Honda G300 ?'s

[Briang701]

I just bought a kart from a friend of mine, it has a G300 on it and I was wondering what I could do for easy and inexpensive upgrades to get more power out of it. I'm going to go buy some tube and a blow through muffler tomorrow and make a header for it. I was also wanting to maybe up the jetting but I don't know where to get the jets for the Keihn (sp?) carb and I was thinking about just drilling the jet; but I don't currently have a set of jet drills all I have is a number,letter, fractional set for my machining work. I have also been hunting around trying to figure out how to take out the governor but I haven't found and good info on how to do it on the G300 engine.
Brian

 

[DirtTrackRacer_07]

You don't have enough motor mods to need to drill the jets out yet.

I would definettly add the header pipe. Any stock muffler doesn't flow worth a flip.

Ima look around on these engines for you and see if I can find some stuff on the internet for you.

 

[anderkart]

Hey I ran on old Honda G400 (406cc./10hp) flathead for quite awhile. After I made a straight pipe and installed a race air cleaner my spark plug was reading way too lean (white). I just used # bits to slowly enlarge the main jet until I got it to run a nice tan color.

Neither of us will find many off the shelf speed parts available for our engines but but I learned lots of kart racers use to do very well racing the smaller G200 models back in the 70/80's.

I just unhooked my Governor arm and didn't have any trouble running it that way for quite awhile, but it would definitely be best to remove the internal Governor components just in case they're not up to revving over 3600 rpm.

 

[DirtTrackRacer_07]

I have looked but I cannot find much on this motor.

I am not familliar with them.

I wouln't of thought that they would be that sensitive to change.

You may have to buy a small set of drill bits and work your way up drilling.

I need to get me one of these honda clones and experiment.......

 

[Briang701]

Sounds like the header is the way to go, I will try unhooking the gov arm and see how it does, I only have about $150 into the cart so if I cant get what I want from the G300 I will just have to go the way one of my neighbors did and grab one of the clone engines from HF. I have the small drills so I may just drill the jet depending on the plug coloration once I make the header for it. Thanks Guys, Brian

 

[anderkart]

Sounds like a plan. Hey Briang, just out-ta curiosity I was wondering If your G300 has a 3/4" or 1" diameter output shaft where the clutch mounts? (my G400 is 1")

 

[Briang701]

From what I measured today it appears to be a 1 inch output shaft, but its a long bugger

 

[anderkart]

Cool, yeah I hear ya. My G400 had a 1" long/larger diameter section right where it exits the case and then the 1" portion protruded a half inch longer than my clutch actually needed.

 

[Briang701]

So in my shopping for a new clutch I have found that almost any 1 inch bore clutch is going to be over 100 dollars, I would really like to get the clutch closer in towards the motor and the clutch thats on it right now has a lip on the bolt side. Any suggestions?

 

[anderkart]

Yeah all the lower priced 1" clutches I've ran across are the outboard-only mounting style that have a lip on the bolt side.

Is your karts engine mounted on the side or rear? (post some pics if you got any)

 

[Briang701]

it's on the back right side, I was thinking I might be able to take the clutch apart and machine off the lip on my lathe but I have not yet looked that closely at it yet

 

[anderkart]

Dang that thing really is hangin out there. That'd be cool if you could mod the clutch but there's not going to be much left of that drive gear once you get a 1" ID bushing in there... Some guys shorten/machine the crank and even turn-em down to 3/4" where you've got a much better selection of lower priced inboard/outboard clutches in most any gear count you'd want. I just ended up going with a 1" Noram Star clutch, they're available in 12 to 18 tooth models but are pretty expensive.

Here's a better pic of my G400: