T140v - Triumph Bonneville T140 Basic Carb Balancing 6mins.
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- čas přidán 8. 09. 2024
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Here is a short video I made for you on how to balance your Amal Carbs on the Triumph Bonneville T140. (Mine was built 1977.)
This basic mechanical balancing technique can also be used on bikes with as many carbs on your bike has as you like, such as the trident T150 or T160.
The important bit is to get the starting point correct and then to maintain that as you use the bike.
I check mine every couple of years but rarely need to change anything once its done other than the mixture tuning which is a completely different set up.
I must seriously emphasise that you cannot get the bikes running mixture correct unless you get this part set up correctly or you will be just chasing you tail and never get it correct, as I have seen many many do.
Some folk just wont listen, lol.
This is great. I've been searching for the best instructions. There isn't much to go on but this definitely makes it clear.
You're very welcome!
I use junior hacksaw blades under the slides to balance them, they are light and they hook under the slides
Yes you can do that but doing that but it will drop the pistons very low and will give you a very slow idle and make setting the speed quite difficult. Using a couple of 5mm drills or a bit of 5mm rod will do. A 5mm dia inserted under the lifter will give about 1200rpm idle and you need that on both carbs to be able to go to the next stage of fine tuning the mixture and the air screw which normally will be 1 to 1 1/2 turns out. Wind out to weaken the mixture and wind out the air screw to richen the mixture. Remember this is only the idle mixture and not the operational mixture of the engine. That is done by the jets and the lifter. Hope this is of use.🙂
Great explanations. Very easy to understand
Glad to hear that!
Each manifold that attaches to the head has a nipple where the crossover balancing tube attaches. Could you hook a carb sync manometer style tool up to those two nipples then fire up the bike and balance the carbs while it's running like you would with an old Honda CB? I never see people do that, so I'm assuming there's a reason for it, but with my 07 Bonneville the carb sync nipples were on the manifolds, so it seems like it could work.
If you want to use manometers then you will need to disconnect the balance pipe between the carbs. Use two manometers, one on each carb individually to balance your carbs for fine tuning. I doubt you will improve on the performance however. Lots of effort for very little reward in my opinion. On Honda fours using manometers is the only way to do it, but on these old twins its very easy. You must still do the mechanical part as I explained on the video first to set up your cables and carb stops. After this just fine tune with the idle air screw to get the best rpm. Hope this is of use.
I’ve always done it with my fingers or touch, but will try this next time!
I do the same thing but with drill bits instead of screwdrivers.
The old ways are often the best. As long as there both the same diameter rod around 5mm then it will work perfectly.
Even easier with a twin cable twist grip easy peasy. Happy days
Yes they are a bit easier to set up, but you still have to set them up correctly down at the carb end as advised. If you don't you will chase yourself around trying to tune your carbs correctly.
Thank you.
You're welcome!
Great video thanks! Did you blind off your choke cable port on your carbs? I didn't see a second cable coming from the top of your carbs.
Been considering disconnecting my own chole. Do you have a few good advice on doing so?
Cheers from Denmark.
If you have mk1 Amals then yes the tickler works fine on its own. Remember to remove the choke slides and blank off the top of the carb top. You can buy brass blanks from Amal to do that. I just use a stainless cap head screw with an o ring to form a seal and held in with a bit of silicone. The fumes will rot away the silicone over time but it lasts more than a few years so its no issue. Hope this is of use.
Why not use a vacuum gauge
As advised this the initial stage of tuning only to set up your carbs.
This video allows you to set the idle point of your lifters on both carbs correctly and your throttle cables. After this you move into carb fuel air mixture tuning which is completely separate item.
If you don't get this bit correct you will never get the mixture tuning correct and will chase yourself around trying to get it set correct as the carbs have a link pipe. Using a vacuum gauge allows you to get the fuel air mixture draw set over each lifter and is great to get the airscrew set up correctly at idle, but it becomes un balanced again as soon as you open the throttles as the lifters are at different gaps if that makes sense for you.. For instance you can say have one carb at 3mm lifter gap and the other at 5mm gap, and then using the air jet open it more to compensate for the lower gap on that lifter by drawing more air in via the air port on the idle mixture port at the front of the carb. That works but at idle only. As soon you open the throttle every thing will then run weak on the 3mm side after you move into the other jets operational areas as the lifter is lower on that side allowing less air to pass over it . You must remember that air gets into the carb via the lifter and the idle air inlet port at the front of the carb. You can read a full write up if you look on the Amal web site of how that all works for now. The idle mixture is only a part of a big subject, as the carb operates differently dependant on the position of the throttle. Different jets come into play at different points or load on the engine. I will make a separate video to explain all this when I get time. Hope you find this of use.
You can for tuning. This vid is for setting the mechanical parts up. If you dont get this bit correct you will never get the carbs to work correctly.