Vintage Dirt Bike Q & A
http://vintagedirtbikeforums.alp-sys.com/

pre mix versus oil pump/tank benefits?
http://vintagedirtbikeforums.alp-sys.com/viewtopic.php?f=21&t=4882
Page 1 of 1

Author:  Harri [ Wed Feb 14, 2018 6:08 am ]
Post subject:  pre mix versus oil pump/tank benefits?

Hi all. The MT I have bought has been running premix I guess as there is no oil tank fitted. I do have an oil tank that could be fitted.

Are there any benefits of running the bike on pre mix rather than pumped oil?

thanks. Harri

Author:  rayivers [ Wed Feb 14, 2018 5:33 pm ]
Post subject:  Re: pre mix versus oil pump/tank benefits?

If the bike's been run with no oil tank you'll surely need a new pump, so I'd just remove the pump before it does something awful and run the bike on premix. The Honda injection system just spritzes oil into the intake so it's basically the same as premix anyway, except it often supplies way too much oil which you have little control over.

Ray

Author:  Harri [ Fri Feb 16, 2018 8:52 am ]
Post subject:  Re: pre mix versus oil pump/tank benefits?

Thanks Ray, that makes perfectly good sense to me. I'll run premix once I give the bike a good looking over and try and get it started. Battery has been ordered so I will connect that up and take it on from there.

Author:  Harri [ Fri Feb 16, 2018 8:52 am ]
Post subject:  Re: pre mix versus oil pump/tank benefits?

Thanks Ray, that makes perfectly good sense to me. I'll run premix once I give the bike a good looking over and try and get it started. Battery has been ordered so I will connect that up and take it on from there.

Author:  ruouthere [ Sun Mar 04, 2018 8:36 pm ]
Post subject:  Re: pre mix versus oil pump/tank benefits?

Ray, I might try going pre-mix, what ratio is best for the MT?

Thanks,

Author:  rayivers [ Sun Mar 04, 2018 9:37 pm ]
Post subject:  Re: pre mix versus oil pump/tank benefits?

Quote:
I might try going pre-mix, what ratio is best for the MT?

With the stock jetting (which is set up for no oil in the gas at all, and is super lean)? The less oil you use the better the carb will probably work, but I'd suggest you jet the bike for pre-mix instead and use a good oil in the 36:1 - 40:1 range (I use Bel-Ray H1R at 36:1). The pre-mix '75 I worked on had much better throttle response & bottom end with a #65 pilot jet and would surely have liked a 70 even more, and I think the main jet should be at least a 122 or 125 for pre-mix, maybe larger (a 2.5 throttle valve might be worth trying too). An interesting richness/leanness test in these bikes is to set the needle clip to the #1 (leanest / top position) and test ride at 3/4 throttle, then move it to the #5 position and repeat.

Ray

Page 1 of 1 All times are UTC - 7 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
https://www.phpbb.com/