[Mavic]

Curious as to the premix and ratio you are using. I am purchasing an 87 CR500 next month from a friend and will probably put a new top end in and rebuild the carb so I need to know what you guys recommend. When I had my 86 KTM 500MXC I ran silkolene but times have changed and there may be something comparable or better.

[MacMan]

Got yourself a stump puller there eh? Careful with that monster. The oil's out there are all pretty good now adays but people still have their favorites. I myself (and for a few years now) use the Yamaha 2-R for my oil. It does it job but the best part is that I have never had any carbon build up problems. I have yamaha's now but my honda's ran it also. Me,myself and Irene..lol.. love that movie would start at 40:1 mix and go from there. Check the plug for color. Needle adjustment or jetting from there if needed. My.02
Good luck

[G-Force Junkie]

32:1 pretty standard for MX bikes. Any modern oil will be fine, find whats available localy. Unless your souping it up, theres probaly no reason to run the best stuff out outhere. Since you asked, I run Castrol A727 in my 2 strokes, but they are high strung GP bikes. My stock 2 strokes I have had good luck with Yamalube 2R as well, and they dye in it makes it easy to remind you that you have premixed your fuel.

Mike

[smkeatr]

Yamalube 2-R @ 32:1 for me too.

[Mavic]

Thanks for the input. I'll do some checking today to find the best price in town.

[johnnycrash]

Klotz super techniplate - 32:1. In my old KX500 it was the only oil I used that didn't foul plugs and it smells great, too.

Be careful with that man-eater, by the way. Those old CR5's were monsters. I had an 83 CR480 that was no slouch.

[luvtolean]

Mobil 1 MX2T in Philips oxygenated race fuel. I like MX2T 'cuz it's fairly cheap (for a quality synthetic), works great, and if you forget to go to the bike shop, you can buy it at an auto parts store on a Sunday on your way to ride. The guys on DRN are really into this combo, and so was I after trying a bunch of different stuff!

Typically around 32:1, although sometimes a little more oil if I want to lean the bike a bit and am too lazy, or don't have a smaller mainjet to put in.

[Jungleboy]

Ive had about 1/2 a dozen motocrossers as well as an RGV and Have used many different oils and I usually just use Castrol TTS, I know its been around for a while and isnt the latest or greatest thing out there but its always easy to get hold of and have never had any problems with any of my bikes! My younger brother has a CR500 at the moment thats has had a bit of engine work done and we just run it at 40:1, The 500 is a big slow reving engine and can handle quiet a lean oil/fuel ratio 50:1 or even leaner shouldnt be a problem (Ive heard of ppl running ratios of up to 100:1 but I wouldnt try it myself )

[luvtolean]

I don't understand what people hope to gain by leaning down their fuel/oil ratios so much. There were ASME White papers by McCulloch (spelling?) showing how more oil in the mix made more HP in their motors. If you want to research it, dirtrider.net has tons of info on the topic, with the experts all seemed to agree 32:1 or lower was best.

I used to run Blendzol (love that castor smell) in my pre-power valve bikes, and Yamalube R too.

[johnnycrash]

Originally Posted by luvtolean

I used to run Blendzol (love that castor smell) in my pre-power valve bikes, and Yamalube R too.

It's the castor beans in Klotz that makes it smell good, too. That oil mixed in VP C-12 race gas is the sweetest smell there is. It smells like race day.

[G-Force Junkie]

Originally Posted by luvtolean

I don't understand what people hope to gain by leaning down their fuel/oil ratios so much. There were ASME White papers by McCulloch (spelling?) showing how more oil in the mix made more HP in their motors. If you want to research it, dirtrider.net has tons of info on the topic, with the experts all seemed to agree 32:1 or lower was best.

I used to run Blendzol (love that castor smell) in my pre-power valve bikes, and Yamalube R too.

On air cooled bikes, when we run the Streets of willow in the summer (105+ degrees) the guys will run 18:1, rejetted accordingly, and it makes more power by keeping the motors cooler. I also never understand why people insist on running 40 or 50:1. I rode offroad with an old timer once (he was 72 at the time on a KX500!) and he swore by 50:1 plus an ounce or ounce and a half of Marvel Mystery oil. Said he never had fowled a plug in 50 years. The oil plus MMO probaly put it around 30:1.

Mike

[Mavic]

Before my water cooled Katoom 500, I had an air cooled 84 YZ490 that I mixed 20:1 since I was in West texas. Never had a fouled plug but I am sure I could have gotten a little more umph out of the beast. That 4 speed tranny wasn't all that bad either. Now a Honda will go into the list of dirt monsters. Hopefully, she has been well taken care of in the past 17 years. I know most of them were sitting in the garage but I don't know how Emery rode it when he did get it out for a spin. I am definitely hoping for more fun than repair work. Seals have a tendecy to go bad just sitting there but he was fairly certain the only things it would need were a new top end and carb cleaning.

I'll post pics when I have her at the house.

Ahhh the smell of Castor...brings back memories even though I never ran the stuff... I can still remember its very distinct aroma.

[G-Force Junkie]

Originally Posted by Mavic

Before my water cooled Katoom 500, I had an air cooled 84 YZ490 that I mixed 20:1 since I was in West texas. Never had a fouled plug but I am sure I could have gotten a little more umph out of the beast. That 4 speed tranny wasn't all that bad either. Now a Honda will go into the list of dirt monsters. Hopefully, she has been well taken care of in the past 17 years. I know most of them were sitting in the garage but I don't know how Emery rode it when he did get it out for a spin. I am definitely hoping for more fun than repair work. Seals have a tendecy to go bad just sitting there but he was fairly certain the only things it would need were a new top end and carb cleaning.

I'll post pics when I have her at the house.

Ahhh the smell of Castor...brings back memories even though I never ran the stuff... I can still remember its very distinct aroma.

Ist pretty easy to make up a case pressure tester. Not only do seals go bad, but sometimes there is no gasket between the cases, just a sealent that can harden and leak. A flat plate of aluminum cut and drilled to fit over the reed cage opening makes a good blockoff, then pressurize the engine to a couple of psi through the spark plug hole.

[Mavic]

Thanks for the info. From what I have heard, 5psi is the starting range with 1psi per minute an acceptable leak rate. You know of any other specs?

[G-Force Junkie]

Originally Posted by Mavic

Thanks for the info. From what I have heard, 5psi is the starting range with 1psi per minute an acceptable leak rate. You know of any other specs?

5 psi max is what I have heard. Listen for hising sound, and make up a soapy water solution and brush it along the case seams, cylinder to block joint, etc.

[LOWBUCKRACING]

I HAVE A 1998 CR250 AND I HAVE USED EVERYTHING UNDER THE SUN I LIKE KLOTZ TECHNIPLATE AND LIKE IT THE BEST ITS RED AND YOU CAN TELL YOUR GAS IS MIXED AND I MIX IT AT 32:1

[pumpkin119]

Well I have to correct my bro (jungleboy) on that i ran 40:1 on my cr125 02 and had no probs, i now run 50:1 on the 500 (TTS)

[Mavic]

Originally Posted by pumpkin119

i now run 50:1 on the 500 (TTS)

I am currently running 42:1 and it seems a little oil rich now but I am in the process or dropping the main jet to see what happens to the plug once I get the chance to run WFO in 4th. However, it is hard to find enough room to get that far into the motor.

[luvtolean]

It's rich because you are running so little oil, which decreases the viscosity of the premix. If you went to 32:1, it'd lean it out.

Japanese bikes were famous for being jetted rich from the factory. Of course nobody paid attention that they were suggesting 20:1 ratios. People went to 32:1 and complained about the jetting and spooge. If they ran the 20:1 and stock jetting, it probably would've been close. And also probably could've made more power.

[ConqSoft]

...this is why I got a 4 stroke.... Fill with Gas. Go.

[Mavic]

Originally Posted by luvtolean

It's rich because you are running so little oil, which decreases the viscosity of the premix. If you went to 32:1, it'd lean it out.

While 32:1 is leaner in the F/A dept compared to the current 42:1, it is still creating too much oil collection on the plug, thus the leaner oil mixture and the reduction in main jet to correct the F/A mixture. I will leave it at 42:1 until I get the results from the lastest jet change. The black oily residue collection on the plug is the current objective to reduce as I try to achieve the mocha coloration of the ceramic. Also, the dwell time of oil in the cylinder for the lower revving 500 allows for a leaner oil mixture toward 50:1 while 32:1 is very good for the higher revving 125's and 250's or that is what Eric Gorr is currently recommending.

Probably going to have to find a drag strip to get this thing opened up and breathing "full" air and do a "plug chop" before I really know what I have in the setup.

[luvtolean]

Did Eric Gorr do your motor?

He's working on mine as we speak (hopefully).

[Mavic]

Originally Posted by luvtolean

Did Eric Gorr do your motor?

He's working on mine as we speak (hopefully).

Nope...just called the shop and asked some questions. Really nice people!!!

[abtech]

You may want to read some of the Motul white papers, particularly in regards to the RGV500 and mixing ratios. Gary Taylor ran 28 to 1 on this "relatively" low revving motor and had no "oily plug" problem. They ran back to back tests on the Suzuki GP motor and found more than 10% HP loss when going to ratios greater than 32 to 1 even after rejetting and multiple custom dyno runs to achieve their desired A/F ratio. At 28 to 1 they also were able to extend the crankshaft life to 500 miles, while the Honda and Yamaha counterparts were seeing needle bearing cage destruction at ~ 300 with 40 to 1 or higher ratios.

Even though your 500 may be a long stroke, slow revver, it does change directions at the top and bottom of each stroke and believe me, the wrist pin bearings need to see a lot more oil than 40 to 1 can provide (I won't even get into the crankshaft requirements).

[Mavic]

Abtech,
Thanks for the reply. I went looking for Motuls white sheets but didn't find them. Maybe you know of a good link. What I did find on their web site concerning their 2 stroke oil was rather surprising as it seemed to support both of our ratios.

"800 2T premix Ratio :
For off road applications, we recommend to use Motul 800 2T Factory Line OFF ROAD in premix at 2% (50:1).
For road racing applications, we recommend to use 800 2T Factory Line ROAD RACING in premix at 3,33% (30:1)."

My guess is due to the number of cylinders and volumes of each cylinders crankcase. A single cylinder bike deplacing 500cc will bring in a large amount of gas/oil into the system for crank and sidewall lubrication. This amount should be proportionate to the multi-cylinder motor or maybe the road enviroment is running higher RPM's and then extra lubrication is required. Interesting stuff. I also found another manufacturer "Maxima" also recommending ~50:1.

http://www.maximausa.com/technical/l...summer2001.pdf.

I run Redline racing oil and they spec out anything between 20 and 100:1. I am definitely wanting to be on the rich side of things as I make my progression to optimal jetting so this may take some time.

Thanks for the insight as it will definitely be factored in as I move forward.