Thunder Products

Hi all, as I am trying to get the best out of my Amal MK 1 Premiers for the race bike until the Mk 2's become available, anyone had experience with these products, and if so was it worth it?
Would like to see if I could get them to fit the Amal # 3 slides
Regards Mike
http://www.thunderproducts.com/u_f_o.htm

Brooking 850 said:

Would like to see if I could get them to fit the Amal # 3 slides
Regards Mike
http://www.thunderproducts.com/u_f_o.htm

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If you can't find one that fits then it then order the next size up. Anyone with a lathe could turn it down in five minutes.

Just as an aside, that cavity is an intentional design feature. It's called a mixing chamber. Mikuni, keihin, Amal, and Dellorto all do it. It could be that it's a trade off of better running at lower throttle openings over wide open throttle. On race bike you probably don't care about lower throttle openings.

thanks Bob, spoke to a guy who has used them on 2 strokes large CC types, he said it enriches the idle and pilot circuit and therefore gives instant response on the lower movements of the slide. He loves it. Have to rejet as it richen's the whole range.
Food for thought
Regards Mike

There are lots of modifications for carb slides and people have tried all sorts of configurations to try and improve velocity.

First I would question the claim that it works as good or better than a flat slide.

Second most of these only effect one portion of the throttle response and make it difficult to tune the other areas. If your up to trying to tune this in then go for it...it's not "Plug and Play" though.

I've seen all sorts of people trying to modify slides to improve flow with mixed results...mostly bad.

Why not just put some flat slide carbs on there and be done with it

Cant use flat slides to make the race class under our rules here in NZ with the NZCMRR I have flat slide on my Roadster
Thanks and understand the 'snake oil concept' was interested to see if there was any history out there.
Regards Mike
http://www.nzcmrr.com/events/rules;jses ... 6E93536758

See Item 20

Hi Mike,
I have some experience with the UFO but not installed on an AMAL, ..In a single 34 mm Mikuni VM carb. Yes they damn sure work. The problem is you have to be a tinkerer. Thunder products provides you with a plastic fixture to accurately locate and drill a small hole into the brass on the upper cavity of the slide ( where the spring goes into). The hole is the means for anchoring the plastic ramp to the bottom of the slide by screwing in from the top into the plastic ramp. The orientation of the little UFO is crucial because if not properly aligned, the ramp may not permit the slide to totally bottom in the throat of the carb.
It sounds like you are committed to AMAL carbs, already. I would suggest if you wanted to see what it can do try picking up a single 34 Mikuni on the cheap ( used ) and give the UFO a try. Mikunis are simple to rebuild and rejet and even to disassemble and clean.
Heres what I experienced. The acceleration with the UFO installed was really much improved at 1/4 to 1/2 throttle and that's where it kicks you in the pants right off. It pulls really hard and feels almost turbine smooth. Going downhill in 2nd gear, it seems like there is hardly any engine compression braking and the exhaust pops some on decompression. Setting it up might require a change to your air jet ( Mikuni) and likely the pilot jet as well. WHen its right, the Commando lights up and it runs like a deer on the first day of hunting season. .
Now there is a second device which Thunder Products sells which is a cross vane stainless steel divider which snaps right into the outgoing throat of the carb. What this does is it intensifies the mixture charge at low throttle openings by simulating a smaller carb throat with the help of the divider blocking off 1/2 of the upper diameter on the outgoing side of the carb. I have not tried this ..but I am willing and interested to do so based on the performance results on my COmmando with the UFO installed.
I stuck with a single 34 Mikuni primarily for mileage concerns with the smallish roadster tank. The guy in customer support at Thunder ( I think his name is Les) is very helpful. The plastic UFO ramp is interestingly fashioned with a wedge shaped ramp with grooves on the bottom side which mate with the lip shaped ridges in the bottom of the Mikuni throat.
I tried a Mikuni flatslide to compare with how the UFO worked and I'd have to say the UFO provides a stronger launch and harder pull. I must admit that I did not do a lot of changes with the Flat slide Mikuni as I did with the VM Mikuni. You may even have to use a dremel to gently shape the plastic piece for proper bottoming. Otherwise you may not be able to bring down the idle RPMs sufficiently with the idle screw and pilot jet.
It takes some willingness to tinker and discover how the jetting circuits of the carb affect the mixture at small throttle openings. I don't see why the same idea wouldn't work with an AMAL carb. The genius of it is that it eliminates the turbulence from the back collar of the slide by filling it in with plastic. Air flies smoothly and cleanly into the intakes to the open valves.
If you try it thinking you are going to get it to work without having to change your jets or not need to investigate why your idle will not lower, its better you just let it be. I ended up using the dremel to deepen the cutaway on the Mikuni slide a bit to lean the mix a bit more. If you are not willing to try stuff like that and to buy a spare slide, you may just give up before you find out what it will do.
I ruined one plastic UFO disk by grinding on it a bit too much...but having experienced the rush of acceleration from the device after i installed it in my Mikuni, I had to give it a second try. I have a new UFO now and plenty of Mikuni jets ( they are not really expensive and most shops will order them for you)

I just have been preoccupied with another machine since last summer, actually 2. One is a 1996 V4 Honda VFR 750F a really great motor, and the other is the 2003 VTEC V4 VFR 800 which I was busy debugging a surge in the VFR VTEC 800 fuel injection low throttle circuit. Both have been incredible road machines for 250 mile touring runs into West Virginia 's Pocahontas and Tygart valleys.
I keep anticipating how much fun it will be when my 850 MKIIA is back in the UFO groove this spring.... and when I get my hands on the new quad vane device. Les said it takes up the power band where the UFO leaves off. The nice thing is you are only using air flow shapers and nothing like turbo charging or such to get a nice... inexpensive... performance mod.
Its nothing you even can see.
It seems I recall hearing the air filter hissing a bit more on power and there is also the bit of exhaust popping you may not find to your liking. ping me on email for further questions.
Ed the_tomato_man@verizon.net
The 3rd CNW Commando.... double O 9. Licensed to Thrill

Wow ! Me need this piece o' plastic...

Tomato man gave my ride buddy Wes's '71 34 Miki a UFO which pulls my wrists from right off idle and is a terror to hang with my Combat dual Amals when he's in a mood. Don't know if UFO can be adapted to Amal d/t bore size and the slide bottom and floor grooves but have thot of making an epoxy version. Thanks for pointing out the flow divers concentrator, another innovation that Amals might like, if you are still in misbehaving stage of maturity. I think the single 34 has potential to flow more than two 32 single throats at least in my Peel's case.
LIve deer jokes are distasteful to me.

Mike, when you get them fitted and sorted and proven to work, then you can knock a batch out on a 3D printer and hand them to all your Amal using friends at Xmas time.

Never knew these existed although it's something I have thought about. Properly done they will reduce turbulence and therefore also resistance through the carburettor and so increase velocity and volume flow rate. The majority of air/fuel mixing is done in the combustion chamber/cylinder on the intake and compression strokes through turbulence in the form of swirl and tumble, or barrel roll. Hence squish bands, TSCC, pent roof combustion chambers, radial valves, port angles etc. Think I'll make up a pair and see how the bike responds. Should definitely improve throttle response from tickover to fully open.

Sounds like snake oil to me, if all these advantages were so simply gained, they why has it not been done by Mikuni Amal Dellotos etc etc. the vane device sounds like the "turbulator (???) that was sold into the 70s for fitting in intake ducts upstream of the carbs.

Snake oil unless the vendors can come up with some back to back dyno runs that could demonstrate the changes in power and torque. If as the customer you have spent hours fitting and fettling the gadget, followed by careful tuning of the carbs to get it to run right, your Butt dyno will record serious changes in power delivery.

IMHO etc etc

A Wal Philips Fuel Injector was, Once bitten ( as a 17 year old with a c15) twice shy.

If these gadgets do work, then let's have some back up to demonstrate . Dyno time is cheap nowadays.

As the parts are small try Surrey Cycles ( google it ).

I know the guy and he knows his carbs.

Andy

chasbmw said:

A Wal Philips Fuel Injector was, Once bitten ( as a 17 year old with a c15) twice shy.

If these gadgets do work, then let's have some back up to demonstrate . Dyno time is cheap nowadays.

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Thunder products claim between .75 and 1 horsepower per 100cc, so with a Commando that means an extra 7.5 BHP , a standard Commando on a dyno jet will probably show around 50bhp, so an extra 7.5 gives an extra 15% horsepower. That's somewhat unlikely don't you think, if only it was that easy.

I figure if Ludwig is willing to add the extra weight, it must work.
Jaydee

Brooking 850 said:

thanks Bob, spoke to a guy who has used them on 2 strokes large CC types, he said it enriches the idle and pilot circuit and therefore gives instant response on the lower movements of the slide. He loves it. Have to rejet as it richen's the whole range.
Food for thought
Regards Mike

Click to expand...

It richens the mixture because it's an air intake restriction. If it was the answer, it would already be there. Another placebo.

It's obvious that the air flow will be improved - not restricted.

Al-otment said:

It's obvious that the air flow will be improved - not restricted.

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Obviously... :roll:

These have been around a long time, tried and discounted.

Ok, so it's not obvious to everyone.

Higher/faster flow over the spray tube and float bowl pilot vent will see greater suction 'signal' to draw up more fuel faster, so tends to enrichen from the restriction, which ain't blocking flow just narrowing the passage same amount of air much flow through as w/o the streamlined narrows.