So Close!...
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I had a good score recently, I got a 3mb barrel with a perfectly good piston in it that has 3mb embossed on the inside skirt, so I’m guessing it’s original? It also has the power valve, pulley & cover/housing as well as the cables with a 3wire servo connected!! (Rubber cover pristine) all still fitted. Also there is a perfect 3mb head
£130 off of fleabay! Of all places...The point is, I was warming it up to remove the temp sensor and I realised it doesn’t have 3mb stamped on it. Looked closer and the head and barrel are P stamped. Someone told me about this before but I can’t remember the details. I think it was originally a TZR top end? Did they come with servo fitted?
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@SpookDog 4DL Series 1 TZR125RR, cast in Italy by polini/minarelli (the italian cast 3mb barrels are a much worse quality in terms of the quality of the cast). The 4DL heads are blank on top with nothing but a P stamp on the side. The original 4DL power valves are the same as the DTR however the powervalve housing has a motor minarelli stamp on the cover that’s both original and unique to the 4DL Series 1. It’s also a nice metallic grey colour too.
Fun fact when I sold my TZR P top end I nicked the cover off it and sold it without just for that reason, makes not a sods worth of difference but oh well
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@Stevie-Wonder The TZR 3MB00P Barrel also had a 1mm raised exhaust port timing. And the connecting rods are slightly different
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Do you mean the pulley cover, or the right foot side cap? The cap on mine is a bit mangled and sealed with silicon
it’s the only down side I can see...
Yep, the head is blank except for the P. The barrel has the P stamped in the middle of the 3mb bit...Do you mean the Conrod itself or the crank throw? (Stroke)...
Is this P stamp a good thing or a problem waiting to happen?...
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Wow! Just took my head off and do you live and learn! I don’t have dome nuts for my head so I’ve been using normal ones, they’ve been letting the road water and rock salt (from a month or two ago) leak down into the studs and cause enough corrosion to lift the nut at the front of the engine! I put new studs in and the back four are still shiny! The front one has white crud like you get on battery terminals all the way down it past the threads!
It must of acted like frost in a crack in stone and forced it apart!
So much white crud!... -
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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...
