Cam shaft Alighment 82 XJ 750J Maxiun

Posted: Tue Mar 05, 2013 6:55 am Post subject: Cam shaft Alighment 82 XJ 750 Maxiun J
Just recently removed valve section of motor,marking and loosening bolts in sequence as I went. Following manual(Haynes)... I marked Cam shaft sprocket to cam, on both intake and exhaust. BUT ! I did not make an alighnment mark from cam to cyld, head. Hopefully this can be rectified. before I go any further.
Reason for dissmantle was oil leaks between heads in front and bottom sump.


Thanks
bobcat

 

bobcat,

The camshafts should be marked I and E. There is a indent in the top of the camshafts that will align with a arrow on the camshaft cap (second lobe from left) which will be used to reset your timing). The indents will be slightly off when you first put everything back together. The sprockets will re-locate in one direction and on one side of the camshafts to allow for the chain. There are only two threaded holes in the sprockets. Top to bottom: Valve Cover, Cylinder Head, Block or Jugs, Crankcase. Are you saying your bike has a head to block gasket leak or a block to crankcase gasket leak? Are you sure the valve cover gasket isn't leaking?

Gary

 

You'll also find a Hex Positioning Flats on the Cam, ... to Wrench the Cam against Valve Spring resistance when reattaching the Cam Chain.

It's good too have an assistant manning the wrench because it takes two hands to maneuver the Sprockets and Chain to align with the timing mark on the Cams to the arrows on the Cam Cover Bridge.
Remove and reset the Cam Chain Tensioner to pull the Slack up from the front of the Block when setting the Timing..

 

Thanks Rick,
It may sound like i've gone overboard when it could have been just a head gasket leak. There was signs of oil near the head to block mating surfaces, and gear shifter o-ring opening as well as bottom pan. This was a good time remove engine and give a through look.Its well worth purchasing a complete engine gasket kit. Ive already performed a valve bucket shim check. Wish me luck, I may have to chime in again if i get stuck.
Bobcat

 

I meant to say Valve cover leak !!

 

so i assume all this information will correlate with an 82 seca 750. And if the cam indentations line up wth the arrow on the caps, where does the #1 piston need to be in order to time it.At the bottom of the intake stroke or the top of the exhaust stroke?

 

Top Dead Center.

THAT HAS to be the Starting Point.
••••••••

© Yamaha Motors Co.

The Crank NEEDS to be positioned with the #1 Piston at TDC.
Before you do anything else, ... the #1 Piston is Tops.

 

So do i have remove the cam sprockets even if they are currently attached to the shaft? what are the ex3 in3

 

Yes.

You have to carefully align the Timing Marks.
Position the Cam to align with the Upper Timing Arrows.
Remove the Slack.
Then, ... position the Sprockets on the held-tight chain to line-up correctly to be reattached to the Cams.

It is vitally important to have ALL Timing Marks lined-up ---> Perfectly.

Once you have the Engine "Timed" ... you then, ... Turn-over the Engine through two (2) complete revolutions ... s-l-o-w-l-y ... by hand ... the Crank back to TDC.

Then, ... you L@@K at ALL the Timing Marks.
If they are not ALL perfectly on their marks, ... do it over from scratch.

 

okay sounds like a a jon and a half. O well jsut like every other task on this seca. But it is a pain in the neck to crank my motor. even with the plugs out i gotta wak the crankshaft with a rubber mallet to get it to turn over

 

STOP ...
Your last comment is frightening.
With the Plugs OUT you shouldn't need to hammer anything to move theh Crank.

Put-out an A-P-B for someone near you who has a WorkShop Manual that could come to your assistance.

 

well i assumed it was just hard to turn cuz the valves and cam chain. I am sure conecting rods bearings are in corectly and torqued to 18.1 ftlbs then i thought that was to much so i brought them down to 15 or so. there should be no problems.

 

Your NEXT move should be getting a Genuine Yamaha Workshop Manual to guide you through repairs and maintenance.

I have never needed to use a mallet to manually move the Crank.

 

Agreed, you need to down tools until you have a manual & then diagnose what's causing your crank to bind up that tight.

Did you make sure the bearings were snapped into place & lubed on reassembly, and at what stage did the crank go tight? (it's good practise when reassembling a bottom end to spin it over each time you fit a bearing to ensure it stays free, then you know exactly what's tight if this situation occurs)

 

Here's the Manual you need that is both Comprehensive and Specific to your bike.

You wont have to order a Owners Manual, ... it comes WITH the Service Manual.

1982 XJ750J -- Genuine Factory Service Manual -- LIT-11616-XJ-71 ©

http://www.yamahapubs.com/index.do

 

Yea, while i was in the shower last night, i was thinking that it was prolly the conecting cap. I had someone helping me reasemble the crank and we had two sets of hands putting the caps on. And sure enough he put the#1 cap on reversed. So i fixed it and now i got the cams in and hopefully timed correctly. All i got is to put everything else back together. Oh and i have orderd a factory repair manual cost me 80 smackers and that was a weak ago and since its comy from the uk it still prolly hasn't even passed through customs yet.

 

Have you replaced the bearing? Chances are it'll have some damage from being forced to turn while tight, worth double checking the crank isn't marked or picked up any material off it too. would hate you to get it back together & fire it up only to hear a knock :?

 

yea i l.ooked it looked preety normal it had a ton of high temp bearing grease.

 

Wait a minute, you've assembled the plain bearings with HMP grease?

You should only use either clean fresh engine oil or specific assembly lubes for plain bearings... You really need to whoa up & research a bit rather than forging ahead if you're unsure of techniques or practices. A lot will be covered in the manual but anything else you're not sure of don't be scared to ask, nobody's gonna ridicule anyone for asking & it's better than having to do a major rebuild twice...

 

+100 that grease will not wash out cleanly; it'll turn into a lumpy mess and could (more likely will) end up blocking the oil passages, which will cause the shaft to wear very soon after startup. You only would use high temp grease on roller bearings that aren't fed by oil (such as wheel bearings). Any bearing, plain or roller, that is lubricated with engine oil should be coated with assembly lube (my preference) or clean oil for assembly.

 

same stuff i used white lithium greases

 

If you have a Crankshaft that is binding on you, ... knowing you are within Specs would have been a good thing to check.

PlastiGuage the Bearing to Journal tolerances.
Easy to do.

http://www.plastigaugeusa.com/

 

That will be OK then (not ideal, but OK). You stated that you used high temp bearing grease, which is entirely different in how it behaves. Be sure to let the engine warm up fully before letting it go any higher than a fast idle so the grease has a chance to be flushed clear of the bearings. Don't let the engine sit very long either. That grease will dry out in short order.