We are new to the 120 scene ,My son and I went to the snow drags this past week end and raced his sled , There was some hopped up 120 there, His is stock with the zip tie governor by passed , He could get them out of the hole 20 ft but then thay went by him , I am looking at the speed kits clutch ,Hub, Chain, And Tensioner,Carb parts ,And a D&D pipe, Will there be a big change? I do not want to lose alot of bottem end out of the hole .Should i do valve springs and a timing key and clean the ports and carb parts up, He weighs about 40 lbs,|Another race in 3 weeks, Thanks Darren & Cohen , Yellowknife NT Canada.
Post by madziarracing on Mar 8, 2011 8:49:26 GMT -5
Before we can give you advice on what to do...are there rules in place on what you can and cant do? Regardless I would say you should start with removing the gov gear. Takes the motor to a whole new level that you can not achieve with the gov just bypassed. Next on the list is an adjustable main jet. Gotta have one. The stock clutch is a great setup that with a little knowedge you can modify to meet your needs. Spare parts can be bought from www.apskarting.com They carry every part and are one of the main suppliers for Max Torque clutches. The tuning of the clutch info will be best if it comes from Jim. Might want to start a new thread in the clutch area. Rec motor has some good tips on there website.
To some it all up with these little motors....If you want more top end than the bottom will suffer. Changing gears on the clutch and rear will change the speed and pull out of the whole.
You do not want to leave the governor inside the crankcase when you have bypassed it. IT WILL COME apart and it will always end up where you don't want it. It will damage the crankcase by punching a hole through it that can be repaired but it can be avoided by just removing it. Or it will get stuck under the rod and possibly break the rod. It is simple on some engines and a challenge on others but someone put it in there by hand and YOU can get it out. It is one of these summer projects you can do and get on the site and ask someone that has done it to walk you through it.
The Vehring's certainly have taken many of them out from ALL types of engines and they are excellent teachers.
As for the clutch don't be afraid to taken them apart. The clutch needs to be maintained. Take the sprocket out of the drum and let it sit in some 30 weight oil at the end of the season and just leave it there until next fall. Leave the drum outside after you have wiped it out and cleaned out all the oil and grease, sand the inside with some 80 grit sand paper and then put on the secret coefficient of increasing friction-- RUST. DON"T spray the inside with WD-40 let it alone, rust is better than a shiny drum.
Next little hint when you put the clutch back on the crankshaft, leave off the outside snap ring holding the drum onto the sleeve. The clutch has no where it can go since you are holding it on with a bolt and washer. This gives you the flexibility of quickly changing center assemblies for different engagements. This way you don't have to find the master link and remove the chain, you just pull out the shoe assembly. I normally only tell that to people that call but Bob wants me to share some secrets with this site.
The stock clutch comes with 6 wedge shoes, but YOU can swap out 3 of them with lighter shoes and increase the engagement but change every other shoe with a light one.
With the green spring (stock) you are coming in at 2,200rpm. Change just the spring to a black one and you have increase the engagement to 2,700 with the same six wedge shoes.
It is TOO cold to make a lot of changes when you are at the race so you want to do it quicly and easily. Have 3 or 4 shoe assemblies marked with different engagements and find out which works best for you at that track for the temperature conditions that day.
I will send Bob a chart showing various engagements with the two shoe styles we have but remember you can swap out and mix the two shoe for different engagments. There is a leading edge and a trailing edge of a clutch. Putting the heavier shoe on the leading edge will make it a little more aggressive. There is a combination that will give you an advantage but YOU must find it for yourself. The engine is the dictator for how well the clutch will perform.