White sweet smelling exhaust

I am at a loss. Took the bike out today for its first true road test and i noticed white smoke coming out of the exhaust. At first i chaulked it up to condensation and it burning away, but that didnt happen. It just kept on. The weird part is that it smells a bit sweet. I am about to do another compression test and check the oil.

To run down what i already done is...
New valve shims.
Rebuilt carbs, already balanced and synced.
Compression test last reading was 150+ for all 4, i am about to do a new one.
New gas
Cleaned and checked spark plugs (wire brush)
Checked for oil leaks.

Does anyone have any ideas or advice?

 

What kind of bike? Air cooled or water cooled.

 

82 xj650, its air cooled which is why i am at a loss.

 

Ok, so now i am getting annoyed. #4 and 2 piston is wet... and shows signs if gas on the sparkplug and the compression tool.

The compression is all over the place.
#4 was 95, #3 was 150, #2 was 115, #1 was 110. This doesnt make sense... it was all in the 150 a month ago when i first started it.

 

I guess i should re check the shims.

 

Where does it get parked?

 

Take a deep breath. If you can i would run it a short while ....let it cool down overnight then do a check of the compression with the throttle open then take your reading. You mention you did the valves it is possible you may have to pull the cover and check again. Another thought do you have stabil in the tank or is it fresh fuel?

 

Anyone you don't like that would fill your gas tank with fog machine fluid?

 

Lol the bike has been in a garage while i worked on it for a year. I am checking my valve shims rigbt now and they are all wrong... i might have gotten them mixed up when i put them in.

I am really concerned about the cam. I am noticing spots on the lobes that aren't as shiney as the rest of it. Is that a bad sign or typical? The intake lobe for piston 1 looks a lil over heated, it wasnt like that before. Its not bad. Just a very slight rainbow shimmer. I'll take some pics.

Update:
The rainbow was a trick of the light. There are definitly dull spots tho.

 

If you ran your bike AT ALL. Today, your engine is too warm to check valves accurately. It needs to be overnight Cold.

 

I'll recheck them in the am, right now i have a gap on the exhaust for #2 at .24mm cold or not that too big.

I hate typing on phones... ;p

 

True, to big either way---

But also true, the engine must be be under 90 degrees internal before checking

 

when you replaced the shims did you write down what you had in there and what you replaced them with?

 

I did i have that in my book at home.

 

Talk about major screw up.

1 e: 20mm
1 i: 15mm
2 e: 23mm
2 i: 15
3 e: 19
3 i: 17
4 e: 28
4 i: 15

I am about to pull the shims to get their numbers but this is redic. I dont know what the hell i measures the last time. Checking an old email to chacal i only ordered 2 shims, not sure for which piston.

 

A 20 mm gap is HUGE. What are you measuring with now? Are you just forgetting to type the decimals?

 

I am using mm gauge feelers. The largest is 28. Maybe i was just blind or just stupid when i measured it last time.
I just finisjed checking the shims themselves. The total numbers are below.

1 e: 20mm, y280
1 i: 15mm, y275
2 e: 23mm, 2-70? Shouldnt there be a y?
2 i: 15mm, y280
3 e: 19mm, y265
3 i: 17mm, y285
4 e: 28mm, 2-65
4 i: 15mm, y280

Unless something really messed happened to the cams. I have no excuse and i am a bit embarrassed by these numbers.

 

Yup i just confirmed it. It was my math that screwed me.

I just looked at the valve sizing chart and it has 20 as in spec for exhaust. Should i just replace it with a 285?

Yes .15 .28 etc...

 

Spec is .11mm - .15mm for I and .16mm - .20mm for E.

#1 is in spec.
#2 E is not. Add 275 to put it in spec at .18mm.
#3 I is not. Add 290 to put it in spec at .12mm.
#4 E is not. Add 275 to put it in spec at .18mm.

Shims can be swapped around but don't rotate the cams without a shim in every bucket. Member Hogfiddles runs a shim pool. Start a conversation with him or click the banner in the upper right corner and tell member Chacal (Len) what you need.

Gary H.

 

Thanks man, this is where i am a lil confused and might be how i messed up last time, based on this chart from the airhead and valves thread it shows i need different numbers for example 2e i would need 275. Is this the wrong chart for our bikes?

 

Sybe, those are the correct charts.

1. Your bike has some crazy clearances. I'd recommend checking them one more time, just to verify those numbers.

2. Based one what you typed, though....you only need 3 shims---
275 for 2E, 275 for 4E, 290 for 3I.

I have all of those in the pool right now......

Start a private conversation with me.

Dave f

 

Hi Dave,
I don't know how to do a private message
I see someone out there said you did carb rebuild? I thought from "carb clinic" you were a nutritionist of something, told you I'm not that smart.
Anyway, if my xj is still gathering dust in the garage when I get back from my job, do you do the rebuild still?
thanks

 

Jt, to start a conversation, go to your inbox, up at the top of the page. From there you can click on the 'start conversation' button, put in Hogfiddles, and send Dave a message.

Edit: You can also click on Dave's username, and select the 'start a new conversation' from there.

 

or click on the avatar of the person and select start a conversation

 

I'll send one to you.....

 

Jt, just sent a conversation to you.....

Also no, definitely not a nutritionist--- I'm a music teacher/band director.

Carb(uretor) Clinic is coming up on June 11, 2016

Yes, I offer carburetor rack rebuild services.

 

I checked them 3 times and compared them to the numbers i got on Saturday vs Sunday afternoon. The numbers on Saturday were close to what i got on Sunday. Warm engine vs cold. Thanks for that advice on checking when it was cold. The numbers i got on Saturday are

1E .20/1I .12 | Compression: 115
2E .24/2I .15 | Compression 115
3E .18/3I .15 | Compression 153
4E .24/4I .14 | Compression 95

The compression numbers has me very concerned. After talking to Len i realized i didn't hold the throttle open during the test, so i am hoping that might have affected the numbers. When i did the compression test one thing i wasn't so sure is if i was cranking it too much. I would hit the start button and have it crank till it stopped then did it again. So two what i call start cycles per cylinder. During the first run the number were low on the compression gauge and would stop moving. On the second try it would go higher, on a third try it wouldn't move anymore, so i just kept it at 2. Is that the right thing to do?

 

is it worth the cost to replace all the intake and exhaust valves? i am estimating it to cost close to 1k if i replace everything.

 

You don't replace valves unless they are burnt or bent. Valves can be recut and/ or lapped, but we ain't there just yet. Slow down a bit.

 

just trying to get this bike back on the road asap. i have a kid coming in June and my wife doesn't want me driving 2 hours to jersey to work on the bike. i'll have to wait till the kid is born or by some miracle i find a spot to work on it in Brooklyn.

 

Under "the tree that grows in Brooklyn"

 

They now charge $2000 for a 5x10 space under the tree. Its part of the new De Blasio (our mayor) initiative for the housing crisis.
http://nypost.com/2015/12/29/de-blasio-wants-to-shrink-city-apartments-into-walk-in-closets/

Le sigh, i tend to question why i stay.

 

1E .20/1I .12 | Compression: 115 exhaust , intake good
2E .24/2I .15 | Compression 115 exhaust bad
3E .18/3I .15 | Compression 153 exhaust , intake good
4E .24/4I .14 | Compression 95 exhaust bad
you need to change E1 and E4 with thicker shim. From what you stated eariler for shim size
1 e: , y280 need 285 , 4 e: , 2-65 need 270
thats quite a spread on the compression, did you do a dry test then an oiled test.
spin the motor until pressure stops going up. Keep the battery charged.

 

I edited my post for correction. I was tired. Sorry about that.

Gary H.

 

I know you guys think i am jumping the gun a bit, i am just nervous about the cost and time to do major engine work. Thinking back to all of the issues I had had with the bike, I am starting to think that it is a valve issue. For example: my oil always has a slight smell of gas. Not enough to burn just a ting of gas. I rebuilt and refloated the carbs, new petcock, oil filter and the slight smell is still there. Also the engine noise... The Yamaha squeal as my friends like to call it, seems to be more pronounced on my bike than on others that i hear. Am i just being a nerous nelly or does the sound of my motor frighten you too?

I just want to add that i am going to jersey tonight to change the shims and do a new compression test and a wet test. I'll let everyone know the results.



This video is right after i rebuilt the carbs and checking if everything was in sync

 

sounds like the cam chain is out of adjustment or the guides are worn out.

 

did you do a sync or is that vid of the bench sync?

 

Classic.

 

i always do a bench sync and then make final adjustments with a a sync gauge

I'll see if the chain has any slack when i pop the valve covers off.

 

Not to sound harsh, but "back on road ASAP" is not the right atitude. I know you've put a ton of work in that bike, but it'll be there when you're ready/have the time. Rushing only leads to shortcuts you'll have to fix later.

I've got three young boys, I struggled with the work/kid time/hobby time balance too. They grow fast, don't trade that time for anything. My old boat and bikes are still there.

 

Just listened to your vids, nothing sounds scary there. How does it run? Throttle respond well?

Yes you need throttle open to check compression.

Gas smell in oil? Leave your petcock on prime for a few hours and then check your fuel levels with bike on centerstand.

I think you're overthinking it. If it runs well, numbers check out, ride it! It takes a lot of neglect to require major engine work. The 650 motors are plentiful anyway.

 

It sounds fine to me. Go ride.

 

Not trying to rush fixing it, i am trying to diagnose and cover multiple possibilities at one time. I know its pricey this way and might have parts i wont need but when and if i pull the heads i can jump right in and fix it.

If i have more to do than just change the valve shims, then i wont be working on the bike again for awhile. Wife doesn't want me driving 2 hours to jersey when she is 7 month pregnant. Once my son is born trust me all i am going to want to do is hold him. So coming back in Aug/September just to finish diagnosing and replacing a valve or change a head gasket when i could have done those things today to me is a waste.

I also wanted the bike done before my son was born, this is something i was building for me and him to enjoy and hopefully to pass on to him. I know i'll have 17 - 18 years to tweak and work on it. Personally it meant a lot to me to have it ready before he was born. I know things happen and we adapt to deal, it just sucks.

Thanks for listening, the throttle response prior was great and is good now, a few rough spots that i expect the new shims will fix but all in all the motor responds as it should. The noise does concern me cause i don't hear that sound on other xj bikes. It sounds like compression might be leaking out.

 

my compression as it stands right now is:
1: 155
2: 155
3: 150
4: 175
is 175 too high?

 

should be

650, 750 air-cooled engines:
Minimum: 128 psi
Standard: 156 psi
Maximum: 171 psi
Max. variance between lowest and highest: 14 psi
so your comp is out of spec mostly because of the Max. variance of 14psi

2) If one or all of your cylinders are too HIGH in pressure, it means that:

a) you piston domes (tops) and/or the cylinder head combustion chamber have a significant accumulation of carbon upon them, which should be cleaned via some type of chemical treatment or engine dis-assembly and manual removal methods. Note that higher cylinder pressures caused by such build-up may be "masking" or hiding other problems that might cause LOW cylinder pressures, such as worn rings, etc.

b) your engine has been fitted with aftermarket, high-compression pistons, or has had the cylinder head "shaved".

NOTE: high cylinder pressures are NOT a good thing, as they tend to blow out head gaskets and can cause accelerated piston, piston ring, or bearing wear.

you can use seafoam to clean the piston if it needs it. pour some in and let it soak over night then you can use the vac port to do short blasts of it with moror running
google seafoam to see videos of this in action

Does Seafoam Actually Work in a Car? (with Proof) - YouTube

or
Does Seafoam Actually Work? (with Proof) - YouTube

 

I just redud the compression test 4 times and #4 is 169. Not sure why it was 175.

How much sea foam should i pour into the motor? Fill it to the spark plug hole?

 

No.
Read the instructions on the can.

 

Lol great, so now i have to pump it out... lol i am a dumbass

Update: well i got it out.. turned the crank piston came up and pushed the seafoam out. Then i used a water bottle sprayer to suck up the rest.

 

I hear ya. Good luck, looks like you are making progress.

 

well i just did a leak down test and here are the compression numbers....
#4 = exhaust leak 100/20 psi
#3 = 100/92 psi coming out the oil cap
#2 = 100/94
#1 = 100/95 psi


looks like im pulling the heads. Unless could the 4E shim cause the exhaust leak? Also should i be concerned about #3