Weak Midrange RPMs. Loss of "Pull".....goes flat...

[Scrambled]

At least now you can stop messing with your carbs . Four strokes - intake - COMPRESSION- ignition - exhaust . I wonder how many other guys on here have been attacking their carbs without doing a compression test first ? Seems like almost every problem gets blamed on the carbs . My own recent problems were ignition , but I had four different shade tree mechanics that wanted to start messing with my jets .

It would be nice if all you needed at this point is to clean up your valves . Look on the bright side ,at least you know your way around your carbs now !

 

[EvenmoreXS]

At least now you can stop messing with your carbs . Four strokes - intake - COMPRESSION- ignition - exhaust . I wonder how many other guys on here have been attacking their carbs without doing a compression test first ? Seems like almost every problem gets blamed on the carbs . My own recent problems were ignition , but I had four different shade tree mechanics that wanted to start messing with my jets .

It would be nice if all you needed at this point is to clean up your valves . Look on the bright side ,at least you know your way around your carbs now !

Yep . I am glad to have an intimate knowledge of MY carbs. Just like my bike. As long as I dont hurt anything Im just learning. Cant do it right the first time everytime. I can guarantee that cleaning my valves is going to have a positive effect on my compression. How positive??? Thats the question.

I do know to do a compression test early now. I will be buying a compresion tester....I rented this one from Orileys. Their tool rental program is pretty helpful Harborfreight leakdown tester, mainly for a controlable air flow and a PSI guage. Its not the greatest tool, but It worked fine for my purpose. Returning both when done.

 

[EvenmoreXS]

Video of timing marks :

Its a little dark. Sorry.

 

[5twins]

Now you'll want to test the valves for leaks. With the way air was hissing out the exhausts during your leak down test, they should be quite evident. After lapping and re-assembly, you'll need to test again to make sure you've fixed the leaks.

 

[EvenmoreXS]

Now you'll want to test the valves for leaks. With the way air was hissing out the exhausts during your leak down test, they should be quite evident. After lapping and re-assembly, you'll need to test again to make sure you've fixed the leaks.

10-4 good buddy

Bought my lapping compound yesterday, and my lapping stick. Oriley's says they cant get me the Flex hone....says they have another comparable "Professional" tool thats 110.00 bucks. They say they are going to give me price match on the 32.00 flex hone from advance auto. Thats pretty good customer service I guess. I will know for sure after lunch, but they say they are going to order it, have it in today, sell it to me for 32.00. I like the People at my local oriley's. Clean stores, knowleable staff, and they have taken good care of me as a customer.

Should I test for leaks with gas, kerosene, water, gatoraid, urine, unicorn saliva, zombie blood.....?

 

[weekendrider]

Put the valves back on/in turn the head over and fill the bowl with gas.

 

[EvenmoreXS]

Thanks

 

[5twins]

I use kerosene and compressed air. Like WER said, turn the head over and set it combustion chamber up, level on your bench. Install an old spark plug and fill the combustion chambers with solvent so the valve faces are covered. Blow compressed air in the exhaust and intake ports and watch for streams of air bubbles emanating from around the edges of the valves where they seat to the head. You will need to work the air gun in/out to find just the right spot and also partially block the port opening around the blow gun with your hand to contain some of the pressure. Too close to the valve with the air gun and you will literally blow it open, and it will appear to be leaking like crazy.

 

[EvenmoreXS]

I use kerosene and compressed air. Like WER said, turn the head over and set it combustion chamber up, level on your bench. Install an old spark plug and fill the combustion chambers with solvent so the valve faces are covered. Blow compressed air in the exhaust and intake ports and watch for streams of air bubbles emanating from around the edges of the valves where they seat to the head. You will need to work the air gun in/out to find just the right spot and also partially block the port opening around the blow gun with your hand to contain some of the pressure. Too close to the valve with the air gun and you will literally blow it open, and it will appear to be leaking like crazy.

Springs in place and everything back in ?....or with JUST the valves SITTING in the guides?

Everything else is pretty clear.


Thanks Everyone

 

[5twins]

You do this with the valves all assembled. They won't seal at all if they're not assembled with the springs. You test 1st before you take them apart, then again after putting them back together. If they still leak, they have to come apart for more lapping.

You should use both coarse and fine lapping compounds. Coarse first to remove all the pits and fine last for a nice final finish. If you just use fine, it will take a long, long time and lots and lots of lapping.

 

[EvenmoreXS]

You do this with the valves all assembled. They won't seal at all if they're not assembled with the springs. You test 1st before you take them apart, then again after putting them back together. If they still leak, they have to come apart for more lapping.

You should use both coarse and fine lapping compounds. Coarse first to remove all the pits and fine last for a nice final finish. If you just use fine, it will take a long, long time and lots and lots of lapping.

10-4. Will test tonight before I pull them apart....assuming I have time to do this after band practice . Then I will try to make a spring compressor to get em apart.

I know they leak, but I will get a point of reference to see how much better it is after lapping.

I have both compounds.

 

[5twins]

It shouldn't leak at all after you're done.

 

[EvenmoreXS]

It shouldn't leak at all after you're done.

Im gonna hold you to that

I expect a noticable difference in overall performance when done.


Oh yea, it did appear that the head gasket was letting a small amount of oil into the cylinder causing my small amount of smoke when revving. I will be sure to do the gasket goo around the oil supply shafts and the cam chain tunnel this time. Base was good.

I still plan to go without the base gasket. I got the whole kit so I have it if i need. Any Nay Sayers on leaving the base gasket out.?

Obviously I will be able eat a full meal on my surfaces after cleaning them before applying goo.

Obvioulsly.

 

[5twins]

Get a little can of lacquer thinner for final cleaning and wipe-down of the gasket surfaces. It dries near instantly and leaves no residue behind. Then, don't even touch them with your fingers.

 

[EvenmoreXS]

Get a little can of lacquer thinner for final cleaning and wipe-down of the gasket surfaces. It dries near instantly and leaves no residue behind. Then, don't even touch them with your fingers.

I've used Acetone in the past. It dries super fast too. I'll get a bottle of lacquer thinner also for the garage.

 

[EvenmoreXS]

Hey, whats a good blast media for cleaning up the valves.

Harbor Freight Media Please. Most convenient for me.

http://www.harborfreight.com/21-oz-hopper-gravity-feed-spot-blaster-gun-95793.html

 

[5twins]

You can use baking soda to blast the combustion chambers and ports clean, pistons too. Or you can use paint stripper to remove the carbon. Or a combination, paint strip most of the carbon off, soda blast what remains. Soda blasting is excellent for cleaning the piston ring grooves. The valves are hardened steel so you can just wire wheel them clean once you have them out.

Cut strips of rags, oil them, and thread them through the guides before you start your cleaning.

 

[EvenmoreXS]

You can use baking soda to blast the combustion chambers and ports clean, pistons too. Or you can use paint stripper to remove the carbon. Or a combination, paint strip most of the carbon off, soda blast what remains. Soda blasting is excellent for cleaning the piston ring grooves. The valves are hardened steel so you can just wire wheel them clean once you have them out.

Cut strips of rags, oil them, and thread them through the guides before you start your cleaning.

Will blasting the valves work fine too. Dont have a bench grinder, just a hand drill and wire brush. Seems a bit harsh.

Thanks

 

[5twins]

Maybe, maybe not. The carbon gets baked on the valves pretty hard because they get so hot, especially the exhausts. I use the knotted style wire wheel (very aggressive) in a 4 1/2" grinder.

 

[EvenmoreXS]

Maybe, maybe not. The carbon gets baked on the valves pretty hard because they get so hot, especially the exhausts. I use the knotted style wire wheel (very aggressive) in a 4 1/2" grinder.

Wow. Tough little bastards.