VF 1000 F Clutch Sliding & cold start / idle problem

Hey Guys,

I decided to move my topic and questions hier as it is more relevant "in the Shed: :wink:

I have almost finished with one of my VF 1000 projects to rebuild and wake my bikes up…

…and I have two important questions:

Clutch sliding
I did some works on the engine and changed all filters, sparks, oil (10W 40 full synth.), cleaned the cooling system (washed it, cleaned it and refilled afterwards), etc… and after all I realised that the clutch started to slide. I must say that the bike was not mooving for 16 years ca. and I did not touch anything on the clutch system…(old fluid, etc…). The clutch felt really hard and worked also only at the end…
I thought that I have to renew the discs as they are at the end of life, but than had the idea that maybe the master cylinder and the slave cylinder, etc… could be “dirty” and blocked by the old fluid…
I had a look and what not, it was brown and dirty… cleaned it (also the piston in the slave cylinder) and rebuilt…now it feels much better but because of the weather and no permission for the bike (yet) could not really try it outside.

Question: do you guys think that it could have been my problem and only with this cleaning and new DOT 4 fluid in the system the problem could be solved?
For sure, the clutch is not xtrem hard anymore as before but also not too spongy. Feels OK, but I should try it while running…

On my other bike: VF 1000 F, 1984 I have the following problem:

  1. When it is cold outside (ca 0 to +2 degree), it is really really difficult to start it. It starts for a second (I guess with the fuel left in the engine from the last ride…) than dies after 1 sec and really difficult to restart it again. After it starts and warm, working perfectly and re-starts immediatly. BUT when it is warm, the idle do not get under 1400-1300, while it should be more 1000 - 1100. When the engine is only a little bit warm, the iddle is perfect.
    With the idle screw, I can not adjust any more as it is completly out.

My idea -to confirm or not by you guys-, is that “maybe” there could be a problem with one of the intake manifolds which is taking air in the system between the carb and the engine… I must add that the carbs were off but still the cables attached when I changed the gaskets on them.

My theory is that in this case:

  1. The cold engine starts hard as it takes too much air and not enough fuel (mix is not enough fuel-rich) and when it is warm it is “acceptable” for the engine so starts immediatly BUT:
  2. the idle stays high when the engine is warm, as the system takes too much air because of the intake problem?

There is no missfiring and the carbs were cleaned (ultrason.) before and “visually” the intake manifolds looks also OK… how could I check that?

…or the second way / idea could be:

  1. Remove the carbs once more and try to clean the choke valves with pressed air
  2. Set the idle by playing with the pilot screws (once in, than 2 1/2 out and than try to play…as described in the manual)

I also bought a carb synchroniser one week ago as I am really passionated to learn everything :laughing:…but never used something like that till now. If it would help to control, check, etc. I would hive a try…:sunglasses:

I must say that I am not a carb-pro as you see, and never played with the jets, pilot screws, etc…
Time to learn!!! :laughing:

Thx a lot for your tips!


Some more info for the idle / cold start prb.:

I attached the carb synchro tool I have on the bike today.
It shows -0,5 Bar on the right cylinders (right front + right back) and - 0,18 - 0,2 Bar on the left cylinders…
With throttle they move together and if I change the gauges it is the same so no prb with the synchro tool…

Pilot screws were on ca. 2 1/4 and now on 2 out (all the 4)

The idle stays at 1500 constantly…
I can only lower it if I turn the pilot screws on ca. 1,5 out which would be quite far from the 2 1/2 - 2 3/4 told by the manual…

Any idea / advice are welcome and I appreciate it! :wink::blush:


Hi, looks like you need to adjust the synchronization of the carbs. This is done by adjusting the screws between the carbs a bugger of a job! Plenty of advice on forum on how to do this but basically you need to get all 4 carbs reading the same on your vacuum gauges untill you get that you will never get a steady tick over or get it to the desired 1100 rpm. Search for carb synchronization on forum and brace yourself for one of the most awkward jobs you will do on any bike. Good luck!



Today a small game with my carbs. trying to synchro them. Nice to spend some time with these nice screws really “well positioned”…no chance to reach them ;D :o

Anyway, I succeed to get all cylinders from -0,5 -0,5 -0,2 -0,18 to -0,28 Bar for all! They are mooving together and the motor reacting perfectly to the throttle! YEAH!!! some happy moments for today.
Idle is set to 1100 and pilot screws are on 2 3/4 out like said in the manual.

…waiting to test it again with a “cold start” as it was till now horribly difficult, but I beleive it should be much easier now with carbs in synchro!

For info: I checked the intake manifolds with some WD40 sprayed on the intakes and checking if engine reacts. No reaction…Fortunatly! …so they seems to be fit without leaking :)))


Always worth replacing inlet rubbers, new ones are softer enabling easier carb fitting and good sealing at a reasonable price, david silver sell them at a very reasonable price. Glad you got synchro done that earns you your first vf1000 medal! You will be an expert before long.


Thanks a lot Garyb! :smiley:

Now the synchro is fine and the bike runs perfectly, reacting good to throttle and re-starts immediatly when warm.
BUT! It is still a hell to start her when it is cold…
Starts for a second than dies…after without the choke it re-starts really slowly after 10 times when I give a try…once starts, I have to hold throttle on ca. 2000-2500 Rpm and in a few minutes, she is warm and everything fine.
Same time, when warm, pulling the choke, it dies in 3 seconds but not in 1 second like I would except. Is that normal?
What could be the problem with cold starting?
Carbs were ultrasonic cleaned by the previous owner but bike did not move for ca.10years after…
When I bought it, changed fuel lines and fuel filter also (air filter is still the old one but I guess it has no effect on this…). The carbs were not drained but got new fuel while restarting her first by me.

I will re-check the choke cable today but if not…?
Could be that the choke valve is partly blocked?
Or any other idea I could use?

Thx a lot guys, any help or idea is welcome! :wink:


Hi I would remove the carbs and get them cleaned again if the carbs were cleaned that long ago either full of old fuel or even no fuel in the bowls, they will be gummed up either way if any moisture was left in them when they were cleaned then that would cause furring up, when removing the carbs leave the bottom alloy part of the air box on the carbs loosen the inlet clips carb side then lift the from the rear 2 cylinders first then the fronts, you can then remove the cables. Note the alloy air box part is the only thing that holds the left carbs to the right hand carbs once you remove the 8 screws holding it on then the only thing holding the carbs together is the fuel balance pipes which are plastic and usually brittle due to heat and age and not cheap to replace when I done mine I stripped them as a complete unit as I have a ultra sonic cleaner big enough to take them all in the way they came off, mine suffered cold starting and flooding issues which was cured once done, also check your starter motor they are known to suffer from bearings going from old age and service kits are easily available, hope this helps

Hi Istvan,welcome to the world of old bikes.
I would totally disregard whatever the previous owner has told you and remove the carbs for a thorough clean.
Check the operation of each choke plunger before disassembly,to be sure they are all working together.
You seem to have narrowed the problem down to the choke circuit,so if the plungers are all operating then a good clean is in order,if possible in an ultrasonic bath.
Best regards Bif

Hi Paul,

thanks for your advices!
Today I removed and re-positioned the choke cable as it was a to loose and also not well fixed on the handlebar.
I also removed the air filter-box and realised that the left two carb inlets (between the carbs and the airbox) and around them, were a bit “dirty”. Some kind of oily stuff. Not full but it was obvious to see…
Than I saw that these inlets are not on their position where they should be! They were simply deformed and not sitting well on the carbs PLUS on this side, two screws out of the eight, fixing the alloy part with the carbs, were a bit loose. I guess the carbs were simply taking air next to these inlets…
Fortunatly I had a carb as “spare part” and could remove two intakes from that one and clean and place them.

For sure, for this, I had to remove the 8 screws and the alloy part…while carbs still sitting on the intake manifolds and on the engine… You wrote that while removing that part, the carbs are not any more fixed together well.
Well…I felt it but did not move or force them and the intake manifolds could hold them I guess… Now I put everything back with the good intakes (airbox-carbs) and put airbox, etc… back.

The bike started -even cold-, for the second try! Was OK, but I had to adjust the idle and screw it in with 4-5 turns, that the bike stays on…
After I turned it off and wanted to re-check the carb synchro as I thought that with the problem coming from the two bad intakes, I could have false numbers while doing the synchro yesterday…Well, when bike was getting warm, the synchro also looked fine (ca. -0,24 -0,25 for all cylinders).

Meanwhile I run out of fuel :))))))
I put some fuel in, but now the bike does not want to start easily… and the battery is empty :slight_smile:
What I “changed” between the “repair today” and time when I run out of petrol is just playing with the idle (giving much more).
I will try tomorrow again, and hope that everything will be fine.
The only points were I am not that I did all right are:

  • I re-set the pilot screws yesterday after the synchro (to 2 3/4, but I am not sure where they were before…could be that some were only on 2 1/4 I guess). Should it have any effect on the cold start with the now good intakes? Should I change some setting on the pilot screws as they are managing the idle settings?
    …and I have (had) problems with that when the bike is cold

  • I turned the idle screw (black plastic), a lot in… and now some back, but not sure where it was before… Normally I should screw it out till it is slightly touching the small metal plate on the spring above the screw or?

What do you guys think?

Hope to have her run perfectly soon!

Hi Bif,

thanks a lot!
Yes I guess it should be a problem with the choke circuit… Or we will see tomorrow.
I checked and the chokes (all the 4) are moving together and after re-setting the cable, also fine (from one end to the other)

If cold problem stays, could I clean the choke circuit (choke valves, etc…) while keeping the carbs together or I should separate them?
I have a carb cleaning set… could I eventually clean these only with these stuff? …or should I contact a motorbike service for ultrasonic?

Thanks for your advice!


Ultrasonic is the way to go,My tank is only 5lt so I split the carbs and do them one at a time.
This lets me replace all seals while they are apart.
If you can’t do this yourself it’s worth paying to have it done professionally.
Best regards Bif.

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