So Close!...
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You live and learn, continuously it seems! I’ve since found out that the carb on my bike is a 1999~2003 variation. It should have 240 main & a 25 pilot jet. Not only that, it seems to like it! It’s running sweeter, which only makes me wonder about my previous escapades with a 17.5 pilot jet. Let alone the 180 main and 22.5 it had when I first got it
Also it seems a previous owner repacked the tailpipe themselves and didn’t just use proper wadding, they literally bound the perforated baffle with wire wool so tight that the fibre wadding was pristine and the exhaust was ‘Braap, Braap, Braaappping’. Might as well of been a straight through pipe...What I guess I’m getting at is that you can work out and mend what has gone wrong, but sussing out what other people have made wrong isn’t quite as easy. Just one of the joys of a project bike I s’pose...
I just gone an got a 4hw TZR125 basket case.. I must be a machinochist!!
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Bike seems to like the new jetting a lot. Just had one scare where the revs were at a maintained 7000+ and the engine just started to splutter, backed off the throttle and it was fine. Ran it out of petrol 3-4 miles after so I think it was just fuel starved at higher revs but scavaging enough at lower speeds. I put it onto reserve and it cut out abruptly (like a heat seazure) 1/2 a mile later. I’m guessing it was water in the carb (my tank is rusty bad inside and seems to ‘gather’ moisture a lot) and not a heat seize because it took a lot to kick it over after. I limped it the 30 miles home!
Since then I wrapped the baffles properly and the difference is amazing, it’s so quiet but the power comes on so much better. I haven’t had the chance to rag it because the piston has had 1 definite ‘mild’ seize on it (I caught it quickly enough that it didn’t stop running!) and I haven’t checked the piston or rings, though the barrel looked ok...
This is my progress ... -
@SpookDog Hhmm interesting. I mean the later models had the exact same engine but with 210 main jet which is odd. And even DEP themselves say no need to up jet with their performance exhaust.
I noticed when I went to a Wossner Forged Piston that it needed up jetting however.
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I’ve got two of the 99~ carbs with 240 main and.25 pilot and I know there are at least two other variations. Different jetting and valve cutaway, ect. As long as they make a 14/86 ratio of fuel mix it should be sweet! I can only guess at different emissions laws at different times...
Then there’s the TZR 28mm Mikuni flat slides!...Truth is that it’s a fecking mystery to me that I’m still trying to suss out
...I’ve never understood the upjet a new exhaust mentality. Why would it want a richer mixture? Then again, a bigger jet making your bike faster was the first ‘old boy~racers tale’ I ever heard! Maybe it’s just endured?...
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Still getting sputters at certain times! This is really starting to bug the bejesus out of me now. It can only be a few things to my mind.
1: Crap in carb (my tank is really rusty inside)
2: fuel starvation (I have a loop of fuel pipe that is constantly full of air a few inches long)
3: a random ignition bug...1: I have another tank that is pristine inside but been sanded down to bare metal and left to rust. I’ve Harpic’d the rust and am waiting to see what happens...
2: The excess pipe is there cause I need a fuel filter on because of the tank crap. So I’m gonna fit the new tank without the clunky filter...
3: I got a new Iridium plug and cap to fit, tho I don’t believe it’s an electrical problem...
I’ve also got a pristine late carb to put on while I’m at it. The floats haven’t been played with and it is so clean inside it’s almost unreal!...Fingers crossed
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I had a partial seizure a while ago. It didn’t even cut out the engine I caught it so quick. The bore looks ok apart from a couple bright lines at the usual points around the gudgeon pin. I haven’t removed the barrel to check the piston yet. I was gonna wait and get a new piston and hone it myself...
I don’t think it’s the piston though just because of the nature of it. Back off from the sputter and it’s fine again after, also there’s just no rhyme or reason to when it happens...
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It’s good. I really think it’s the air gap in the fuel pipe. If the motor is drinking it faster than it’s getting in, it sputters. It’s about 5 or 6 inches of airlocked pipe...
I can’t do pics at the moment cause my phone dies if you unplug it... -
Harpic is actually the Dogs Bollox at dissolving rust! As long as you keep it ‘saturated’ and don’t let it dry out it keeps on dissolving. Top Tip whoever it was who mentioned it! The outside of my second hand tank is now rust free after the previous owner sanded it down to bare metal and left it...
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Hi me! A lot of this is for future reference so I can remember the timeline until I can finally chase the bugs out of my bike..
After putting a couple tanks of petrol through the new tank I finally got it to run sweet and true with smooth power delivery. No fuel ‘lag’ problems with the new pipe routing without the airlock...
Head gasket is leaking again though
only changed it in March and can’t blame this one on the lean jetting. I gotta stop buying cheap Athena gaskets off of fleabay? Try again with a Vertex gasket...Check if it’s the same spot as well...
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@SpookDog Never had a problem with Athena gaskets they're quality parts.
I'd say something is wrong with the engine if you're having problems.
That said, I'd only get my gaskets from PJME or other reputable sources, not randomers off of eBay.
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Oh yeah, absolutely. I’m not knocking Athena as a product. They’re the best affordable option. I just don’t know the history of the fleabay ones. I don’t know if the coating on the aluminium gasket has a shelf life, maybe? They might of been exposed to high or low temps?
I wish I could find fault in the way I’ve been doing the top end rebuilds but I can’t
Sure I’ll suss it in the long run. Maybe you’re only supposed to spread the peanut butter on one side of the gasket?
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@SpookDog
IIRC:
Since I put a new barrel & piston & head on with new gasket (last August) it lasted 7 months until the head gasket went in March. I blame road salt corrosion on the head studs for that one.
This one lasted a month with new gasket, relapped head & barrel and Yamaha dome nuts and washers. I’m hoping that this time was either gasket fault or my fault fitting. I even lifted the engine out so I could get to it with the torque wrench nice and evenly. Cleaned and degreased all surfaces with Wurth degreasant. So I’m gonna have to be extra surgical next time -
@SpookDog WTF - There has GOT to be something wrong with your engine. There just has to be!
I've never had any problems with head gaskets except the cheap white ones you get off of fleabay. I've had some horrible engines in my time too and they were absolutely fine.
So this is very odd.
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I know, I don’t even ride aggressively. This is a new barrel and head since my ‘old’ problems. The first gasket on this top end lasted 7 months and rust got into the studs and nuts, so that’s acceptable. This one has lasted 6 weeks. I’m hoping it was a bad gasket (I’ve had a scratched one before) or ahem user error
We’ll see when I can be bothered to strip the top end again...I don’t seem to have much luck though, that and a painfully slow learning curve are working out worse than a Gypsy Curse!
I will get there thought. I’ve got a 93 4HW TZR project to get my teeth into yet. Can’t find any info on that thing...
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@SpookDog Definitely not putting the gasket on upside down?
You're torquing the head up evenly in a star pattern up to around 22nm? Are you using grease in the bolts as this will impact the reading you get from the torque. Greased bolts torque higher than ungreased?
Sorry if this is very basic but I'm literally baffled!
