DT125 With 175 Engine?

[81DT125]

Hi everyone,

I picked up a bike yesterday which was advertised as a 1981 DT 125 with a rebore done. When I looked at it though it had the numbers 2A700 on the bottom of the cylinder. The numbers on the second line had been filed/scraped off, I believe these are supposed to tell you the cc.

After reading through some of the parts catalogues I found that the "Model-IBM ID Number" in the service data for the 1978 DT175E is 2A7 so I'm assuming that's the engine I have.

When I pulled the sparkplug out of the bike to replace it the plug was an NGK B8HS but the service data sheet said to use a Champion N-7Y. I went into the local motor factors and asked for one but they had none in stock but he gave me a BoschWR7DCX+ which he said was compatible. When I compared it to the plug I took out it seems to be around 9mm longer.

Can anyone tell me whether has he given me the wrong plug or was the one that was in the bike the wrong one? I don't want to put in a longer plug and have the piston bounce off it when I try to start it up. I won't get to the bike again until the weekend as I had to store it about an hours drive from where I live otherwise I'd just check it out when I got home from work. Any help would be greatly appreciated

[Cynic]

There are loads of 125's with 175 top ends, easiest check. Count the cylinder head bolts. 125 has 4, 175 has 6, simple as for the plug all DT175/125mx's have NGK B8ES except the g and h they had a B9ES.

As to what the bike is pop the frame numbers up and we can nail it for sure.

[81DT125]

Cheers Cynic, it'll be the weekend before I can get the rest of the numbers off the bike but I'll post them up as soon as I have them

[81DT125]

Hi guys, I have a quick question. I was out to the bike one evening during the week to check some stuff out for ordering up parts and noticed a black wire on its own in the CDI wiring loom with a black rubber cap on it which is disconnected and looks to have been cut. Where does this need to be attached to or is ot just a ground that can be attached anywhere?

Here's a pic (sorry about the crappy quality, it was taken with my antique phone and a flashlight)

[Cynic]

Hi guys, I have a quick question. I was out to the bike one evening during the week to check some stuff out for ordering up parts and noticed a black wire on its own in the CDI wiring loom with a black rubber cap on it which is disconnected and looks to have been cut. Where does this need to be attached to or is ot just a ground that can be attached anywhere?

Here's a pic (sorry about the crappy quality, it was taken with my antique phone and a flashlight)

Does your neutral light work? Other than that from the picture i can't really say. If any of the other wires in that part of the loom were disconnected then its unlikely she'd run. Although that neutral light wire should be light blue.

Better picture would be handy.

[81DT125]

I reckon you're right about it being the neutral switch wire Cynic, it doesn't work but the wiring on the bike has been absolutely butchered at some stage. There's no battery in it and inside the headlight there was a ball of wires in crimps and connector blocks. I've just taped up any exposed ends of wires for the time being, it's just going to be a field bike so I'm not too worried about the lights working.

Main thing is I got it fired up today and it seems to be running fine. I got the oil pump bled and took it for a spin. I think I'll have to have a look at the clutch because it's not really working right but it was getting alot better after running up and down through the gears for a while.

I'm just glad that it seems to be running fine, most of the other stuff is just cosmetic stuff that could do with being tidied up.

Here's a pic of it before I stuck the side covers back on