symonh2000

Thanks for the reply.

No one?

Hi Everyone, I have been a member here for a while and haven't posted in ages. I apologise if this is posted in the wrong place but here goes... A couple of years back I bought a DT50MX as a project. Unfortunately I just haven't had the time to do much with it and have had trouble sourcing a few important bits, so would like to sell off the parts. I have a frame which was professionally sandblasted and painted in two pack, and an engine in good mechanical condition which needs tidying up cosmetically. Both of the numbers on the engine and frame match, and I have the v5 in my name for them. I also have the fork yokes and a set of taper rolled bearings to go in there. I was just wondering how much should sell the frame and engine for, as I don't want to get ripped off. Many Thanks, Simon

I will make sure. I think draining it and leaving it in a warm place for a few days should do the trick.

I could silver solder it at work come to think about it. I will have a look to see where the leak is once all of this resin is out. At work I can also fill it with helium and use a Mass spectometer to "sniff" where the helium is leaking from.

I can't be sure the tank is good until I get the petseal out, althoyugh the paint on the tank is original and I cannot see any evidence of paint dadmage through fuel leakage. Is it possible that there was some surface corrosion in the tank and someone added petseal to stop it blocking the fuel filter?

I did consider a replacement tank, but I don't want to do that unless there is no other option. The reason being other than the resin liner the tank is in very good condition. It is original, with no dents or major marks. Good ones also fetch silly money. I suppose I could always sell this one on ebay, then buy another good one, but I am throwing the dice again on the replacement.

Thanks for the help. I was thinking of getting a length of chain and inserting that into the tank. If I put nuts and bolts in there I might have a real headache getting all of them back out. I will use a remover chamical if I have to, but that risks knackering up the paint if I spill it.

Hi everyone, having a bit of an issue with my newly aquired TZR125... I knew it had been stood for 3 years before I bought it, so I decided that before trying to fire it up I would drain the tank and clean out the carb. The carb was full of a sticky snot like substance, which I managed to eventually clean out. However the tank appears to have been filled with an epoxy tank liner at some stage which has obviously been partly dissolved by the fuel. This had also caused the gunge in the carb (as well as reed valves). I have managed to get most of it out, but there is still one big lump still in there. What is the best way of removing the lump? I don't want to damage the paint on the outside of the tank if I can help it, as it is pretty good. Also even with the failed liner the tank wasn't leaking, so what are the odds of me getting away with not putting in new lining compound? Many Thanks.

Did you do a port map or are you just directly measuring? As due to the curvatuure of the bore the port will be larger than it appears when measured with a vernier etc. Basically roll up some paper stick it down the bore and use a crayon/pencil to take an outline of the port. Then unravel the paper, this will give you an accurate measurement of the port area. If the port is smaller at its outlet than the port area in the cylinder it will be restrictive, if not then the step is probably there for another reason, possibly to interrupt exhaust pulses and give more midrange torque.

Indeed it would be 115cc, and there isn't any replacement for displacement. 115cc is around 15% more capacity, so all things being equal should give 15% more power and torque. I think to get the best from the exhaust port mod you would also need to modify the inlet to get more fuel in there in the first place. As long as you don't raise the top edge of the exhaust port or the angles of the transfer ports then you shouldn't loose too much torque. Removing the step in the exhaust port will not change the compression ratio as long as the top edge of the exhaust port where it meets the cylinder stays the same.

I didn't modify it in the end. The spare barrel I had (The one in the picture) needed a rebore, and I figured it would be cheaper to sell the RXS and buy a 125 that could be de-restricted. If you look at the inlet on the RXS it also looks quite restrictive. There is a big flat area in front of where the reed valve fits, which could possibly be sharpened up. I would spend £120 or so and send the barrel to Stan Stephens or Mick Abbey, they have been tuning 2 strokes for years, and will give you a good result, if you mess yourself chances are you will make the engine worse. The engine as standard is designed to produce a set amount of power, and be reliable and tractable. You could get more power I am sure if you are willing to sacrifice the other two. I think it is possible to get a barrel and piston from an Asian market RX-115 and fit it to the RXS, but I am pretty sure the 135 uses a longer stroke so the crank is different along with the engine cases.

I will do, the bike is being delivered tomorrow so I will post up some pictures of how it arrives and how the project progresses. Thanks for the welcome Simon.

I was wondering this exact thing when I had my RXS, in fact the first picture of an exhaust port was taken by me, as I asked the same question on another forum. Most of you will probably know that a 2 stroke engine uses reflected exhaust pulses to keep the fuel charge in the cylinder (Hence why they use expansion chambers). Removing the step will change how these pulses arrive back at the cylinder. Removing the step might make an improvement, it might make matters worse. It could also be that to get the best affect from removing the step that you need an expansion type exhaust (Micron, Allspeed etc) as the original isn't a true expansion chamber type. Secondhand cylinders are easy enough to come by, maybe buy a couple and do some experimenting? The RXS is in a fairly mild state of tune, and I have heard that 17bhp is quite easy to achieve, if you are prepared to loose some low rev tractability. The book by John Robinson "2 Stroke Tuning" is a good read if you want a better idea of how 2 stroke engines work. Simon.

Just wanted to say hello to everyone... I have had a few Yamaha bikes in the past, and have just got myself a TZR125 as a project. Previous bikes include 2x DT50MX 2X RXS100 2 X RD125LC 1X TZR125 Sp I certainly like my Yamaha's. the TZR will be the second one I have owned. I am looking forward to spending more time here.