What should my 77 yamaha dt 175 rpm be when idling

SOURCE: won't idle steadily

did it have old gas in it for any amount of time

SOURCE: Yamaha TTR 250, Idling Problem

check the inlet manifold rubber has not seperated from the aluminium part of the manifold ,this is very common on the ttr 250 and will cause the exact problem you have,if it is seperated either replace it or repair it with some good quality rtv sealant avoid sillicone sealant as it is not petrol resistant and will turn to jelly.adam

SOURCE: won't idle steadily

Check the rubber boot that joins the carby to the engine to often have seen the hose clamps over tightened therefore creating a split in the rubber letting to much air in giving the rough idle eventually you wont be able to start it at all (have a good thorough look inside an outside of boot doesnt take much)

SOURCE: i have a 1984 XR200R with the dual carb set up

You need to remove the top cap off the carb(s) then lift the slide out of the throat of the carb. You will see a long needle in the center of the slide. Lift the needle out then move the clip on the top of the needle down one notch. Two notches may be needed but start with one. Now re-assemble the carb(s). Doing this will richen the low end fuel mix.

Go to the site below where you can see a parts diagram for your specific bike. You will select the actual brand, year, model, etc., once you go to the site. Part numbers and prices are also shown. You can order parts from this site. In the event no price is shown on a particular part, the part is not in stock.
www.babbittsonline.com/pages/parts/viewbybrandand/parts.aspx

Top rating due on this answer for sure! Thanks!

SOURCE: Yamaha DT 125 1986 - High Revs when idling

There have an air leak between the carb and the cylinder and/or the head and cylinder. Old hard / cracked rubber fittings and O rings are usually the problem. When extra air gets into the system it leans the fuel mix and the high idle is the result. It also means the engine runs hotter. Also, cracked or broken reeds can be a source.