So I have 2 CT70KO's that seem pretty sloppy with the kickstart (meaning seems like something is slipping) when I kick them over. I have a 1970 z50 that is nothing like these, you kick it and it spins the piston nice and quick. Once running they shift nice and run great. So is this an indication of a weak clutch? Or am I missing something else. Thanks
sloppy kickstarter
- Thread starter hoyt1967
- Start date
Yep...you'll also get rapid shift fork wear, adding injury to insult. Zinc went bye-bye from automotive oil in 2006.
I'd suggest ordering new plates, discs & springs for you clutch. That'll fix it. Running the right oil (Honda GN4 is a sure thing) will keep the slippage from returning. H.D. clutch springs wouldn't hurt...and can be retained should you decide to increase displacement, at some future date.
I am just running 10w30 in them. I will try switching to the GN4 oil or something compatible. any suggestions?
Viscosity should be selected based on peak operating temperatures. Straight 30W, with the formulations available when these bikes were new, no longer exists. 10w30 or 10w40 should be fine in ambient air temps below 60F (as stated on the clutch cover). With a bone-stocker, that might be fine all the time, unless you're running flat-out, on the road, for miles at a stretch. Low speed riding, such as offroading, won't heat the engine enough to take oil temps over ~220F. Road use, particularly speeds above 40-45mph and in summer when ambient air temps are into the 80s, or higher, can spike oil temps well beyond 180F. That's enough to thin-out 20w50, which is the closest you're likely to get to straight 30W, enough to make it flow freely.
What's most important is the oil formulation. It must contain enough zinc, to protect the transmission and not contain friction modifiers that will contaminate clutch discs, resulting in slip. Honda GN4 is just one brand among many, including: Valvoline, Yamalube, Castrol, Spectro, AMSoil, et al. Mobil 1 has a wet clutch compatible formulation. They're probably all acceptable. The synthetics are superior oils but you can't, or shouldn't, try extending oil change intervals to recoup the cost; these engines lack full-flow, cartridge-type, oil filters. At the other end of the spectrum, there are those who go with Shell Rotella, which is a diesel formula. It has some zinc content and won't contaminate a wet clutch, unlike automotive oil. The zinc content is marginal, at best; barring further reductions in zinc level, transmission wear would take a while to occur. The basic fact is that no one has even accumulated significant mileage on one these these engines to support anecdotal proof either way, let alone done any scientific testing, to really know the effects. IOW, it's a bit of a gamble.
The fact remains, Honda GN4 is simply a known quantity at a midrange price, i.e. a sure thing. Most don't put on enough annual mileage to make cost an issue. ~8 operating hours is a reasonable oil change interval and that usually translates into 200-400 miles, depending upon operating conditions. If you're riding in sandy, dusty, offroad conditions, or through a swap meet, you might want to go even below those mileage numbers, same as with power equipment. I reckon that most won't put more than 500 miles on the clock in any given year. Very few of us cross the 1K mile mark. That's maybe 2-3 quarts of oil per year...not many bucks.
FYI, this time of year, Autozone (and others) typically put bike oil on sale. And they usually sell Valvoline and Castrol. GN4 can be found at a discount too, online, with a bit of patience.