Engine goes flat on declaration

Hello, I'm trying to track down an issue when I let off the throttle.

I accelerate hard and then when coming to a light or stop sign, when letting off the engine goes totally flat and I have to twist the throttle on/off to keep it from turning off. She also 4strokes like crazy when doing this. (On/off throttle)

Has smallest pilot jet available already (10) TM24. Need bigger pilot or needle adjustment is the culprit?

Re: Engine goes flat on declaration

give make,model, size engine, etc.

Re: Engine goes flat on declaration

Overpriced Parts /

> Roger Suarez Wrote:

> -------------------------------------------------------

> Hello, I'm trying to track down an issue when I let off the throttle.

>

> I accelerate hard and then when coming to a light or stop sign, when

> letting off the engine goes totally flat and I have to twist the

> throttle on/off to keep it from turning off. She also 4strokes like

> crazy when doing this. (On/off throttle)

>

> Has smallest pilot jet available already (10) TM24. Need bigger pilot

> or needle adjustment is the culprit?

Sounds like Idle/pilot jet size and air screw adjustment, pretty sure they make a 7.5 jet but I never needed one, one of my tm24’s have larger 12.5 size, all my air screws come in at 1.5 to 1.75 turns and 1/8 throttle makes the braaapp sound which is about optimal,

if you have all that, you could be too rich in overall jetting or you need needle clip changes,

The float level are very sensitive on those carburetors too.

Even though I had all that right, I have one polini reed kit bike that has a dellorto 21 mm PHBG that was doing (though not as bad) the symptoms you described, I put a spring loaded float needle in it and it eliminated the problems

Re: Engine goes flat on declaration

I'm ordering a leaner atomizer and leaner needles with needle shims to get the length right. WOT is almost perfect 170 light cream--> 175 coco cream color 177 should get me there next. (water cooled).

Bike don't matter. Universal problem that effects all makes and models

Re: Engine goes flat on declaration

Overpriced Parts /

> Roger Suarez Wrote:

> -------------------------------------------------------

> I'm ordering a leaner atomizer and leaner needles with needle shims to

> get the length right. WOT is almost perfect 170 light cream--> 175 coco

> cream color 177 should get me there next. (water cooled).

>

> Bike don't matter. Universal problem that effects all makes and models

Yes bike matters a lot, variated engine that has engine movement, One speed, 2 speed or manual shift bikes all different,

Powerband rpm location matters, exhaust pipe matters, gearing matters, vibration matters and reed kit and piston port cylinder kits are like night and day when it comes to tuning the carburetor,

Re: Engine goes flat on declaration

Of course the bike matters .

There's no way you could tune my '57 Simplex the same as my FA50 . Not even close .

They are both 2 strokes , but vastly different .

Be specific .

Re: Engine goes flat on declaration

get a smaller carb/intake n your problems will go away.

Re: Engine goes flat on declaration

Sounds like a exhause restriction to me, but no one knows which bike you are asking about so we have to be generic in our investigation.

Let me mansplain how the exhause works so you can fix it yourself. On most engines, the exhaust ports stay closed because of a vacuum which has developed in the headers. The cause of this vacuum is several fold: First, a rarefaction was caused during the intake stroke when hot exhaust gases were sucked into the cylinders. Second, the heat sinking effect of the long mufflers (whose job it is to cool the exhaust in order to most efficiently extract spent implosion products) has caused the exhaust to cool during the intake/compression cycle. Third, the acoustical resonance of the pipes reinforces the vacuum pulses at certain frequencies.

In order to transfer the noise caused by a loose fitting on the carbochamber gasket flange, you need to have a propersized muffler bearing spanner or a 10.5mm 8 sided socket and a large screwdriver. After locating the fanotinizer sensor you will need to disconnect the reversion module and make sure it is grounded before opening the access panel.

Find the localizer flange and hold it while rotating the left sprocket couper located to the right side of the plenum adjuster. usually it looks like a Stanley gasket or earlier models have a longer shaft on the kirtsheimer flashing bracket that you need to remove with a 19/16 open sided socket or a short handle wrench.

After you should measure the size of the down pipe, if you look along the exhause you will see the carbon stained point where the leak is located and measure the approximate diameter of the pipe at that location. Using a pair of glassofler cutters open the top and bottom of a large beer can then slice it down the sides. Wrap it around the break in the pipe and use a pair of appropriately sized jubilee clamps to secure the can wrapped around the pipe.

Since the advent of permanently lubricated biturbo muffler bearings 50cc bikes have been boosted to 65 or even 70cc. This rating is based on the old Caster oil Containment measuring system where motorbike mufflers were rated by the capacity of the amount of oil they needed to contain to keep them lubricated. Modern technology has replaced the oil containing mufflers with specially designed 'expansion chambers', these get their names from being expanded but without having to contain extra muffler oil. These were developed by the invention of synthetic oil which is an odorless and colourless gas, further development has not given us totally oil free mufflers which has boosted the fuel milage to over 1000km per litre in Europe.

Muffler oil containment factor is always expressed as a ratio - 25:1, 33:1, 50:1, 75:1, 100:1 etc. This ratio is derived from taking the quantity of muffler oil rating based on the Caster Oil measuring system in cc's and multiply it times the cube root of the peak rpm rating of the expansion chamber and compile the result into the peak temperature of the combustion chamber.

For some machines the manufacturer has added a oil injection system, which uses a high pressure pump to inject the needed quantity of oil into the muffler bearings. After the oil has been through the bearing section there is a scavenge tube which will recover the oil and route it back to the storage tank. The convenience of this system provides the operator with not having to worry about the muffler oil containment factor, when the oil reservoir is depleted of oil a special monitoring system will lock up the piston from moving and shut the bike off. The operator then just needs to replenish the oil in the reservoir and unlock the piston. Because this only happens after many many miles of driving, most operators will sell their bikes rather then doing the proper maintenance required to unlock their piston.

Re: Engine goes flat on declaration

Man, I know I'm going to start sounding like a fan boy but I'm really digging these technical posts of your Reb. Mind if I use some of the content for a class on Moped tuning that I'm starting up? I'm thinking I'll charge around $300 a head. I'd be willing to pay royalties for the use of your content if you agree to my proposition. Think about it..could be a real opportunity for you to capitalize on your knowledge base! ;)

Re: Engine goes flat on declaration

Overpriced Parts /

> Norris Hall Wrote:

> -------------------------------------------------------

> Man, I know I'm going to start sounding like a fan boy but I'm really

> digging these technical posts of your Reb. Mind if I use some of the

> content for a class on Moped tuning that I'm starting up? I'm thinking

> I'll charge around $300 a head. I'd be willing to pay royalties for the

> use of your content if you agree to my proposition. Think about

> it..could be a real opportunity for you to capitalize on your knowledge

> base! ;)

He’s kinda trolling but at the same time there’s some good info goin on ha ha

He is of my own heart runnin small 2t engines with stock ignitions

Re: Engine goes flat on declaration

Indeed - you caught me a trolling - well sort of trolling and entertaining rather than just posting shyte or being excessively spiteful...

I call it TROLLTERTAINING...

> Overpriced Parts Wrote:

> -------------------------------------------------------

>

> He’s kinda trolling but at the same time there’s some good info goin on

> n ha ha

>

> He is of my own heart runnin small 2t engines with stock ignitions

Indeed - running 2t on points and using limited resources because there was not a lot of off the shelf stuff around for speed for so many decades I sort of got the hang of getting speed without a catalogue. Here, performance is built not bought.

Re: Engine goes flat on declaration

You could contract me to speak at your moped class if you want your audience to learn the mysterious art of moped mechanics. When on tour I also offer alchemy, wizardry and spell casting, as well as an advanced class of constructive cussing for the layman (or laywoman) who specialize in mechanics.

> Norris Hall Wrote:

> -------------------------------------------------------

> Man, I know I'm going to start sounding like a fan boy but I'm really

> digging these technical posts of your Reb. Mind if I use some of the

> content for a class on Moped tuning that I'm starting up? I'm thinking

> I'll charge around $300 a head. I'd be willing to pay royalties for the

> use of your content if you agree to my proposition. Think about

> it..could be a real opportunity for you to capitalize on your knowledge

> base! ;)

Re: Engine goes flat on declaration

FYI for future searches. TM24 ideal setup

Atomizer P8 454 series combined with a 4DH7 needle= WOW got rid of all my midrange 4 stroking and decel issues. Super clean hard WOT acceleration now and no more 4 stroke cruising speeds.

« Go to Topic — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account