matt_the_blat Posted January 31, 2009 Report Share Posted January 31, 2009 When I got this bike I had to re-shim all bar a couple of the inlet & exhaust valves. Since then I've used it on and off - sometimes daily, sometimes not for a while but it's generally run OK (it's a hoot to ride - when it's working!). It runs well at revs but has never really idled right - blocked idle circuit I think, a consequence of being laid up too long by it's former owner I suspect. It has started playing up again - I've fitted another (identical) set of carbs I got from e-bay which I've balanced but it's still not running right - The no.4 cylinder (RHS of bike) isn't firing as the downpipe is only getting warm (and I mean warm, not hot!). It's getting a spark, it's getting fuel and it's getting air but I suspect it isn't getting compression (I don't have a compression tester to prove this though)..... A known problem on these bikes is the valves go "tulip" shaped - specifically I think it's the inlet valves IIRC..... When I re-shimmed it before some of the valves were a little out of spec here and there, but the inlet valves on no.4 cylinder were WAAAAY out of spec, and I mean really out - according to the (offical Yamaha) manual, the shim I fitted was near the minimum end of the range of sizes you can fit before it means the valve/valve-seat is well and truly bolloxed..... I strongly suspect this is the reason this cylinder isn't firing now. If I check the valve clearances I suspect I may well find that I can't just fit a new shim now, and even if I could I reckon it would just be delaying the inevitable..... As this isn't my main bike and it was given to me gratis by a mate before he emigrated I'm fairly easy either way about keeping it or getting rid..... The bike is otherwise reasonably tidy (if a bit scruffy) for its age and all original - so my options as I see them: 1. Try and sell it "as-is" as a project (possibly not worth all that much even in tip-top condition though) 2. Break the bike for parts. 3. Fit a complete new engine (maybe pricey but doesn't scare me too much) 4. Re-shim if possible and hope for the best/delay the inevitable/flog it quick 5. Fit a complete new cylinder head (doesn't scare me too much - might be pricey and might just have the same problems though) 6. Can I "fix" the existing valves/cylinder head? I'm capable of removing the head myself (done it before!) Could I fix it myself or should I get a pro to do it? What is involved? Is it a case of fitting new valves AND re-grinding the valve seats? Special tools needed? One thing I need to consider is cost/benefit - what is the bike worth even if it was 100% compared to what it would cost to put right? On the other hand it's not always just about money. This bike is fun to ride when it's working right and could be made even better, but on the other hand I love riding my main bike even more (RSV-R) so it wouldn't be so bad if I didn't have the FZR. Your thoughts/advice/comments/suggestions would be appreciated - cheers, Matt Link to comment Share on other sites More sharing options...
Marb Posted January 31, 2009 Report Share Posted January 31, 2009 Break the bike, i'd buy all the fairing off off you! (Seriously, if you do break it, lemme know) But otherwise. I have two of these bikes. Had a similar problem. My bike WOULD NOT start. I could spends 15 mins running up and down the street trying to jumpo start it but it wouldnt fire. Then i'd leave it for a day or so, and then it would fire rite up. So then i went through the usual check list. Spark plugs, leads, carbs, fuel filter, exup. But no, didn't do shit. Then went to do a valve check. And again, the RHS cilinder was WAY off. The smallest yamaha shim is 120, and even with that one in it i still had no clearence. Seeing as this bike was going to be getting an FZR600 engine soon i didn't want to remove the head. Had a look down the at the valves and they looked good. So then i made my own shim. Got a 120 shim and sanded it down to 100. And had to do that twice. Put those in, and she starts and runs like a dream. Starts everytime, warm or cold. I've done 30000k's since and she is still running so well that i'm putting off putting the FZR600 engine in. What also helpen alot was to put the carbs one notch richer. Yes, it does mean that the valves are quite buggered but if you are gonna fix it it's gonna be quite an expensive procedure. 2 new valves, get the valve seats reground. You could get a 2nd hand head and make sure all the valves are good. Before installing it reseat all the valves and make sure the clearances are good. But again, its a known weakness with the FZR4's Link to comment Share on other sites More sharing options...
levo Posted January 31, 2009 Report Share Posted January 31, 2009 Check diaphram in carb that's what was wrong with mine .........it was trapped in the top Link to comment Share on other sites More sharing options...
Evilchicken0 Posted February 1, 2009 Report Share Posted February 1, 2009 Yup chances are it's a valve dished. Now last I heard Hipringle had a head from a 3en1 which would fit straight on, or worst case give you a couple of reasonable inlet valves ... chuck him £20 Try disconnecting your exup and see what happens Ooooh those fairings are a bugger to find .... I have a spare pair of 3en1 black lowers though. Link to comment Share on other sites More sharing options...
matt_the_blat Posted February 1, 2009 Author Report Share Posted February 1, 2009 Yup chances are it's a valve dished. Now last I heard Hipringle had a head from a 3en1 which would fit straight on, or worst case give you a couple of reasonable inlet valves ... chuck him £20 Try disconnecting your exup and see what happens Ooooh those fairings are a bugger to find .... I have a spare pair of 3en1 black lowers though. Why disconnect the exup? Link to comment Share on other sites More sharing options...
Evilchicken0 Posted February 2, 2009 Report Share Posted February 2, 2009 Why disconnect the exup? The exup causes back pressure at lower revs so it might be just enough to slow the engine. My 3en2 was running ok without the exup (I was waiting for new cables) when I connected it up it strangled the engine ... never di get to the bottom of that ... I really should do something with that bik, like fit the race system. Link to comment Share on other sites More sharing options...
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