CT70 valve and points adjustment- what's your choice?

Meangreenhk0

Meangreenhk0

Member
We have CT70s, K0s and HK0s.

I understand valves are .002 intake and exhaust (cold) and points are .012-.016 by the book, but I was interested in where most people have ended up setting these on their own stock bikes, or if there was any different thoughts for an 88 upgrade. I have seen a few different options on the forum and wondered if there was slight benefits to the different choices.

I have read some people say to set the intake .002 and exhaust valves at .003 to "run cooler", others say follow the book, and I've read adjust both to "a tight .003 on both when cold" Thoughts?

I've also seen all options on the points gap. Do most of you set points at .012, .014, or .016, and why?


Thanks,
Christopher
 
cjpayne

cjpayne

Well-Known Member
.002in and .003ex. .016, because that's the most advanced and gets a better top end. I read somewhere, awhile back, that someone got .017-.018 to work, but I never could. I've also had better luck with the NGK C6hsa plugs running better. 91pure fuel works best for me, but 87pure will work just fine. Ethanol is a bad joke that causes top end lean out, has the shelf life of milk, and rots all the rubber.
 
Cleato904

Cleato904

Active Member
Like cjpayne said stay AWAY from ethanal gas. I work at a Honda dealership and 80% of the bikes & ATVs we work on are ETHANAL related problems. If you let a bike set for 3 months with ETHANAL fuel in it, the carb will look a lot like apple jelly in the bowl when removed.Remember corn is for cooking and drinking
 
6

69ST

Well-Known Member
0.002/0.003" are ideal valve clearances; you could "split the difference" and go 0.0025" on the exhaust, I suspoze...but why bother? How much horsepower is in the balance, from a 0.0005" change in valve lift. That's a rhetorical question, btw.

As for point gap, factory spec is fine with a 4-speed which has an advance mechanism in the flywheel. 3-speeds, which have fixed timing, benefit from a little wider gap, which advances timing. There is a limit. Most guys think, incorrectly, that advancing spark timing always means more peak power. The correct explanation is that every engine has an optimal ignition advance, deviating from that works against you, period. I'll spare you a longwinded tech dissertation, it's not needed here. The 3-speeds have less lead (a.k.a. advance) at speed than the 4-speed models. You can't go more than ~0.018-0.020" gap before the points will no longer close and the engine won't run. IOW, it's a failsafe.

On the pump gas front, if you have a reliable source for corn syrup-free gasoline, it's preferable. Just don't fool yourself, unless it's from a specialty source, since 2006 even the ethanol-free flavor ain't what it used to was.:( If the machine will be sitting, unused, for more than a month, the fuel system should be drained dry...tank, lines & carb. IMHO, it's good general practice to drain the carb before parking the bike, regardless. A float bowl can dry out via evaporation in under a week, under the right conditions, and gasoline residue is what causes carb problems. FWIW, I've run pump gas all along, no carb problems, only the petcock packing & fuel lines have been affected. It's more a question of practicality; I'm a serious road rider, so it's less hassle being able to refuel at any gas station. If you can live with the short tether of a gas can, then it's a different situation.
 
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