DT125R ARCHIVE

FunkeyMunkeyDavid · Guru

RE: What shall I do?

Harry · Guru

Thing is, if the tank isn't fully empty and you want to top it up for a long ride and you have to put the oil in first, how do you know how much petrol is going to go in? May just pre mix in jerry cans at home haha

Bit of an update

Current piston is standard, so over sizing to 56.50mm

Ordered the piston, took 5 days to come which was a bit annoying in itself but then they have sent me the standard one.. even though the invoice clearly states I ordered the 0.5mm oversize. I didn't realize the shop was only 15 miles away so just going to check if they have it in stock and drive down on Monday.

Also if anyone is interested the head gasket bore is 57.5mm so unless you are over sizing more than that it should be ok.

AndyYam · Guru

Harry wrote:
Thing is, if the tank isn't fully empty and you want to top it up for a long ride and you have to put the oil in first, how do you know how much petrol is going to go in? May just pre mix in jerry cans at home haha

Bit of an update

Current piston is standard, so over sizing to 56.50mm

Ordered the piston, took 5 days to come which was a bit annoying in itself but then they have sent me the standard one.. even though the invoice clearly states I ordered the 0.5mm oversize. I didn't realize the shop was only 15 miles away so just going to check if they have it in stock and drive down on Monday.

Also if anyone is interested the head gasket bore is 57.5mm so unless you are over sizing more than that it should be ok.

Glad your making progress and thanks very much for the info on the head gasket. Very useful.

Harry · Guru

No problem, well unless there has to be a clearance like piston and bore but if there is it's probably very very small

Just waiting for the barrel to be done now, got the new piston and they are boring it to fit. Probably a couple of weeks till it's all finished.

One concern I do have is if the piston I already have had windows, it could have been jetted to suit, so putting in a non windowed piston could set it all out of sync? This is what I was told don't know how true it is

FunkeyMunkeyDavid · Guru

what size jet has it got in it now fella? most dt's run bang on with a 240 main...

AndyYam · Guru

Once it's all set up you'll wanna check. At th end of the day like dave says, a 240 jet should be good. Start high thought and if you need to, work your way down. Better to over over fueling than starviing and being back at square 1!

Harry · Guru

I have no idea didn't change it myself just the previous owner said he had

How would I know?

GADGET · Guru

There is a std tolerance for piston clearance to bore in th manual ,if it's not been on th machine yet phone th guy up quick with your specs ,ring end gap etc ,and he'll have to do it right th first time coz he will know that you've done yer homework

the carb jets is small fry compared to th piston/bore etc ,that can be fixed for a few quid !hope this helps man ,oh and we wanna hear it on its first startup

Harry · Guru

Yeah it's 0.050mm already told him :)

Cheers yeah I will film it, I know it's not going to be perfect either way

Harry · Guru

Will throw an update here

Bike is now re built and finished, went pretty smoothly except it bogging out - turned out just to be the bloody battery!

New piston

Re bore

All back together

And a cheeky vid, it's not the first start up. I had to slightly adjust the throttle so it pulls - otherwise it just cuts out so it does stick a little

Was also going to try pre mix, but decided I didn't trust myself really. Got a transparent hose and tested the pump was working correctly, everything seemed ok so put it all back together and it seems good.

Bike rides well, and pulls but it's difficult to say if it's better than last time, don't want it blowing up again haha

Any tips on riding it in? Just riding it like a nancy for now