Leakdown test?

Ok so I'm trying to figure out why my 2000 buell blast smokes like a train when the engine gets warmed up. I did a compression test and here are the results.

Compression test: 120psi is what the manual states the compression should read when the engine is hot.

Cold compression: Dry: 1st 80psi Last 110psi but needle bounces past 120psi Wet: 1st 85psi Last 115psi but needle bounces to 125psi

Hot compression:
Dry: 1st 100psi Last 115psi bounce to around 140psi Wet: 1st 110psi Last 130psi

I am working on doing the leakdown but am having some trouble figuring out where TDC compression stroke is. There are a couple of marks on the crank but I can't figure which is TDC. There are a couple of round dots that are used for timing, there is another round dot on the crank, and then there is a notch. I tried to line up the leakdown tester to the notch but I guess the engine moved or something because I noticed the air was blowing out the car but the time mark had moved. The leakdown is being performed with the bike in 5th gear and the rear brake locked.

Any suggestion? Thanks folks, I can't wait to get the buell back on the road, it runs very well so I'm thinking something might be amiss in the valves. The bike has various leaks around the head top and bottom gaskets.

Given that you don'T see much increase in the compression 'wet', I'm also leaning towards a head issue...

To find TDC... take the #1 plug out, put your thumb over the hole. The stroke you want is the one that tries to push it out of there. You can use a pencil in the hole to roughly find the top and then mark the crank/block.

OK, from what I read I raised the rear wheel, put the bike in 5th, then turn the rear tire until the TDC mark lines up. Then you plug the leakdown tester in and hook up the air.

If I'm doing it correctly it seems the air is blowing straight out the exhaust meaning the exhaust valve is probably toasted.

I'm going to check to make sure I'm doing it correctly but thanks for the help folks, sure you know how much help I need.

Ok, I set the engine to TDC in 5th gear, and pulled the exhaust to make sure the exhaust valve was closed.

I pressurized the cylinder and looked at the exhaust valve it looks like air is breaching past the exhaust valve at the seat. I sprayed it with lube and watched it bubble through the valve. The bike was cold when tested but I'm pretty sure the problem is the exhaust valve or the valve seat. Hopefully it will be an easy fix.

check the valve lash lately?

I don't think you can adjust the valves so much as the bike uses tappets, but I'm no expert. I was thinking that a leaky tappet, worn rocker?, bent pushrod could give me the same issues with the exhaust valve not seating. Thanks for the hint Dwarf, I will investigate the possibility that something is worn elsewhere or out of spec.

The problem is where is the smoke coming from? Just because the exhaust valve isn't seating perfectly doesn't explain where the oil is coming from. I bet either a valve guide or seal is letting oil in because there isn't any lubication on the valve seat to smoke.

tight lash = hot valve = hot stem (face can't tranfer heat to seat) = fat valve stem = worn guide = toasted valve seal = oil past guide = smoke.

Been a while since i looked in to a stock blast head...can you hook the valve with a bent coat hanger? if so try to see if when its off the seat if you can easly move it before you pull the head. Be gental don't bend the valve but see if theres movement.

44

I pulled the exhaust back so I can look at the exhaust valve.

I just tried moving the valve when it is off the seat and it doesn't move any, but I did notice that when the exhaust valve is open that I can see oil on valve stem. I think the guide/guide seals are probably shot. I should also order a exhaust valve but maybe it is still good and just the seat/seal might be bad.

I just went to harley and ordered up a bunch of parts so hopefully the bike with be easy to put back together once I get the good stuff.

Thank for the help, I need all I can get.

roll the engine back a few deg then feed Cotton rope in the plug hole and roll back to tdc this will hold the valve if you have the proper on engine spring compressor. Try just doing the seal 1st. unless its cold where you live then pull the head and have it done.

I need to put new gaskets on the bottom cylinder so I'll end up pulling the head to inspect everything.

Thanks again for the help 44Dwarf, I really don't know what I'm doing but the buell seems very easy to work on. The whole question is how far do I go on the rebuild. I figure if I'm in there I might as well do the piston rings and check the cylinder for scoring. I did get good compression so if the piston and bore looks good I'm going to rering the piston, have the valve seat redone on the exhaust valve and slap it back together.

Thanks again and wish me luck!

If the cylinder isn't scored or doesn't have a lip, I would do a valve job and call it good.

I've gotten most of the BS off the bike and am getting ready to pull apart the engine. This bike is very easy to work on. The only thing I have to do to undo the wiring harness from the front frame and undo the rear motor mount and I think the whole front end will roll away, easy walker style.

When I pulled the carb off I took a look at the intake valve. Aside from some discoloration it looks like it is in great shape. Almost brand new compared to the exhaust valve. Judging by the amount of carbon buildup and the visible oil on the valve stem I think the exhaust valve is the likely culprit. The bike might have other problems also so I'm not concluding anything until I open the beast up.

I also washed the bike thoroughly for the 1st time in my illustrious 5 year ownership so it will be cleaner to work on. Who knew their was a bike under all that grease and grime?

Another part of the repair process for the punky buellster is a front fork relube and reseal. I was able to take the two spare forks I have apart and drained. There isn't much to a fork, I think maybe 15 parts each. The hardest part of redoing the fork seems to be removing the spring seat retaining clip. You have to push the top of the fork down and pull the retaining clip out, which allows the spring stop to be removed. The first stop came out at a slow velocity and went across the room.

I'll post some pics when I get back next week, but thanks for the help folks!

OK here are some pictures of the piston and bore. There is wear and pitting in the area around the top lip of the piston. I don't know how big of an issue this is or if the piston is reusable.

The bore looks good without any large gauges but it still might be worn out.

Here are some pics let me know what you think of the piston condition.

pitting is from detonation from E36 M3 gas to much timming or oil contamination it to the cyl from leaky intake guide or worn rings etc. But it a lunky big single...Buff the top best as possible and toss it back in if it were mine. I can see all the rings still move in the groves so it should be fine.

Thank you for the info, today I am going to make a valve spring compressor and pull the head apart as I think that is where the problem is in the engine. The exhaust side has much carbon on it so I'll see what happens and post more pictures of what I find.

If you have a glass bead cabinet wrap the piston skirt in electrical tape then blast the top. Next slap on a buffing wheel on the bench grinder and buff the top to a nice shinny shine it will help keep the carbon build up down. You can blast the head to but be careful of the rocker area and make dam sure you clean it better then you clean your privates.

Ok I just pulled the valves out of the head. The exhaust valve stem seal was gone, a piece was actually stuck to the valve near the top of the stem. The valves and seats don't look too bad but I think I'll go talk to the machinist. Maybe a three angle would make everything seat better.

I'll post some more pics later.

IIRC the older Harley heads always benefitted from at least a cleanup, don't know if that's still the case for more modern ones but it might be worth spending a couple of bucks on it.

If you don't have the shop assemble the head try to use a drinking straw on the valve when installing the seals that way the lip on the seal don't hang on the keeper groove. Trick it to find right diameter straw for such small dia stems...

The seal was stuck in the keeper grove of the valve, you nailed it 44Dwarf.

I just found a small crack between the exhaust valve seat and the spark plug hole. The crack is small but goes up three threads of the plug hole so I don't know if it is repairable. I guess I'll have to go talk to the machine shop and see if the head is repairable.

Any good machine shop that deals with diesel engines will be able to peen weld and re-peen it to make it better than new.

Ok I went to the local machine shop and the guy actually specializes in building harley engines. I showed him what I have and he said I need an oversize piston and to have the cylinder bored out. I just ordered the parts to go .010" over. I guess the crack isn't serious, the machinist said not to worry about it.

Looks like in a week or two I'll be back in business. Thanks for all the help.