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  1. #1

    Default Evo dyna loses torque past 65 - Problem, parts or business as usual?

    Gotta preface this by saying Iím still learning a lot about the ins and outs of bike mechanics so apologies in advance for any dumb questions. Looking to figure out if this is a problem or down to the parts/jetting.

    Iíve got a 94 FXDL which I thought Iíd got running pretty well. It was rough as hell when I got it but itís now pulling smooth and hard from standing up to about 65. WOT doesnít struggle at any point before that and I can take it to the limiter without any hesitation or misfiring.

    However above about 65 it just feels like it doesnít really pull like it should, Iím not really looking for a rocket that goes much past that but it definitely feels like itís strangled a bit. I noticed it having to accelerate hard up a hill at that speed.

    The bike is largely stock but has an EV27 cam, CV carb with 45/180, stock headers with SE mufflers, and a (probably restrictive) small louvred air cleaner like the Moon style one.

    Things Iíve checked:

    Carb is clean and running 45/180 jets. It had a DynoJet kit in when I bought it so I took all those parts out and returned it to stock, cleaning everything in the process.

    VOES switch is ok as per the resistance test in the shop manual.

    Fuel screen in the tank and petcock were replaced when I bought it so clean and working.

    Plugs are a light brown colour. These were white originally when I bought it and having issues.

    Could it be the air cleaner just being crappy and I need a higher flowing one? Different jets? Or is there things I could check in addition to the above.

    Thanks

  2. #2

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    1) When you took the Dynojet kit out of the carb (a good move in my opinion) did you install the stock emulsion tube?

    2) Does this bike have the stock vacuum petcock, and, if so, have you checked it for a vacuum leak?

    3) Did you check the VOES for a vacuum leak?

    That bike should hit a hunnert at will, if the motor is sound and the tune-up is not too far off. Period.

    Jim

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    I'm wondering about timing- too retarded can give good bottom end at the expense of top end, but you still have a working VOES...? That filter could be the culprit. Is it clean? Can you tell us what it is? All my bikes bar the Pan run K&N elements with either S&S , SE or Edelbrock housings and backing plates. They ain't small, but they work... I don't know whether that main jet is a touch too small?

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    You already said your air cleaner might be too restrictive. Really easy to check that, pop the cover off and f go for a ride.

  5. #5

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    Thanks for the replies.

    Quote Originally Posted by JBinNC View Post
    1) When you took the Dynojet kit out of the carb (a good move in my opinion) did you install the stock emulsion tube?
    Yeah, I realised it had the DJ kit in when the main jet I was about to install wouldn’t fit in the emulsion tube that was in there. So that all got swapped at that point.

    2) Does this bike have the stock vacuum petcock, and, if so, have you checked it for a vacuum leak?
    I swapped it for an aftermarket non-vacuum petcock since the one that was on when I got it had a vacuum leak. I also capped the hose that went to it originally.


    3) Did you check the VOES for a vacuum leak?

    That bike should hit a hunnert at will, if the motor is sound and the tune-up is not too far off. Period.

    Jim
    The way I tested it was with a pump and ohm reading and just checked for resistance/pressure continuity when applying a vacuum. Seemed pretty consistent. I also changed the fuel/vacuum hoses when I got it as they all looked a little dried up.



    I figured it should have plenty of life left past 65 so good to hear I’m not imagining it.

  6. #6

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    Quote Originally Posted by Hoghead View Post
    I'm wondering about timing- too retarded can give good bottom end at the expense of top end, but you still have a working VOES...? That filter could be the culprit. Is it clean? Can you tell us what it is? All my bikes bar the Pan run K&N elements with either S&S , SE or Edelbrock housings and backing plates. They ain't small, but they work... I don't know whether that main jet is a touch too small?
    It’s just a MoonEyes Filter and cleaner, just the little circular louvred ones you see on a lot of bikes these days. I think TC Bros or LowBrow do the same one. I pulled it off my old Sporty as a quick replacement for the stock element/cover between getting something better.

    Main jet would be an easy change to try, thanks for the reply.

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    Quote Originally Posted by TeeJayE View Post
    It’s just a MoonEyes Filter and cleaner, just the little circular louvred ones you see on a lot of bikes these days. I think TC Bros or LowBrow do the same one. I pulled it off my old Sporty as a quick replacement for the stock element/cover between getting something better.

    Main jet would be an easy change to try, thanks for the reply.
    180 should be about right, but who knows? I ain't pro like JB but what he suggests should be well worth a look.

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    Apart from the air cleaner, which could be a problem, I would be looking hard at fuel delivery.

    Jim

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    Quote Originally Posted by JBinNC View Post
    Apart from the air cleaner, which could be a problem, I would be looking hard at fuel delivery.

    Jim
    Did you remove the plug from the carb when you installed the new backing plate for the air cleaner? If I’m not mistaken the mooneyes ones block the vent that the stock one has a hole for

    I was thinking you were running a super e with the mention of the thunderjet

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    Just a shot in the dark here. I installed a CV on my shovel using the existing s&s manifold/insulator block. The cable pull on the carb was hitting the insulator block. Different manifold for an evo I know.You said you were able to get wide open so IDK. Another vote for a ride without the air cleaner.

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    Yet another vote for removing the air filter cover.

    I always perform a compression test when a bike ain't behaving. Takes a few minutes and then you know your top end health. Testers are cheap (they're just a Bourdon tube gauge and plumbing) and every biker should own one. Any auto store will have one if ya want it quickly.

    As others said, stock jetting or close should get it well above 65 without it falling flat.

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    Quote Originally Posted by TeeJayE View Post
    Itís just a MoonEyes Filter and cleaner, just the little circular louvred ones you see on a lot of bikes these days. I think TC Bros or LowBrow do the same one. I pulled it off my old Sporty as a quick replacement for the stock element/cover between getting something better.
    See post I made here awhile back http://www.chopcult.com/forum/showth...528#post785528

    I ran that air cleaner on my old Sportster and immediately had problems. Could never get it to run right. Granted it was a Super E but as soon as I went back to the Super E air cleaner it ran great.

    I gave that small air cleaner to a friend with an Evo Sportster with a CV. It too, ran like shit. It ended up in the trash.

    Some things just ain't made for function.

  13. #13

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    My 1995 evo 1340 had the Dynojet kit in it and i replaced it with stock HD kit. I also installed the EV27 cam and I can bet you right now you are running too small a main jet.
    The andrews website states you need a 195 main when running the ev27. I tried a 185 and it felt laggy under full throttle. Replaced it with a 195 and it absolutely rips. Try a 45 low jet, 195 main combo. This may solve your problem

    For reference, this is from Andrews site under instructions for installing the cam in 80" big twin (48 low jet was too big for me, i prefer the 45) -

    9. Final tuning of carburettors with bigger cams sometimes requires richer jetting. For stock H/D Keihin butterfly carbs #60 slow jets and #165 main jets work well. CV carbs (’89 and later) use slow jets #48 to #50 and 195 main jets. For 1988 and earlier Keihin carbs, an Andrews Products High Flow Accelerator Pump kit will also improve low speed and mid range throttle response. (Part# 269050
    Last edited by Sugarcubes; 05-13-2020 at 3:32 AM.

  14. #14

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    Thanks for the further replies.

    Compression is 89psi on the front cylinder and 90 on the back.

    I put the stock filter back on as the element on the Mooneyes one is held by the cover so you can’t run it without the cover. With stock filter and no cover it runs much better, pulls smoothly certain as far as my balls will let it.

    So as stated, clearly those air cleaners are just for show. My Sporty never really ran great at the top end with it on either.

    Gonna try a bigger main jet too, sounds like it won’t hurt.

  15. #15

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    Quote Originally Posted by TeeJayE View Post
    Compression is 89psi on the front cylinder and 90 on the back.
    That sounds pretty damn low for a 1340? most stock healthy 80" evos seem to run around 145PSI per cylinder.
    Was that with the throttle wide open?

  16. #16

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    Yeah good call that was my bad I hadn’t fitted the adapter on my compression tester properly. I’m getting 138 on the front and 135 on the rear.

  17. #17

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    That sounds more like it! Run that stock filter and bump up your main jet, you should be good to go

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    I had 45 jet in mine when I got it with similar issue it wouldn't pull up hills without dropping a gear went through cleaned carb it helped some but still wasn't great. On recommendation from a guy on HDforum I went to 48 jet and it's much better can hold 5th and walk right up a hill no problem!

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