coombehouse
Velociraptor
Posts: 34
Reg: May 1, 2013 22:54:41 GMT
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Post by coombehouse on Apr 9, 2015 22:50:34 GMT
Personally I cant see that mineral or semi synthetic oil will make a huge difference to the problem particularly semi synthetic is mostly mineral anyway. It sounds to me as though there is a problem with the oil draining back from the top end & its getting down the guides. I have heard of problems with pattern valve stem seals giving problems & I have always been told to use genuine even though they are not cheap so maybe you used APE seals & they are causing this problem perhaps. If you do decide to investigate & find excessive amounts of carbon (lumps of oily carbon)on the port side of the inlet valves then its mystery solved. Nick
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Post by sparky1074 on Apr 10, 2015 19:47:51 GMT
Thanks for that Nick. I only ever use genuine Suzuki gaskets and seals, and the valve stem seals were definitely genuine Suzuki. If I remember correctly I am sure I remember the chap who rebuilt the top end say he was going to ream, skim the inside of the new APE guides so there would be enough clearance for expansion...not to much friction. Thinking about it I am sure I read somewhere APE valve guides come ready to fit and don't require modification. If they don't and he has it would make sense that oil would be entering the combustion chambers easily through the guides...its just a thought I don't profess to be an expert. I did a test over a couple of nights when the motor was cold. I turned the tick over up removed plug cap one and started the motor it still smoked even worse it seemed after changing to thicker mineral oil. I did the same over the next few nights and the results were always the same on all four cylinders. So it seems oil is getting into all the chambers which would make sense if the new guides had been unnecessarily modified. Gonna ride the bike for the rest of the summer and enjoy it as it runs and starts ace. There is no smoke whatsoever after its warmed up, and doesn't smoke if I leave the bike standing for several hours on start up after use. If at the end of the summer the smoking issue hasn't got any better I was thinking of whipping the motor out again and giving it to Roger Upperton in Leeds (is he any good as I am running out of experts) unless someone on the forum could take a look obviously not for nothing. Thanks again for all the top input great site this is.
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Post by katana on Apr 10, 2015 21:23:59 GMT
Never known APE guides need reaming. Are they new or re-used valves? Obviously new would be tighter for clearance so if a race type build then a degree of start-up oil smoke would be inconsequential? Rupperton is deffo one of the good guys and has turned out some seriously good race motors so is classed as a go to guy!
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Post by sparky1074 on Apr 10, 2015 22:22:48 GMT
Thanks for that...the original valves were re used and re lapped into the original seats. Its not a little Blue smoke on start up its quite a lot and smells of oil.
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coombehouse
Velociraptor
Posts: 34
Reg: May 1, 2013 22:54:41 GMT
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Post by coombehouse on Apr 10, 2015 23:14:36 GMT
Thanks for that...the original valves were re used and re lapped into the original seats. Its not a little Blue smoke on start up its quite a lot and smells of oil. Sounds like you have found the source of the problem. As you say though if it doesn't smoke excessively then live with it until the next strip down. Roger Upperton is one of the very few I would trust. He did a head for me & the quality was great for very sensible money. Nick
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Post by katana on Apr 11, 2015 8:13:36 GMT
Thanks for that...the original valves were re used and re lapped into the original seats. Its not a little Blue smoke on start up its quite a lot and smells of oil. Well I don't think it will get better but on the bright side you won't get valve seizure! One other thing and it may just be your terminology use but if you fit new guides you must re-cut the seats, a grind / lap won't suffice as the geometry will have changed by a few thou or fractions of degrees.
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Post by sparky1074 on Apr 11, 2015 10:53:10 GMT
Thanks for that Katana...yep no chance of valve seizure. In fact when I start it up it brings back fond memories of my GT250B when I was 17
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madmikeracing
Velociraptor
Posts: 28
Reg: Jun 11, 2014 13:07:59 GMT
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Post by madmikeracing on Apr 19, 2015 13:18:20 GMT
uzuki. If I remember correctly I am sure I remember the chap who rebuilt the top end say he was going to ream, skim the inside of the new APE guides WOW why would anyone resize sized Guides? Yes unfortunately that is it , If stock ape guides yo uwould have no problems, but resized probably with a reamer in a hand drill goin at it like a garage monkey after a few tinnies and some smoke?? Sorry to hear that, Mike
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Post by sparky1074 on Apr 20, 2015 20:04:28 GMT
So basically Mike, the inside of the new APE valve guides shouldn't have been reamed out just fitted as standard. Thinking about it, it does make perfect sense to me, that oil would ingress into the cylinders if the tolerances in the guides was to big. Thanks Mike.
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madmikeracing
Velociraptor
Posts: 28
Reg: Jun 11, 2014 13:07:59 GMT
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Post by madmikeracing on Apr 21, 2015 20:40:22 GMT
Hey Sparky It sucks that happened but Ive seen heard of way worse things so ,,,!!! The only stuff I have had to hone were connecting rod small ends in my sprint engines, I liked to have .0012 to .0015 clearance or so had some tight ones occasionally when a Load of redone cranks would come in to my shop. If the top end gudgeon pin (is that how the Brits call that?) is too tight it can gall the pin and it can force the piston wrist pin clips outa the piston and there goes the Motor, I had it happen once and came to the conclusion the pin galled in the small end of the rod, since opening them up a wee bit i have never had that happen again just other shit ha hya Good Luck Mike
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Post by sparky1074 on Apr 24, 2015 16:49:20 GMT
Thanks for that Mike. Tell you what is odd...If I start the motor from cold and don't pull the choke all the way out so it just starts at low revs and doesn't rev to high there is no smoke. The motor only smokes when it revs high from cold when the choke is pulled all the way out...if it is pulled out just a little so the motor will start it runs clean. Being honest Mike its not a big problem and certainly doesn't affect the running of the motor. Its just that if I ever do (and I certainly have no plans to) sell the bike its going to be difficult to explain the blue smoke away to potential buyers. Thanks again David.
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