I was wondering what the best fuel ratio is for the 79 Yamaha's. The guy I got the bikes from said to run 50:1 but the book calls for 20:1. That seems like a HUGE difference to me. I've been running 40:1 with lots of smoke. And I've noticed that the bikes run better and smokes less when the mixture is richer towards the 50:1 range. I want to make sure if the book calls for 20:1 that running it 50:1 doesn't mess the bikes up. What mixture do you guys run?
Fuel mixture on 79 Yamaha IT250
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Thanks
Thanks for the reply kdx. I read through and found where this topic had been gone over before, apparently many times. And I saw where the 32:1 ratio was the most suggested. So thanks for conferming that for me. I live in middle Tenn so the summers get pretty hot. I mostly trail ride so the bike rarely gets revved up enough to get the soot out. Ha! One reason why I asked was because I noticed what appeared to be oil leaking around where the exhaust connects to the motor. I was wondering if that was a result of mixing to much oil and what wasn't getting used was getting blown out through the exhaust. There seems to be a small build up of oil around the end of the tailpipe as well. This would mean (to me) that the 50:1 that was told to me would be more correct. But I don't want to mess the bike up so I'll try the 31:1 and try and reset the carb and see how it goes. Thanks again!
Thanks for the reply kdx. I read through and found where this topic had been gone over before, apparently many times. And I saw where the 32:1 ratio was the most suggested. So thanks for conferming that for me. I live in middle Tenn so the summers get pretty hot. I mostly trail ride so the bike rarely gets revved up enough to get the soot out. Ha! One reason why I asked was because I noticed what appeared to be oil leaking around where the exhaust connects to the motor. I was wondering if that was a result of mixing to much oil and what wasn't getting used was getting blown out through the exhaust. There seems to be a small build up of oil around the end of the tailpipe as well. This would mean (to me) that the 50:1 that was told to me would be more correct. But I don't want to mess the bike up so I'll try the 31:1 and try and reset the carb and see how it goes. Thanks again!
TRexRacing
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- Jul 23, 2002
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I run 32:1 in my '80 YZ 465.It loves it.Check your transmission oil at that age the crank seal may be gone.
If the manual says 20:1, then its BEST to run it 20:1. The carb is also jetted for 20:1. In bizarro world people figure and take advise from the wrong people. They come up with all kinds of stories about 32:1 all the way to 100:1. When these engineers drop the amount of oil, that means it will get more gas! Now if they know how to jet, no problem, make your own baseline and altitude and temperature corrections, piece of cake? Run the correct mix, look in the manual, start with stock jetting for your temperature and altitude, already in the manual. And it can help you jet, specifically for your bike! Here is what bizarro world will say to the easy method: I ran it 20:1 with premium fuel, stock jetting, and it keeps fouling plugs. You have to have an engine in good working order, jet it and it should be fine. As long as some guy from bizarro world has not ported and polished the engine, it will never be able to jet it correctly, or run correctly. Sorry for the rant, but this kind of mis-information question comes up way too often!
TRexRacing
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And Yamaha YZ's of that era were notorious for being jetted rich regardless of pre mix ratio.Horribly rich.I guess we forget to mention proper jetting is required no matter what the fuel:oil ratio used.
When you gonna buy a motorcycle foxforks?
When you gonna buy a motorcycle foxforks?
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Actually, jetting and engine reworking may be an issue here. I was told the bike was used to ice race up in Michigan. So there truly is no telling what has been done to this bike. All I can say is that it runs OK at low rpms, sputtery in the mid range, and very strong in the high rpms. It won't idle well at all and it's a pretty heavy smoker with the oil residue previously described. My brother says it's hard to ride behind me because of the smell of fumes and smoke. The bike looks great however. I discovered an inexpensive painting method that appears to be working. I've painted the tank with it and after two weeks the paint has yet to peel or bubble as so often is the case when painting these old plastic tanks. I'll be sharing it soon on here as well as a link to a video I'm making describing how I did it. I want to wait and make sure it holds before I start touting success. Thanks for all the help and input on this bike guys.
jb_dallas said:
Don't be so sure.;)
When I find out if I can get a rod somewhere for a 78,79 rm400?TRexRacing said:When you gonna buy a motorcycle foxforks?
TRexRacing
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- Jul 23, 2002
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I believe Falicon would be your best bet.
Minimum order of 10@209 dollars a rod? I will need stimulus money for that one! Or 8 more guys who want a really nice looking rod for a 76 to 78 RM370/400?TRexRacing said:
TRexRacing
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You didn't say anything about a low budget rebuild.
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