TZR 125 engine help

[pilot300]

Hi guys I have a 1990 tzr 125, it looks like a i need to do a re-bore however its is nikseal coated so going to be a little pricey. Im wondering are there any 250 two stroke barrel and pistons which would fit onto the TZR engine? something like a yamaha SR250 perhaps?

[Kickstart]

Hi

Not really. Ones from a TZR250 (250 2 stroke twin) might be similar (not sure) so you could possibly use one but it would probably be at best just as cheap and easy to sort out the 125 barrel (even assuming the 250 barrel needed no mods).

SR250 is a 4 stroke and certainly not usable for this.

Why do you think you need a rebore? Nicasil is very hard wearing so only likely to need major work if the barrel is scored. They can be replated for ~£100.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[pilot300]

im picking the bike up on sunday. it has no compression so expecting the worse. it could just be a set of rings. i would of like perhaps a larger capacity two stroke if i could though for more power. are there any larger capacity 2 strokes out there? as the largest bore kit you can get is 150cc (which actually works out to be 134CC once you've done the maths)

regards
duncan

[Kickstart]

Hi

Not really. SDR200 engine (or DT200) are pretty much the same and should fit easily, but they are pretty rare (to the extent that plenty of SDR200s probably now have TZR125 engines in them).

There is a 170cc kit for the TZR125.

Which model of TZR is it that you are getting? If an early shape UK one (rather than an Italian market one) then there are over size pistons available as they do not use a plated bore.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[pilot300]

Hi there

Got the bike yesterday and took engine out. The piston and rings have had it and scored the barrel. I was under the impression they were nikosil barrels although mine seems to have a sleeve. Also with barrel and piston off ive noticed the big end bearing needs replacing too. So for re-bore and piston plus a crankshaft and con rod im looking at £130 im looking at complete engines for a little less then this.

Would a newer engine with the power valve already in place fit straight in or will i need a similar year engine? Also can the power valve easily be fitted to these engines? and finally can you recommend any good motorcycle breakers in the west midlands?

cheers guys

[Billing]

As Keith said, only the later TZRR's had nikasil plated barrels, not the UK 2RK bikes. The YPVS kit is getting hard to get hold of, but if you get one and all of the seals etc then it's a piece of piss to do, I fitted mine with the engine in the frame in about 20 minutes from start to finish, you only need to take one side panel and the fuel tank off to fit it
____________________
'84 TS50X, '91 TZR125, '89 CBR400RR, '91 VFR400R NC30, '98 R1
"Hey copernicus! Why don't you navigate yourself to the back of the line with your feet and stand there with your shit."
BCF Eastern members map here ---> g.co/maps/2tm8b PM me to be added to it!

[Kickstart]

Hi

£130 is pretty cheap for a rebore and crank rebuild.

Think the later engines have different mounts, but not sure or sure on when they changed.

Your engine has the power valve in it, just nothing to operate it. You could get kits to fit from Yamaha years ago, but these are rare now and expensive if you can find them. You need the control unit, servo unit, cables and a few minor bits for the housing on the barrel.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[pilot300]

on the bright side ive found different parts across ebay so looks like will b able to rebuild my engine for less than £50 including postage of all parts. Found a complete power valve kit but he wants £125 for that. bearing in mind the bike including new engine parts will owe me £210 is the powervalve gain really worth the £125?

regards duncan

[Kickstart]

Hi

Afraid only you can answer that. You can get the same top end power by pegging the power valve in the open position, but you will say goodbye to any bottem end or mid range power.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[pilot300]

Thanks for the reply guys. Im currently looking for parts to re-build my engine myself. ive located new barrel, piston and rings fairly cheaply. the problem im having is a replacement crank & conrod. I jave a couple which im wondering if they would fit, they are as follows:

DT125 twin shock from late 1970's
DT125 3md from 1989-1992
XT125 2005
YZ125 2002

I have a 1990 TZR 125. from things ive read i think the DT125 3md would fit. am i right?

Kind regards
duncan

[Billing]

I'm not sure any of those will, the stroke on the later DT engines is different to the TZR's. The early ones ('87-'89) should be ok as the engines were the same, it was the carbs and gearboxes that were different
____________________
'84 TS50X, '91 TZR125, '89 CBR400RR, '91 VFR400R NC30, '98 R1
"Hey copernicus! Why don't you navigate yourself to the back of the line with your feet and stand there with your shit."
BCF Eastern members map here ---> g.co/maps/2tm8b PM me to be added to it!

[pilot300]

Hi guys

Thanks for all the advise, in the end i replaced the engine and the bike is now running nicely, except for a knackered alternator got got the replacement from the old engine.

Got a question about the YPVS, i've found one from a 4dl engine stupidly cheaply, not sure the owner knows how much its worth but was wondering if this would fit my 2RK engine?

best regards duncan