Do smaller jets matter with an Injector Pump?

[WetBehindEars]

I was thinking of putting in a smaller lo speed jet and and starting jet because of plug fouling and running rich. Although I suspect it is because of using Mobil 1 and AMSOIL Domint. - which is the wrong app. for my bike. I bought the original oil - I have a '75 Harley sx 175 - they stopped making 2 stroke enduros in '78.

Since I am using the injector and not premixing - would this make a difference? The oil goes right to the engine on this bike. I mean in theory with smaller jets I will have more air, but less gas and the same thick as ever oil in my engine - right? thanks

Nick

 

[cryptokid]

you would have the same ammount of air, less gas, and the same ammount of oil.

 

[WetBehindEars]

With leaner jets I would have more air less gas, you mean - right?.

I also noticed one other strange thing, and that is air pockets in the oil line tubes. Which I know is bad since there is an oil filter screen to prevent that. I think I just have to get that synthetic oil oughtta there and use the orginal oil.

 

[tmorris1]

quote:

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Originally posted by WetBehindEars:
With leaner jets I would have more air less gas, you mean - right?.

I also noticed one other strange thing, and that is air pockets in the oil line tubes. Which I know is bad since there is an oil filter screen to prevent that. I think I just have to get that synthetic oil oughtta there and use the orginal oil.

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I don't think the synthetic oil is going to hurt anything. How is the compression? Have the rings ever been changed? At that age they are probably worn out or sticking which will also cause the same problems you are having.

 

[WetBehindEars]

Well first I want to get everything back to original and go from there. I actually have the largest lo speed jet in there that I inherited from previous owner(s).

How would smaller jets affect how it runs with an injector pump? Would leaner help in this case - it would just be less gas/same oil to foul plug/more air, correct?
Nick

[ September 30, 2004, 04:57 PM: Message edited by: WetBehindEars ]

 

[tmorris1]

The only time the low speed or pilot jet is going to do anything is at idle or at less than 1/4 throttle. If it is fouling at greater than 1/4 throttle you have a different problem. The oil isn't always what is fouling the plug. Having too much fuel will foul the plug just as bad. When an engine is too rich, it is getting too much fuel. If you drive a lot at idle or very slow speeds, use a smaller pilot jet, or lower your needle.

 

[WetBehindEars]

I did a lot of work today on that bike. I flushed tank, oil also, and replaced lo jet, float pin and height. I knew something was up when that mobil 1 wouldn't even drain out of the hoses it was so thick, and it didn't even have oil flow in the hoses. I suspect it wasn't even getting past the oil pump in adequate supply. No wonder the thing seemed like it was over-heating. It probably was!

Anyway, the bike runs really good now.

I ordered the original oil and it came in today. It's from the '70's and came in this funny, pint-sized oil can with flip top. This stuff was like pouring gas into the oil tank, it was so thin, compared to the synthetic stuff. What is strange is that I think I might have put in a bigger lo jet. I can't read the size of the old one - it's either a 55mm or a 60mm (the largest). I put in a 57 just to be safe.

My problems were mostly in lo speed/idle. But it made the bike run poorly all together and stall out/start hard. It would rev up high when I would come to stop.

Anyway, thanks everyone.

Nick

[ October 01, 2004, 08:34 PM: Message edited by: WetBehindEars ]

 

[WetBehindEars]

Spoke too soon - having more of the same but less pronounced: start hard cold / conking out / rolling on throttle and engine doesn't want to go.

Although it's less pronounced with the new oil and gas in there - the bike starts easier.

I am going to change that meter pin posit. and try running it without the air box in the morning.

One cool thing that happened. There's all this construction near my parents house, and I took the enduro on the dug up road. I went over this big jump with this 80 yr old Chinese guy looking at me like I was nuts from the sidewalk - it was really funny. I didn't even see the jump since it was getting dark out. ha ha ah ha.

 

[tmorris1]

If the idle surges then you probably have an air leak somewhere. You never have said if you checked the compression, which would indicate worn or stuck rings.

 

[tom slick]

i would try a modern oil that is specifically for oil injection systems, since you want to stick with the oil injection. if you want the bike to be reliable then premix the gas and forget about the oil injector. they are known for not working correctly.
4oz of oil for 1 gallon of gas is a good start

 

[blano]

Here we go again. With your level of knowledge you might be smart tot ake it to a dealer or shop in your area.
I have ran mobil1 two cycle oil in -10 degree weather in my snowmobile with none of the flow issues you are running into.

 

[WetBehindEars]

It can't be coincidence that the high revving/start hard occured when I tried to use synth oil. I even went back and read my first post here when I first noticed this was happening, and I said the same thing back then. The AMSOIL Dominator is a race oil and the wrong app for my bike - mobil 1 is a pre mix oil also designed for racing, and I am using oil pump.

I wonder if mixing synth oil with gas, and then running it through an injector would work. I mean this original oil is thin as ever.

It was revving high because it was running rich. I took out the air box and got it running the way I wanted to. I put in a leaner lo speed jet.

I also lowered my float level. This was a big deal because I was smoking a lot.

Now my problem is fouled plugs. I checked the manual and it said low battery could cause this. I am going to Pep Boys and picking up some dirt cheap NGKs and charging the battery. First things first, before I start replacing rings and/or seals.

I already spent 1000 bucks on mechanical work including 300 bucks for some dildo who didn't know what he was doing - that I had to sue and only win back 150 bucks - forget mechanics. They don't know this bike/cost too much/I bought the bike to do this myself because I thought it would be fun.

I was looking at buying other bikes - got my eye on the 500 ninja (2002).

[ October 03, 2004, 12:47 AM: Message edited by: WetBehindEars ]

 

[WetBehindEars]

Take it easy man. What questions? When did you ask about things I have done. I don't even know how to check compression.

I charged the battery, and it doesn't stall/foul plugs any more.

[ October 04, 2004, 02:25 PM: Message edited by: WetBehindEars ]

 

[Brett Miller]

The reving up when you stop means you are way lean or have an air leak. Does this bike have rubber boot/manifold between the engine and carb? If so, that's the first place I would look. Spray some WD-40 around the carb when it's running and you'll find your air leak. Also, I would ditch the injector pump on a motor that old. I would premix the MX2T 40:1 and never look back.

 

[tmorris1]

I done here. If you don't want to take advice or answer simple questions then fix it yourself and quit babbling on. Sorry, but it gets frustrating when people that have knowledge try and help you out by asking questions about things you have done, and you just blow them off and come up with some off the wall statement. There are reasons for the problems you are having that probably don't have anything to do with the oil!

 

[WetBehindEars]

That coupler hose is new. I make it a point to mash it on really hard when putting on the air box - could that be it. I even have real hose clamps, and not the original junky rings.

It is so hard to tell what thing is responsible. Last night - it didn't rev up at stop - but it stalled and the plug wasn't wet. I guess that mixture was bad.

I read in: off-road.com/dirtbike/feb2001/feb01rsVintageMikuniTech.html

how it is normal for the engine to rev up when messing with the lo needle screw - I could have just left it on the setting since I didn't know it was supposed to do that.

Although I did hear a weird whistling noise in higher gears that could be air leak - but where?

Someone else said that it could also be dirt in the start jet. There is a lot of dirt in the round slot in the float bowl for the starter jet, every time I open up the carb.

Why do you suggest I ditch the oil pump? I thought it was running rich in low gears before - HA! Its a mikuni

Thanks

 

[Brett Miller]

When the oil pumps get alot of hours/age to them they can fail suddenly and bad things happen. More peace of mind just to run premix.

 

[dustyjoe1]

If Its a two stroke. MONITOR THE PLUG COLOR CLOSELY!!!!. Its better to be a bit rich than lean. Should you go too lean, beware the dreaded "pop" sound of the lean mixture burning a hole in the top of your piston....been there , its not pretty.

 

[WetBehindEars]

Looks like I was barking up the wrong tree with that foolish assumption that my bike was stalling because of the carb settings/plugs fouling.

I have ignition problems. I have been testing for spark with new plugs and a charged battery, and I'm not always getting spark. Anyone have any experience with an ohmmeter? How close is this stuff supposed to be?

My problem is testing the ignition coil. When testing the primary
side (using a lead from one thread and testing it against the other),
it should have read something low, like 0.5, and instead it reads in the 2+ ohm
range. Also on testing the secondary side of the coil (testing where
the spark cable goes to either of the threads - I think) it was
supposed to read 2800, but was in the 3100 range. This isn't as
troubling as the first reading however.

Is it close enough or should I just get a new coil ?

 

[XS650]

quote:

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Originally posted by WetBehindEars:
.
My problem is testing the ignition coil. When testing the primary
side (using a lead from one thread and testing it against the other),
it should have read something low, like 0.5, and instead it reads in the 2+ ohm
range. .

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You're in good company, many of us have been misled by ignition problems masquarading as fuel problems and vs versa.

Reading single digit resistances can be tricky. First, short your leads and take that reading, for instance, my cheap meter reads about 0.5 ohm shorted. Then subtract that reading from whatever you are measuring.