Ace 100 Fuel Mixture/Cooling

[dscinta]

I have owned my Hodaka Dirt Squirt '79 for nearly 20 years. Some years ago I came across an Ace 100 motor mounted to a Fuji streetbike frame that had never been assembled and showed 0 miles. Dream come true time capsule motor. I replaced the side seals as suggested on an old forum post because they could have dried out and cracked. Motor now has about 20 hours on it running good but hot. The gas cap says 20:1 on my Dirt Squirt but my father had many vintage/classic bikes including a few Hodaka's and he said run it 40:1. I have been recently running 32:1 but it just doesn't seem to have the pep and I am afraid to lean it out too much. Also my original motor would litterally start with a half a kick cold. This "new motor" wants 10 kicks or so to start cold. Warm maybe 2 but most of the time 1. What do you guys run your oil ratios at?

[taber hodaka]

It is not what we run our bikes at, as much as how are they tuned and used. I would be good to run at 32:1 or 40:1 with good oil. The main factors include tuning, quality oil, mixing ratios, temperature, elevation and use racing or riding.

[Bullfrog]

Both 32:1 and 40:1 are "richer" on gasoline than 20:1 - more of a given mist drop of pre-mix is gasoline at 40:1 than at 20:1. So, in terms of carb jetting, 20:1 is "leaner" than 40:1. Having said that, I don't think mix ratio is your problem. Check for a plugged pilot jet or plugged pilot circuit. That would cause leaner/hotter running AND harder starting.
Ed

[dscinta]

I use Yamalube 2R only.

[dscinta]

Bullfrog:

I must be naive to carburetor jetting. Admittedly I am not a mechanic but a pretty good part swap monkey. 20:1 is 2x the oil of 40:1 so my theory was more oil would lubricate better thus lowering temps. Thoughts? I also know that this is the factory Carburetor so other than another thorough cleaning I feel the jetting should be "correct." I am not racing this dirt squirt but do live in the world where if the bike is not performing at it max potential something is wrong.

[taber hodaka]

Factory carburetors are not jetted correctly. Factory stock hodaka motorcycles were not jetted correctly, unless you were lucky and lived at a certain elevation. Excess oil can lubricate better and at the same time run hotter. The air fuel ratio controls the heat and a reasonable amount of oil must be added to provided lubrication. You are on solid ground using 32:1 or 40:1 but the carburetor would have to be jetted for where and how you ride. This is only my opinion that has server me with thousands of miles / trouble free riding and racing. ---------------Clarence

[dscinta]

Because I now live at basically sea level that did not occur to me. When I live at 1 mile of elevation everything I owned had to be re-jetted. I didnt even know how to boil spaghetti. Great tip. I will look into buying some additional jets. THANKS CLARENCE. Is there a simple way with modern technology to know what temp the bike should be running at. Like using the laser thermometers pointed at the side of the head? Seems like it could be a valid way to help tune...

[Joe Ormonde]

Go at the problem 1 thing at a time. Ignition timing first. Spark plug. just because it`s new doesn`t make it good. Carb. Just pull it and clean it. As previously stated, that pilot jet is almost the biggest problem in starting. Anything blocking it even just a little bit will make it impossible to tune.As for oil, the guys are right. 32:1 under 5000 RPMs is perfect. Anyone follow NHRA Pro Stock? If you run your bike like they run those cars all bets are off concerning oil. Remember: A Task Slowly Done Is Surely Done! Just go at the tuning one step at a time. Joe Ormonde.

[junker2k]

Ed, It took me awhile the get my head around what you were saying. (So, in terms of carb jetting, 20:1 is "leaner" than 40:1).
when it come to mixture you think oil to gas and I think gas to oil.
Too much oil can also be a very bad thing also, over heating, fouling plugs and array of other problems.

Jack K

[dscinta]

Ya. Took me a second also. The extra oil displaces the gas. Never thought about that before... Always learning. Thanks Ed

[Makotosun]

This article from a recent post may be helpful:

viewtopic.php?f=1&t=3095

[taber hodaka]

We need to be careful as to where data will lead us. So if 40:1 is richer than 20:1. Is 60:1 richer than 40:1 and is Amsoil mixed at 100:1 richer again. There is nothing that replaces proper jetting. If the engine idles your pilot jet is fine am I correct? -------------Clarence

[Joe Ormonde]

Sounds good to me ! Lets not get lost here. Simple: When you mix more oil in the gas, You have less gas passing through the jets because you now have diluted it with oil.If you mix in less oil, you get more gas passing through the jets because you have less oil mixed in . The flow volume doesn`t change, just the amount of pure gasoline. More pure gasoline: richer: Less pure gasoline, leaner. Joe Ormonde.

[Bullfrog]

I'm kind of "old school". I don't really care for the concept of changing pre-mix ratio to bring about a jetting change (though apparently some modern bike guys do like that concept). In "old school think" applied to fifty year old Hodaka air cooled engines . . . one should select an oil and a mix ratio appropriate to the intended use based on lubrication requirements. Then one should fine tune the jetting by, ahem, changing jets. This discussion about "richness/leaness" due to changes in pre-mix ratio ought to ONLY inform you that changing pre-mix ratio WILL have an effect on jetting - at least in "old school think".
Ed
PS: If the engine idles well, the pilot jet may be fine - but there is a bit more to it than that. Idle is just one characteristic to check. I really want the transition to the slide (1/4 throttle) to be seamless . . . and I want the idle to settle in beautifully when the pilot air screw is somewhere between 1 turn and 2 turns "out". 1.5 turns out is the target.

[Joe Ormonde]

Same Here! Old School Rules!! Joe Ormonde.

[taber hodaka]

And here I am, home schooled at old school. We are in agreement and I would add the Hodaka manuals covers this quite well. -----------Clarence

[junker2k]

Really old school would be 30wt shell oil and 5 gal of gas = 20-1. But i prefer the new oil at 40-1 or leaner. what ever ratio you select stay with it and if it the bike runs to rich put in a smaller jet or too lean put in a larger jet.
Jack

[dscinta]

When I bought this bike over 20 years ago with the original motor we ran it for years on 30wt motor oil and gas mix. My father used to mix it by color in quart size glass mason jars. Calibrated eyeball technique. Brings back memories.

[Joe Ormonde]

Oil conversations are great! Remember back in the day when Union 76 and Shell 2 stroke oil had printed on the bottle: Pre-Diluted For Easy Mixing? Basically,you got 3 cups of oil and 1 cup of Kerosene.So, if you mixed 6oz. to the gallon, you really only mixed 4.5oz. to the gallon! Remember that? Oil. Strange thing Oil. Years ago, there were two guys that we would all park our bikes and watch do battle on our outlaw track called the Chino wash. A Maico 501 and a Husqvarna 400 Cross. Both guys had El Caminos. We knew which one belonged to the Maico guy and the Husky guy. Do you know how? The Maico guy had Blendzall GREEN on his tailgate and the Husky guy had Castrol R on his! Everywhere you saw a Maico or a Husqvarna in the early 70s it was the same! It seemed that it was just an unwritten rule. You had to use Blendzall in a Maico and Castrol R in a Husqvarna. Strange! Joe Ormonde.

[Makotosun]

Seemed like a good time to add this . . .

[Joe Ormonde]

That`s Great!!! Joe Ormonde.

[Joe Ormonde]

What ever happened to the fella whos name started with a K ? You guys got him so mad that I`ll bet he`s STILL kicking the same rock non stop around his yard! Joe Ormonde.

[dscinta]

So I started this thread because of what happened to my original motor and after reading and learning from this thread I think I may have initially jumped to a few conclusions. I originally used "Bean oil" with this motor because I was also riding a kx250 air cooled 2 stroke and I thought the smell was cool. Stupid! As most people now know that oil is not awesome and specifically does not store well. I used some old mixed fuel that had been in my garage for about a year and I believe that is why my piston seized. After I fixed that I rode it with pretty much lawn grade 2stroke oil (walmart) for about 20 hours and I burned a hole in the piston. Truthfully it was running better than ever so I assumed that I had leaned it out too much. What I am thinking now is that I was getting pre-ignition (bad timing) and that is why the piston burned through. I think I need to stop worrying about the mix, just go with a safe 32:1 with Yamalube 2R and focus on jetting and timing. Sound about right Gents?

[Dale]

Agree!

Set the points carefully. Best to confirm your case marks with a dial indicator and then use a timing light to confirm that you are firing at the correct time.

Then set up your carburetor rich and work back down.

[dscinta]

I am considering buying 4 or 5 jets to make myself a kinda tuning kit. I own 3 of these motors so it feels like its not a waste of money.