Mad Scientist Lab test - Boost Bottle

[ElMicNip]

so size is important

just curious? are not all 66, 67,80cc all actually 66cc? just asking because I ignored what the seller of the engine claimed and assumed it was just 66cc, then I ordered a Boost Bottle for a 66. Did I do right? I dont want to have to send it back for a different one. I'm still waiting for mine (silver). I understand shipping, but I get impatient and that is my fault. Seriously though, if it is a 66 then it should be called 66 not 67 or 80. for newbies it can get a little confusing when its is used in technical explanations. I'm just asking for accuracy in peoples expplanations not assumptions. Thank you.

 

[ElMicNip]

just wanted to reiterate... i just would like accuracy not estimations or rounding off. If all the large motors are actually one size then wouldn't it be prudent for the bottle measurements to be accurate. The bottle sizes aren't estimated, so then, why should the motor size be.

 

[rjcullis]

Engine size

It's easy enough to get the engine displacement by multiplying bore times stroke. This measurement is listed by several sellers quite accurately. The tricky part is finding out the volume of the cylinder occupied by the head. That's something I have not seen listed anywhere. It would come into consideration for a super exact boost bottle calculation.

Richard.

 

[piecepatrol99]

I've lost top end power after boostbottle install :-(

Hi folks.
My name is Ryan. I purchased a dual boost bottle kit for my 49cc 2 stroke.
Before the purchase I had near no low end power but decent mid and top end.
After installing the bottles, low end went from mouse to charging bull in comparing power. But top end is now barely a house cat with a bad attitude.
I've adjusted the C clip on the NT carb for better idle (I had to lean it one notch). Still no top end power to speak of :-(
My question is: does any one have a suggestion on how best to tune the carb (specifically jet change) to get my top end back and bring the idle down a little more?
I ordered a set of jets and I'm trying to avoid the trial and error phase...

On a side note: the nut that holds the muffler end cap/tail pipe came loose and bottom end power went through the roof (for such a small motor). I can't/won't run with no exhaust. I'm looking to quiet it more as it is...
Any help in getting my idle down (with out stalling) and getting my top end power back is greatly appreciated

 

[Fabian]

Boost bottles are a waste of time and money. It's a subject that's been workshopped to death.

 

[piecepatrol99]

Boost bottles are a waste of time and money. It's a subject that's been workshopped to death.

Thanks for the fast reply Fabian.
I only mention the boost bottles as they are a form of engine modification/upgrade. Bottom line I need to adjust my carb for my new combustion area/dispalcement/intake configuration.
What I'm specifcally looking for is the information on what direction do I go to properly adjust my carb. I don't want to fill my jet with lead and drill it half a dozen times or buy parts only tonever use them because only 1 out of 10 worked...

In short, I did a plugh chop and have a nice medium brown color on the electrode. But I'm lacking power in higher RPM range. How do I correct that via carb adjustment as my needle is already set in the best position?

 

[Fabian]

If you want a simple and no fuss intake system that gives benefits greater than improved drivability and mess free operation, i suggest purchase of the Rock Solid Engines reed valve intake (suited to your intake stud spacing) as well as purchasing the Walbro style diaphragm carburettor.

Make sure that you purchase the thermal isolation spacer. It is critical to the reliable operation of this kind of carburation system.

 

[piecepatrol99]

I'll keep that in mind. Right now I'm waiting for a carb jet kit and a set of clutch pads.
The only time I had any issue with mess was connecting two tanks and having both valves open. Ultimately I plan on installing 3 tanks for long distance riding. I plan to only have to stop to turn the empty tank off and turn on the next...

The reed valve sounds like a completely different carb set up, I'm still learning the ins and out of the NT carb the motor came with. The little I know about carbs in general is the more air you can deliver, the more fuel you'll need to go with it and vice versa... every thing I've worked on before has been maintainance. This is the first mod I've done.
I know the boost bottle isn't increasing CFM, its only using the previous flow rate more efficiently. For that I'm having a little trouble wrapping my head around what course of adaptation/corrective measure I need to take to get the mixture just right.
Because the boost bottles steady the pulse wave of the intake, I believe a larger jet will help me to lower my idle RPM while returning power to my higher RPM range.
I suspect that the 'mellowed' pulse wave the bottles have cause is causing the engine to require a higher intake flow rate to keep running (I'm lean at idle). A larger jet may fix this as more fuel will be allowed to flow with out the vaccum force generated by a higher idle.
Strangely enough, if I'm lean at idle I must be lean at WOT despite the nice medium brown on my plug electrode. If I'm good on the fuel mix @mid RPM and hitting the kill switch when it starts to foul/bog out, my plug color will be the result of mid RPM running...

The theory I plan to test is "higher CFM does not equal reduced fuel economy". When I get the high idle down and eliminate the top end bog, my next step will be to drill out my new intake manifold as it is 1/4" narrower than the stock piece.

So far this has been an "Apollo 13" kind of mod. I have to get this working right with out a big budget for hardware or new(different) components.
I'm not trying to hold 50mph on flat ground, I did 72mph on a down hill when I was 15. I'm 42 now and I know "God protects babies and fools". I'm too old not to know better...

I just want to get it running right ;-)

 

[Fabian]

Don't even waste your time on the boost bottle concept. It is a method that gives no useful advantage.

The only thing a boost bottle does with any certainty is to add excess weight to your bike.

 

[piecepatrol99]

Don't even waste your time on the boost bottle concept. It is a method that gives no useful advantage.

The only thing a boost bottle does with any certainty is to add excess weight to your bike.

Fabian. Thanks for the advice on "How to tune my carborator". That was and still is my overall question.

Like I said I'm still learning the tricks with my stock NT carb. I am not got to buy a piece of hardware that does the same job but has more parts, methods of adjustment and ultimately is probably just a pure breed dog that requires a higher level of diagnosis to correct when its ailing.

Its really starting to seem like there 'IS' and advantage to the bottle you want to keep to your self or you just couldn't figure it out...
There's always the third possibility that you had a falling out with the distributor and you're trying to ash can his business buy saying his product doesn't work.

Regardless of your drive, I don't care to know...

I asked a specific question and gave sufficient details for an accurate response. All you've said is its junk, buy this instead....

Am I really supposed to trust you after you've skated out of answering my question in every reply you've posted?