50:1

[Rocketman]

This is for you guys running a 50:1 mix. How long have you run it and how have your motors held up? I've been running a 32:1 mix. But I've got some Bel-Ray MC-1. That is supposed to be run at 50:1 Just not sure I want to run that lean of a mix. Worried about long term life of the motor.

[Fuzzy]

That sounds a bit lean for my likeings. If you dont have any trouble with fouling plugs at 32:-1 i would keep running it. Better safe then sorrry i guess.

[Caterpillar]

I have been running Bell Ray MC1 at 40 to 42 :1 for over a year, with no problems at all. I can still foul plugs, and may lean out to 50:1. At least at 40:1 you are safe!! It is good oil for sure.

[Dirtsquirt]

I ran MC-1 @50:1 in my '84 250r for atleast 25 hours, the topend still looked new. I'm running HR-1 @ 50:0 in my '85 R now, just pulled it apart (about 8 hours on the topend), very little wear.

I've heard to drag racers running 100:1 with no problems too.

[da_catt]

i ran mc-1 at 50:1 in my 86 250r with no problems. I rode at the beach at sea level and just made sure the jet was the right size.

[Rocketman]

Ok, but how long have you run a 50:1 mix, months, years? And how did the motor hold up. Did you have to rebuild the top end after only a year or so?

[350xhilaration]

If 32:1 is working well, no plug fouls, carb jetted correctly, why the need for change?? I ran MC-1 for quite a while in a KX125, 4 years actually and had no rebuild or plug fouling, was running around 40:1..switched to Honda HP1 after reading an article/review and someone had called MC-1 "Black Death" can't remember why they claimed that, but changed anyway no problems since and no rebuilds either.

[Rocketman]

I've been running Honda HP-1 at 32:1 also, why consider changing? Well if something else will work better why not? That is why I was wondering, from the guys that have been running Bel-Ray at 50:1, how there motors have held up over time.

[da_catt]

i ran the mc-1 the entire time i had it like 1.5 or 2 years. i had to rebuild the topend soon after i got it. the guy i got the bike moved here to oregon from arazona. he rode it twice at the beach with no problems. i got it and never looked at the jet or plug. one day i was wide open in 6th gear at the beach which is at sea level. the engine quit because the piston melted. the top of the piston had almost a hole in it . it had been running lean for a while. the jet in the carb was a 134 and stock is 150. after the rebuild i had a 155 jet with no problems. i do not think the 50:1 mc-1 had anything to do with me having to rebuild the top end. it was the small jet.

[250rAL]

OK everybody, this question is for me. I've been running MC-1 at 50:1 in my '85 R since 1990. I rebuilt the topend about a year ago for the first time since before I started using MC-1. I really wasn't having any problem with it, I just figured that it was about time for a rebuild. I didn't measure the ring gap(I wish I had) but the crosshatch lines from the last bore job were still plainly visable.

[Rocketman]

250rAL, thanks for the info. How about the bearings in the lower end, and crank. How were they when you rebuilt it?

[250rAL]

I checked for play and didn't find anything that I thought was excessive- both side to side and vertically on the rod. Also it runs as quiet as when I got it with no rattling. When I opened it up, there was oil on the crank so I think there should be plenty for the bearings. Keep in mind that the lower end is all stock and untouched for 17 years of (not babied) use.