Problems with new Top End

OK, here's the situation. I just installed an all new top end, timing is dead on I just re-did that this morning, piston is in correctly with all rings on properly. I can not think of anything that would be wrong but when I kick it over, it's normal the first time plenty of compression but nothing comes out the exhaust, and then the next couple kicks feels like the kick starter is just going down and doesn't feel like the piston is moving or anything.. :thumbsup: I've never even heard of this so I didn't know what to search for sorry if it's been covered before. I just want to get some riding and practice in before the race next friday!

I am looking forward to hearing the outcome of this one.

My first thought is timing out one stroke???

That does sound very strange....

What was done, did you just pull the jug and put a piston in or did you do other stuff too??

I pulled off the cylinder, put a new piston and rings in, cam chain, MCCT and sent my head to MX time, got that back, bolted it all together and it should've started but something is def not right.. I don't know if the piston is actually not moving but thats just what it seemed / sounded like to me.

So you made damn sure you put the cam assy back together correctly and checked your valve clearances and de-comp clearance several times after manually turning the engine over??

You mention a manual cam chain tensioner.....how do you come to the right tension with one of those ?? maybe somethings off with that.

I would at least pull the valve cover and check to make sure the cam tower is installed correctly.

Wow, you don't have a manuel?........Pull the spark plug and insert something like a pencil in there to feel if the piston is moving. I'd be very surprised if it wasn't.....My guess is that your timing is off. And probably your shims. And probably your rings. And probably your torqued bolts. And probably anything else you touched in there. You need a manuel to put your engine back together! Without one, your just wasting your time and money. I hope you didn't mess anything up yet!

Wow, you don't have a manuel?........Pull the spark plug and insert something like a pencil in there to feel if the piston is moving. I'd be very surprised if it wasn't.....My guess is that your timing is off. And probably your shims. And probably your rings. And probably your torqued bolts. And probably anything else you touched in there. You need a manuel to put your engine back together! Without one, your just wasting your time and money. I hope you didn't mess anything up yet!

I agree, unless you some pro wrench or have done it a few times a manual is priceless.

Piston was installed with the word "IN" facing toward the rear of the bike?

Both piston clips were installed?

Timing is not on the wrong stroke? - marking on left and right case holes are lined up, and the cam sprocket marks are level with the head....and the cam lobes are facing toward the REAR of the bike.

Any tape or rags that were used to cover the carb or intake were removed?

Air boot is on properly?

Both sides are oiled?

Spark plug is installed?

Gas is on?

Cam caps were installed properly (with the dowel pins and bearing pins (the little half moon shaped things)?

Nothing fell into the engine on the rebuild?

Cam chain is tightened properly (the bolt is finger tight and the nut is tight)?

Stupid but the exhaust plug is out and the exhaust pipe is installed properly?

Has your cam chain come off the countershaft sprocket ??

Did you hone the cylinder?

Are you sure your kick starter is engaging? If it is then I would measure the compression of your engine with a compression guage. If it's low then pull the plug and add one teaspoon of oil down the cylinder and re-check with the compression guage. If it improves, then your rings are not sealing properly. If it doesn't, then your valves are not working properly.

Sorry guys it's been so long since I wrote i've been staying at my parents and they don't have the internet there...

I didn't do all the work just by myself in the garage guess and testing... I had one of my bro's friends that knows what he's doing watching over me and I had my owners manual too. I'm getting ready to bring it in to the shop and give up... We've checked over everything you guys have listed many times and haven't seen anything out of place or anything, it's rediculous.

Also, why would my kick starter not be engaging when I kick it over but it would when I push it with my hand?

I have no idea why your kickstarter would only engage when you push it over by hand................:thumbsup:

Are you sure your decompressor has been put together properly?

Can you take some pics so we can see it? I'm not understanding you very well. Maybe we could see something not right in a pic.

maybe bump start it and see if it turns over to see if its your kickstart or engine

Sounds like the decompresser for sure. Betcha got it too tight and its letting all the gas out of the cylinder.

Where the hell is the decompresser anyway? I just did the whole top end rebuild and didn't think to check it.

im gonna guess the compression of the new top end is making your old clutch slip when kicking it through. thats maybe why when you push the kick starter down slowly by hand it grabs but when you kick it hard it slips. pull your clutch cover and kick it over seeing if it slips.

carlos752

Where the hell is the decompresser anyway? I just did the whole top end rebuild and didn't think to check it.

There you go, read your shop manual and make sure its assembled and adjusted to specs.

Thats probably the reason you had compression by hand but no compression when you kicked it.

There you go, read your shop manual and make sure its assembled and adjusted to specs.

Thats probably the reason you had compression by hand but no compression when you kicked it.

Wrong person...I got no problems! Moto has the problem.

I'm just a bystander wondering how I got lucky and didn't end up with the same problem. And I did use my manual but never read anything during the installation of the top end about a decompresser. That's why I asked.

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