Any 2 stokers out there

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).

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).

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.

[luvtolean]

Mavic, if you search DRN, they talk about McCulloch white papers and richer ratios making more power. The "gurus" on DRN all seem to like ratios 32:1 and below for everything.

[abtech]

Originally Posted by 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.

The white papers were handouts to Motul sponsored teams a few years ago. I don't know where they may be located on the web unless you check the various DIN reference sites.

32 to 1, worked for twenty yrs.

I used to run 24:1 in my CR125. It was ported wicked and the head was shaved good. Ran it on AV gas or race fuel only. That was a snappy little bike. Wish I still had it for chucking around on.

In my CR500 I ran about 25-30:1. It was either digging a trench or the wheel was nowhere near the ground. Kind of a heavy beast, but I will have another one someday.

My CR250 Ran nice at 32-36:1 It was a nice all around play bike. Sold it after I got my 929 and sold my truck.

Originally Posted by Nodge

In my CR500 I ran about 25-30:1. It was either digging a trench or the wheel was nowhere near the ground. Kind of a heavy beast, but I will have another one someday.

I have decided to go 32:1 as that seems to very popular and the extra oil will always help so long I can keep the spooge down. I have dropped the pilot and main down 1 on each and it seems to clean up really nicely. Tried dropping the needle to the lowest/richest slot and it was still to rich for the current conditions. It seems to be happy right in the middle. I hope to get a jetting run done sometime before March but the rains have started this week so it may be a little bit.

Thanks for all those who have replied. It is good to have a big KB to pull from.

[luvtolean]

FYI, so you don't "tune yourself into a hole". Spooge isn't necessarily due to premix ratio (though you can typically help a spooge problem by running more oil). It is your jetting. If you don't change the jetting, and you lean out the oil ratio, the spooge will get worse.

Actually while were on the subject of two strokes theres a guy over here in Oz named Chris Dowd that builds (used to build, not sure what hes been up to lately) methanol burning V twin CR1000 engines using two CR500 cylinders , mainly for speedway sidecars but he was going to put one in a GSXR750 frame, I cant seem to find any info on the net about them but did have a good look at one he had in his workshop about 8 years ago! that would have been one intresting bike to ride!