Timing Lesson

[mrichard]

OK I've read all the post, looked at all the web sites, and have a clymers manual. But I still have questions. You line up the F mark and turn the flywheel counterclock wise till the points fully open and check the gap. The window is about 1 1/2" long how do I know when the points are fully open, I can't seen once the window has passed, do the points continue to open more? If the points don't start to open at the F mark then what? I've read that a timing light only dims that doesn't seen to exact. I've set the points 3-4 times and checked the timing about the same and the bike still is REALLY hard to start, and want to backfire every now and then. I set the carb like I was told to and checked for air leaks while the bike was running and found none. The engine was rebuilt by PRC and sent to me but hasn't run worth a !#%*& since I got it. I even broke down and took it to a shop to have the timing set and carb adjusted. 200.00 later he said he set the timing changed a new condenser with another one and put in a set of old points he had. Brought the bike home and I couldn't even start the bike. Back and forth a couple times but still no good. In the time I have in this bike I could of rebuilt a couple of VW's. I don't think I'm a dummy but I am about ready to give up. ANY help would be greatly apprecated.

Mike

 

[hondaman]

You said someone put in a set of old points he had laying around. They might be just that --Old Points. Put in a set of new points. If the points just begin to open when the F mark is aligned to the notch on the casing then that is all that is needed. Do not worry about the gap setting. Did he put in an old condensor he had lying around also? Put in a new one and make sure wires are soldered securely to it. Many so called mechanics do not have a clue when it comes to working on these old little bikes. Most of them were not even born yet when they were built. Yes if you keep running to a mechanic to fix every problem that comes up the bank will soon be broken. Changing points and condensor is really not very hard. Good Luck.

 

[mrichard]

I did put in new points and condenser, the bike still won't start. I don't understand about the gap, don't worry about it? I set the gap at .016 when the points are at the end of the window or when they were as open as I could see. The bike still wants to back fire when trying to start it.

Mike

 

[hondaman]

Like I said do not worry so much about that gap setting. Make sure you can see the points just begin to open and I mean just begin when the F mark reaches the notch on the casing. Its much easier to set your points this way. If the points are good the gap should not be greater than .016 at there maximum opening. Like the manual says anywhere between .012 and .016
is good. Are you getting spark at the plug? If not it could be as simple as a bad plug or plug boot to a bad ignition coil. You have to take it one step at a time and illiminate the possible causes.

 

[hondaman]

If the points and condensor are good and your getting good spark at the plug and it still will not start then I would check the following.
1 Check and adjust your intake and exhaust valve clearances to
.002 in
2 Make sure your carburetor is clean inside and out paying special attention to the little holes in the jets inside the carb.
3. Make sure your idle and air screws are adjusted properly to there specified settings.
4. Make sure there is no blockage in the exhaust.
If your getting good spark and good fuel flow it just about has to start. Like I said take it one step at a time.

 

[mrichard]

The engine is a brand new 88 kit from PRC racing, and the carb is new, but I did remove the jets and check for blockage. I should say that PRC did the rebuild not me. I called and asked them about valve adjustment and points when I first got the engine back and they said it was ready to go. Just bolt the carb on and put gas in it. Well it hasn't been quite that easy so far. I have gas and spark to the cylinder I've checked that about 10 times. I just don't know what it is but thanks for the suggestions.

PS I just now checked again for spark, good. I also went and bought some cigarette papers (don't smoke) and checked that the points were opening right at the F mark. They were alittle late so I adjusted them closed alittle. It still won't start. suggestions?

 

[OLD CT]

Backfire sounds like the timing is off.Cigerette paper is way too thin.Try a feeler gauge.Also ensure fuel is getting to the cylinder..014 is a good start.

 

[mrichard]

I used the paper to find out when the points started to open, and yes there is fuel in the cylinder.

 

[hondaman]

Take off or disconnect your air filter and try starting it. I am also running out of suggestions. If its getting gas and good spark it should at least sound like it wants to start. Try some starting fluid sprayed into carb. Is carb nice and tight to the intake? NO air leaks?

 

[mrichard]

Is there anything on the inside of the flywheel that could stop the points from opening completely or is it just a ramp that opens them? Also I'm not sure that it is the right flywheel. The marks are near the center of the flywheel and the notch on the case is up at the top. It is also a 4 speed if that helps any. Thanks for all the suggestions, if I can't get this to run soon I'm going to take it to Jeff at Minigunz. I'm about ready to give up, but I think its a timing issue.

 

[hondaman]

The F mark and T mark should be on the edge of the flywheel not the center. If it is not the right flywheel then that could throw the whole timing issue out of wack. 3 speed or 4 speed should make no difference. Where did you get this flywheel? Was it on the bike when you got it?

 

[mrichard]

Yes it was. I sent 2 engines to PRC and they used the best parts from both to build me a 4 speed H motor. I thought a 3 speed and 4 speed manual shift had different fly wheels, but I could be wrong maybe it was the cranks that were different. One of them was longer than the other. I'll take pictures today and try and post what I have so there is no doubt about what I have.

Thanks, Mike

 

[MSZ]

I need more information to work with. Take a picture of the flywheel and post it up.

Additionally, when you speak of a 4 speed, are you referring to a CT70 HK0 or HK1 engine?

Are the springs in your mechanical advance worn out? What carb are you running on this setup? How do you have the bike jetted?

Please provide more information so we can troubleshoot accordingly.

 

[clubford00]

Sounds to me like the cam chain is a tooth off, its easy to do and if the goof that rebuilt your engine didnt line up the little marks it will backfire like an old man after a bowl full of chilli !

 

[mrichard]

HERE is a link to the pics of the motor

http://pg.photos.yahoo.com/ph/crazy9119/album?.dir=/5ba9scd&.src=ph&.tok=phtIVHGBkfjyuKCB

Pony Express
I did not build the engine PRC did but what I know is that we sent them a 4 speed cl70 engine and a 3 speed ct70 engine We had them install an 88cc kit and port the head. When we got the engine back we also received a 20mm sheng wey carb with a 89 and 35 jet. The engine was suppose to have been run and ready to install. The engine has run 3-4 times but it is REALLY hard to start, when it does run. Like I said in my post it has been to one mechanic already and come back no better than it originally was. I don't know if the advance springs are worn out how do you tell?? The engine is getting spark to the plug and gas to the cylinder. It has new coil, plug, points and condenser.
The point open at the F mark but I don't know how far they are opening. Do they continue to open past the opening in the flywheel?

Mike

 

[hondaman]

My flywheel looks nothing like that but mine is a 3 speed. It looks like it would be a best guess proposition to line up that F mark with the notch on the casing.

 

[hondaman]

I also agree with clubford that the cam gear could not be aligned properly. Did you have to send this motor in to be rebuilt or is this place in your local area? If it is I would go back to them and tell them to fix it right or get your money back.

 

[Gary]

That flywheel looks like it's been machined which is no problem other than the missing marks and it is a automatic one at that. These are my CT70H flywheel pictures- http://i94.photobucket.com/albums/l119/garys_01/Dcp_0683.jpg
Here you can see inside the slots and see the advance springs.http://i94.photobucket.com/albums/l119/garys_01/Dcp_0682.jpg
Now if you have the flywheel cover with the removable center, it has a timing pointer at the top,which uses the timing marks on the face of the flywheel which you do have. It looks like this http://i94.photobucket.com/albums/l119/garys_01/Dcp_0681.jpg
You could remove the left hand cylinder cover and check cam timing, do you have a shop manual? If not some of us could walk you thru the process.

 

[Gary]

Here's a way to check if your cam timing is correct- pull spark plug rotate engine to top dead center on compression stroke, line up "T" on flywheel to pointer. Remove left cam cover. There is the letter "O" on the cam sprocket. At this point if you lay a ruler like in this picture, the "O" is on the left side of the ruler and lines up with the crank on the right side of the ruler as if you were to draw a line thru each other. This of course is null and void IF they used an after market cam sprocket that does not have markings or turned it over,I can't remember if there are markings on both sides of a Honda sprocket.
http://i94.photobucket.com/albums/l119/garys_01/Dcp_0686.jpg
Hope this helps,Gary

 

[69ST]

While it could be a timing issue, carb issues are more common. Pull the plug, attach it to the HT lead and check for spark. If you've got good spark, then try a few drops of gas directly into the cylinder and see if it fires. Starting fluid is easier to use for this, but it's rough on the upper end.

If there's no spark, then you'll have to go through the process of elimination. Yes, I know how frustrating it can be, but these motors are pretty simple and ignition problems are simple, too...just not always easy to trace. I've seen everything from rat-chewed primary leads inside the frame to slight surface contamination on the contact points (and I do mean slight), that prevented starting. The nice thing about igntion issues is that, usually, you'll either have spark or not. There's precious little in-between and as long as the point open & close, timing should be a virtual non-issue.