ignition timing procedure...please...

[ARVENO]

Dang Marco I got it now. What you are feeling is "surging". Feels like you are running out of fuel then picks back up except in this case you're not running out of gas but running rich on one cylinder: Check that choke!

If you pull both carbs off you can weigh the floats to see if the bad side is heavier, a heavy float will cause a carb to run rich or flood. Float "height" on those carbs is 24 millimeters. If you don't know how to set the float tell me & I'll email a picture with instructions.

You can check the needle & seat to see if it is shutting off the fuel supply by leaving the bowl off & hooking the carb back up to the tank. Put a can or big jar under the carb to catch the fuel. Turn the petcock on and with the float hanging down gas will flow freely (careful some floats will drop too far and the needle fly's off) . GENTLY push up on the float and feel for resistance, the fuel should stop flowing. Bear in mind this a very rough check & pushing to hard on the float can cause damage to the needle & seat or float. Other than the Float-Needle-Seat I can't think of anything else that would cause it to run rich enough to foul a plug on a gravity fed carb.

Marco it looks like I'm needing to eat a little crow here. You already had the carb figured to be the bad guy and I had you re-checking the timing. I apologize if I caused you extra work it surely was not my intent. As the saying goes: The road to hell is paved with good intentions".

Peace. Trout. PS You better post what you find out!

Trout ,
A little bit of update:

I just pulled both carbs

The right hand carb was soooo dirty !!!

The left was a bit better but needed cleaning as well.

I checked the jetting size with the manual and everything is ok

Atomiser 265

idling jet 50

starting jet 80

choke 40

needle V9

BUT ! the manual says Main jet 142 model : 750S, S3, & 850T
120 model : 850T3
130 V 1000

My bike is a 1980 1000 SP i got a 142 ( don't know if the carbs are the stock ones or someone changed them with a 850 model, but i don't think it is a big deal having a 142 main jet. ( i think is better )


WHERE THE DIRT WAS COMING FROM ?

i don't know why, but there is a " X " shaped metal pipe which is connetted to the fuel hoses coming from the petcock. the inside or this metal X was rusted, so the rust was going into the carbs.( the filter before the banjo was clogged )

here i found the X pipe i am talking about

http://www.mgcycle.com/product_info.php?products_id=684

BUT THE ONE I GOT IS NOT CONNECTED !! I MEAN ONE PETCOCK FEED ONLY ONE CARB. !!
I saw there were AIR BUBBLE in the fuel hoses , can that be the causing me the "surfing " ??

I believe the PO messed up the fuel line.... i have that problem since i got the bike.
Now i am going to try to eliminate the X and run , ( temporarily ) left petcock hose to left carb , right petcock right carb.

If the bike will runs well , i will buy that crossover i saw on MGCYCLE website.


Does it make sense ?

btw yes, please send the instruction regarding how to set the float..

now i gotta go put the carbs on the bike and see how it runs... i'll post later

thanks A LOT
Marco

 

[ARVENO]

WAIT A MINUTE... i was wrong , the X cross is the same as mgcycle, and is connected so every petcock feed let and right carb .

 

[Trout]

You can do away with the "X" on the fuel line but depending on which petcocks you have you may not have a reserve.

Not sure about those "air bubbles" in the line. Do you have clear plastic hose you can see through? Wouldn't be a concern at this point because you're not starving for fuel.

Well I'm curious to see how this turns out.

Send me your email via private message & I'll shoot the float setting to you.

 

[john zibell]

Marco,

The 142 main is too large. Go back to the jet size in the manual, or at most one size over. Bigger mains don't make you go better, they in fact can make things too rich and you loose power. Also to eliminate the X pipe I use double banjo fittings. Harper's http://www.harpermoto.com/ usually has these in stock. In addition, if you are going through the fuel lines, I like to use the cloth covered 7mm fuel. I get it from a VW car repair shop where I live, but most BMW motorcycle dealerships stock it as well.

 

[ARVENO]

You can do away with the "X" on the fuel line but depending on which petcocks you have you may not have a reserve.

Not sure about those "air bubbles" in the line. Do you have clear plastic hose you can see through? Wouldn't be a concern at this point because you're not starving for fuel.

Well I'm curious to see how this turns out.

Send me your email via private message & I'll shoot the float setting to you.

Yes i got the clear fuel lines, i like to through...and that's why i saw rust coming from the X .
I got classic petcock on/off/res
I compared both carbs floaters and the sit at the same level, my manual ( i should learn to read first LOL ) has the description on how to measure the float level, but yet not how to adjust it. ( but seems good)

John , the manual says V 1000 main jet 130 , i assume every 1000 cc engine ( 950 cc ) has the same jetting so the SP1000 should have 130, am i correct ?
Question : why the 750 and 850T have 142 ? I don't get it. those engine are smaller than mine...

Its' true that the manual says to adjust the air mixture screw 1 1/2 turn out for the V 1000 and 850 T3
and 2 1/2 turns for the 750 and 850T LH and 2 1/4 - 2 3/4 out RH for 750 and 850T
Also manual says needle V9 ( as what i got )for all 750 ,850T and T3 but V1000 I-convert model U9 , SHOULD I GET A DIFFERENT NEEDLE AS WELL ?



I am understanding the whole issue was due a MESSED UP JETTING ! which at least make sense to me .
Also it's an easy fix. i am gonna order jets and an extra needle ( just in case ).

I am going to get 130 and 135 main jets , i cannot find the U9 needle. should i just try to keep the V9 needle i got and downsizing the main jet ?


Thank you guys...finally i see the light !!

 

[john zibell]

Marco,

Difference in mains may be due to carb type, do you have round or square slide carbs? The earlier bikes had square slides, when the change to roud was I don't remember. This PDF may help you.

 

[ARVENO]

Marco,

Difference in mains may be due to carb type, do you have round or square slide carbs? The earlier bikes had square slides, when the change to roud was I don't remember. This PDF may help you.

John , i have square slide carbs, same as 750 and 850. I am not sure if the 1000 sp come from the factory with those carbs or the PO somehow swap them.

The jet comparison i posted before was on same carbs ( square slide )

But now make sense to me , i was running rich for a reason... i am gonna try 135 and 130 and see which one works better.

thanks
M.

 

[Trout]

Hey John, I'm curious if that jet Marco has can dump enough fuel to foul the plug & wet the piston like he is describing? Doesn't feel right to me. I totally agree that stock or one size over is all that is needed & if it was me I'd go back to stock until the mess is fixed then start playing. Marco I'll be glad when you got this thing running right.

 

[ARVENO]

Hey John, I'm curious if that jet Marco has can dump enough fuel to foul the plug & wet the piston like he is describing? Doesn't feel right to me. I totally agree that stock or one size over is all that is needed & if it was me I'd go back to stock until the mess is fixed then start playing. Marco I'll be glad when you got this thing running right.

Well , i tell you what.

the carbs are a stock VHB ( square slide ) stock jetted for models : 750, 750S , S3 850T.

Why should not work on my 1000 SP ? because according with the manual with a 142 main jet the air mixture screw MUST be turned out 2 1/2 turn LH and 2 3/4 turn RH.

What was wrong with the carbs in my bike ? Heck , the air mixture screw was turn out ONLY 1 1/2 turn.
So was way to rich.PERIOD.

1 1/2 turn out is ok IF the main jet is a 130 . ( model 850T3 and V1000 )

To solve the problem i need to turn out the air mixture screw as per manual specs. on early models .

In the 70's nobody gave a f**k about emissions and all the bullcrap !!
So the bikes were jetted differently.
At the end on the 70's beginning of the 80's they started ( especially in the USA ) to annoying the motor companies to build engine that pollute less.
So here you go , the jetting on the bikes started to be downsized....and that was the beginning or what brought us today to have fuel injected vehicles. etc...

Note: the Guzzis imported in the USA were jetted a bit "leaner" than the European models.

ah ah !! was so easy to fix , but heck without knowing what was inside the carbs , was impossible to figure it out.
At least now the crabs are clean , the fuel lines are clean and timing and points are set .

Just need to go for a test drive !!

ttyl
cheers
Marco

 

[john zibell]

Marco,

The idle mix control screw position is a relationship between the pilot jet and the screw, not the main jet. If the screw isn't as open as far as specified, the pilot is too large, if open more than specified, the pilot is too small.

That said, first get your jetting and needle correct as per the manual. Then make any adjustment from there one item at a time.

 

[Trout]

who can explain me what was wrong and how he fixed it, so to learn something.... but looks like is not easy meet mechanics who are willing to "teach"... I will keep you posted...we'll see....thanks Marco

John I think we have a lost cause here. Marco is going to do what Marco is going to do, time to say "bye now".

MARCO: There are quite a few of us who are willing to teach but are you willing to learn? In order to learn one must be silent & attentive, do what he is asked to do & learn from the process. You are not the bullet speeding to the target you are more like a bomb.

Arivaderci

 

[ARVENO]

who can explain me what was wrong and how he fixed it, so to learn something.... but looks like is not easy meet mechanics who are willing to "teach"... I will keep you posted...we'll see....thanks Marco

John I think we have a lost cause here. Marco is going to do what Marco is going to do, time to say "bye now".

MARCO: There are quite a few of us who are willing to teach but are you willing to learn? In order to learn one must be silent & attentive, do what he is asked to do & learn from the process. You are not the bullet speeding to the target you are more like a bomb.

Arivaderci

Trout , John i did not mean to disrespect any of you , I listen to you and i've ordered already the jet ( 130 and 135 )
They will be delivered sometime next week .
In the meantime i just tried to do some adjustment to learn something.
I cleaned the carbs and that's a good thing , i know now what there in inside.
Adjusting the air mixture screw i got rid on the "surging " issue the bike had , but still the right hand plug is too dark, but less than before, so turning out the idle mixture as per specs. on early models , did something.
Maybe is not the right thing to do, but heck let me see what happen and i will learn something too.
What i learned , i "fixed" a problem but not the WHOLE thing. Going to try small jet .

Manual says

VHB square slide

Atomiser 265
idling jet 50
starting jet 80
needle v9 second notch
choke 40
main jet 142 750 S S3 and 850T 120 850T3 130 V 1000

mixture screw turn out

750S and 850T 2- 2 1/2 ( LH ) , 2 1/4 - 2 3/4 ( RH )

750S3 2- 2 1/2 ( LH ) , 2 - 2 3/4 ( RH )

850T3 and V1000 1 1/2

My carb jetted the way it is will be good for the following models : 750,S , S3 , 850T.

I got a 1000 engine, so it will require a 130 main instead of a 142.

Can anyone explain me what the difference between the 750,S , S3 , 850T and a V1000 engine ? ( beside the size )

Why a carb that will work on a 750,S , S3 , 850T will NOT work on a V 1000 ?
Maybe because different Valve size ?
Why i am ONLY running rich one on one cylinder ( the right one ) being the carbs jetted the same , I would expect to run rich on BOTH cylinder.

I have understood that i MUST wait for the jets to come before to play again with that bike.

I am sorry i don't see anything wrong in my attitude, i mean , often ...working on a bike and making mistakes.... is a way to learn what does not have to be done.
Of course listening guys with more experience will avoid lot of headaches too.

Respectfully
Marco.

 

[john zibell]

Marco,

It is not uncommon for one side to be a little richer on a carb bike. It shouldn't be wet, but a little richer is acceptable. As Trout mentioned, float level can make one side rich as well. Also a worn atomizer on that side would pass more fuel. There are many variable to consider. That is why I suggested going to stock settings, then just change one thing at a time. Put the correct mains in, then let us know the results.

 

[Guzzi_don]

Marco,

The reason the earlier carbs (850-T, etc) had larger main jets (142) is because they don't use air cleaners and therefore a lot more air is admitted through the carb throat and requires more fuel to retain the correct air/fuel mixture ratio.

 

[ARVENO]

Marco,

The reason the earlier carbs (850-T, etc) had larger main jets (142) is because they don't use air cleaners and therefore a lot more air is admitted through the carb throat and requires more fuel to retain the correct air/fuel mixture ratio.

Thanks Man !!

 

[jerryS]

Hi Marco & Trout, I'm reading this thread with much interest. I have just bought a mk3 le mans that isn't running well. Different symptoms from yours though I think. I been thinking about your symptoms a bit.. it seems to me that an engine that is running rich has black sooty plugs. If it looks wet, that would indicate to me that it's not burning at all.. ie. poor spark? I have in the past had problems with worn out coils that produce a spark when bench testing but the spark breaks down under load.. ie under acceleration.. same could be said for HT leads. I know you used to be able to get coils tested at your local mechanic but I don't know how easy it is now. That would account for 'feeling like you're running out of gas' feeling.. Hope that's helpful. .. now for my little misfire problem...