1. Husqvarna Motorcycles Made In Sweden - About 1988 and older

Answer Roost Boost???

Discussion in 'Vintage/Left Kickers' started by Bigbill, Nov 17, 2014.

  1. Bigbill Husqvarna
    Pro Class

    Husqvarna Motorcycle:
    '83 250wr
    Other Motorcycles:
    0 right now
    Has anyone ever tried the answer roost boost on a husqvarna Swedish bike?
    The roost boost increases the rpm and supplies a hotter spark in the higher rpm range.

    Now we tried it on a built 85 Honda 125cr. I ported it and added the roost boost. Since I advanced the port timing I advanced the ignition timing a tad too. This 125 was quicker than the newer 250's. We never had a 125 with the hit this one had.

    Now I'm wondering if anyone has tried it on your old husky?

    I'm not sure if some of the original ignitions on the husky could handle it.

    Does the newer replacement ignitions they offer today have a hotter spark at the higher rpm range?
  2. justintendo klotz super techniplate junkie

    Location:
    mercer, pa/northwest pa
    Husqvarna Motorcycle:
    84 250,86 400,87 430,88 250,95 360
    Other Motorcycles:
    99 kawasaki zrx 1100
    i have heard the motoplat is good at pumping hotter spark as the rpms increase. not as good at low rpms for starting as a modern replacement. i personally wouldnt use a roost boost. sounds like it would burn a hole in your piston. i set the timing to what it likes and it good to go. but im not sure what a roost boost actually does
  3. troy deck Husqvarna
    Pro Class

    Location:
    Republic MO
    Husqvarna Motorcycle:
    87 250wr 12 cr125
    Other Motorcycles:
    kx65 ty80 rm80 kdx250
    WTH wood you find a roost boost today im sure its NLA:excuseme:
  4. 86 400 XC Husqvarna
    Pro Class

    Location:
    Calgary
    Husqvarna Motorcycle:
    75,82,83,2x84,85,3x86,87,88 and 89
    Other Motorcycles:
    more Huskys
    I have one, came with one of my 86s. Makes no difference in starting it up or power gains..
  5. Bigbill Husqvarna
    Pro Class

    Husqvarna Motorcycle:
    '83 250wr
    Other Motorcycles:
    0 right now
    Roost Boost keeps the electrical out put of the ignition coil up. They say it increases the rpm by 1,000 rpm.

    I believe making one change is like putting a four barrel carb on a car with nothing else.
    We advanced the port timing, made the ports wider for more flow, advanced the timing. Cleaned up the transfer ports, opened up the transfer ports, matched the cylinder base to the case. The hotter spark from the roost boost seemed to work with all the rest of the work we did. Two stroke engine response is all about the flow. How fast can the exhaust get out so it actually draws in the new fuel behind it. To me flow = chee.
  6. 86 400 XC Husqvarna
    Pro Class

    Location:
    Calgary
    Husqvarna Motorcycle:
    75,82,83,2x84,85,3x86,87,88 and 89
    Other Motorcycles:
    more Huskys
    I know in theory it should help.
    But like adding a MSD 6AL to a good working ignition on a V8, and doing before install and after dyno testing.
    Zero gains, even after playing with gap and so on.
    I had it on my bike and rode it for a while and then took it off and felt no loss.
    Sometimes the best way to feel a gain is to take it away and see if it feels slower to the butt dyno.
    adam6402 likes this.
  7. justintendo klotz super techniplate junkie

    Location:
    mercer, pa/northwest pa
    Husqvarna Motorcycle:
    84 250,86 400,87 430,88 250,95 360
    Other Motorcycles:
    99 kawasaki zrx 1100
    i think theres a reason no one else has ever come out with piggyback things like this.
  8. dkwkid Husqvarna
    A Class

    If I remember correctly-they only lasted so long before they quit. How electrical thing wore out is beyond me. A gimmick at the time along with roost bottles on the intake. I tried one on my Yamaha-made no difference.
  9. Bigbill Husqvarna
    Pro Class

    Husqvarna Motorcycle:
    '83 250wr
    Other Motorcycles:
    0 right now
    Back then the ignition lacked the high end wattage. Today the ignition are way better on the high end. The older bikes lost the wattage as the rpm went up. On the net it was dunno tested and it added another 1,000 RPM. It boosts the wattage out put of the coil.It's like adding a hotter coil in your higher rpm engine. Let's say as an example just saying not a fact the coil puts out 8,000 watts at an idle. As the rpm goes up to 8,000+rpm the wattage may drop to 4,000 watts or less. Now bump the wattage up to 10,000 watts at idle and at 8,000 rpm the wattage may drop to 6,000watts. The stronger wattage at the higher rpm raises the rpm.I know it worked on our 125.
  10. silverstreakNZ Husqvarna
    Pro Class

    Location:
    Christchurch nz
    Husqvarna Motorcycle:
    82cr500,76gp360,90wr250,81 420AXC
    Other Motorcycles:
    74 tm400 , 02 gasgas ec 300
    jeebus . 10 kw at idle ? thats like 13 hp . was this a hybrid engine ?:D
  11. Kartwheel68 Husqvarna
    Pro Class

    Location:
    Newnan, Georgia
    Husqvarna Motorcycle:
    82 125XC, 250XC, 430XC, 430WR, 250CR
    Other Motorcycles:
    83 175WR , 76 250WR, 74 250 Mag
    Roost Boost was a scam, it did noting but take money out of your wallet.

    In relation to a Motoplat, they increase spark energy as they increase in RPM, where a Japanese ignition has very high energy at low RPM and tapers off as RPM increases.
  12. Paul P Husqvarna
    AA Class

    Husqvarna Motorcycle:
    CR400 OR390
    Other Motorcycles:
    Maico Montesa Rickman OSSA Triumph
    The roost boost does not give an advantage to a Motoplat because Motoplat ignitions don't use a box to control timing advance or retarding. Honda's do, and most of the Japanese companies do. There is a little diode in the roost boost that tricks the timing box to keep the advance going an extra 1000 RPM.
    We took one apart in the mid 80's to see what was in it. It was a diode that you could get at Radio Shack for about $1.50( yes, one dollar and 50 cents)
    I tried the roost boost on a Maico with no change in the way it ran. A waste of $50. But on my Honda CR500, there was a noticeable difference, especially on top end over rev.
  13. dukkman Husqvarna
    AA Class

    Location:
    Warwick Queensland Australia
    Husqvarna Motorcycle:
    85/WR 400,86/WR 240,83/430 is mates
    Other Motorcycles:
    69@71/TS90-76/TS100-72/DKW-78/PE
    We had a gadget sold around the shows over here in Aus that went in the coil lead on your car.
    It boosted the spark and cost $50.
    It DID boost the spark too but when pulled to bits it was just a GAP.
    If you force a spark to jump a gap before the plug it increases in voltage.
    Old trick on electric fences is to almost shut the switches [ small gap ] which makes for a bigger voltage on the meter at the end of the line.

    Lot of money for an air gap.
  14. Bigbill Husqvarna
    Pro Class

    Husqvarna Motorcycle:
    '83 250wr
    Other Motorcycles:
    0 right now
    I just figured I'd ask you husky guys about it. I knew it worked on our Honda. I found one for a husky but I'm Leary of the SEM we have enough problems with them without adding a roost boost on it. The huskys don't need it anyway. Thanks for sharing your experience with this.

    With my drag race engine I installed a 10k volt coil. This way the high rpms had plenty of power. Life before electronic ignition.