have to agree with seanbarney41.  After riding the bike last night whether I am accelerating hard or slow in third gear it would hesitate.  As soon as I changed to 2 or 4th gear all was fine.

For oil I am just using Honda GN4 10w40 oil.  I always do an oil change before I put the bike away for the winter and never had a problem the next season.  I installed a new Barnett clutch with springs 2 years ago and I have not put a lot of mileage on the bike since.  If my clutch was slipping I would think it would happen it other gears.

I have never done transmission work before.  Would I be better off finding another engine and swapping the transmission or split my cases and repair whatever gears may be damaged?

[akabek]

The symptoms occurred a week ago.  Since then I have ridden the bike with pods, stacks with filters and straight stacks.  The hesitation is still there and it only happens while in third gear during acceleration.  As soon as I get into 2nd or 4th gear the hesitations are gone.

[Don R]

Humor me and check the clutch lifter adjustment, my 750F1 acted like that. It gradually got worse until I adjusted it at the lifter. A new clutch wearing in can cause that.

[akabek]

Humor me and check the clutch lifter adjustment, my 750F1 acted like that. It gradually got worse until I adjusted it at the lifter. A new clutch wearing in can cause that.

Do you mean the clutch cable lower adjuster where the clutch cable connects to the arm on the crankcase cover?  It is worth a shot.

[evanphi]

The slotted one with the lock nut is what I think he means.

Also:

Does it only happen on the "upshift" side from 2-3 or will it also happen on the "downshift" side from 4-3?

[akabek]

The slotted one with the lock nut is what I think he means.

Also:

Does it only happen on the "upshift" side from 2-3 or will it also happen on the "downshift" side from 4-3?

I will assume he means the adjustment at the lower end of the clutch cable. 

Whether I shift from 2-3 or 4-3 it does not matter....once I start accelerating in 3rd gear the hesitation happens.  I don't think it hesitates when I hold the throttle steady in 3rd gear.  I will have to check.

[evanphi]

The slotted one with the lock nut is what I think he means.

Also:

Does it only happen on the "upshift" side from 2-3 or will it also happen on the "downshift" side from 4-3?

I will assume he means the adjustment at the lower end of the clutch cable. 

Whether I shift from 2-3 or 4-3 it does not matter....once I start accelerating in 3rd gear the hesitation happens.  I don't think it hesitates when I hold the throttle steady in 3rd gear.  I will have to check.

I'm talking about the one under the cover that has three screws (#1 in photo). This is for adjusting the lifter.



The one at the end of the cable is just for taking up slack.

[pamcopete]

Hopefully it is not a catastrophic transmission issue. Although I am not familiar with the CB550, in all the other bikes I own, there is access to at least some of the shifting mechanism that can be adjusted, repaired in the bike, including loose actuators, springs etc., so I would certainly review that and take  a look under the cover before tearing the engine / trans apart.

[seanbarney41]

The slotted one with the lock nut is what I think he means.

Also:

Does it only happen on the "upshift" side from 2-3 or will it also happen on the "downshift" side from 4-3?

I will assume he means the adjustment at the lower end of the clutch cable. 

Whether I shift from 2-3 or 4-3 it does not matter....once I start accelerating in 3rd gear the hesitation happens.  I don't think it hesitates when I hold the throttle steady in 3rd gear.  I will have to check.

I'm talking about the one under the cover that has three screws (#1 in photo). This is for adjusting the lifter.



The one at the end of the cable is just for taking up slack.

this is a 550, not a 750, quite a bit different

[akabek]

I am going to see I can drain the oil and drop the pan.  That will allow me to look at the gears.

[evanphi]

The slotted one with the lock nut is what I think he means.

Also:

Does it only happen on the "upshift" side from 2-3 or will it also happen on the "downshift" side from 4-3?

I will assume he means the adjustment at the lower end of the clutch cable. 

Whether I shift from 2-3 or 4-3 it does not matter....once I start accelerating in 3rd gear the hesitation happens.  I don't think it hesitates when I hold the throttle steady in 3rd gear.  I will have to check.

I'm talking about the one under the cover that has three screws (#1 in photo). This is for adjusting the lifter.


The one at the end of the cable is just for taking up slack.

this is a 550, not a 750, quite a bit different

Damn this is two in one week for me. I need to read more closely!

-1 point for me.

[akabek]

I decided to drain the oil and pull the pan.  The oil sediment in the oil drop pan has more flakes then usual but no chucks of metal.  I need to remove the little pieces from the oil pan and clean them up but there wasn't anything large indicating a broken tooth.  I will look at the transmission diagram to see which gears I should be looking at for third gear wear.

[pamcopete]

akabek,

OK. Pull the appropriate side cover as well and check the shifter mechanism. Could be that it is just not engaging 3rd completely due to a loose part, broken spring or adjustment.

[akabek]

Just a quick update.  Last Saturday I rode to a buddies place on the 550 to play around with 3rd gear and have him test ride it.  The issue seems to be getting worse.  Now when I am cruising in 3rd gear or slowly accelerating it feels like it is slipping.  Similar to a slipping clutch.  When you accelerate quickly in 3rd gear you will reach red line but with 5-6 quick jolts/hesitations.  My buddy initially thought is was the clutch but after a couple of rides he also found the issue baffling.

I am leaning toward the transmission or clutch related.  Next weekend I am hoping to have a spare almost complete CB550 engine I can scavenge.  I have dealt with the seller before and the engine was in use last summer and apparently no issues with the bottom end.  Hopefully when I dismantle my engine I will find the issue and transplant the required parts.