High rev upon start up

Discussion in 'Engine' started by QuickEK, Aug 15, 2019 at 3:58 AM.

  1. QuickEK

    QuickEK New Member

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    New to the blaster game. Bought this blaster (of an unknown year) 2 weeks ago. Was told it needed a new kickstart which turned into it had no compression. Replace top end and upon start up with choke engine revved higher than what I would call normal, with choke removed it revs sky high. Immediately killed it and started reading. I’ve made my homemade leak down tester and leak tested and found both crank seals leaking. Replaced both crank seals and re leak tested and it passed, holding 9psi for well over 10 mins. Put everything back together and still same problem. Replaced carb still same problem. Air screw is backed out 1 1/2 turns and has no effect on rev when testing. Tors delete kit on the way. Bike to my knowledge has an fmf pipe with bills pipe silencer, vforce3 reeds, saw hot rod written on rod when replacing top end (not sure if relevant) running a 25:1 fuel mix. Could jetting be an issue? Has 230 main jet with needle in third setting from pointy end. At witts end with this. Bought my son his first 4 wheeler (he’s 16) and he can’t even ride it. Any help is appreciated.
     
  2. Larry's Shee

    Larry's Shee Active Member

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    Did you do a leak down test after assembly? Retorque after heat cycles? Did you use cheap Chinese junk parts?
     
  3. QuickEK

    QuickEK New Member

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    I leak down tested after assembly and haven’t ran it really long enough to put it through a proper heat cycle but I have rechecked torque on both jug and head.
     
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  4. QuickEK

    QuickEK New Member

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    I should also note that if choke is off and it’s revving high I was able to bring it back down by covering breather tube on intake box. Only did this once and didn’t have it running long (really not trying to mess anything up) I also have old oil injection port in carb capped off
     
  5. Awk08

    Awk08 Administrator Staff Member Technician

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    Have you messed with the stock idle screw on the TORS box ? they've been known to mess up and not adjust the slide.
    throttle cable routed correctly with correct slack ?
    needle down into needle valve as you assembled it ?
    carb slide in correctly with notch aligned with pin on kicker side ?

    any of those could be holding the slide open, look in the back of carb and see how far the slide is being held open ? it should be barely open, like 1/8"

    edit: the suggested jetting on here is for 32:1 < the most popular and proven mix ratio for these engines.
    25:1 adds more oil and leans out the air/fuel ratio and may require 1-2 main jet sizes larger, that has nothing to do with starting and idle, only 3/4 throttle and above. but worth mentioning.
     
  6. QuickEK

    QuickEK New Member

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    Throttle cable is routed correctly. Needle is in correctly with slide in correct position. Tors idle screw seems a little fudged, it just free spins either way ( doesn’t feel like it’s grabbing threads) but I do have tors delete coming. I appreciate the advise on the oil/fuel mix. I will be changing to 32:1 on next tank. Slide looks to be more than an 1/8th up. Maybe closer to a 1/4.

    Side note: your posts from the past awk08 got me to where I am now in regards to checking everything I have already checked so thank you for that!
     
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  7. QuickEK

    QuickEK New Member

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    Update: Vito’s tors eliminator kit arrived and is now installed. I also jetted the carb with Dyno jet kit dxp 220 main and needle that came (clip in third space from top)with kit. Followed direction of jet choice (stage 1)accordingly due to have after market silencer/exhaust. Now have new issue. Bike will not start without throttle pressed and will not rev when throttle is pressed. Tors brain is unplugged and plug at throttle is remove and plug at carb is disconnected. Any help is appreciated!



    Side note: high idle I believe was caused by broken throttle cable previous owner wrapped in electrical tape as a repair. Blended in nice would’ve never saw it if I hadn’t removed it
     
    Last edited: Aug 17, 2019 at 3:50 AM
  8. Awk08

    Awk08 Administrator Staff Member Technician

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    NO, a 220 main is leaner than the stock 230 main, and the stock needle in the middle slot is the only needle that should be used.
    I don't recall one person on here having any luck with these "jet kits"
    get yourself 270 thru 310 genuine mikuni jets, put the stock needle back in there
    and do the plug chops to determine main jetting
     

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