What happens when a "professional" bike mechanic rebuilds a TZR???
Well,in my case, the story goes the owner prior to the guy I bought the bike from had restored my 2MA, admittedly this was early 2011, but it's since only done @2500 miles.
I have probably mentioned in other posts some odd things with the bike, I knew it had 1KT engine, but not how and when that was fitted.
Allegedly it had been "profesionally" rebuilt by a mechanic from a local (to the previous owner) Honda dealer, the previous owner was provided with photographs of the rebuild (although anyone could probably get a set of such pictures from the web) but no receipt for the parts.
As there was insufficiant evidence to prove beyond all reasonable doubt anything had been done, and even if it had it was 12 years prior I was not gonna pay top dollar (and the 1KT engine and no matching numbers would upset the "collectors)
But the previous owner only wanted just over £3k for a running TZR in reasonable looking standard trim with an MOT, I hankered after an LC (as I had one in my yoof) but shit non runners were going for more than this running & MOT'd TZR so deal done.
Shortly after purchase I tok it for a checkup and dyno run, a borescope showed signs of some grinding on one powervalve, but not t'toher and with t'other the two halves did not look perfectly aligned, but pistons and barrels looked very good, power was quite good (46BHP) fuelling safe (if not perfect)
...next I got some MJ77 pipes and ignitech ignition / PV controller and went back for full setup, and setting up proved tricky, with fuelling off from one side to the other, and it responded a bit oddly to PV timing changes, so I was not 100% happy and I decided a top end strip after the summer for a proper look was worthwhile.....
...So, booked a day at 2T engineering, compression and leak down tests showed things were OK there, but when the head came off it had some minor pitting, who would rebuild a bike and not get that sorted? - That was the first question of the day, the answer was the same kind of guy that would bore the cylinders out and not widen the head to match ;-)
Then who would machine a load of meterial of the PV on one side, but not the PV on the other side??? Maybe this was starting to explain why the bike responded stargely to PV timing changes and fuelling being off?
Some "pointless" (as Andy at 2T described it) "knife edging" of the transfer ports at the bottom of the barrels had gone on, luckily he said this would not do any harm, but was a wasted effort that would do no good either.
So, it was time for a costing excersize, re-work head, fix powervalve bodges, tidy up ports, re-assemble and setup properly.....
...The crank "looked" good, but I was now a bit nervous, when was it rebuilt? who by, with what parts? (we could see the conrods were not OE Yamaha)
Andy then asked if the output bearing was changed during the last rebuild - well, with what I had witnessed so far and no parts receipts I was not going to assume it had been, so now the engine is coming out and the cases are coming apart....
...So at this point any budgeting was out of the window!
Anyway, I then get a picture through from 2T, one of the main bearings had started to collapse, and it had a pattern lab seal fitted (which may or may not have failed, or been fitted the wrong way, or some other horror?)
I think you get to a point where for the sake of "a few dollars more" you just do the bloody lot, I am 56, ride the thing <1000 miles a year, and the chances are it will last longer than me after a rebuild....
...And I will know it is as good as it can be, perfect bores, best pistons money can buy, brand new OE Yamaha crank assy, genuinely profesionally rebuilt, dyno setup with custom ignition and PV maps to suit the MJ77 road exhausts.....
....Roll on Spring 2026.
At first I was thinking "oh shit", but then I remembered I paid "unrestored money" for it, knew one day I might have to refresh the engine, and this way I no longer have any doubts about thrashing it around, and it should be a great bike when done.
Maybe next year I will fit a new shock and get the forks done, then it will be 100% sorted mechanically,as good or better than new in every way, with modern electronics.
Don't forget to factor in some other parts ie shift shaft might be worn on splines and where the seal rubs a groove in it, ( still available ) clutch plates and basket ( mitaka), oil pump ( protect your new crank) intake rubbers all eye watering £££. Leaving the central heating off for a few months will pay for the crank. Sell a kidney will pay for the rest. I've just bought a YSS shock but I don't know what they are like I did ask but got no reply. Are you going to refurbish the rest of the bike ?. Most heads have indentations where the rings have tried to make a break for freedom as long as there are no sharp bits it's ok. What oversize piston are you on? Mine are + 1.25 the bore size matched the head circumference the only thing was to enlarge the head gasket apertures and make sure the power valves don't touch the pistons.ive taken leave of my senses and started throwing titanium fasteners at mine £££ 😱
Andy at 2T has inspected the internals and said gearbox, clutch etc are all looking very good.
Meteor pistons are slightly different to original TZR which starts life as 56.4 and goes up in 0.25, mine was on +1 IIRC, the meteors start at 56.0, so I think I will be going to a 57.5 Meteor;
https://www.meteorpiston.com/shop/1399-p1399-piston-yamaha-tzr-dtr-125-d-56-25885#attribute_values=23,5363
Canot remember the current piston brand, but was told a few race bikes have had the pins move inwards allowing the rings to spin, quite rare, but at this point I want to minimize any chance of future failure....
...Which leads me to the oil pump - my understanding is they are pretty reliable, assuming I can find one they list at £200. The other option is go to pre-mix.
My intake rubbers are OK, and I bought a set of the Yambits ones, I know they are a bit crappy, but at least theyre new - will save these in case the day comes where mine start to leak.
Quote from: Rasher on October 13, 2025, 07:47:51 AM...Which leads me to the oil pump - my understanding is they are pretty reliable, assuming I can find one they list at £200. The other option is go to pre-mix.
Arrow on this forum does most uk tzr and rd oil pump rebuilds and is reliable and a better option than premix.
Got a new oil pump for @£180 so will go with this, might consider rebuild of old one as a spare for the future.