Thread: Low Budget Performance Upgrades

There's a small bolt on the back side of the muffler at the tip, you remove it spray a little wd40 in the edge of the baffle and gentely move it back and forth tilll it pulls out. when you take it out you might have to change the main jet too.

Originally Posted by ZJGMoparman

I could not find any SL70 cams anywhere. The only place I have seen the hot cam was on dratv. I searched ebay and other websites.

Here are some options:
72-73 HONDA SL70 CT70 MOTOSPORT K0 CAM CAMSHAFT: eBay Motors (item 400089551726 end time Sep-29-10 1018 PDT)
1973 Honda SL70 SL 70 Camshaft Assembly #3 - AHRMA: eBay Motors (item 200054068410 end time Sep-11-10 1038 PDT)
1973 Honda SL70 SL 70 Camshaft Assembly #1 - AHRMA: eBay Motors (item 200054068462 end time Sep-11-10 1047 PDT)

I may go with one of those cams. Do you have any idea what the stock main jet is in the carb? I will probably be changing the jets. Any recommendations for what jet I should go with if I go with that cam and remove the spark arrestor?

I've installed this cam in a number of engines. It'll really wake-up an H-motor, even with the stock carb. It works very well with an 88cc kit, too, even a 3-speed, semi-auto, which has fixed spark timing. The specs may appear tame, but the key is as Grant mentioned - the usable powerband. This grind is tractable enough to work well with a semi-auto clutch, meaning that you don't really give up significant torque. Just completed a 3-speed/88cc rebuild and, with nothing more than the Honda "fast road" cam, wider point gap and minor re-gearing (smaller wheel sprocket) the bike was easily accelerating to 45mph, with a lot more to go. The motor had less than 50 miles on the clock, making this bit of over-enthusiasm risky enough. Between an otherwise stock 3-speed, 4-speed and either of those with a bore-up kit added, I'd guesstimate anywhere from about 45mph to low 50s when fitted with the stock carb & head, plus stock exhaust. An 18-20mm carb, plus open-element air filter should add a few mph to the top, especially to the latter two combos.

This assumes a healthy top end, i.e. full compression.

There's a reason for the long lead-up. I've built & tuned engines in the configurations described. They all ran fine with the stock jets, needing nothing more than jet needle height & pilot airbleed screw adjustments. There was enough adjustment range to make the engine run pig-rich. I suspect that the larger displacement and/or increased lift/duration of the cam results in higher flow velocity through the venturi. The faster the airflow, the greater the pressure drop, the stronger the vacuum "signal". In more direct terms, the engine pulls more fuel through the same jets, making them "act" slightly larger, just enough. Carburetors are remarkably self-adjusting devices. Bottom line is that changing over to this cam should be a simpler process than trying to explain the technical details.

I was looking on Dratv at carbs and intake manifolds. How do you think this carb/intake kit would work on my ct70?

CRF50 XR50 Z50R AND OTHERS 20MM PERFORMANCE CARB KIT

stay away from that sheng wey!they dont work very well.hard starting too!Grant will back me up on that.the carb you need is a WEBLLC ebay left choke dual inlet carb PZ19.32.99 delivered.THE SHENG WAY IS A SINGLE INLET.check out ebay item#400144262684 non cable choke.

Alright, I have seen a bunch of those carb on eBay. I will go with one of those. Do these carbs bolt up to the stock intake manifold or should I replace the manifold. If the manifold is smaller than the carb, I don't see how a larger carb will make any difference.

it's a real easy fix.open up the stocker and insulator with a dremel as seen in photo.stock on left and customized for 19mm webllc carb.

Yea stay away from the sheng carb, No need to add to your troubles. Their might be a way to make them work but I ran out of patience...lol