4Skins

Gidday from NZ. Do you still have a copy of this wiring diagram. I need to fix the lights on my DT175G and am trying to track down the diagram. Would appreciate a copy if you have one (or something similar.

But seriously guys, can anybody RELIABLY tell me whether you can replace the crank seals without stripping the motor. I know you won't find the procedure in the Yamaha workshop manual, but I seem to remember being able to do this. All depends on whether the seal has a lip around it. Johnny

Gotta agree with the Cynic here, take off the whole exhaust system and you'll prolly find it'd choked up with a lifetime's gunk. As soon as the pipe gets a bit of heat in it it starts burning the oil out. We used to burn them out with the oxy acetaline set and compressed air when I was in the trade. If it's got a removable baffle in the muffler, take that out too, even if you have to use brute strength and vice-grips. If you can't manage this in your own workshop, it's worth taking to a shop to get it done. Also, you never mentioned the air filter, I presume you checked that.

The bike is totally standare trim. I might have a look at that intlet/reed block idea, the 'O' ring did look a bit flattenned. I did apply a bit of sealant to the gasket on the other side of it. The boot is not split, it's remarkably still flexible for it's age. Air filter is literally new, and oiled. Thanks for your prompt replys guys. I wish we had these forums available when I was a Yamaha mechanic in the 80s!

Yup, the oil pump was the first thing I chacked when I got it going, it's pumping sweet. It's not a lubrication seizure anyhow, it's heat. The plug is no colour and dry.

This bike is 29 years old, I bought it 18 months ago with 2,000km on the clock. It's been running good, the boy has done a further 2,000km on it. Then when on a trip up the highway after about 50km it seized up (while doing about 80 - 90 kmh) So I rebored it and put it back together. I found a mis-fitted gauze in the fuel tap with a build-up of crap behind it. This I summised caused a reduced fuel flow, leaned out hence excessive heat and seizure. I was 100% confident with that theory so sent the boy off to put some miles on it. Next thing, I get a phone call from the roadside, it's seized again - F*%K I said, several times over. He was not experienced enough to know it was about to seize again. So I pulled it down again and found that it was not too badly messed-up. I had my engine recom man clean up the piston and bore and try and suggest what went wrong. He reckoned it had got really hot, probably due to lean-ness. So I've put it back together today and had a short test ride. It seems OK under load (anything upwards of half throttle) but seems flat below that. Feels like it's got a blocked pilot but the carb is all sweet and correct float level. The plug is correct, the exhaust isn't blocked and the air filter is brand new. I'm a bit knackeded as to where to go next. I'm thinking perished crank seal on the magneto side letting in air?? That's a 'split the cases' job isn't it? How can I test that theory? Any further theories or suggestions welcome. Thanks Johnny Wellington NZ