I was reading one of the other threads about oil and fuel in the NSR, what premix ratio should an NSR use? there must be a starting point? Mines on 40:1 and i havent really thrashed it yet (cause it broke) but the plugs looked good at road speeds.
. The larger sizes quoted by Jha and HRC are for use with pre-mixed, race octane rated fuel.*
*Normally the oil is injected by the pump downstream of the emulsion tube nozzle, but with pre-mix, the oil is in the float chamber, already mixed with the petrol (gas). This means the fuel passing through the MJ is weaker than normal (oil is now making up 3.2% of the volume @30:1) and so a larger size is needed to compensate. Don't even bother trying to run Jha's base sizes until you've removed the oil pump and thrown away the airbox, it'll run like shite!!
This is what it says in tuning in jetting section _________________ MC21 SP
The carb has been jetted, the airbox is a modified one, pump is in a box in my garage, pipes blocked off, and its been set up!!!! using 40:1 all was well on the dyno!!! and road but is it recomended to go 30:1?
If anyone reading this is running premix, maybe you could add a quick line with the ratio your using, im just intrested. Ta
As far as I know Steve and Bill both run 30:1, the 300 definately did, I don't know anyone else who bothers running premix as it's nothing but hassle and no one has ever heard of an oil pump packing up.
But yes, changing your oil mixture does change the fueling, if you set it up on the dyno running 40:1 then run 30:1 you're staring a detonation seizure right in the eyes.
Premix, a whole bundle of worms you can avoid, and the little oil bottle with its clip look sweet _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
I run 32:1 in my NSR. Only time I seized was when I had an intake leak, and it leaned it out on one cylinder (that was my mistake).
All other times, my pistons/cylinders look perfect on rebuild. I also run 100 octane race gas, and Castrol A-747 oil. You could run the perfect ratio, and still have issues is you use crap oil. So use a good quality 2-stroke oil and you should be fine.
My RS I run at 24:1 so it's a little more oil to keep the good parts good. Again, never had an issue with that bike either. Again, I run C12 race fuel, and Silkolene Pro2+ oil. Never had an issue with this bike either. Each 300 miles I do a top end (needed or not), and my pistons look perfect. I am sure I could go further, but I would rather spend the extra money now rather then later (on more expensive parts like cranks and cylinders). _________________ Charles Gallant
I ran 35:1 on my 18 with no seizures and no problems last year. It's just a real hassle, even though I'm a great fan cos it ensures 100% that well mixed oil is getting were its needed.
I just got sick of carrying bottles of oil under the seat and constantly thinking I was going to run out!
Now running an oil pump with two more 1/2" holes in the lid!
Technical eh? _________________ When the flag drops............................!
Yeah im using A747 (fecking expensive) but oh that smell is worth it LOL, do you chaps think 40:1 is to high? Im assuming that a tunner would make sure it was set to the right ratio? when jetting and running it up on the dyno!
im running a stock filter with a modded air box. HRC jet kit etc. she made 62 hp on the dyno and the plugs looked good, that aside it still went pop LOL but i think thats gona be for ring/powervalve issue not a mixture issue.!!
Way back when Grandma was a boy we tested 747 at 20:1, 25:1 etc. up to 80:1, on track and on dyno. Also sat in on Castrol tests at their technical centre with tests up to 400:1! They all looked close on the dyno, but track testing worked best at around 25~30:1. 40:1 ran hotter. 20:1 lacked snap off the corners.
My 300, Pauls 300 and the NRS run 30:1. My CR500 Supermoto runs 40:1 ('cos it doesn't rev)
I ran 35:1 with jetting but engine died in top end speed(SHOULD BE AT 220KM), I'm also looking at the problems... _________________ 1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine
nsrmonkey wrote:why would you want to run pre-mix on the road
Wow your alive, youve been quiet for a while, I dont really use the NSR on the road, its more a toy than anything else and only see's the track from time to time, if i do go out its only for half an hour or so, and i dont need to take oil with me as i head out with a full tank!!!!
Not sure though if im gona stay premix, ive got my pump and oil bottles so maybe ill sling it back on, we will see. I did it as an exercise and to start using A747 as it smells nice, (SAD HUH) i wanted to see if it performed any better!, I like the fact there is alot more space around the engine now. makes it look a bit lighter, even if its not!
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