82 xj 650 startng problem - surpise!

ok will run (rough) with fresh plugs for a few minutes, then no
carbs are clean, bench synched, mix screws set at 2 turns (except #1 stuck), floats set,

trying to get idle to plug YICS and vaccuum sync!

ok wierd part when tryng to start a second time it sputters and trys, then i noticed the pipes on 1&2 are warm but not 3 & 4?

switched 1 & 4 wires same spark at 1 but still weak at 4!? (same coil!)
pluck look black (rich) #1 dry and #4 damp?

:x

petcock was rebuilt,

new battery

(assume valves are done please unless this is REALLY a strong possibiility)
i have been reading tons here for last couple months just not posted, you guys seem to have it covered

no safety circuit stuff

this bike seems light and nimble compared to my honda cb750s really anxious to ride it!

 

have you done a compression test? this is done to establish a viable plant and that oil is not getting past the piston rings.

 

I.B.F. (In Before Fitz)
YES....Valves are THAT important. Unless your valves are in spec you'll never get it to run right. Do the valves.

 

I.B.F. (In Before Fitz)
YES....Valves are THAT important. Unless your valves are in spec you'll never get it to run right. Do the valves.

 

agreed ^. is #4 wet with fuel or oil?

 

valves aside- it ran last summer so we will skip for now. running right vs running at all are 2 very different things...

compression- yes checkd 110-115 across board sorry i meant to include that

#4 fuel wet foul #1 slight dry foul
I just dont get the R vs L side? dont share coil or carb?

thanks fellas

 

Probably not this, but is the enrichment circuit in carb bowl base REALLY clean?
Here is a post that covers it
xjbikes.com/Forums/vie...60246.html

 

Valves NOT "aside" based on what are actually pretty low compression numbers, I'd check the valve clearances.

CHECK. Then when (yes, when not "if") you discover that a majority of them are tight, get them in spec so you can actually adjust the carbs.

You can't just brush aside the critical first step in the process and hope to get anywhere.

 

the good...your bike will run with tight shims. the bad...if the valve clearance is not in spec you will not be able to sync your bike. the ugly...tight shims will blow the engine.

Gary

 

carbs are zestfully clean

 

great!^. now you can get the shims right and air leak test the carbs so you can dial in that beast.

Gary

 

um nevermind....its not the valves, but whatever

 

Dude; you're barely above running numbers on your compression, below about 90 the motor will barely run if at all.

These are "interference" motors, there is a lot of valve "overlap" and a few tight valves can mean the mixture is going in one side and out the other without ever having a chance to burn.

CHECK the valve clearances; then report back. No need to go doing anything radical yet like actually getting them in spec; just check them.

 

Enygma64, there are a handful of people on this board who's opinion I follow no matter what I've done or think I should have done, and one of those people is BigFitz.
You are clearly within your rights to toubleshoot however you feel best and in accordance with your previous experience...but, if you want to save time, save money, and get done correctly the first time...take his advice. Why reinvent the wheel?
Lastly, there are also a handful of people on this board who ask for advise then summarily dismiss it as frivolous for whatever reason...eventually most of those people have final post stating "I'm done with this piece of junk".
Checking and adjusting valves is remarkably simple...just follow the advise given..first time for me it took all afternoon...I'm now on my 4th or 5th go-round and with my 15 year old's help I can check-replace/record-recheck in about 2 hours.
I wish you success!
P

 

I just LOVE when people ask for advice and then don't take it because they don't like the answers that are given. Might as well just go figure it out for yourself and quit wasting everyone's time! Sooner or later you'll (hopefully) realize that the advice given was spot on and finally decide to listen to it.

 

glad you feel sarcasm isnt wasting YOUR time, moose

anyway found that the carb 'expert' who ultrasonically cleaned them switched the air jets around!

synched at 7" with yics isolation rod.
runs great high rpm, cant get idle to settle from 3k though. think its a vaccuum leak...

 

So what were the valve clearances when you checked them?

Dave F

 

It's not the valves, Dave, you heard the man.

Must have been the transposed jets causing the crappy compression numbers; you know how that works.

(IT DOESN'T YOU STILL NEED TO CHECK THE VALVES.)

The "hanging idle" is more likely a function of being out of sync; and you can't GET a truly good vac sync with out-of-spec valves.

But hey, what do I know anyway.

 

Oh, I am 100000% sure it's not the valves....... He made that perfectly clear - I'm just curious to know what the clearances were. It would help me to better understand what size shims I don't need to keep in the shim pool.

Dave

 

if you think giving me grief about my valves is annoying me have at it.

they're all within the tolerances bigpiss posted. i just dont feel all this extra posting is constructive. but if thats all you have to do, have fun.

funny how i post one thing every couple days and a couple people immediately reply... get a life

like a bunch of women eeeew did u here what she said...? lol

bye