3TJ Engine Transplant

[Motorcycle Solutions]

I put a 3tj1 rr which was a g plate onto my sp and it did not work properley so i put the original on and it worked fine, but after racing at cadwell i feel that my valve clearences need to be done, or the timing is out.


I am only give a comment on what i have found to work, for no 3tj engine is the same... parts wise yes but they all have been either ridden hard or soflety and worn down different.

[nry]

Yep I had a swap around of 4 cdis, no probs. maybe you've got a dicky cdi ?
Neil.

[oollit]

Thats me back from sea so i will get a chance to work on the TJ tomorrow with a bit of luck.

I will be swopping over the flywheels, checking the pick up sensor on the flywheel cover and then getting the compression checked.

It might be worth trying a RRSP cdi as the ignition timing might be different, but i would have thought any cdi would get the bike running as the ignition maps should be very similar between all the models.

[oollit]

I have found a bit of time to work on the TJ. I checked everything that has been suggested on this thread, but drawn a blank.

I eventually tracked down a 10mm adaptor for my compression tester, did a compression test and found that the engine has very little compression. 3 bar being the HIGHEST reading that i got. The workshop manual states 10.69 bar so i guess there is a fairly serious problem with this motor too.


Looks like i will have to pull the engine out of the bike and strip it down to find out if it has bent valves, blown head gasket or fried piston rings. Either way it is not going to be any cheaper to fix than my original motor. I will probably build the good top end off my original motor onto the bottom end of the 2nd hand motor and hope for the best, as this will be the cheaper and quicker option for getting the bike running again.

So it looks as if i am back to square one again , bikeless , the summer is flying past and i am stuck in my cage.

Does anyone know where i can get a cylinder head gasket and a cylinder base gasket without having to buy a complete gasket kit as i am in the middle of setting up my own business and money is a bit tight at the moment and i can't justify spending £100 for the kit.
I'll try Fowlers in the morning to see if they sell them seperately but Yamaha prices will probably be high enough to make it more viable to buy the full kit.

[Evilchicken0]

You say there's little compression on all cylinders.
It would make more sense that it's something with the valve clearances or cam timing. That could mean none of the exhaust valves are sealing so the compression is leaking past. So check this before you tear down the engine - I have a habbit of thinking well I've done it right so it's ok ... and then finding some stupid small mistake, like putting the idle and main jets in the wrong holes ... so go over it expecting something's wrong and check it by the book
Have you done a wet compression test - that will at least test the piston rings.

Seperate gaskets are available from Fowlers I bought them for the 3en2 project

[oollit]

I didn't even bother doing a wet test as the readings i got were so low.

No1 cylinder is 2 bar.
No2 cylinder is 0 bar.
No3 cylinder is 0 bar.
No4 cylinder is 3 bar.

The valve clearences seem ok so i don't think there is a problem there.
I have tried advancing and retarding the cam timing 1 tooth and the bike wouldn't run at all so i am sure the cam timing is correct. My brother has even had a go when i was at sea and he also thinks that the cam timing is correct. He has been telling me from the start that the compression was low as thought it was turning over too fast on the start button and poping from the exhaust and i have to admit it does turn over a lot quicker than my old engine did.

It is a easy enough job to drop the engine so i might as well do that as it will be easier to get to the top-end and see whats going on. I have spend well over 40 hours trying to get this engine running so i am pretty sure i have covered every angle at least twice.

The previous owner removed the cams and cam buckets to remove oil from the head before posting the engine so i will have to check that he put it all back together correctly before i strip the head off to check for bent valves/blown head gasket. If nothing is found on the head i will have to look at the rings/bores.

[Evilchicken0]

If you do a wet test and get higer comp then the bores / rings are worn as the oil in the cyliders forms a better seal than just the rings. If it's still low then it's the valves.
If the cams have been of then they may not have been retorqued causing them to be "high" on the valves .... either way from what you say I'd suspect the valve clearances.
If it was the head gasket then I'd expect two of the readings to be low ... maybe

[Dobbie]

Hello Oolitt,
I'm sorry to hear your bikes still not up and running. Does it sound right to you, that it was stripped to remove oil before sending it? Sounds a bit overboard. Surely it could have just been flushed and drained in some way.
Anyway I can't remeber where I found this little article about compression testing (mgb's I think) but I thought i'd copy and paste it for you. I found it quite interesting, It wasn't discussing a bike engine but there are some good points that may help you.Especially the bit where they use compressed air to diagnose things 100% accurately.

After a compression test if cylinders #2 & #3 are ok but there is too much difference between #1,4 and the other two. Be careful that you don't condemn an engine unless the compression test was done with the throttle wide open and many revolutions were run on each cylinder. In a shop we would not condemn an engine on just these readings. It just means you need to do further tests to be sure. We would run the same test a second time and if the results were close to the same we would remove the valve cover and reset the valve clearance. If any clearance was found to be tight we would run the compression test a third time. This time we would do a "Dry" and a "Wet" test. (A wet test is done by putting about 4 or 5 squirts of engine oil in the plug hole just after you do the standard dry test and do another compression test right away) You will see an increase in the pressure but it should not be more than 10% to 15% higher. For example, if the "110" cyl. goes up to "165" on a Wet test it is MOST LIKELY a ring problem. If it only went up to 115 or 120 it is MOST LIKELY a valve problem.
After the wet and dry test and we would do another test and this one is only done when all the compression tests show there is a problem. You need compressed air to do this test but it is a final and very exact test. Meaning this test results no longer is MOST LIKELY but it is 100% SURE.
You also need a fitting (available from pro tool trucks and some auto parts stores) The fitting adapts an air hose to a spark plug threads.
The method of testing is to put #1 piston as close to TDC (on the compression stroke) as you can. (timing mark)Pull all the plugs and screw in the fitting into #1 hole. Put the car in 4th gear and pull the hand brake up hard. Then apply the air hose to the fitting. Now, open the throttle and listen in the air filter intake. If you hear even the slightest hiss, the intake valve is bad. Go to the tail pipe and listen up close and if you hear even the slightest hiss, the exhaust valve is bad. Open the radiator cap and watch for bubbles or a raise in fluid level. If anything is noted, you have a leaking head gasket or a crack in the head. This test will pick up even the slightest gasket leak even before it is noted as an overheating problem.
We would open the oil filler cap and listen but here you will hear hissing. ALL engines hiss here, we learned by doing this test on known good engines and known bad ring engines to be able to tell how much hiss is acceptable. This part is not necessary as the wet test is sufficient to test rings.
Keep in mind that a ring leakage after an engine rebuild where they used the same pistons and only put in new rings can be noted if the rebuilder did not deglaze the cylinders and the rings have not seated. (They will seat within about 500 mi of normal driving) However, the 110 and 115 reading would be considered too low to blame on normal ring leakage so if the readings are correct you have something wrong. Do all of the tests and don't skip any.

[oollit]

I have borrowed a professional quality compression test kit from a friend which will allow me to do a "leakage" test to see where the all the combustion gases are escaping from and i have also got my hands on a dial kit so i can find out exactly when the valves are fully open and TDC, so i can eliminate the valve timing element. I will do the full tests as described in Dobbie's post, as that is the method we used at the garage i used to work at and it will definetely rule out or confirm several possible problems.

I did raise an eyebrow when i was told by the previous owner that the cams/valve gear had been removed to drain oil from the engine before dispatch. A few bits of cloth placed under the cam cover would have easily soaked up any remaining oil in the top-end, but i just assumed that the guy wouldn't have ripped the engine apart unless he knew how to put it back together again. I certainly would have objected to this procedure taking place if i had known it was going to happen.

But thats a story for another day. I will have try and find a moment to have another poke around the TJ but there always seems to be something else that has to be done. I have been invited to a housewarming barbecue/piss up on Saturday so i will be 3 sheets to the wind by dinner time with a bit of luck. Hopefully i won't have too much of a hangover on Sunday and i can get a few hours in on the bike.
I need a good blow out as i have had a stressful couple of months setting up my own business. This will be my first full week working for myself and everything seems to have gone alright and i have actually made some money. Long may it continue. :D

[Dobbie]

Well good luck with the business oolitt, If it all goes amazingly well will you be giving your Tj a burial at sea?