Rank stupidity (again)

A

AndyB_11

Full member
Location
Bedford
I'd been planning to test ride the maybeamontjuic this weekend after blowing yet more money on pointless bits and pieces and was fitting the carbs when thought something was a bit odd. A bit odd doesn't describe finding that one of the rubber adaptors that mounts the carbs on the inlet manifolds has a split in it.

I can get new ones from Dellorto and only need to trim 2mm off the length to get them so the carb butts up against the manifold properly but it's still annoying. How annoying? How annoyed would anyone be if they'd spent ages pissing about trying to get it running right then gave up and bought 2 new carbs. I'll put the old ones up for sale when I've calmed down and get back some of the outlay but it's my own stupid fault for not spraying easy start at the manifolds to see if the revs went up  >:(
 
We learn, we learn...

I do the same all the time.

However the easy-start is a good tip I have used on my training wheels earlier with good result.
They were OK, so I will only change plugs, oil and filter.
 
Hi Andy

you can slather some silicone seal inside and outside of the cracked inlet manifold as a short term fix while you wait for new inlets. Would let you ride the bike this weekend.

and hey, who wouldn't like a brand new set of carbs on their old bike, all is good!

Paul LeClair
 
I've used bias binding coated in high modulous silicone sealer then wrapped externally on off-road bikes and cars to beef up airbox to carb snorkels.

Normally something else failed terminally before it did.
 
Paul LeClair said:
and hey, who wouldn't like a brand new set of carbs on their old bike, all is good!
Click to expand...

+1 - it's one of the best things you can do for an older bike. I have a serial-Triumph-buying acquaintance who automatically refreshes the carbs on every bike he buys (then sells off the flogged out old ones.....)

H.
 
I used self amalgamating tape on one of my carb to airbox rubbers, it's still on there today.
 
I've got today off and the sun's shining so everything has been reassembled and the bike fired up  :o

It sounds a lot crisper with new carbs (hardly a surprise) but the fucker still doesn't like to tick over though unless my memory is worse than I thought Montjuics were never the Worlds best at low revs. I'll set up a remote fuel feed so I can run it with the tank off and check the obvious things like timing then reach for the Colortune and see if the mixture is right.

It'd be nice to get it out for a quiet ride around North Bedfordshire later just so I can find a heap of other faults to leave me scratching my head.
 
Mine always got hot pretty quickly when static with little air flow meaning the carbs picked up a lot more heat if run for any time.
On the original ignition I could get each cylinder to idle cleanly at 1200 revs but as soon as you connected them both up, no way.

If you keep the revs over 5,000 and don't make the engine lug a high gear it is far more pleasant.
Once you realise you don't have to use the brakes much it is easier to get comfortable and things start to come together.

I think the quiet ride is perhaps going to be a bit more elusive than tick-over.
Have fun.
 
Well the timing is bang on and using the colortune both sides were running slightly lean so in went the airscrews 1/2 turn and now I've got a nice blue flame from about 4k revs upwards but that doesn't really tell me too much because it'll change slightly when the engine is on load.

I've left the carbs with separate choke levers on and it's near enough impossible to get at the R/H one when the tank is on the bike but that's not too bad a thing because with both chokes on it revs its tits off so I'll just use one choke and be happy that it starts  :)

I'd forgotten that one of the wires had come off the reg/rec so it's not charging and while a quick look at the manual would normally put that one to bed it's got a Ducati unit on there so there's some guess work involved. It's not a big deal because I'll bung an Optimate lead on it so the battery is always charged and let the battery take the strain until I feel happy enough to go further afield.
 
Well I've been and put about 20 miles on it and it needs some love and attention lavishing on the fuelling.

Once it's properly warmed up it stalls if the revs drop and to start it again it needs about 50% choke. Once the revs are up it doesn't need that choke (stating the obvious there) so I need to mess with the low speed fuelling. Now it's been a long time since I did this so patience is needed but am I right in thinking that moving the clip on the needle down (lift the needle) will make a richer at low speeds and replicate the use of the choke but without touching the choke?



 
The best way of thinking needle is a plug in a hole that stops fuel from flowing,less plug = more fuel = richer.So raise the needle = richer.
 
Andy,
Sounds about right for the original ignition and carbs.
Tick-over was about 2,000+ on mine and you had to blip it to about 3 if it was hot and sitting for any time.
As soon as it dropped below1,800 it was stopping and needed choke to restart.
Not much power below 5k so no point in dropping below 2 and having it get fluffy on pick-up.
Ran best between 5,500 and 9,500 with a real step at 6,800 when the exhaust note changed completely.

Have you still got the 140 main jets?

The newer ignition sets that are available seem to make a big difference to low speed running.

 
sonicboom500 said:
Andy,
Sounds about right for the original ignition and carbs.
Tick-over was about 2,000+ on mine and you had to blip it to about 3 if it was hot and sitting for any time.
As soon as it dropped below1,800 it was stopping and needed choke to restart.
Not much power below 5k so no point in dropping below 2 and having it get fluffy on pick-up.
Ran best between 5,500 and 9,500 with a real step at 6,800 when the exhaust note changed completely.

Have you still got the 140 main jets?

The newer ignition sets that are available seem to make a big difference to low speed running.
Click to expand...

It's running on 140 main jets though I've got new spares one size either way so I can change them if I need to. I've lifted the needle which may or may not have helped because I need to give it a good run out to get it hot then see what happens. After the first run the plugs were black so it's obviously rich somewhere in the range but until I take it out and do a proper plug chop by cleaning the plugs then giving it a quick blast I don't know where.

I'm back at work tomorrow but I'll fit new plugs on Saturday so I'm starting from fresh and see how it goes. Sooty plugs aren't going to be helping it at all though it's slightly reassuring that you had similar symptoms to the ones I'm getting.

One thing that's a bit odd is that even though I've got new carbs on the bike I'm seeing unburned fuel on one of the velocity stacks  so something is blowing it back there and I need to work out what  ???

I checked the mixture using a colortune again and it looks ok but there's some uneven detonation on the side that's blowing back which you can both hear and see down the tube when the colortune is fitted. I'll suss it out eventually and it'll be good practice for setting up my H2 now I've got new expansion chambers on that brute.
 
Lads steady on now - 2000 rpm tick over!!!!!
It goes without saying that you should be setting carbs unless your happy with valve clearance and ignition timing.

Set your mixture skrews to 3 to 3.5 turns out anticlockwise (from fully closed) - quite rich.
Connect vacuum gauges.
Start motor ,warm it up,hold at steady revs say just over 2000 rpm and balance the carbs using the cable adjusters on top of the carbs.
Once done turn both throttle stop skrews right up so motor runs on skrew setting rather than throttle being turned.
Now turn each skrew down keeping the carbs in balance by watching balance gauges. The trick is to bring the revs down equally on each cylinder.
Once you have the revs low around say 1100 you can start turning the mixture skrews clockwise to lean the mixture off.You need to listen to the change in engine note.Listen out for a even steady noise if that makes sense.
When adjusting the mixture skrew(s) the revs may raise adjust the balance with the throttle stop skrews.
You may need to adjust each mixture skrew a coulpe of times to achieve the best setting.
Lower the revs the easier to hear/feel the difference in engine note when turning the mixture skrews.
Once you feel you have set the mixture,resert the throttle stop skrews to get an equally balance from both carbs at approx. 1100 rpm or whatever level you believe gives a nice steady tick over.
    Note:Mixture setting cannot be set correctly unless you get the revs low.

Andy
 
Going nowhere unless all valves are sealing properly.  They rarely do, even if clearances are ok.  Quite often the exhaust valves and seats are badly burnt, inlet valves rarely give cause for concern.

With a freshly rebuilt head I attain a rock steady idle at 800-900rpm. :D

piet
 
Ok, the clearances are all ok and the timing looks good using a strobe so those together should give me a good base line. The carbs are brand new with jets as per the specs on Laverdamania. Taking the head off and reseating the valves is something I'd sooner avoid right now but the fact that it's blowing back unburned fuel doesn't fill me with optimism when it comes to them seating properly.

The bike isn't charging due to the wiring being disturbed on the regulator and me not sorting it out yet so does the standard ignition rely on having a minimum voltage running through it? I know that the old Rita ignitions used to sulk if the voltage was low so now I'm wondering if this is the case. I can give it a basic check by using jump leads off another bike so it's got a bit of extra power and if that helps I'll be stripping the cover off yet more of the wiring harness to trace everything back.

The wiring is a mess with a lot of joints (some soldered, some just twisted and some with decent connectors) and a fair bit of the wiring has been replaced with whatever the previous owner had in his box of bits so I should probably start to consider replacing most of it.

If I'd got half a functioning brain I'd be out riding one of my other bikes but there's no way I'm going to admit defeat and throw a cover over this one so be prepared for more tales of woe next weekend  ::)
 
so does the standard ignition rely on having a minimum voltage running through it?
Click to expand...

Yes.  If the volts get too low, then the timing can jump about markedly.  A particular problem when cranking on the starter, and so hammers the sprag.  A fully charged battery in good condition should be OK.  I think it's fair to say that once running, the battery will be flat before you drop below the ignition amplifier box threshold.

Sounds like that wiring will forever be letting you down at a moment's notice.  Running the alternator without a functioning reg/rect will be stressing its insulation, not to mention being a fire risk.
 
when we bought and imported Maxene's Monty from the UK it was a pig to get to idle and as it was for Max I figured I better do some work to it to get it to be a better bike for her to ride
first thing we changed was the standard ignition, we installed a Sachse ignition and wow, that made a difference, was far easier to start but still had a habit of coughing at idle and stalling

so, as I am known to do, I binned the damn Dellorto's and made up a set of Mikuni RS 34mm flatslides, they transformed the bike totally
now it starts easy, idles like a proper engine should, is crisp right through the rev range
different bike all together

don't forget that a standard set of Monty cams have a significant cam lobe overlap so it is not uncommon to see them spit back through the carbs, is the nature of the engine set up
if you are worried about your valves sealing then the only way to confirm that is to perform a leak down test, that will give you a very good indication of the state of your valves
 
Looks like I have some more work to do on my bike.
Had to slot the original Bosch pickups to get the timing correct.
The cam sprockets probably need slotting too as the timing is not spot on at a full tooth.
Cam timing moved to 'pick a tooth' gave either better pickup and less frantic over 8 or fluffy low end pickup and 2 stroke type top end.
Bought a Sachse ignition to give the sprag a break but it sounds like that is only part of the story as the cough and stop that Red mentions is familiar.

I always use a starter pack on the solenoid as well as the 20ah battery from cold at home.
I only have half a mile to go from my door to open roads so a stable idle has never been a priority.
Bike returned about 50-55mpg in general use/abuse and plugs were tan.
Many of my local roads are twisty off/on type B roads and the side panels were often stained with fuel.

Do you have a modern blade type fuse box or the original continental type with the wobbly fuses?

 
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