I need advice any input welcome

Discussion in 'Norm's 2 stroke repair center' started by dob1385, Aug 20, 2016.

  1. dob1385

    dob1385 New Member

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    Well I have my new engine on my bike. Its a thats dax bottom end with arrow

    reed middle and fred head. The problem is the drive train and also the carb.

    I have an adapter that bolts into a disk brake mount on the back wheel. I threw

    the chain wich bound the back wheel and broke spokes. I want to be able to

    keep up with traffic, whenever Im at full throttle things tend to brake I need

    ideas for a solid heavy duty back wheel setup. Additionally my keihin carb is

    problematic. the acceleration is poor. I was hoping for more low end torq with

    the reeds but it is slugish. It definately has a higher top speed and the dax

    bottom end keeps it a lot smoother than my previous engine. I have the

    needle set to the lowest fuel seting with the choke halfway on to run it.

    lowering the needle clip makes it worse. I think I need to down jet it but the

    jets are not marked with the size and I have been unable to contact arrow.

    do I need a moped hub and smaller jets? can I get a moped hub to replace a

    26 inch wheel. when the engine picks up speed its fast but lagges on the low

    end. Im sorry for the length no other choice.:-||
     
  2. Tyler6357

    Tyler6357 Well-Known Member

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    Is it 4 stroking? If so you will probably want to jet down to a smaller jet. However, its best to break the engine in before messing around with jets. I think the standard stock jet is a size .70, maybe you should try a .65 if it's 4 stroking badly. Also, the engine chain must be as straight as possible between the engine sprocket and the rear sprocket. If it's straight and it keeps jumping off the sprocket you might have the chain too tight, move the chain tensioner down a little bit, the chain should have some slack in it. I doubt your rim is the reason it's jumping the sprocket and you probably don't need to change it, it's probably the chain tension, just fix the spokes, true the wheel, and test it by hooking up the chain, getting the back wheel off the ground, and turning the peddles as fast as you can with the engine disengaged to make sure the chain won't fly off before riding.

    http://www.ebay.com/itm/231458900645?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
     
  3. dob1385

    dob1385 New Member

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    I dont believe it is four stroking. It is just very slugish until I get up to higher

    rpm's. like after i have gotten up to 35-40 percent of top speed wich I think is

    about 30mph. even then if I open throttle to full it wont accelerate as fast as

    if I have it 2/3- 3/4 open depending on speed. I dont think I have an air

    leek. I

    took gasket maker to some of the areas that could leak. The keihin has an

    internal seal and I have the hose clamp on tight. When one checks for an air

    leek do you spray with very soapy water and look for bubbles?

    Thank you for your input and assistance.
     
  4. ZipTie

    ZipTie Active Member

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    If its not 4 stroking then yes it maybe too lean. I do not have that carb nor reed valves, but your intake since its sucking air won't make bubbles but rather will suck them in.
    Some guys dangerously in my op spray starter fluid where they suspect the intake leak And if rpms increase it signifies a leak. Possible fire danger here so not recommended. You certainly may have an air leak, could try running without the reed valve and see what performance is like. I would report back after that is tried. Or just try to look for bad gaskets, rough mating surfaces etc.
    I believe with a reed setup you have an extra joint where un mixed air can get in .if your connections are not fairly perfect. A small amount of permastex maybe what the doctor ordered also. Your fuel petcock may be too restrictive also, starving the engine at higher rpms. Not uncommon either. Just try one potential fix at a time.

    Zip
     
    #4 ZipTie, Aug 25, 2016
    Last edited: Aug 25, 2016
  5. Tyler6357

    Tyler6357 Well-Known Member

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    Okay, if you can get up to 30mph I doubt you have an air leak. What kind of pipe are you using? Do you have an expansion chamber?
     
  6. dob1385

    dob1385 New Member

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    right now its a cut of exhaust. I have a sbp expansion chamber. Im learning to

    weld to get it on now. Didnt have luck with the silicone and I broke the loop

    where you attach the springs. I figured I would go with Jaguires calculations

    and guestimmate header length for about 16 inches.

    The bike is currently down. I was stupid and had the chain too short cause the

    bike side chain was too short. This caused the chain to rub and threw it which

    froze my rear wheel and busted spokes. Thankfully I ride low in the seat

    and had front disk brakes and rear v brakes. Skiing on my feet and using

    both brakes I just barely avoided biting the dust.
     
  7. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    This means that the carb is too lean.
    Whenever you add a reed valve, you need you install a much larger jet!


    As for your problem with the chain... Can you post a few pics of your whole setup so we can try to spot any problem areas??
     
  8. Tyler6357

    Tyler6357 Well-Known Member

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    Venice is an expert, put in a bigger jet! Also, I have a SBP expansion pipe and I've got about a 16" header. I have found that I have tons of low end but the power band ends at about 85% throttle and after that I will be out of the power band and won't get any more. I've been thinking of cutting the header down some but I really like all that low end and don't really care about going much faster on it. I've already got a Fred Head with a squish gap of about .03" and my weight (bike, tools, and me) is about 265lbs, using a 40 tooth sprocket, your results might be different.
     
    #8 Tyler6357, Aug 25, 2016
    Last edited: Aug 25, 2016
  9. dob1385

    dob1385 New Member

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    First let me thank everyone for there input I really apreciate it.

    Tomarrow I'll take pictures. I finally got acces to a phone that has a decent camera.

    Im down to get a bigger jet but when I lowered the needle clip it seemed to

    make it worse. To complicate the matter neither the pilot or main jet are

    marked. I was running a 65 on my old RT carb seemed to work well. I think I

    might have opened the choke up a little when I dropped down the clip. Its got

    five setings or notches. I droped from top notch to third. anyone know how I

    could figure out the size of the jets? I dont have micro drills or anything like
    that.

    I should also add I dont have a air filture. I accidentally pulled it off the

    rubber where it was glued, I stuck it bike on but it fell off while I was riding

    never to be seen again.
     
  10. dob1385

    dob1385 New Member

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  11. dob1385

    dob1385 New Member

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    ok so that little square links to my new photot bucket. If you have any advice on how to

    do photos please share. I looked in the forum rules area but i couldnt find. Im probably

    looking in the wrong place
     
  12. Dave31

    Dave31 Moderator
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  13. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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  14. dob1385

    dob1385 New Member

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    thank you.
     

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