Carburator sync/clean

Richard tea

Decided to remove carbs again as they didnt seem airtight around the rubbers. Also reseated the mixture screws and gave them 2 rotations instead of the 2 3/8 I initially done as this seemed off. I got it all back together and was delighted at how snug it fitted. I wanted to give the idle mixture screw a few turns just to have it idling ok. The poxy thing came off in my hand:mad: I have had enough for today. I just home I can refit the screw by feel or ill have to remove the carbs again:( Im also waiting on a 90 degree screwdriver to be delivered.

Richard tea

Any reason why the bike will die after a few mins of having the carb sync tool connected up? it seems to be the breather/vac pipe that goes to the fuel tank that causes the problem.

On a side note, the carb mixture screw tool I ordered is no use. Its too small:mad: €24 down the drain

Roadcraft

Richard tea wrote: »

Any reason why the bike will die after a few mins of having the carb sync tool connected up? it seems to be the breather/vac pipe that goes to the fuel tank that causes the problem.

On a side note, the carb mixture screw tool I ordered is no use. Its too small:mad: €24 down the drain

You will have to blank off or plug the vacuum pipe so there is no suction on it.

Richard tea

Roadcraft wrote: »

You will have to blank off or plug the vacuum pipe so there is no suction on it.

Ill close off the valve going to that gauge and see if it makes a difference.

Roadcraft

Richard tea wrote: »

Ill close off the valve going to that gauge and see if it makes a difference.

If it is coming from one of the carbs to your gauges you would have to leave it open, if it is from the fuel tap you would have to plug it.

Richard tea

Roadcraft wrote: »

If it is coming from one of the carbs to your gauges you would have to leave it open, if it is from the fuel tap you would have to plug it.

Each of the 4 gauges connects to a slot on the engine block. This one in particular connects to the vac pipe on the left side of the engine close to where the fuel tap is. Im nearly sure its a vac pipe anyway.

2 pipes coming from tank. 1 is fuel and the other is the vac? Correct?

Roadcraft

Richard tea wrote: »

Each of the 4 gauges connects to a slot on the engine block. This one in particular connects to the vac pipe on the left side of the engine close to where the fuel tap is. Im nearly sure its a vac pipe anyway.

2 pipes coming from tank. 1 is fuel and the other is the vac? Correct?

If you are using your fuel tank to run the bike to balance the carbs & it has a vacuum feed to the tap & you have not got the vacuum pipe connected to the tap it will not run right & run out of fuel. Plug the vacuum hose & put the tap in the prime position so that it does not need the vacuum to make the fuel flow.

Richard tea

Roadcraft wrote: »

If you are using your fuel tank to run the bike to balance the carbs & it has a vacuum feed to the tap & you have not got the vacuum pipe connected to the tap it will not run right & run out of fuel. Plug the vacuum hose & put the tap in the reserve position so that it does not need the vacuum to make the fuel flow.

Ahhh good stuff. That makes sense.

On a side note. Has anyone ever heard of colourtune. This thing looks the biz for fine tuning. http://www.carbtune.com/colortune.html

Hotblack Desiato

It's for seeing if you are running rich or lean, but you can do that for free with a plug chop. No use unless you are changing jets/needles, the mixture (above idle) is fixed by the needle/jet combination. A lot of bikes have plug caps that cover the entire spark plug hole, so you couldn't see this thing anyway.

CJhaughey

Hotblack Desiato wrote: »

It's for seeing if you are running rich or lean, but you can do that for free with a plug chop.

I can't make out anything with plug chops these days, they all look the same.
This new petrol is funny stuff, must be the ethanol.

Richard tea

CJhaughey wrote: »

I can't make out anything with plug chops these days, they all look the same.
This new petrol is funny stuff, must be the ethanol.

Seems like alot of effort but I guess its a sure way of fault finding

CJhaughey

Richard tea wrote: »

Seems like alot of effort but I guess its a sure way of fault finding

I used to do it with 2 strokes back a few years, but these days the plugs don't show much difference.
They all seem to be a light tan, running lean all the time is what they look like to me.

Richard tea

Ok I have her running well ( I think ):P

I took the bike for a quick blast but 5 mins into the ride the bike died. Turns out I left the fuel in the off position. I found it hard to restart the bike so I ( for the first time ever ) jump started the bike. The battery was dying very fast so I really needed to get the bike going quick or it would have been a 30 minute push home.

When it idles at say 1200 rpm, now and again it will jump a little to 1300 rpm. Just for a second and pop back to 1200. Is this normal? I cant remember what it was like before I cleaned the carbs.

Wossack

yea they can hop and vary, and the bikes tach isnt great at reading at the smaller end of its scale (think they recommend idle adjustment with a dedicated tachometer for that reason)

Richard tea

All is not well. Started it up today and it sounded like it wanted to die with the choke on. If I tried to open the throttle it would die. Im guessing its too rich or too lean. Im sure the culprit is the air/fuel mix screw under each carb. There are 4 of them.

I went with 2 turns out from seated and she started and I adjusted the idle screw until it ran well enough ( or so I thought).

The procedure for these screws is as follows

1. manufacturers recommedned ( 2 or 2 3/8 out from lightly seated )

2. adjust screw by 1/4 out or until engine starts to die.

3. put screw back to original position and turn 1/4 in until engine starts to die.

4. At this point you should be able to find a happy medium where the engine runs smooth.

My question is, with my carbs there are 4 screws to adjust. Do I follow the above procedure for each screw/carb

According to the Russian translated manual I have im nearly sure I should start from 2 3/8 turns out from seated but many forums posters state they start from 2 turns out?

Im also aware that this must be done with a fully warmed up engine.

The carbs are balanced as I confirmed with the carb sync tool.

Hotblack Desiato

You can do that on a single carb engine (adjust one way until too rich, other way until too lean, then find a sweet spot in between) but you can't on a multiple carb engine, so you'll have to set all the screws to the same position. If you can get confirmation of what the correct number of turns out is, that should work well (assuming engine/carbs are stock parts not modified)

This only affects the idle circuit anyway

You can't balance the carbs properly unless all other settings are right, you need to get the bike idling ok and then re-balance it.

Is the choke cable correctly adjusted, is the choke linkage moving properly when the cable is pulled, are the little plungers (or whatever) on each carb moving when the choke linkage moves? Were all of these parts reassembled correctly?

Richard tea

Hotblack Desiato wrote: »

You can do that on a single carb engine (adjust one way until too rich, other way until too lean, then find a sweet spot in between) but you can't on a multiple carb engine, so you'll have to set all the screws to the same position. If you can get confirmation of what the correct number of turns out is, that should work well (assuming engine/carbs are stock parts not modified)

This only affects the idle circuit anyway

You can't balance the carbs properly unless all other settings are right, you need to get the bike idling ok and then re-balance it.

Is the choke cable correctly adjusted, is the choke linkage moving properly when the cable is pulled, are the little plungers (or whatever) on each carb moving when the choke linkage moves? Were all of these parts reassembled correctly?

My way of looking at it was this. Before I removed the carbs they were fine afaik. I removed the jets and cleaned them and cleaned the carbs. I did not disassemble the carbs at all, only removed them cleaned and fitted new seals. So I shouldnt have to adjust any screws except for the 4 air/fuel mix screws. Curiosity got the better of me and I removed them to clean them but didnt take propper note of the position they were at. They are Keihin carbs but for the love of me I cannot find any decent guides on the settings for it.

Regarding the choke and throttle cables... I will have to replace them as they have a slight kink in them. The choke linkage moves fine.

Richard tea

So after spending €55 on 2 special screw drivers ( one broke & the other was no use due to its size ) I managed to reach all the air/fuel mix screws and adjust.

I knew the bike was running 75% ok but when I hit 6000 or 7000 rpm the bike would just hit a flat spot- if thats the right term. This flat spot might last for 3 to 7 seconds then sort itself.

So I turned each of the mixture screws out another 1/4 this morning and tested the bike. She pulled like a train:) ( stop laughing at me cb:P ) 3rd gear and full throttle was unreal, I dont think it ever had such poke. Anyway I went up through all the gears and the bike had no trouble getting above the 7000 rpm range.

Im going to stick a fresh filter and fresh oil in the week and shake off the cobwebs. Dont think jack frost will be back again any time soon.

Thanks all who helped out with info

Richard tea

Back to square one:(

I have removed the carbs again and will strip them tomorrow and recheck float heights and so on. Im going to order new rubber carb boots also as the ones I have now are not great.

Cpuld someone take a look at the 2 pictures and tell me what they are. One of the pics is a hole in the side of the engine between the fins. It could be just for fitting crash bungs but I just want to make sure its not for something else.

The other pic is a tube that comes from the top of the engine to the airbox. The tube that was connected was split.... What is this tube for and how could a split tube affect performance???

blade1

Pic 1 if I am looking at it correctly is a breather hose.
Pic 2 is a weep hole.
Fix pic 1 and pic 2 should be like that.

Richard tea

blade1 wrote: »

Pic 1 if I am looking at it correctly is a breather hose.
Pic 2 is a weep hole.
Fix pic 1 and pic 2 should be like that.

Ok so Pic one is a breather hose. This had a split in it. Could this split affect performance above 6000 rpm?

blade1

I'd imagine it could effect performance right through the revs.
What's your tickover like?

Richard tea

blade1 wrote: »

I'd imagine it could effect performance right through the revs.
What's your tickover like?

Tick over, as in idle? it was slightly jumpy. Barely noticeable to be honest. The problem was above 6000 rpm.

blade1

Richard tea wrote: »

Tick over, as in idle? it was slightly jumpy. Barely noticeable to be honest. The problem was above 6000 rpm.

She'll be running lean with that split hose.
I'd be be fixing that anyway.
Hopefully it will sort it and if not at least it's another thing sorted.

Richard tea

blade1 wrote: »

She'll be running lean with that split hose.
I'd be be fixing that anyway.
Hopefully it will sort it and if not at least it's another thing sorted.

I'll still strip themy for peace of mind. But what you have said about it running lean is making sense.

Hotblack Desiato

You'll also have oil mist coming out of the hole in the cam cover, unless you replace that hose

Richard tea

Hotblack Desiato wrote: »

You'll also have oil mist coming out of the hole in the cam cover, unless you replace that hose

Yep there was an oil substance in that tube alright

Richard tea

I'm having no joy in finding the correct float heights for my keihin carbs. Anyone know? Can find it in the manual and I have asked on 400greybike but nobody has answered yet.

Richard tea

I copped something today that I missed before. Two of my main jets are size 98 and the other two are size 95. Perhaps I didnt put them into the correct slot before. Should it make a difference which order they slot into???

Hotblack Desiato

I remember hearing that some air cooled fours used to have different jet sizes between the inner and outer cylinders - the cooling of the inner cylinders wasn't as good. Surprised if a water cooled bike would be set up like that though.