Timing Lesson
- Thread starter mrichard
- Start date
MSZ
Moderator
Silly question to the original author of this thread. Since you switched to a 20mm shengway, did you install an aftermarket petcock? If you didn't, that could be a problem as well. The 20mm shengway will flood terribly if you don't have a petcock on the bike. Remove your sparkplug and blow out any residual gas, reinstall a new sparkplug and see if your bike starts easier.
Also, the cranks are different on the 3 speed and 4 speed motors, and using a 3 speed flywheel on a 4 speed motor isn't exactly optimal as the crank tapers are a different shape.
Let's keep troubleshooting and we'll get this problem licked.
Also, the cranks are different on the 3 speed and 4 speed motors, and using a 3 speed flywheel on a 4 speed motor isn't exactly optimal as the crank tapers are a different shape.
Let's keep troubleshooting and we'll get this problem licked.
Racerx, yes I do have a very good spark.
Gary, the points are about 26 hours old now and the bike has not started since they were put in.
Pony Express, I did install an aftermarket petcock so the fuel would shut off. I don't know what to say about the crank to flywheel taper. What is so flusterating is that PRC is suppose to have a good reputation for building good motors, comparable to Jeff at minigunz. I would think that they should know about any problems that would show up with mis-matched parts. I did try and call PRC a couple of times but they were in the middle of moving to Florida. I think I have done just about everything most of you have suggested. Adjusted the carb as per Racerx's instructions and installed the points. I still don't know at what point you guys are gapping the points at .012-.017, when the flywheel is at the F mark or when they reach fully open which is where on the flywheel. Thanks for all the suggestions.
Mike
Gary, the points are about 26 hours old now and the bike has not started since they were put in.
Pony Express, I did install an aftermarket petcock so the fuel would shut off. I don't know what to say about the crank to flywheel taper. What is so flusterating is that PRC is suppose to have a good reputation for building good motors, comparable to Jeff at minigunz. I would think that they should know about any problems that would show up with mis-matched parts. I did try and call PRC a couple of times but they were in the middle of moving to Florida. I think I have done just about everything most of you have suggested. Adjusted the carb as per Racerx's instructions and installed the points. I still don't know at what point you guys are gapping the points at .012-.017, when the flywheel is at the F mark or when they reach fully open which is where on the flywheel. Thanks for all the suggestions.
Mike
MSZ
Moderator
PRC does not have a clean reputation building motors. There are a ton of people who have had issues with them as well. I had port work done by them, and my 5 year old kid could have done a better job. Seriously. I've give them 5 stars out of 10.
Jeff Tuttobene on the other hand has been one of the top engine builders for these motors going on 30 years now and he won't do you wrong. I'd give Jeff 9 stars out of 10 with 1 star subtracted for his labor rates. He's the logical choice since he's a stones throw away from you. If you lived in the midwest, I'd recommend Bob at ct70honda.com for engine work.
Toss a new set of points and a condensor in there, no matter how new they are. With some of these aftermarket parts, the stuff just plain doesn't work correctly when new, so no matter what you do cover all bases.
I wish I could be there to help you out, as it's the little things that drive us crazy..
Dan
FastMC
Member
I'm kind of surprised PRC is still in business actually. I'm sorry you had to find out first hand how poor their workmanship is. I too found out the hard way. Fortunately though my dealing with them was just purchasing a so called "ported race head" which BTW looked like it had been ported by a blind guy with a chain saw (valve seats damaged). I did get my money back for the destroyed head though. I think there's a bit of pipe smoking going on in that shop and it's not exhaust pipes. Not to turn this thread into company bashing but maybe it will save a few others the headache. So with that said I would double check everything they did on your motor. Compression, fuel, spark, cam timing,and ign timing. There's a lot of good information in this thread but, do you definately have good compression ? It's not mentioned. And like someone else said check your cam timing. Then move on to the fuel and ignition systems. Keep at it, you'll figure it out and next time you'll be an expert and wont need someone else to build your motor.
One more time. The F mark is where the points are suppose to just start opening. Thats why it says in the manual when using a continuity light it should just begin to dim at this point. Thats because the points are beginning to open breaking contact and dimming the light. It also says replace points if point gap can not be obtained between .012 and .016 in
Look through the slot in the flywheel and measure the gap when they look to be fully opened if you really want to measure it. Anywhere between .012 and .016 is fine. Somewhere in between is perfect. If I payed good money for a rebuild and ended up with the problems you seem to be having I would be relentless with that person in getting it fixed or my money back. Its a shame there are people out there like that with no respect for their workmanship. I wish you the best of luck.
Look through the slot in the flywheel and measure the gap when they look to be fully opened if you really want to measure it. Anywhere between .012 and .016 is fine. Somewhere in between is perfect. If I payed good money for a rebuild and ended up with the problems you seem to be having I would be relentless with that person in getting it fixed or my money back. Its a shame there are people out there like that with no respect for their workmanship. I wish you the best of luck.
If there's good spark, then the toughest issue is removed from the list of possible causes, that's a biggie. Low compression & correct timing are easy enough to verify. At this point, though, I'd get some fuel directly into the combustion chamber, try a few drops down the carb (by removing the slide & replacing it) and seeing if it will fire. I'm assuming that the cam timing is correctly set and that the motor has decent compression. There simply shouldn't be enough variation of spark timing, through point gap adjustment alone, to prevent the engine from running.
That said, lack of compression and/or having the cam timing out by even one tooth can leave you dead in the water. H-model flywheels have a centrifugal advance mechansim and a different taper that will only fit an H-model crankshaft snout. A damaged centrifugal advance could potentially throw-off spark timing enough to cause this. If you've removed the flywheel previously, then it's simple enough to do it again to inspect the centrifugal advance.
That said, lack of compression and/or having the cam timing out by even one tooth can leave you dead in the water. H-model flywheels have a centrifugal advance mechansim and a different taper that will only fit an H-model crankshaft snout. A damaged centrifugal advance could potentially throw-off spark timing enough to cause this. If you've removed the flywheel previously, then it's simple enough to do it again to inspect the centrifugal advance.
MSZ
Moderator
I was thinking the same thing as well in the centrifugal advance. I've seen some of those flywheels with no springs and some with the mechanism welded together that can lead to problems.
And Honda made two different flywheels for the 4 speed motors, and the semi-autos if I remember correctly were all Hitachi. Mitsuba was the other manufacturer.
OLD CT
Well-Known Member
Pull the plug to make sure ur top dead center.The piston all the way up in the cylinder.Close to TDC.Then set ur point gap.Look at the O mark on the cam sprocket and line up with the mark in the head.U may be 180 degrees off.Just cause ur F lines up doesnt mean ur close to TDC.Hope this fixes the problem.
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Well guys I couldn't take it anymore and took the bike to Jeff at Minigunz today. First off let me say that Jeff was the one I wanted to build the motor in the first place. He had done a great job on my younger son 88cc for his z50 that I want him to build my older sons ct70. After not being able to get ahold of Jeff for several weeks I had PRC build the engine. We put the bike up on the hoist and there were so many things wrong with the engine I don't think anyone could have found all the problems without seeing the engine. Among them were, condenser not soldered in right, worn out timing chain, chain adjuster missing a spring and ground down with what looked like a belt sander. O-rings missing behind stator plate, flywheel LIGHTENED and had lost almost all of it's magnetism, to name a few. After fixing most of the problems ( glad I brought 2 extra engines for parts) Jeff adjusted to points and the bike started right up. We then adjusted the carb which was actually very close thanks to racerx's help. So after about 1 1/2 hrs my son got to ride his bike for the first time.
I can't stress enough how important it is to find out all you can about the engine you want to build and the people you want to have build it. I had read alot of good things about PRC on other web sites but most of it turned out to be wrong in my dealings. If you can't find someone you trust and hopefully close to home I would strongly suggest you build it yourself. I am by no means a motorclcle mechanic, but I do know my way around V8's and VW's, and I am sure I could have built an engine of better quality than what I got. What I received and what I paid for were light years apart.
I can highly recommend Jeff at Minigunz, it is nice to see someone that takes pride in their product and stands behind it. After spending a few hours with Jeff I learned far more than the money I paid to have the bike fixed.
On a side note after coming home I started my z50k1 with what I learned a minigunz, so I really got 2 bikes fixed for the price of one. I'd like to thank all of you that offered suggestions on my bike, but I really don't think anyone could have solved all the problems with this engine without seeing it in person.
Thanks Mike
I can't stress enough how important it is to find out all you can about the engine you want to build and the people you want to have build it. I had read alot of good things about PRC on other web sites but most of it turned out to be wrong in my dealings. If you can't find someone you trust and hopefully close to home I would strongly suggest you build it yourself. I am by no means a motorclcle mechanic, but I do know my way around V8's and VW's, and I am sure I could have built an engine of better quality than what I got. What I received and what I paid for were light years apart.
I can highly recommend Jeff at Minigunz, it is nice to see someone that takes pride in their product and stands behind it. After spending a few hours with Jeff I learned far more than the money I paid to have the bike fixed.
On a side note after coming home I started my z50k1 with what I learned a minigunz, so I really got 2 bikes fixed for the price of one. I'd like to thank all of you that offered suggestions on my bike, but I really don't think anyone could have solved all the problems with this engine without seeing it in person.
Thanks Mike