Anyone delete their stock boost bottle?

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sleeper_dave

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I have a vmax 600 twin (94-96, kind of a bastard) and when we were pressure testing it it leaked like hell around the boost bottle. So we plugged the holes with a couple of pieces of aluminum, and left it like that. We really didn't see any purpose in having a crossover between the carbs, it would really just mask any carb problems that we would normally see clearly on one cylinder.

Has anyone else deleted their boost bottle? If so, what were the results? How did it affect carb tuning?

I haven't gotten enough miles on mine to make any real judgement, and didn't have any miles on it at all before rebuilding it (bought it blowed up).

I've read a lot of threads on them and some say they're great, some say they suck, but most are talking about the triples. Nobody seems to mention removing them from a twin.
 
No idea on the performance, but just a general comment... The seal on the boost bottles isn't meant to hold pressure, so it will leak very easily. Under normal conditions that area experiences a vacuum, so it seals like it should.

At least in my experience with other engines, boost bottles DO help performance, not just mask issues between carbs. Be interesting to hear if anyone has some first hand experience with it...
 
The purpose of a boost bottle is to increase performance, that is why Yamaha spent the money to put it on.

What is it called? - a boost bottle. It acts like a mini supercharger and adds boost. It accumulates pressure from one side and then supplies it to the other cylinder.
 
The way it was explained to me is it smooths out the pulses between the 2 cylinders. Making the engine more responsive at low RPM and easier to tune, not as finicky which was a big problem with some 2 cylinder 2 strokes at the time.
 
PZ 1 said:
The purpose of a boost bottle is to increase performance, that is why Yamaha spent the money to put it on.

What is it called? - a boost bottle. It acts like a mini supercharger and adds boost. It accumulates pressure from one side and then supplies it to the other cylinder.
Click to expand...

Not really. I did a lot of reading on this yesterday, and some say they work, some say they don't. The most credible information I found indicates that on some engines, if the carb is tuned appropriately, they can provide a small improvement at low to medium throttle, with no benefit or even a negative impact at high RPM. They don't accumulate boost or anything of the sort, and based on what I saw during my pressure test, if they did they'd cause an air leak. At best, they are a resonator and a crossover and may smooth airflow across the carb improving tunability at low speed.

I'm looking more for real world experiences. Ie: I took it off and gained / lost power and the mixture shifted richer / leaner. Not a generalized "well, yamaha did it so it must work!" Manufacturers do a lot of things that don't work, or are a compromise. They also took them off some of their newer machines, so maybe they don't work!

If I had the time, not to mention the snow, I'd experiment with it on and with it off and come to a conclusion myself. But in the meantime it's off and I'd like to get someone to chime in with some real world experience on if it's worth it to reinstall it an whether I'll have to make any carb adjustments if I do.
 
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.I have a boost bottle added to my sxr and can tell you there is a difference. Im not gonna say it made a world of difference but a throttle responce difference as well as some HP
 
Just look at a dyno chart, it will tell you what a boost bottle does. Check at Dynotech, they may have done a test. You will see an increase in the curve on the lower end. Boost bottles have been used for many years on single cylinder engines to increase performance - there is no balance on a single.
 
Well, I'm leaning toward putting it back on. From what I've read, removing it may have shifted things richer, so I'll have to play with the air screw and the needle height again once I do. I just need some freaking snow! And I need to go through the clutches first.
 
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