TIPS AND TRICKS

TIPS AND TRICK 

We are working to put this page together so we can provide you with the best information possible on 50cc, 125cc, 150cc, and 250cc Scooters.

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The following tips and tricks are from www.50ccracing.com 

TIPS - CARBS & JETTING  

Do I want a bigger carb?

Carburetors offer wonderful tuning opportunities. On most XR/CRF 50's, it is very common to replace the stock carburetor  with a larger one. The larger the bore of the carb, which is measured in millimeters, the more fuel it can flow.  Stock on a Honda 50 is a 13mm carburetor, that's tiny.

How big should I go? Big carbs increase mid-and-up power ,at the cost of low-end. In order to flow fuel through a larger opening, the engine has to create more vacuum. The larger the carburetor throat the greater the vacuum required to draw the fuel into the engine. At low rpm settings, many four-stroke engines don't produce enough air velocity to get the fuel flowing, therefore low-end power is lost until the air flow is sufficient (at higher rpm). On the flip side, smaller carbs flow fuel more easily, start better and have better throttle response.

Jetting on your Takegawa 88cc kit with the 18mm carb.

I've gotten several emails regarding the jetting on this kit. I was also having problems but now I seem to have resolved them. Altitude here is 750 feet, temp was 80 deg and humidity was low. The engine also has a lot of other stuff done to it, but the tip I have here is to lower the needle and run the 85 main. Give it a try, it made a dramatic difference with mine today. I'm at the second notch from the top now and went there from the bottom notch (needle was raised, that's what you do with the stock carb). Cleaned up the middle of the rev range that was crap before.

Second hint is don't be afraid of the air screw. That is on the right hand side of the carb (don't burn yourself on the pipe) and it's the lower left screw. The upper screw is the idle adjustment. The lower left screw is the air screw, and it should run between 1/2 and 2 turns out from all the way in.

Jetting on your stock carb.

All XR50s can benefit from raising the needle (lowering the clip). It works magic and I recommend it to anyone that has a fiddie that isn't quite running up to par. Leave the stock 58 main and move the needle. I have mine on the second notch from the bottom, but don't be scared to go all the way. Play around, its an easy change. Air screw goes anywhere from 1/2 turn to 1 1/2 turns out and also makes a little change, but nothing compared to that needle.

These are a must have. The thing I noticed right away was a little firmer pull on the shifter because you are pulling against the stiffer springs. But once you let the shifter back to it's home position, your bike is in gear and there are no doubts about it. No slipping are sliding going on any more, you are in gear and going forward. Or if you are savvy enough, you can slip it by letting the shifter back slowly, just like your big bike with the handlebar clutch. You can slip the clutch with your foot. Try it, but you'll wear out your clutch fast unless you have Heavy Duty clutch springs.

These are a must have. The thing I noticed right away was a little firmer pull on the shifter because you are pulling against the stiffer springs. But once you let the shifter back to it's home position, your bike is in gear and there are no doubts about it. No slipping are sliding going on any more, you are in gear and going forward. Or if you are savvy enough, you can slip it by letting the shifter back slowly, just like your big bike with the handlebar clutch. You can slip the clutch with your foot. Try it, but you'll wear out your clutch fast unless you have Heavy Duty clutch springs.

Tip on Installing HD Clutch Springs

Sik50s has a kit with new plates and springs.

	Here's the easy part. Lean your bike over on a stand so the oil doesn't drain out. You'll want the bike in this position to keep parts from dropping on the floor.
	Get the area freed up by removing the brake pedal, kick starter and footpegs. Because its laying on its side, the foot peg mounting bar comes off nice and the bolts are easy to get at.
	an 8mm socket will get you this far. After this it gets a bit harder, but not rocket science. Nothing is on these things. When the cover comes off so does the engagement mechanism consisting of plates that roll on balls. Take care to notice what order everything is. Mine all fell on the floor but I got them back in the right way without the help of a manual. The shift shaft has a lever that reaches over to the engagement mechanism, and it is shown in the wrong position in this picture. After the  clutch is reinstalled the lever points at the center of the unit. It's mounted on a splined shaft.

After this point I quit taking pictures because the dirty work began, but I will talk my way through it. Boring reading if you're looking for entertainment, but if you're changing out your springs or clutch plates, it may help you out.

The face of the clutch basket has 8 screws, 4 of each type. They all need to come out. The inner cover plate was a bitch and I stripped the heads of real quick and used and "easy out" to get them out. The outer bolts loosened up with an impact driver.

Once the small cover plate is off you'll notice a nut turned onto a shaft that holds this whole assembly on. Knock back the tab on the washer and the nuts turns off normally, or counter clockwise. I used a screwdriver after I wedged another screwdriver into the gears so the assembly wouldn't turn. Note: the spring washer on top of the tabbed washer has writing on it that says outside. Reinstall it that way with the writing out.

OK, now the clutch can be pulled out of the bike. Remove those little springs you see, and then turn the clutch over. Its all held together with a big 'ol c-clip. It pops off  pretty easy and the clutch all comes out in plates. Lay these plated down in the order they came out and reassembly will be easier. Now you'll be able to swap out the springs and the reassembly process can begin.

After putting the plates back in, you'll notice you need to press the unit together and hold it there until you install the c-clip. I used a roll of tape and a vice and very carefully pushed it together making sure it wasn't catching on a tang, and then installed the clip.

The next hurdle you may encounter is when placing the clutch assy back on the shaft it needs to slide over and engage a gear. Mine didn't go on real easy like it was a slight press, so I marked a tooth groove so I knew it was lining up with the gear teeth, then got it started and it slipped right on.

When reinstalling the engagement mechanism, be sure all parts are just like they were when removing, or look at an exploded view in a manual. Incorrect installation could result in some bent or mangled parts.

Good Luck!!!! and have fun with a clutch that will translate all the power you're putting out down to the ground. Hang on tight!

Putting Heavy Duty Fork Springs 

Here you go, the big secret. Safely support your fiddie in the middle, and remove the front number plate, fork guards and wheel. Pull down the fork wiper so you can see the snapring underneath. Unbolt the top bolts holding the forks to the top triple plate. Take a minute now to notice a notch in the top of the leg, and how it lines up with a notch in the top triple plate. This notch forces the inner leg into a position so it must be addressed. Explanation--the inner fork is two halves held together with the spring. You are removing that spring and replacing it with a heavy duty spring. The amount you thread it together will determine where that notch lines up relative to the bottom fork leg. It will all make sense once you have everything out and are dis-assembling it.

OK, you are ready to pull the guts out of your forks. Take your snap ring pliers and remove the c-clip that was hiding underneath the fork wiper. Once that is removed the guts will slide right out the bottom.

You don't need to punch out any spring pins or anything....

Put the bottom portion in a vise, but don't clamp down so hard you deform it. Take a punch (or screwdriver) and tap the coil end of the spring and start it unscrewing off that half. Once started it will turn off easily. Remove it completely. Loosen the vise and clamp the other half and repeat the spring removal procedure.

Now, before you install your new heavy duty springs, file the burr off the spring end so it won't gouge into the soft aluminum inner thread on the fork legs. Now you can turn the new springs onto the tread opposite of how the old ones came off. Get them close to fully treaded but leave some thread at the end so you can line up the top and bottom halves so they are the same as before disassembly. If you thread them to far, clamp them in a vise again and tap the spring loose a little.

After you do yours, go over to your friends house and help him. You'll be amazed at how easy the second set goes together relative to the first one.

Heavy Duty Spokes

Installing your spokes is a breeze, just takes patience.

When you get your old wheel apart and start to stick the new larger diameter spokes though the stock hubs holes it will start to become more clear what you need to do. You will copy the pattern that they came out. If you forget, look at your other wheel, they are the same pattern. Stick a spoke through the hole and you may see you can't get it to point in the correct direction to get out to the rim. If that is the case, then you need to use a drill bit the same size as the hole and rock it a little to open it up slightly. After you get the spoke to turn the corner, you may see that it is not sitting correctly to seat in the hub, or the "mushroomed" end will not "suck up" to the hub. If so then this is where you need to use a 1/4" drill bit and countersink those holes so the spokes sit up tight on the hub. If I remember right I had to do this to every spoke hole, so half the countersinks are from the inside, and half from the outside.

Getting the spokes to sit relaxed in the hub will reduce the stress at that connection. Sharp corners are bad (stress risers) so rocking the drill bit in the hole will take that sharp edge off the surface the spoke sits against. If the mushroomed end is not seated in the hub, it will load the hub at a circle instead of a surface. It wants surface contact so it will try to work its way there and the hub will gouge the spoke, or worse, the spoke will crack the hub. Either way it is loading a small area and you want a large area.

For those who don't know, countersinking is when you remove metal so a bolt head will sit below a surface. Counter boring is for socket head cap screws, and countersinking is for flat head cap screws. Since this has a piloted angle it resembles a countersink more than a counter bore. If you still don't understand this, talk to your local bike mechanic and he can explain it also.

When using your stock rims, you'll need to enlarge the holes with a 1/4" diameter drill bit.

Tips on Trouble Shooting 

Here's what I did on a cold snowy afternoon here in Wisconsin. A buddy of mine had installed a Takegawa 88cc S-stage kit w/ the 18mm carb and couldn't get it to run right. He poked, prodded and turned but nothing seemed to work, so he asked me if I could give it a shot. I told him "no guarantees", but I'd put some effort into getting his bike running like I know it should. I have two bikes with these kits on and they rip.

Now this baby is one sweet looking ride. As soon as he showed up to drop it off, I was getting a little envious. It's a Sano inspired bike, but I think it has a few trinkets from other vendors also. It's a 2002 with the new CRF bodywork, and I must say that new plastic is a vast improvement over the XR plastic. Sleeker and sharper lines, much more modern. I may have to invest in some of that.

Anyway, this poor little guy showed up with a real bad sore throat. It would run, but only with the choke on and and revving pretty high. When we shut the choke off, the R's dropped and it quickly died. You could keep it running, but you had to work at it. Not the way it was intended for sure.

There are easy things to check, and there are more difficult things to check, but none of them are super hard. Some things just require a little more effort. Me being the kind of guy I am (a little lazy) I decided to check the easy stuff first.

1. Spark plug- I can't explain why, but sometimes the plugs on these things just crap out. Installing a new one can work miracles. That didn't do it for this bike.

2. Air Screw- Often turning the air screw will clean up a poor running motor. If your bike ran good yesterday, but not today, that is probably the cure. That screw is located on the right hand side of the carb and is the lower left screw. The upper right is the idle adjustment. (don't burn yourself on the pipe) It's designed to be run at 1/2 to 2 turns out.  Nope, not that either.

3. Timing chain- Believe it or not, I had mine off one tooth, and it ran but ran really bad. When you have the top end off, sometimes when it's all going back together you can booboo that arrangement and be off one tooth one way or the other. Line up the "T" on the flywheel with the mark on the top of the engine, and the "0" on the timing chain sprocket will be straight out and line up with it's arrow. A-OK

4. Valve clearance- the way this thing was surging made me think maybe it wasn't holding compression in the cylinder. I popped the two tappet covers off and checked the clearance to make sure there was .003" of clearance. The intake appeared to be a little tight, and I had to actually leave the gauge in, hold the screw and tighten the nut to keep from closing up the clearance. Always check it after tightening the nut to make sure the clearance is still there. A wee bit off, but that didn't solve it.

4. Hyper CDI- Pete had one of these installed (it's the little black box under the seat), and I didn't know if it was a dud so I swapped it out with a stocker I had laying around. Darn, done with the easy checks, now I need to dig into the carb.

5. Carburetor- Don't be afraid. These carbs are real simple and you're not going to hurt it by taking it off and poking around. Before attempting to work on it, take the seat/shroud/rear fender combo off, and take the tank loose to ease access.

The reason I knew Pete's carb had issues was I had his off and checked the jets and dropped the needle. After re-installing it still ran crappy. I swapped a carb from my bike and it ran great. OK, now we're getting somewhere. It's in the carb but where? I checked his pilot jet and it was the 35 just like mine. He had the 92 main in and mine had the 85, but that wouldn't cause it. I took the pin out of the float and removed the needle valve, had all the jets out and just blew through everything and make sure nothing was blocked shut. I checked the jets and blew them out and could see light from the other side. After I did all this, I put it all back together and reinstalled the carb it ran great. Whew, I'd done it.

All that switching around and looking at everything burned up about 2 hours. Actually, most of it was spent just taking carb off and putting it back on. I'd take it off, swap something or turn something, then put it back on to see if it was it. What did it was just blowing everything out and making sure nothing was blocked.

Other Tips 

Input: How do you get the carb. cap off the stock cable and onto a 70 cable. Thanks

Output:

Input: Hey, I have an old manual clutch CT70, can I take parts off it and put them on my fiddy?

Output: Everything transfers over fine-- no modifying or filing.  Basically 1st throught 3rd are exactly same ratio of course and 4th is about the same ratio from 2nd to 3rd. (I think that means the same gap as going from 2nd to 3rd from the stock tranny) I think for most tracks-- 4th wont be used unless there is a long flat or down hill straight. (I'll use it, trust me)   But for cruising roads or doing "urban assults" this gear is perfect.  If you take your time-- it's easy to see what has to be transplanted for this ordeal (splitting the cases on these bikes is very simplistic).  You could also do it in two stages, 1st stage just install the manual clutch to have a 3sp manual.  Forgive-- I don't have a manual to give the exact part names but-- to get the manual clutch to run you will need to transplant-- CT70 clutch basket, small sprocket behind the clutch basket, large sprocket to the left of clutch basket, replace the shift shaft, and finally the clutch cover with all the small mechanisms with the clutch cover.  As for cable-- I'm using an old XR75 cable which is a bit too long but works fine.  Second stage-- adding 4th gear is almost as simple. 

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Input: CAN I RUN 110 RACE GAS IN MY STOCK 2000 XR 50 AND WHAT IS THE BEST 70 KIT OR 80 KIT I CAN BUY FOR THE MONEY. THANK YOU FOR YOUR TIME.

Output: If you are truely on a budget, there are used big bores out there. AtomRotten@cs.com has some 88cc kits I know of. Don't know anything about running race gas. I think you reach a point where the added octane doesn't deliver any benefit, but I don't know where that point is. Craig at info@fast50s.com can help you out. I have a powroll kit on my bike and am very satisfied with the performance. I have a Fast50s kit on the display bike and it was equal or better than the powroll. Haven't put time on it because I want to sell it as a new bike. They both were $500, but had the cam. Cheap kits may not have cams.

More output: Hey wut up?
As far as the race gas question. That is a big no to the use of 110 race gas in a 4 stroke. High octane race gas burns at a slower rate and makes jetting a big pain. Jetted right this morning and rejetting by the second moto. Great for a 2 stroke but not as good for the 4 stroke. With a 4 stroke you are better off with 91 octane pump gas as the 4 stroke needs fuels that burn quicker. If you want that race gas smell and the fuel I feel for now is the bomb. Use VP's Ultimate Four I think its 94 octane. My bike has not missed a beat on this stuff. It is formulated for the 4 stroke and has all the odor of race gas we love.
The big bore kits I suggest if you are on a budget is the Tekagawa 81cc E stage or 88cc S stage complete kits. These kits come with the barrel, high compression piston, rings, clips, pins, complete 18mm kiehin carb kit, air filter, throttle cable, high lift cam, and a complete gasket set. These 2 kit sell for under $450 and are totally worth every penny. I have a few of these kits so if your interested let me know.

Engine Tuning

So you'd like to increase the power in your little fiddy? Here are the ways to get more punch, the how's and why's. Always be careful when changing your motor! If the changes cause a lean condition in the combustion, you'll cook your piston. Check your spark plug for a white tip. If its white it's running lean, and probably running hot.

The easiest, cheapest power: Take your carburetor cap off and raise the needle (lower the clip). All I can say is try it, you'll be amazed. The bike will run better, start better and idle better. You have to wonder why they don't do it at the factory.

Big Bore Kits: In the fiddy world, there is no replacement for displacement. Popular steps include 75cc, 81cc, 88cc, and if you decide to stroke is then 106cc and 124cc. When you go that big be careful of everything else breaking in your engine. You need to do the whole deal and beef up everything. Power improvement is astonishing and I highly recommend a big bore kit from your favorite vendor, they all have good ones and stand behind them and they usually come with a cam and a bigger carb. I run the Takegawa 88cc S-stage kits and love them.

Pipes: I didn't notice a big jump in power just from adding a pipe. It felt more like someone took a rag out of the stock muffler and it could breath a little easier. The additional noise can be a blessing and a curse. It sounds cool, but I don't thing your neighbors will agree.

Bigger Carburetors: Big carbs increase mid-and-up power at the cost of bottom.  In order to flow fuel through a larger opening, the engine has to create more vacuum. The larger the carburetor throat the greater the vacuum required to draw the fuel into the engine. At low rpm settings, many four-stroke engines don't produce enough air velocity to get the fuel flowing, therefore low-end power is lost until the air flow is sufficient (at higher rpm). On the flip side, smaller carbs flow fuel more easily, start better and have better throttle response.

Porting: To properly port the head on a four-stroke requires a flow-bench. A flow-bench measures how much vacuum it takes to draw air out of the intake port and exhaust flange. Porting and polishing the cavities of a four-strokes cylinder head can increase the flow rate for more performance. A big valve head can also be used to up the flow through the cylinder.

High compression pistons: A high-compression piston typically delivers more punch at the cost of some top-end.  Be careful, increases in compression might require higher octane gasoline.

High lift cams: When the camshaft rotates, it brings with it a lobe that pushes on a rocker arm (or tappet) that pushes on the valves. When the lobe passes away, then the springs on the valves return them to a closed position. High lift or performance cams alter this lifting and releasing from stock to allow more fuel into the cylinder, and more exhausted gases out. 

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