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Not reving past 16k and..

Discussion in 'Kawasaki 250cc In-line 4's' started by Tom Kenny, Sep 9, 2013.

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  1. Tom Kenny

    Tom Kenny Member

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    Hey guys first post..

    Everything iv read here has been fairly helpful so far! Ok. Iv got a zxr250c that iv had troubles with since the day i got it. Classic 2 steps foward 1 step back. My current problem is the bike isnt reving past 16k and seems quite sluggish. Since iv had it iv cleaned the carbs out, full of ****. Twice. It had a bung peatcock and bowls wernt shutting off the carbs so it flooded my engine with petrol and pissed out every where, so much so it was coming out of the exhaust. Thats all gone now. New float bowl seals and carb to airbox seals. So as it stands now its a bit temperamental. Its blowing some whitish smoke not sure if its a result of the exhaust being soaked with petrol once upon a time or if iv still got a carby issue somewhere along the lines. Any advice?

    Cheers Tom
     
    Tom Kenny, Sep 9, 2013
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  2. Th3_Huntsman

    Th3_Huntsman Senior Member Contributing Member

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    The only input I would have is, white smoke is water and unfortunately can point to a blown head gasket. You were lucky to get her to start after the petrol leak!
     
    Th3_Huntsman, Sep 9, 2013
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  3. kiffsta

    kiffsta Senior Member

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    Hey Tom

    I have the same problem with a motor I have here, I thought it was the head gasket but turned out it wasn't the gasket. I was talking to my mechanic and he said it could be tired rings as the oil scraper rings on the ZXR's do wear out, else he said he could be the valve stem seals giving way. I do know that KDS1 has issues with his water pump seal so it could be as simple as that as he had reported the same problems.

    Cheers

    Chris
     
    kiffsta, Sep 9, 2013
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  4. Tom Kenny

    Tom Kenny Member

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    Should also mention that it dosnt blow smoke when its cold. I have a feeling my float levels might need adjusting? Any suggestions?
     
    Tom Kenny, Sep 9, 2013
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  5. kiffsta

    kiffsta Senior Member

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    same as mine... Im leaning towards the oil scraper rings
     
    kiffsta, Sep 9, 2013
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  6. Phil

    Phil Senior Member Contributing Member

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    Quick question Tom, have you adjustment or played with the floats?????
     
    Phil, Sep 9, 2013
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  7. kds1

    kds1 Active Member Contributing Member

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    Like chris said i had same problem and put new mecanical seal and oil seal in but what I allso did was rerun my vacum lines to carbis when i got the bike thay put new engine in but did not run the vacum hose right so check that first
     
    kds1, Sep 9, 2013
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  8. Tom Kenny

    Tom Kenny Member

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    Had a wee tinker with it tonight, took off the carbs and hopefully balanced the floats. Also what i noticed when taking them off was the carbs wernt in the sleves as tight as they could of been resulting in a bit of an air leak i imagine. I think if it isnt running well when i go for a ride tomorrow then ill do what youve done kds1. Have the roadie booked for wednesday morning so hopefully its sorted before then. Ill let you know how all pans out. Cheers guys

    (also phil, did previously slightly adjust the floats the other day. May pay for me to get them done properly is this doesn't pan out)
     
    Tom Kenny, Sep 9, 2013
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  9. Jim

    Jim Active Member

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    How did you go Tom? Fix the rev out issue?

    I have the same problem on my bike as well. Had the carbs stripped and cleaned by a mechanic. Run much better after that, but still wouldn't rev out.

    Since then, I've started looking at the electrical side of things. Went through the manual and went to test the CDI box. Did all the resistance checks and 1/4 of them were out of limits. According to the book, it meant it's time for a new one.

    Newer(2nd hand) box is coming in the mail and will see how it goes.

    I've already replaced the spark plugs, plug caps and ignition leads. Only things left would be the pickup coil and ignition coils.
     
    Jim, Nov 9, 2013
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Tom,
    My two cents.
    Worn rings will blow white smoke (burning oil). With a warm engine hold the throttle open at about 60 - 70%. If it is blowing smoke then you can bet your bottom dollar you need rings or at worst a rebore. Are your spark plugs wet, or anything other than bone powder dry? If you answer yes to these then the next step is a leakdown test to see how bad it is.

    If it's bad, then top end strip and pistons measured with a micrometer and cylinders with a dial bore gauge (certified instruments not eBay specials).

    If bore and hone then you have to find someone who can actually do this. The boring and honing of motorcycle cylinders is a fine art and should not be trusted to your local auto engineering shop (too coarse and nowhere near accurate enough). Ron Russ in Brisbane used to do the best work I have ever seen and measured, but I do not know if he is still operating, and I do not know where you are (please put your location in your profile so members can help you). There are good operators everywhere but the trouble is finding them. The road to hell being paved with good intentions and all that, I only believe what I can measure and nothing else. Finally if you do have a fine cylinder finish then your new rings will bed in very, very quickly. You have to get on the gas, none of this running it in for 1000 miles malarky.

    If your bore tolerance is ok then your cylinders must be deglazed (lightly honed) prior to fitting new rings.

    It is very rare that oil being burnt is a just result of worn valve guide seals. We all want to believe that "it just needs new valve guide seals", but unfortunately it is rarely the case.
    cheers
    Blair
     
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    Last edited: Nov 9, 2013
    maelstrom, Nov 9, 2013
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  11. kds1

    kds1 Active Member Contributing Member

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    also remember the specs in the manual for the c model 94 and up wher limitide to 15500 rpm get a cdi of a 91 model and taco and shel be all good check your cdi number if you have 21119-1322 your good if you have a 21119-1384 you have a restricted cdi good luck check those numbers
     
    kds1, Nov 9, 2013
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  12. Jim

    Jim Active Member

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    Thanks for the info kds1. I suspected the CDI my be restricting something and I have a 21119-1384 fitted to my bike. Strange how I have that part number since my model is a 92. Somebody must've changed it.

    How come you need to change the tacho as well? Is there a speed limiter built into it like the MC22?
     
    Jim, Nov 10, 2013
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  13. DougFella

    DougFella Well-Known Member Premium Member Contributing Member

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    Does anyone know where this is in the manual or can confirm as well? I didn't think they blanketed the RPM for restriction but it may explain a similar hesitation for my bike to rev past 16k under load.
     
    DougFella, Nov 10, 2013
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  14. Jim

    Jim Active Member

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    Not sure if these CDI restrictions affect A models, Doug. Those CDI part numbers in kds1 post are for C models.
     
    Jim, Nov 10, 2013
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  15. DougFella

    DougFella Well-Known Member Premium Member Contributing Member

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    True but I have a C model engine I'm not sure of the CDI i have not checked it yet. Most ZXR250's you buy these days are going to be a mix and match of parts from every model due to their age and people replacing/fixing things.
     
    DougFella, Nov 10, 2013
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  16. kds1

    kds1 Active Member Contributing Member

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    Sorry guys bit late but it`s 16krpm not 15500rpm and the info for this is in the genral infomaition section of the manule you can down load in resources. Jim from all my research i have done yes theare is a speed limiter and i think from memory its in taco thears alittle magnet or somthing that when you go past 15500rpm it kicks in ill try and get some links to the info check back soon. Dougfella if you have a Cmodle engine then you will need to check your cdi the fireing order is diffrent to the a A an B modle so good luck. the cdi 21119-1322 was discontinued because of the restrictions intreduced in japan between late 93 onwards hope this helps you guys out.
     
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    kds1, Nov 10, 2013
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  17. DougFella

    DougFella Well-Known Member Premium Member Contributing Member

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    Yea will have to check that out. I'm assuming that the it means when you go past 16k RPM the restriction cuts in. Not that it stops it from revving past 16k?

    Is 1322 the A/B model part number or the one for the C?
     
    DougFella, Nov 10, 2013
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  18. kds1

    kds1 Active Member Contributing Member

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    Yea that's right mate AnB modles have difrent numbers 1322 is C model unrestricked
     
    kds1, Nov 10, 2013
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  19. Jim

    Jim Active Member

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    What are you experiencing, Doug? On my bike, it'll barely go past 16k in 1st and 2nd. Maybe touch 17k, but you can feel something hindering it. Higher gears and the rpm is limited to 16k flat.

    21119-1322 is a C model CDI box.

    x-1263 and x-1290 are A model CDI PN's. The A model CDI has two electrical receptacles side by side ( rectangle and square). The rectangle on an 'A model' has 4 pins and the square has 4 pins. On the 'C model, the rectangular plug has 6 pins and the square has 4 pins.
     
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    Jim, Nov 10, 2013
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  20. DougFella

    DougFella Well-Known Member Premium Member Contributing Member

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    Similar to yours. Revs ok up till about 14.5k then starts to back off and once you get around 15.5-16 it's not work it and you just change gears. I have not tried forcing it past the 16k mark, I know it'll free rev past it.

    When I get some time to check the CDI box I'll have a look. Got a lot to do at the moment.

    I know you can get a de-restricted CDI box as well has anyone used one of them before? I hear they help quite a lot but the downside is there's no rev limiters on them. I've also got the 180km speedo
     
    DougFella, Nov 11, 2013
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