Project : 1979 175 dt

[theheadschoice]

Greetings. I've noticed some very knowledgable feedback from this websites members and since I'm now a Yamaha owner, I've got a question.. or two, since all I've ever worked on previous to yesterday is my 1985 Dodge 500.

First of all, what gas/oil mixture should i be using? I've seen a more convincing post say 40:1, another 32:1.. does anybody know for sure?

Secondly, the bikes previous owner, like a champion , ran it on straight gas. What kind of problems should I expect? He didn't use it alot, but it has been ran through at least a whole tank on straight gas. I've already emptied the tank and purchased a liter of 2stroke motorcycle oil the pep boys guy assured me is a universal 2 stroke fuel mix.

Third, do all 2 stroke bikes use the same gearbox oil? i was told by one guy i needed a certain weight for whatever bike I have, another friend of mine has some oil he assures me will work for all 2 strokes. which one of these dudes is right?

and last, but.. certainly not least, I'm leaking oil out of the top rear of the bike, and when its layed down on its right side, it leaks gas. When it's tipped far to the left, it drips a considerable amount of oil.

Where should I start..? Thankyou for making this far in my post, even if you've know clue how to help.

-p.h.

[Cynic]

Welcome, interesting questions.

First off the 2 stroke. The bike would originally have had a pump, people remove them for some unknown reason i can never fathom. If you pull off the side covers (they are rubber/plastic so wont break) you should find the oil tank. On a 79 it could be on the right or the left hand side. If the pumps working fine you can run on pump gas. ( See i speak Americano )

What is the sw arm like square or round steel? Better still a chassis/frame number.

The oily bits in the box want a straight std 10/30 engine oil. Thats straight out the manual. You can check yourself its written with the quantity by the gearbox oil filler on the right side of the engine, above the base of the kick start.

Need a bit more detail for the last bit, 'top rear of the bike' is a bit too ambiguous, any bike will start to leak gas leant over a long way with the engine off, more than about 30degrees will have it coming from the overflow without the cornering forces keeping it in there. So laying it down will have fuel everywhere.

The gearboxes are pretty good as far as leaking goes, i would say the leak on the left side could be the 2 stroke tank. Or again if you could give some more accurate info on where its coming from. We can probably narrow it down some.

[theheadschoice]

the bikes actually a 1978 175 mx..DT? It has all the wires for an Enduro but I just got the pink today and it says MX on the body style. whaa?

the guy at the yamaha parts center today informed me to use 80 weight oil in the gearbox when its hot like it is now or 85 in the winter, and it is in fact a 2 stroke mixed at a 40:1 ratio.

Unfortunately the muffler bracket is discontinued and I'll have to improvise. I'm going to install the complete gasket kit next week and if that doesn't stop the leaks I'll ask around.

I'll post some pictures so we can get a before and after, I'm going to clean it up a bit and paint the frame on a free weekend.

[Cynic]

the bikes actually a 1978 175 mx..DT? It has all the wires for an Enduro but I just got the pink today and it says MX on the body style. whaa?

the guy at the yamaha parts center today informed me to use 80 weight oil in the gearbox when its hot like it is now or 85 in the winter, and it is in fact a 2 stroke mixed at a 40:1 ratio.

Unfortunately the muffler bracket is discontinued and I'll have to improvise. I'm going to install the complete gasket kit next week and if that doesn't stop the leaks I'll ask around.

I'll post some pictures so we can get a before and after, I'm going to clean it up a bit and paint the frame on a free weekend.

So, is the 2 stroke pump disconnected? If the bike has had a full tank of just fuel through it it should be dead, siezed tighter than a ducks arse?

MX is just a model code, they are refered to as MX's to separate them from the twin shock version thats all. Nothing to do with it being a Motocrosser.

There is a little confusion here on my part. Are you talking about a straight EP80 gear oil? Like the stuff that goes in Landrover axles?

[Airhead]

If its an MX 175 these were never exported to the UK, not sure about them but I assume they do have an autolube set up. How about an engine / frame number and a photo?

[theheadschoice]

I'm going to snap a picture tomorrow, a before shot. It will take some time to be able to find those numbers, they're buried beneath years of grease, well earned im sure. After it's removed I'll supply any numbers, and a picture of their location with some crude editing to display where they were found.

this bike may be old, but I'm looking forward to hitting the trails. Next week I'll have enough time to replace all gaskets and install new clutch pads, after that, I have only a chain guide to replace.. and it's ready to rumble.

this is the second bike ive ever owned.. my first 50cc honda I wrecked racing my dad on the trail in his old back yard when i was around eight. I guess I've got some green in me, despite my past experience on a 1984 200s 3 wheeler I used to trail ride and hill climb on.

Thanks for the replies folks, I'd have some pics up already but my digital cameras battery is kaput.

[theheadschoice]

So, is the 2 stroke pump disconnected? If the bike has had a full tank of just fuel through it it should be dead, siezed tighter than a ducks arse?

MX is just a model code, they are refered to as MX's to separate them from the twin shock version thats all. Nothing to do with it being a Motocrosser.

There is a little confusion here on my part. Are you talking about a straight EP80 gear oil? Like the stuff that goes in Landrover axles?

After you mentioned a 2 stroke pump, I peered around a bit and noticed a brass nozzle without a hose on the bottom of the carburator that leaks gas when the bike is anything but ^ upright.

I have a feeling this isn't a good thing.

thankyou for the clarification on the MX. I bought the 80 weight gear oil from a guy at a rather large motorcross store that seemed knowledgable, and rather convinced it was indeed a 2 stroke. the 80w gear oil is designed for motorcycles.

I haven't added the new oil yet, just started it up a little and let it run with the different gas in it.

Should I wait before I put this 80 weight in the gear box? I won't be running it for at least a week again.

If this guy is wrong, I'd love to know that before I ruin a 4 stroke romping about at a 40.1 mix. the motor ran alot smoother after I drained the tank and added 1.85 mixed as instructed by the parts guy at the shop, wasn't as loud as 2 stroke could be but I suspect that may change after the gaskets are replaced and my muffler is more.. securely attached. it's tied on with a piece of rope at the moment, rather sad to look at, and leaks a bit of exhaust before it hits the end of the pipe.

id have ordered the muffler bracket but it's out of stock and the nearest neanderthal cycle pickapart is some distance away..

any ideas on where I might find a muffler bracket, and even better, an appropriately fitting muffler for my bike?

Pictures coming within next two days. 35 mm.