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Help with my FZR not wanting to run properly

Discussion in 'Yamaha 250cc In-Line 4's' started by hagenstew, Aug 13, 2009.

  1. hagenstew

    hagenstew New Member

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    G'day everybody,
    So I have had my FZR for about 4 months now and for the last 4 weeks I have been sorting some problems out. It had a stupidly noisy cam chain so I have dropped the engine out and changed it over. Havin never worked on an engine before I thought I had done a bloody good job getting it all going right. The cams are perfectly timed with the crank and all should be going well.

    However...

    I have since tried starting it and have had it going but when I went to ride it gently around the block I got 2 blocks from home and had to give way to someone and she just stopped in the middle of the intersection (at least I got my excersize for the day). Then yesterday we tried to start it again and managed to get it going but now it's making a horrible farting noise like it's missing.

    Any ideas guys? I have read quite a few threads on here talking about inlet valves/clearances/compression but I checked the clearances while I had the rocker cover off and they are all fine.

    Cheers,

    Hagen
     
    hagenstew, Aug 13, 2009
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  2. glen5122

    glen5122 New Member

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    does it start better with the choke?
    did you o anything at all to the carbs?
    does it start easyier with aerostart?
    where is this sound coming from?

    these bikes will run fine in the garage with no air box but when you try to ride it trust me you need the air box on.

    check that the exup is on properly.
    check the cam chain tensioner is in properly(and not worn away) cuz if it wasnt the note* exhaust cam might have slipped a tooth or two(really bad fix imeditely)

    if you check all that the only thing i can think of it that the exhaust or inlet cam is no in time.

    note* the inlet should slip first but i am assuming that this sound is comin from the exhaust.
     
    glen5122, Aug 13, 2009
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  3. hagenstew

    hagenstew New Member

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    It won't start on the starter motor anymore, we had to push start it yesterday only to hear said horrible noise. The first time we got it going was on the starter motor and yea we used a bit of engine start.

    I have checked the ignition and am getting nice big blue/white sparks from all plugs. Exup is on fine and working correctly (that was the first thing I checked). The cam chain tensioner was in perfect condition, but I haven't checked it since putting the rocker cover back. In saying that, I did give it about 10 full rotations with the cover off to make sure the cams were timed perfectly.
    I haven't done anything with the carbs except take them off and put them back on. They were sitting under some rags to stop dust getting to them in the garage while they were off.

    It definitely wasn't making a metal on metal noise when riding it. It just sounded as though it was misfiring on a cylinder.

    Today I have charged up the battery again and have tried to start it, but no luck getting it going. It made a few puffs of exhaust every time the starter motor would crank round but the battery got tired after quite a few tries so I have given up.

    Thanks for your advice (even though it means that the engine will have to come out again)
     
    hagenstew, Aug 13, 2009
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  4. glen5122

    glen5122 New Member

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    you dont have to drop the engine to this work just take out the radiator including thermostat and radiator cap gives heaps of room to do timing. it's much easier.

    im playing the shim swap game right now with the motor in and it's easy
     
    glen5122, Aug 13, 2009
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  5. glen5122

    glen5122 New Member

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    with lead acid batteries if you want them to last as long as possiable drain them as little as possiable. A normal car battery could only take about 200 compleate drains and fill cycles(about 3-6 months) but if you only use a little bit and it's charged shortly after it could get 10'000 cycles. Also if your gona leave a battery for time it is best to leave at full charge.

    Bassicly they like to not get used much and stay at full charge all the time.

    maybe use a running car with jumpers to your bike(leave bike battery in) to help start bike. This gives you an added bonus of a little bit higher voltage and like 500cca so the starter motor will turn over faster which helps start troubelsome bikes. just remember to give your starter a rest and cool off every now and again(it's only designed for very short term use)
     
    glen5122, Aug 13, 2009
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  6. dave

    dave Well-Known Member

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    I think first I would be checking the valve clearances again plus the cam timing. Make sure that you do not have a valve stuck slightly open.

    Other things to check...

    Is the fuel tap on??

    Do you get the same amount of fuel out of each carb when you open their drain valves. Then test does it keep running out?? (need ignition on and fuel pump running for the last bit).

    Get a compression test done..
     
    dave, Aug 13, 2009
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  7. hagenstew

    hagenstew New Member

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    Ok, I have just checked everything mentioned:
    The cam timing is still perfect,
    Carbs drains all had the same pressure and looked like the same volume of fuel came out of all four,
    Fuel tap is on and I'm definitely getting fuel,
    Exhaust valves are all within 0.2 and 0.3 mm,
    Intake valves on cylinder 2 and 4 are great around .15,

    Now intake valves on 1 and 3 are pretty tight... the smallest feeler gauge I have is 0.05mm and this wouldn't fit under 3 of the four intake valves on 1 and 3, the other one is pretty marginal and would pass a 0.075 but not a 0.1.

    Obviously I am going to have to reshim these valves but would that really have much effect on starting? And would it make the engine misfire like what I was hearing?

    Thanks heaps for all the help guys.

    By the way I should probably introduce myself as I'm new..

    I'm Hagen, from New Zealand and have had the FZR for about 4 months and before I began taking it apart it was the best purchase I have ever made.
     
    hagenstew, Aug 14, 2009
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  8. dave

    dave Well-Known Member

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    That it ran ok for a short period is interesting. It stopped when you pulled up. Flat batteries do this. Try starting with jumper leads off a car battery.

    Check the bike battery voltage and charging system. Now this is going to be hard to test when not running properly, but should be 11.5-12.5Vdc when idling and 13.5-14.5Vdc when revving 4000rpm+

    If still no go then seriously do a compression test to make sure there are no problems with valves, rings, etc. The FZR will run with tight clearances but can make it hard to start once the clearance is all used up.

    Remember - to run properly you need spark, fuel and compression..
     
    dave, Aug 14, 2009
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  9. ashman01

    ashman01 New Member

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    I had a simlar problem when i accidently mixed up the spark plug leads. Not saying that they are wrong just might be a short somewhere in a lead coarsing what i understand to be the "farting noise"
     
    ashman01, Aug 15, 2009
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  10. dave

    dave Well-Known Member

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    [​IMG]
     
    dave, Aug 15, 2009
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  11. hagenstew

    hagenstew New Member

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    Hey guys, thanks fr the suggestions. I've been doing valve shims and my god they are bad... Of the four that were tight I've managed to remedy two. The other two I have gone down to the lowest size shim and even ground that down a bit and they are still tight. I've taken roughly 0.65mm off the two problem valve shims and they are still tight (although one is now passing a 0.05mm feeler gauge). This is bad right? Burnt valves, etc. I really don't want to take the head off. I know I can do all the work but I have almost had enough of buggering around with this bike and just finding more problems. Should I let the professionals handle it?
    Cheers guys
     
    hagenstew, Aug 20, 2009
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  12. dave

    dave Well-Known Member

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    The normal thing to do is exchange the shims at the bike shop. They usually take the old ones if they are not worn/damaged. The exchange is usually only a modest fee around a few dollars per shim.
    0.65mm off a shim size does not sound good at all. I can't believe it actually ran at all...
     
    dave, Aug 20, 2009
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  13. hagenstew

    hagenstew New Member

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    Okay just a quick update...
    I have now sorted out 3 of 4 valves that were tight. The last one I have taken the shim completely out and the clearance is only about 0.75mm. Not good at all. Head is coming off tomorrow and I'm going to be replacing a few valves. Just as well I have a spare engine...
    So a lesson can be learnt from this I guess, if the guy you are buying the bike off has set the idle really high (around 3500 rpm) and tells you it can be hard to start sometimes, ask him if the valve shis have been checked recently. Or better yet check them yourself before you pay for the bike.

    Cheers guys for the advice
     
    hagenstew, Aug 21, 2009
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