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Project ‘89 FZR250r 3ln1

Discussion in 'Your 250cc Projects' started by Brandon Otte, Jan 8, 2021.

  1. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    OK, tip for you Joker had an issue with his 3LN? after putting a keyster kit through his carbs - the inside pair kits -v- the outer pair kits had the wrong main jets in them - this had previously been noticed by @my67xr - it's wrong on the boxes

    His bike wouldn't rev out properly either - I'm sure we get weird looks at being so pedantic about 'bloody fizzer carbs' but they are finicky and need to be set correctly

    Some discussion took place, connections were made and we realised that the same error had caught him out

    Now, this much is certain, the inner pair because they intake warmer air, which is less dense run leaner, SO the inner pair of carbs get the smaller main jets AND the outer pair, because they intake cooler air, being cooler/cooled on the outside edge get the larger main jets

    Easy to check before you delve into everything else
     
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  2. Frankster

    Frankster "Play stupid games, win stupid prizes" Staff Member Premium Member Ride and Events Crew

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    Okay Brandon, just to add to what @maelstrom wrote...

    When you pull the plugs out, check the gap. If it's at the higher end of recommended or higher, then put them back in with the gap at the lower end of recommendation.

    Also, sight testing carbs (or bench testing) is okay, but it's never 100% right. I don't care if your mechanic has been at it since he was in diapers, but you have to sync the carbs with a hot engine and allow the individual cylinders and their compressions to affect the sync.

    And finally, I always run fuel into a rebuilt set of carbs (to check for leaks and that the needle/seats are 'working' ) before they go anywhere near a motorcycle. All you need is a bit of fuel hose and a funnel. You can empty the fuel bowls once you've completed the test.

    Cheers
     
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  3. Brandon Otte

    Brandon Otte Active Member Premium Member

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    6F365EB6-99EB-4AD3-88CF-87E665546E7F.jpeg How good
     
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  4. Brandon Otte

    Brandon Otte Active Member Premium Member

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    Hi all,

    I am finally taking my bike in for a reregistration check this Friday… have been putting it off for so long waiting for those carbs, now she’s back together I’m hoping it all goes smoothly and passes.
    Here in NZ because it’s previously been vinned and registered it should be fairly straight forward - much like a warrant of fitness check but a lot more thorough.

    Will let you guys know!
     
  5. Brandon Otte

    Brandon Otte Active Member Premium Member

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    @Frankster @ruckusman thanks I’ve just noticed your replies sorry didn’t get the notification.

    I’ve had it running for an hour or so and seems to be revving up just perfect atm, yet to change the other 2 plugs but will do that this weekend. Cheers
     
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  6. Brandon Otte

    Brandon Otte Active Member Premium Member

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    So I’ve noticed spark jumping from the #1 cylinder lead jumping to the valve cover. Is that a clear sign I need new leads?
     
  7. jmw76

    jmw76 Well-Known Member Premium Member

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    Well that shouldn't happen. Check the quality of the insulation on your leads. Also check your plug. If they are resistor plugs, maybe the resistor has gone open circuit. Maybe if there are resistors in the plug caps they may also have gone open.
    You could also just move the plug lead away from the cam cover :dance2::dance2::dance2: but that will not solve the problem.
     
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  8. Frankster

    Frankster "Play stupid games, win stupid prizes" Staff Member Premium Member Ride and Events Crew

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    So I’ve noticed spark jumping from the #1 cylinder lead jumping to the valve cover. Is that a clear sign I need new leads?

    I've never seen that happen, so I'm curious to know what's causing it. The idea of a spark outside of the combustion chamber where there are fuel fumes and other potentially ignitable gasses worries me a tad!
     
  9. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    You need to pinpoint exactly where its coming from .... run the bike in the dark

    3LNs run 10K ohm caps which can be hard to find and removing the leads from the coil end is not an easy task either as the holding clips usually break

    Have the leads been trimmed and screwed back into the caps recently?

    Read thru these posts ....

    https://www.2fiftycc.com/index.php?threads/help-required-please-fzr250.10045/page-3



    coil clips.jpeg

    plug caps.jpeg
     
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  10. Brandon Otte

    Brandon Otte Active Member Premium Member

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    Yeah I've been hearing a clear 'click' from which I know see is the spark jumping from the spark plug cap right about where it reads "NGK" as in your photo above and directly across onto the inner face of the valve cover. I noticed while running it in the dark but can see it clear as day in the light too.

    I was wondering about the leads, I bought a set from the local super cheat but I suppose they wont be suitable. I'll read through that link thank you!
     
  11. Frankster

    Frankster "Play stupid games, win stupid prizes" Staff Member Premium Member Ride and Events Crew

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    Brandon, if it's just one lead doing it, then just check the lead is installed properly. It might just be loose.
     
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  12. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I got some high quality replacement lead wire, proper suitable stuff for bikes from the local bike mechanic

    Getting the clips off of the coils is a real trick, as others have noted, not breaking them is the knack - it can be done
     
  13. Brandon Otte

    Brandon Otte Active Member Premium Member

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    2768E78D-59F0-4E96-998C-5019D01F5243.jpeg B8C47F6B-5C5B-43EE-9CBC-85FD9EAC827B.jpeg 0DD2EB44-C31F-45A3-B470-7E72E05F9DAB.jpeg
    So changed the #1 + 2 plugs. Noticed the lead caps are 5ohm. Anyway put the caps back on and the #1 lead fell out of the coil…with two cable ties which I assume were there to hold it in place.
    So I have managed to buy a second hand pair of coils with leads etc - will try them out on the weekend and fingers crossed she runs abit better.
     
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