rich on one side

[Macbeth]

Problems of richness have to be addressed by reducing the richness.

Ta. I’m not much of a mech. I didn’t think rich mixture could do that so fast. So it can then

[jhg1958]

Not sure if this will help but the difference between the 2 cylinders is either one getting too much fuel or the fuel not being fully burnt.

There has been some comments on unequal inlet manifolds. But this seems unlikely if it ran ok before. If you have 2 carbs can you swap the internals to see if this swaps the problem.

If it is the ignition, then swapping the leads might give you a clue.

I assume you have checked the valve clearances.

John

[Macbeth]

Not sure if this will help but the difference between the 2 cylinders is either one getting too much fuel or the fuel not being fully burnt.

There has been some comments on unequal inlet manifolds. But this seems unlikely if it ran ok before. If you have 2 carbs can you swap the internals to see if this swaps the problem.

If it is the ignition, then swapping the leads might give you a clue.

I assume you have checked the valve clearances.

John

Yep head came back off after startup (gasket blew) & mech rechecked valves. I need to start doing this myself. I don’t have a shed but retirement is near & im going to buy rural & def get a big shed

[limeyrob]

Go up one hotter on the plugs to stop the fouling.  Then do a plug chop and see if its rich.  You need to do a flat out main jet run before going down a size.  You could drop the needle one notch and see if it runs cleaner at 3/4 throttle than full throttle before going down one on the main jet.

[chaterlea25]

Hi All,
Macbeth wrote " running on Mikuni's"
Has the bike twin carbs?
If so then the left being more rich is down to individual settings
Do the Mikunis have lever or cable enrichers (chokes)?
Check the rubber seals at the bottom of the plungers and or the cables for no free play that would allow excess fuel in the mixturea..

Then check float level in the carbs.

If all those are OK
Lower the needles one notch and open the pilot air screws 1/2 turn
Run the bike and do a plug chop and report back to us

It's not an ignition problem

John

[berger]

if you have a lever choke on your miks you have to really make sure the lever is turning the choke off , the mik i had on mine was a swine for letting it run rich until i found out i had to give the lever an extra pull up , even though it appeared to be up enough it wasn't and after giving some more pull it cured the running rich problem

[Macbeth]

Hi All,
Macbeth wrote " running on Mikuni's"
Has the bike twin carbs?
If so then the left being more rich is down to individual settings
Do the Mikunis have lever or cable enrichers (chokes)?
Check the rubber seals at the bottom of the plungers and or the cables for no free play that would allow excess fuel in the mixturea..

Then check float level in the carbs.

If all those are OK
Lower the needles one notch and open the pilot air screws 1/2 turn
Run the bike and do a plug chop and report back to us

It's not an ignition problem

John

yep twin mikunis. I feel this is my next check 👍

[Macbeth]

if you have a lever choke on your miks you have to really make sure the lever is turning the choke off , the mik i had on mine was a swine for letting it run rich until i found out i had to give the lever an extra pull up , even though it appeared to be up enough it wasn't and after giving some more pull it cured the running rich problem

Yes a left choke & im going to check it this afternoon as it feels & looks just like a choke issue. Since the engine is so fresh I’m pre-occupied over thinking this. I played with its choke as I left this morning on my other bike & it didn’t quite have typical hard click up & down. Not sure if I’ve noticed that before yet clearly needs looking at

[KiwiGF]

All I know is that it’s 6v. 1960 SR. The engine only has 20klm on it & running in just fine however I’m fouling plugs at 3 to 4 klm. Plugs are NGK B7ES. Being fed by mikunis that were cleaned. Idles & pulls very well until it fouls. So I read as much as I could & found some electronic ignitions need resistor plugs so yesterday I popped BR7ES in last night & the bike ran fine again just for 3-4klm.

The left cylinder seems to suffer the most. I’d say the builder has it running rich & im starting to think maybe it’s just too rich yet I’m very tentative to change anything before taking it back to him. Not sure if it’s maybe just richness. I’m tempted to just go for a new 12v system or would you think 1 step hotter plug may help ?

Reading more now. The petrol is exactly 12 mths old 🤔maybe ditch stuff that as job 1

Using google lens brought this thread up 😀 so Thorspark?


https://www.a7a10.net/forum/index.php?topic=15146.0

[Macbeth]

if you have a lever choke on your miks you have to really make sure the lever is turning the choke off , the mik i had on mine was a swine for letting it run rich until i found out i had to give the lever an extra pull up , even though it appeared to be up enough it wasn't and after giving some more pull it cured the running rich problem

I had a look. It certainly operated ok but I don’t have any experience with them & have a new one on the way ..only $10

I’m not sure if that face would seal ok

[berger]

Macbeth that looks like the washer i took out of a kitchen tap the other day that was dripping and doing my head in. as for the carb the brand new mik i put on mine didn't stay on long because i didn't get on with it and put a new amal type on. the only thing i know is that after starting with the choke on and then pulling up the lever and going about a mile it was chocking itself, this is when i pulled the lever up some more which didn't appear to have any discerning movement but it cured it.

[muskrat]

G'day Mac.
Same as the enricher (choke) on my Keihins on the Cafe. I got rid of the buttons and put cables on. Make sure there is slack in the cables when their in the off position.
Cheers

[chaterlea25]

Hi Macbeth,
The plunger rubber seals always look like that as they seat on a narrow edge.
I have a single 30mm Mikuni on my SR. It has been on the bike since I rebuilt it back in 2001/2
I am very happy with it, I have fitted Mik's on a few other bikes as well, All Good

John

[Macbeth]

G'day Mac.
Same as the enricher (choke) on my Keihins on the Cafe. I got rid of the buttons and put cables on. Make sure there is slack in the cables when their in the off position.
Cheers

Ta mate. I’ve just got the button enricheners on small flat slides. Whilst it appears to operate ok..god knows how the spring is really operating inside once it’s screwed back in. So I’ve got a new one ordered.

Sensible thing to do is swap them over but I can’t guarantee the condition of the other so I’m going to see how the new left side replacement goes before I go further & pull both carbs off & get them up into the kitchen with full kits & start at the beginning

All operating fine before sitting for 12mths getting this engine built. God knows when the fuel gremlins attack or a seat on the enricher decides to stick / gives bad seat

It was running very well over 1 hr rides prior to build so I’m assuming jetting was accurate- they were not changed hence I’ll start at a dodgy enrichener 👍

[Macbeth]

Hi Macbeth,
The plunger rubber seals always look like that as they seat on a narrow edge.
I have a single 30mm Mikuni on my SR. It has been on the bike since I rebuilt it back in 2001/2
I am very happy with it, I have fitted Mik's on a few other bikes as well, All Good

John

Tks John. From wanderings online I did start to think that yet for $10 I’m putting a new one in before I go further hoping it is some weird thing going on with the spring & I’ll check the sleeve it moves in