78 DT175 on road ???

Alright everyone I have a question that no one seems to be able to answer with any specificity. I own a 1978 DT 175 I recently rebuilt. it because I took it for a spin one sunny afternoon on an old country road and burned a hole in the piston. Well everything is back together and running OK. The question is were these bikes meant to be driven on the road (they have lights, signals, etc.). Everyone tells me you can but not to hold it at a constant RPM for to long but no one will specify what that means exactly. I drive it around town and would like to take it on some country backroads but do not want to burn another hole in the piston. The bike had never been rebuilt before that so there was alot of wear now rings, piston, bore, main bearings and seals, crank pin,etc. are all new. There is about 300 miles on it since the rebuild. But after the bike has been running around 20-30 minutes or so it starts to ping at around 4000-5000 RPM. I know that I have the bike running on the leanest carb setting. It runs like crap if I lower it one notch. Or is this something I need lower the needle setting one notch then let it warm up and ride it. I know this is alot of info. I would appreciate any help. The bike has been in my family since 1984 so I would like to keep it going and be able to ride it a little off and on road. Thanks again

you should do some plug runs. run wide open throttle and just as you hit max RPM pull in clutch hit the kill switch and let go of throttle same time. pull your plug it should be no lighter than a medium brown if it has white spots your lean. what ratio are you mixing your fuel/oil what octane fuel are you running

Running 93 octane gas still has the stock oiler running on it I have it set to puff alittle smoke at idle (just enought to see its working).

Running 93 octane gas still has the stock oiler running on it I have it set to puff alittle smoke at idle (just enought to see its working).

i guess i dont know much about it but you ajusted the oiler system? not a very definitive ratio... is it how it was stock or you changed it?

According to the Clymers manual which verifies the position of a pin on the pump it is correct. I have never changed the adjustment much. I know if there is to much oil it like it is running lean. But again that adjustment according to the clymer is set where it should be.

According to the Clymers manual which verifies the position of a pin on the pump it is correct. I have never changed the adjustment much. I know if there is to much oil it like it is running lean. But again that adjustment according to the clymer is set where it should be.

lean would be not enough oil, rich would be too much...but running too rich means fouled plugs and sputtering, running lean means melted and burnt up engine components so its better to aire on the side of rich rather than lean if your having top end failure or pinging issues. Im not an expert so i would wait for somebody who knows more to give you a more detailed response.

lean would be not enough oil, rich would be too much...but running too rich means fouled plugs and sputtering, running lean means melted and burnt up engine components so its better to aire on the side of rich rather than lean if your having top end failure or pinging issues. Im not an expert so i would wait for somebody who knows more to give you a more detailed response.

I agree with this but I am no expert either.

Oilers were a really cool system. Virtually foolproof. In many ways it would have been great if they made their way on to mx bikes. They were a little, cable operated pump (basically from the throttle cable). The pump sent oil into the carb through a misting tube looking thing. What ratio? God only knows. However, almost like our yz 250's, we dont care...there just has to be enough. Between myself and family we rode oil injected bikes well over 75,000 miles. The only mishap was when a side cover on a g5 100 Kawasaki pinched the oil supply tube. A new engine and a trim with an exacto knife make it ok again..Well, maybe the trim was with a Arrowhead..It has been a while. Your oiler is probably ok. The lower end will lock up if it is not.

Lets presume your oil system is ok. Take the side cover off and make sure its working. If so, your ok. Double check the spark plug. make sure its the recommended plug and not one rated too hot.

The bike burned up your piston from being too lean. We account for that with larger main jets. I say main as I suppose your bike has abotu a 65=70 mph top speed. If you were anything above about 50 you were on the main jet.

Buy a min jet 3 sizes larger than whats in the bike. Test it. If your bike runs good, this will probably do it. Try the bike and look at the plug color. You want a sort of darkish brown...chocolate like. This will give you some insurance against this happening again. If the plug is still light, try another 3 sizes larger again. Once you dial in a slightly rich Main jet, you can ride at top speeds. I am not saying I would use the bike to replace my Goldwing, but around town jaunts will be great.

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