I think the slides are in the wrong bodies

[Sesman]

Hang in there Eldrick. If you have got it running nicely at 1200rpm you must be doing something right. Keep at it.

[Eldrick]

Unsure if I've got the understanding of that correct.

The twistgrip must have some degree of slack when setup properly, this to avoid the throttle being pulled when you turn the steering left & right. Too tight and the throttle will open as you go from centre to full turn, also it'll likely pull the nipple off the end of the cable without a certain amount of space to operate.

These are specified in the manual.

I do have some slack whereas before I had lots, as in very poor responce. A short run up and down the street tomorrow will let me know if it is not enough slack but it is certainly going to be better  than the play I had before.

[Eldrick]

"Jam a drill bit in there" is not what you do, you use the parallel shank part of a small drill bit as a feeler gauge

Understood, it was total  sarcasm to follow from the previous statement I made in the same post, honest.

[Cappodimonte]

Took photos of one of my carbs and the needle slide just to have them seen separately before  I start reassembly.. as you can see the curve on the slider which should be facing away from the engine is clearly evident.
Inserting the slider and it completely drops to the bottom of the inlet tract as you would expect with a smooth action and no sticking.
Once fully assembled the adjustment to raise the sliders will be made and equalled out on bench, they will then be properly adjusted via 4 vacuum gauge so that all readouts are  the same.
Not difficult just time consuming.
All my carbs are stored in separate boxes so no cross contamination occurs, before anyone points out the rusty bits they will be zinc plated and passivised before assembly.
Secret in dealing with multi cylinders and carbs is TAKE YOUR TIME and DONT RUSH., if in doubt consult the manual every time.

[Oddjob]

Trouble with the manual is that it virtually tells you nothing. They don't appear to think anyone would ever take them apart.

Couple of pointers if you don't object.

You'll find Honda fitted screws that are in fact too short for the drilling, the carb tops are a perfect example. Most of the thread is left unused and corrosion of that thread left unused mean if you attempt to fit a longer screw if starts to grab and then strip away the thread. Clean the threads with a tap, measure how much thread is left unused and fit a longer screw, that why a lot of them strip out, they are only really gripping on a few threads. IIRC, the top screws are 16mm and you need 20mm, the float bowl screws are the same, look at the pic and you'll see the screws don't reach the top of the thread, the pressure of the spring washer tends to strip these threads out as only a few are getting used. If in doubt, fit longer screws and trim to suit the position. Don't have threads of the screw exposed as they corrode and when you try and remove them it can strip out the threads as it passes down them. Go for a flush finish.

[Eldrick]

Ran the bike today and it all seems great, put the vacuum gauge on the carbs when I got home and I get this;

[ Guests cannot view attachments ]
#3 does show 10-15cmHg when I blip the throttle but otherwise, adjusting that slide just increases or decreases all the others by variable amounts.

Plugs are new, air flow upto the carbs is sealed so it could be a leak on the other side (the boots?). I did swap the vacuum tubes over to make sure that #3 tube and the carb tune wasn’t faulty. If it wasn’t for the vacuum gauge I just wouldn’t have known anything was wrong as the running response and idle seemed good. Well to my untrained mechanical brain anyway.

[Nurse Julie]

Are all the exhaust headers the same temperature, ie, equally bloody hot when you've been riding?

[Eldrick]

Are all the exhaust headers the same temperature, ie, equally bloody hot when you've been riding?

I will check the next time
Thanks

[Oddjob]

No Vacuum to that cylinder, which means a massive loss somewhere. Check the valves on that cylinder, remove tappet covers and check they are first of all going up and down as the engine turns over. Either there's a valve stuck or the tappet is way too tight or there's a bent valve. Do a compression test if you can.

[Cappodimonte]

Trouble with the manual is that it virtually tells you nothing. They don't appear to think anyone would ever take them apart.

Couple of pointers if you don't object.

You'll find Honda fitted screws that are in fact too short for the drilling, the carb tops are a perfect example. Most of the thread is left unused and corrosion of that thread left unused mean if you attempt to fit a longer screw if starts to grab and then strip away the thread. Clean the threads with a tap, measure how much thread is left unused and fit a longer screw, that why a lot of them strip out, they are only really gripping on a few threads. IIRC, the top screws are 16mm and you need 20mm, the float bowl screws are the same, look at the pic and you'll see the screws don't reach the top of the thread, the pressure of the spring washer tends to strip these threads out as only a few are getting used. If in doubt, fit longer screws and trim to suit the position. Don't have threads of the screw exposed as they corrode and when you try and remove them it can strip out the threads as it passes down them. Go for a flush finish.
No objection Ken,
Learnt a long time ago about Hondas plasticine screws, so all my screws bolts etc are stainless steel replacements, usually but not always hexagon headed cap screws. Again from experience I always use a tap to clean up the threads so I don’t get caught out with stripped threads..
Just got my BZP kit from Gateros so all the rusty bits you did see will be brought back to original look, a new venture for me but I enjoy doing something that poses a challenge.😀👍

[Cappodimonte]

Ran the bike today and it all seems great, put the vacuum gauge on the carbs when I got home and I get this;

(Attachment Link)
#3 does show 10-15cmHg when I blip the throttle but otherwise, adjusting that slide just increases or decreases all the others by variable amounts.

Plugs are new, air flow upto the carbs is sealed so it could be a leak on the other side (the boots?). I did swap the vacuum tubes over to make sure that #3 tube and the carb tune wasn’t faulty. If it wasn’t for the vacuum gauge I just wouldn’t have known anything was wrong as the running response and idle seemed good. Well to my untrained mechanical brain anyway.

Is the bike running on all four cylinders or does it feel lumpy, as a 3 cylinder runner will sound ‘off’ and certainly will lack power. Do a quick check of the vacuum gauge by a light continual suck to see the mercury rises on each tube,
If all tubes rise and maintain their reading then you have discounted the gauge as a problem, if three falls as you maintain a suck then their is a fault in the gauge probably the rubber or it’s fixtures at either end.
Once you have ascertained if the gauge is faulty or not then proceed with the next step with engine running use a spray water bottle with soapy water and lightly spray the inlet tracts from carb to head, if there is an inlet leak the soapy water will stop it up for a short time and the gauge will rise, then fall which will prove or disprove this particular part as the problem, it has an ‘O’ ring seal which can flatten and leak, if the inlet rubber tract has a split then the soapy water will seal it but get dried out by the vacuum in a short time.
It’s all time consuming as is checking the inlet valve which in my opinion have closed up to almost zero mm to cause a vacuum drop.
Enjoy finding the fault

[Sesman]

Try swapping the vacuum tunes to make sure it’s not the instrument.If the bike is running as well as you mentioned earlier in the thread I doubt the issue can be catastrophic…

[Oddjob]

One persons running well isn't always an accurate description unless you know exactly how it should feel.

Ted ran his 400 on 2 cylinders and even though he said it seemed to lack power he didn't spot it was only running on 2. Sorry Ted for bringing that back up but it's a good example.

[McCabe-Thiele (Ted)]

Not only that but it did some trips to Ashbourne on 2 cylinders! 😁

[Eldrick]

One persons running well isn't always an accurate description unless you know exactly how it should feel.

Ted ran his 400 on 2 cylinders and even though he said it seemed to lack power he didn't spot it was only running on 2. Sorry Ted for bringing that back up but it's a good example.

True, I thought it was running great and sounding great, the vacuum gauge told me otherwise. I would have happily run the bike forever in ignorance otherwise. Now, I'm on a mission to fix it and expand my knowledge.