I've searched and read for an easy way to adjust my valves to zero lash cold, but haven't found an easy way. If I bring it to tdc on the compression stroke and tighten them down where a .002 feeler gauge won't fit between the lash cap and rocker arm, the pushrod still has a lot of play up and down. Can I tighten them down and be good as long as I can spin the pushrod easy? Can anyone tell me an easy way? I've about ripped my arm off when it kicks back over and over from valves being too loose. I even pulled the flywheel off to make sure it hasn't slipped and it was good so I retorqued it to 70lbs. I'm about positive it is the valves. Any help will be much appreciated.
I know I'm a little late to the game, but...
I was having kickback and hard start problems with a Predator 224 build. I literally spent months trying to lash and re-lash at .003. I contacted everyone in the mini bike game I knew or had a channel. They all had the same advice. Check your lash, check your compression release. One night I had torn down my entire engine to check rings and compression release. When I was reinstalling the rods and rockers I noticed it was significantly easier to hand crank with 0 lash. I did some searching and found this and another thread about 0 lash and finger spinning the rods. I set set the lash at 0 using the EOIC method and being able to finger spin the rods.
It absolutely worked first time. It is in a whole other universe. It starts easy, first pull, every pull. No hard start, no kickback, no problem.
I have started and stopped the bike several times while tuning the carb with a Wideband 02 Sensor and Tachometer. With no problem what so ever.
The bike is tuned at 1800 rpm and a cool 14.6ish stoic on the carb. It has a mean .308 cam growl and zero bog, poping, or backfire. It seriously doesn't sound like a mini bike at all. The person who came up with this is tops in my book. I'll never do anything else on other builds.
My build:
Predator 224 block.
Governor removed.
Low oil removed.
ARC connecting rod.
Dyno Cams .308 cam.
Flat top piston.
Big valve, shaved head - polished and ported.
32# duel springs
Chrome 5.11 push rods.
Thin head gasket
3:1 stamped rockers, lash caps on both sides.
Push rod guide.
AR 3910x plug.
Makuni 24mm flatslide - 25 pilot, 135 main at Washington State sea level.
Tuning with Bosh Wideband 02 sensor and Tachometer. Again, 1800rpm and 14.6ish stoic at idle. I might need to enrich a little after riding.
Adjustable coil bracket with unregulated coil - I put 2 pennies behind the coil to get the business card gap correct.
3 magnet flywheel at 6 degrees advance.
First generation Baja Warrior frame with the headlight working off the flywheel.
I was having kickback and hard start problems with a Predator 224 build. I literally spent months trying to lash and re-lash at .003. I contacted everyone in the mini bike game I knew or had a channel. They all had the same advice. Check your lash, check your compression release. One night I had torn down my entire engine to check rings and compression release. When I was reinstalling the rods and rockers I noticed it was significantly easier to hand crank with 0 lash. I did some searching and found this and another thread about 0 lash and finger spinning the rods. I set set the lash at 0 using the EOIC method and being able to finger spin the rods.
It absolutely worked first time. It is in a whole other universe. It starts easy, first pull, every pull. No hard start, no kickback, no problem.
I have started and stopped the bike several times while tuning the carb with a Wideband 02 Sensor and Tachometer. With no problem what so ever.
The bike is tuned at 1800 rpm and a cool 14.6ish stoic on the carb. It has a mean .308 cam growl and zero bog, poping, or backfire. It seriously doesn't sound like a mini bike at all. The person who came up with this is tops in my book. I'll never do anything else on other builds.
My build:
Predator 224 block.
Governor removed.
Low oil removed.
ARC connecting rod.
Dyno Cams .308 cam.
Flat top piston.
Big valve, shaved head - polished and ported.
32# duel springs
Chrome 5.11 push rods.
Thin head gasket
3:1 stamped rockers, lash caps on both sides.
Push rod guide.
AR 3910x plug.
Makuni 24mm flatslide - 25 pilot, 135 main at Washington State sea level.
Tuning with Bosh Wideband 02 sensor and Tachometer. Again, 1800rpm and 14.6ish stoic at idle. I might need to enrich a little after riding.
Adjustable coil bracket with unregulated coil - I put 2 pennies behind the coil to get the business card gap correct.
3 magnet flywheel at 6 degrees advance.
First generation Baja Warrior frame with the headlight working off the flywheel.
If it is significantly easier to hand crank when going for zero lash, then you are enough into negative lash to be releasing compression. For zero lash you would back off the adjuster in tiny amounts until you feel compression. And this is another way to go for zero lash without needing to spin push rods.
If you are able to cold start with a tiny amount of negative lash then great. Once hot you will have positive lash. If you were getting kickback when it was cold while set for say .003", then why wouldn't you get kickback when trying to start a hot engine? Hot lash on the exhaust side would be at least .003". Either way do what works for you.
With all the compression you are using, it shouldn't sound like a minibike.
If you are able to cold start with a tiny amount of negative lash then great. Once hot you will have positive lash. If you were getting kickback when it was cold while set for say .003", then why wouldn't you get kickback when trying to start a hot engine? Hot lash on the exhaust side would be at least .003". Either way do what works for you.
With all the compression you are using, it shouldn't sound like a minibike.
Actually, I have read studies that claim the cylinder expands more (lengthens more) when at operating temperature than the pushrods do.
I run zero lash on all OHV engines. I have not done it in a while, but before I started running zero on a regular basis, I set a 212 at zero lash cold, got it good and hot, and measured it again. Both were greater than zero, but I do not remember the actual numbers...close to .002, IIRC
Be sure you are not on the CR when you adjust.
I run zero lash on all OHV engines. I have not done it in a while, but before I started running zero on a regular basis, I set a 212 at zero lash cold, got it good and hot, and measured it again. Both were greater than zero, but I do not remember the actual numbers...close to .002, IIRC
Be sure you are not on the CR when you adjust.
AND IT WILL BE AWESOME!!!