Tappet adjustment

[NicBeeee]

Sorry for delay but here`s the update, secondary choke is opening up ok,

1. 160 psi
2. 160 psi
3 157 psi
4 155 psi

all vacuum pipes leak free,
manifold brake pipe leak free,
carb gasket leak free,
fuel filter replaced, carb inlet cleaned,
emmisions good, no smoke on start up or hot engine
timing good,
fast idle works well,
choke works well,
engine temp maintaining best its ever been,
all electrics, fuel cut off, manifold heater, choke bi metal all ok,
slow idle speed spot on,
gearbox change no crunching or noise,

Checked vacuum unit on dizzy, suspect, easy to blow down with little restriction, ordered one and the posty has just turned up with it so its plan Z, hope it works as I am at the end of the alphabet, if it doesnt then I am going to plod to cornwall for our holidays as if its not broken and all that,

Slow but working van X too much messing = 3 weeks under canvass

[NicBeeee]

Vacuum unit had shot it, replacement didnt make much difference to top end speed, altered tappets to 1 turn instead 1 and half. Definate difference uphill, go figure, I am begining to wonder if my CO meter is accurate as the exhaust pops occasionally but gives a reading of 1.5 %, could be down to the bike can though as it changed tune when I first put it on. Also there is very little adjustment left on the slow idle screw, half a turn anti clock wise before disengaging at the most, which also seems strange. I will give it a good run over the weekend to see if it settles and returns to its normal sluggish self.

[kevtherev]

The idle speed screw opens the main throttle butterfly
Which allows more air to flow through the carb.
Remember
The idle speed when cold is higher due to the cold idle mechanism
Is the idle speed set from a hot engine like it should be?

[pionte]

just a thought..... your exhaust system , you say that your are using a bike can ? Exhausts make a huge difference to performance. Too much back pressure and you loose power, too little back pressure and again you will loose power. Its all about the correct amount of back pressure.... , the back pressure helps with the control of the burn inside the cylinders, Im guessing that its a can of a litre plus sports bike ? they generally make peak power around 9-10k rpm , twice that of the WBX but designed for half the volume of gases , so guessing again that it may equal out.

I would be really tempted to try an original fitment exhaust , I know from my days car and bike racing that fitting different exhausts would move the power around in the rev range, sometimes more bhp was required sometimes more torque , the length of the exhaust manifold tubes where 'tuned' lengths , and the size of the silencer was also very important .

I laugh when i see and ' hear ' a 1.2 Corsa with a dustbin sized exhaust ... i know that if put on a rolling road it would be making less power than a standard car would.

anyway, just a thought.

[NicBeeee]

The idle speed screw opens the main throttle butterfly
Which allows more air to flow through the carb.
Remember
The idle speed when cold is higher due to the cold idle mechanism
Is the idle speed set from a hot engine like it should be?

Yep nice and hot until the fan kicked in

[NicBeeee]

just a thought..... your exhaust system , you say that your are using a bike can ? Exhausts make a huge difference to performance. Too much back pressure and you loose power, too little back pressure and again you will loose power. Its all about the correct amount of back pressure.... , the back pressure helps with the control of the burn inside the cylinders, Im guessing that its a can of a litre plus sports bike ? they generally make peak power around 9-10k rpm , twice that of the WBX but designed for half the volume of gases , so guessing again that it may equal out.

Hi, thanks for the thought, however it lacked power prior to having the can fitted which came from a gsxr 1000, however I have also got a gsxr 750 knocking about, as a straight swap it might be interesting too see what happens. I can see me getting my tent out with thoughts like this. Good job I am bust at work

[NicBeeee]

Kev, If I could tap your brain for a minute, I am currently using silicon vacuum tubes, I believe that the vacuum tubes are meant to have a 4mm ID, theses tubes are around 3mm even though they were sold as 4mm. Would this cause problems with air pressure/flow

[BOXY]

The bore on the vac tubes shouldn't make a difference as there isn't a flow through them. All they do is transmit a negative pressure to a closed part of the system. You could check they aren't collapsing if they're not rated for vaccum.

[kevtherev]

WHS... ^^

[ghost123uk]

I am currently using silicon vacuum tubes,

Defo what they said ^^^

Silicone tubing will defo collapse under any amount of vacuum (at least all the stuff I have ever seen).

[NicBeeee]

The bore on the vac tubes shouldn't make a difference as there isn't a flow through them. All they do is transmit a negative pressure to a closed part of the system. You could check they aren't collapsing if they're not rated for vaccum.

Thanks for your input,

The tube has got 4mm side walls and is meant to be vacuum tube, trawling throught the internet I am having trouble finding the older braided stuff as it all seems to be silicon now. I was curious about the ID as I believe there has to be an initial flow to create a negative pressure, I am aware that the pressure would be the same no matter what size tube however the time it takes to get there would be different, larger tube in length and or diameter = longer time, probably pinching at straws and it doesnt matter a jot though

[BOXY]

You are right in a way. If the tube & vacuum chamber were initially at atmospheric pressure there would be a flow as the vacuum was applied to the downstream end. But there are four cylinders doing the sucking remember. Changing the tube from 3mm ID to 4mm ID will take longer for the full vacuum to be achieved but I would guess the difference would be less than fractions of a second.

For what its worth the vacuum tubes on my van are semi-rigid nylon with short pieces of silicone tube acting as joiners at the connections. The nylon butts up against the metal spigots so there's no way the tubes can collapse.

[kevtherev]

nylon or ptfe tubing.

[NicBeeee]

nylon or ptfe tubing.

Finally got some time to replace tubing with ptfe, unfortunately it hasnt made any difference, going away this week so I have come to the conclusion that we will stick to 55mph all the way (except for steep hills), would have stuck to this speed anyway. Thanks to everyones suggestions and I will be able to delve deeper after our hols as I will not have a deadline to keep.

Cheers
Nic

[NicBeeee]

Quick update, back from hols two weeks of sunshine in cornwall, how did that happen.

Anyway van performed better than has done before, took the hills with a breeze, could do a steady 70 on motorway if wanted to, fully laden with as much as could carry. Perhaps it was the silicone tubing after all or he just needed a good run. Also he began to perform better after filling up with fuel away from our usual local station, coincidence or not. All is good and well and cheers for the tips. Going to run him down a bit and return to the local filling station too see if anything different happens.

Nic